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authorroberto <roberto@FreeBSD.org>2004-07-20 15:01:56 +0000
committerroberto <roberto@FreeBSD.org>2004-07-20 15:01:56 +0000
commit929f0d3746a58193ac8dc035aa48576f9aa9a123 (patch)
treeea5508aff2ac8212297e62f289a4c1a0837085cd /contrib/ntp/ntpd/refclock_wwv.c
parent48b85c3e6e03456dfe99bf9415411c0d4030c1b4 (diff)
parent118e757284cbb8fc4f43a713e892b41504b50a5f (diff)
downloadFreeBSD-src-929f0d3746a58193ac8dc035aa48576f9aa9a123.zip
FreeBSD-src-929f0d3746a58193ac8dc035aa48576f9aa9a123.tar.gz
This commit was generated by cvs2svn to compensate for changes in r132451,
which included commits to RCS files with non-trunk default branches.
Diffstat (limited to 'contrib/ntp/ntpd/refclock_wwv.c')
-rw-r--r--contrib/ntp/ntpd/refclock_wwv.c2143
1 files changed, 1122 insertions, 1021 deletions
diff --git a/contrib/ntp/ntpd/refclock_wwv.c b/contrib/ntp/ntpd/refclock_wwv.c
index b1d05c7..11aae7f 100644
--- a/contrib/ntp/ntpd/refclock_wwv.c
+++ b/contrib/ntp/ntpd/refclock_wwv.c
@@ -21,7 +21,7 @@
# include <sys/ioctl.h>
#endif /* HAVE_SYS_IOCTL_H */
-#define ICOM 1 /* undefine to suppress ICOM code */
+#define ICOM 1
#ifdef ICOM
#include "icom.h"
@@ -32,7 +32,7 @@
*
* This driver synchronizes the computer time using data encoded in
* radio transmissions from NIST time/frequency stations WWV in Boulder,
- * CO, and WWVH in Kauai, HI. Transmikssions are made continuously on
+ * CO, and WWVH in Kauai, HI. Transmissions are made continuously on
* 2.5, 5, 10, 15 and 20 MHz in AM mode. An ordinary shortwave receiver
* can be tuned manually to one of these frequencies or, in the case of
* ICOM receivers, the receiver can be tuned automatically using this
@@ -40,16 +40,16 @@
* night.
*
* The driver receives, demodulates and decodes the radio signals when
- * connected to the audio codec of a Sun workstation running SunOS or
- * Solaris, and with a little help, other workstations with similar
- * codecs or sound cards. In this implementation, only one audio driver
- * and codec can be supported on a single machine.
+ * connected to the audio codec of a workstation running Solaris, SunOS
+ * FreeBSD or Linux, and with a little help, other workstations with
+ * similar codecs or sound cards. In this implementation, only one audio
+ * driver and codec can be supported on a single machine.
*
* The demodulation and decoding algorithms used in this driver are
* based on those developed for the TAPR DSP93 development board and the
* TI 320C25 digital signal processor described in: Mills, D.L. A
* precision radio clock for WWV transmissions. Electrical Engineering
- * Report 97-8-1, University of Delaware, August 1997, 25 pp. Available
+ * Report 97-8-1, University of Delaware, August 1997, 25 pp., available
* from www.eecis.udel.edu/~mills/reports.htm. The algorithms described
* in this report have been modified somewhat to improve performance
* under weak signal conditions and to provide an automatic station
@@ -64,66 +64,69 @@
* Interface definitions
*/
#define DEVICE_AUDIO "/dev/audio" /* audio device name */
+#define AUDIO_BUFSIZ 320 /* audio buffer size (50 ms) */
#define PRECISION (-10) /* precision assumed (about 1 ms) */
-#define REFID "NONE" /* reference ID */
#define DESCRIPTION "WWV/H Audio Demodulator/Decoder" /* WRU */
#define SECOND 8000 /* second epoch (sample rate) (Hz) */
#define MINUTE (SECOND * 60) /* minute epoch */
#define OFFSET 128 /* companded sample offset */
#define SIZE 256 /* decompanding table size */
-#define MAXSIG 6000. /* maximum signal level reference */
+#define MAXSIG 6000. /* max signal level reference */
+#define MAXCLP 100 /* max clips above reference per s */
#define MAXSNR 30. /* max SNR reference */
#define DGAIN 20. /* data channel gain reference */
#define SGAIN 10. /* sync channel gain reference */
-#define MAXFREQ (125e-6 * SECOND) /* freq tolerance (.0125%) */
+#define MAXFREQ 1. /* max frequency tolerance (125 PPM) */
#define PI 3.1415926535 /* the real thing */
#define DATSIZ (170 * MS) /* data matched filter size */
#define SYNSIZ (800 * MS) /* minute sync matched filter size */
-#define UTCYEAR 72 /* the first UTC year */
#define MAXERR 30 /* max data bit errors in minute */
-#define NCHAN 5 /* number of channels */
-
-/*
- * Macroni
- */
-#define MOD(x, y) ((x) < 0 ? -(-(x) % (y)) : (x) % (y))
+#define NCHAN 5 /* number of radio channels */
+#define AUDIO_PHI 5e-6 /* dispersion growth factor */
+#ifdef IRIG_SUCKS
+#define WIGGLE 11 /* wiggle filter length */
+#endif /* IRIG_SUCKS */
/*
* General purpose status bits (status)
*
- * Notes: SELV and/or SELH are set when the minute sync pulse from
- * either or both WWV and/or WWVH stations has been heard. MSYNC is set
- * when the minute sync pulse has been acquired and never reset. SSYNC
- * is set when the second sync pulse has been acquired and cleared by
- * watchdog or signal loss. DSYNC is set when the minutes unit digit has
- * reached the threshold and INSYNC is set when if all nine digits have
- * reached the threshold and never cleared.
+ * SELV and/or SELH are set when WWV or WWVH has been heard and cleared
+ * on signal loss. SSYNC is set when the second sync pulse has been
+ * acquired and cleared by signal loss. MSYNC is set when the minute
+ * sync pulse has been acquired. DSYNC is set when a digit reaches the
+ * threshold and INSYNC is set when all nine digits have reached the
+ * threshold. The MSYNC, DSYNC and INSYNC bits are cleared only by
+ * timeout, upon which the driver starts over from scratch.
*
- * DGATE is set if a data bit is invalid, BGATE is set if a BCD digit
+ * DGATE is set if a data bit is invalid and BGATE is set if a BCD digit
* bit is invalid. SFLAG is set when during seconds 59, 0 and 1 while
- * probing for alternate frequencies. LEPSEC is set when the SECWAR of
- * the timecode is set on the last second of 30 June or 31 December. At
- * the end of this minute both the receiver and transmitter insert
- * second 60 in the minute and the minute sync slips a second.
+ * probing alternate frequencies. LEPDAY is set when SECWAR of the
+ * timecode is set on 30 June or 31 December. LEPSEC is set during the
+ * last minute of the day when LEPDAY is set. At the end of this minute
+ * the driver inserts second 60 in the seconds state machine and the
+ * minute sync slips a second. The SLOSS and SJITR bits are for monitor
+ * only.
*/
#define MSYNC 0x0001 /* minute epoch sync */
#define SSYNC 0x0002 /* second epoch sync */
#define DSYNC 0x0004 /* minute units sync */
#define INSYNC 0x0008 /* clock synchronized */
-#define DGATE 0x0010 /* data bit error */
-#define BGATE 0x0020 /* BCD digit bit error */
+#define FGATE 0x0010 /* frequency gate */
+#define DGATE 0x0020 /* data bit error */
+#define BGATE 0x0040 /* BCD digit bit error */
#define SFLAG 0x1000 /* probe flag */
-#define LEPSEC 0x2000 /* leap second in progress */
+#define LEPDAY 0x2000 /* leap second day */
+#define LEPSEC 0x4000 /* leap second minute */
/*
- * Station scoreboard bits (select)
+ * Station scoreboard bits
*
* These are used to establish the signal quality for each of the five
* frequencies and two stations.
*/
-#define JITRNG 0x0001 /* jitter above threshold */
-#define SYNCNG 0x0002 /* sync below threshold or SNR */
-#define DATANG 0x0004 /* data below threshold or SNR */
+#define SYNCNG 0x0001 /* sync or SNR below threshold */
+#define DATANG 0x0002 /* data or SNR below threshold */
+#define ERRRNG 0x0004 /* data error */
#define SELV 0x0100 /* WWV station select */
#define SELH 0x0200 /* WWVH station select */
@@ -131,75 +134,72 @@
* Alarm status bits (alarm)
*
* These bits indicate various alarm conditions, which are decoded to
- * form the quality character included in the timecode. There are four
- * four-bit nibble fields in the word, each corresponding to a specific
- * alarm condition. At the end of each second, the word is shifted left
- * one position and the least significant bit of each nibble cleared.
- * This bit can be set during the next minute if the associated alarm
- * condition is raised. This provides a way to remember alarm conditions
- * up to four minutes.
- *
- * If not tracking both minute sync and second sync, the SYNERR alarm is
- * raised. The data error counter is incremented for each invalid data
- * bit. If too many data bit errors are encountered in one minute, the
- * MODERR alarm is raised. The DECERR alarm is raised if a maximum
- * likelihood digit fails to compare with the current clock digit. If
- * the probability of any miscellaneous bit or any digit falls below the
- * threshold, the SYMERR alarm is raised.
+ * form the quality character included in the timecode. If not tracking
+ * second sync, the SYNERR alarm is raised. The data error counter is
+ * incremented for each invalid data bit. If too many data bit errors
+ * are encountered in one minute, the MODERR alarm is raised. The DECERR
+ * alarm is raised if a maximum likelihood digit fails to compare with
+ * the current clock digit. If the probability of any miscellaneous bit
+ * or any digit falls below the threshold, the SYMERR alarm is raised.
*/
-#define DECERR 0 /* BCD digit compare error */
-#define SYMERR 4 /* low bit or digit probability */
-#define MODERR 8 /* too many data bit errors */
-#define SYNERR 12 /* not synchronized to station */
+#define DECERR 1 /* BCD digit compare error */
+#define SYMERR 2 /* low bit or digit probability */
+#define MODERR 4 /* too many data bit errors */
+#define SYNERR 8 /* not synchronized to station */
/*
- * Watchdog timeouts (watch)
+ * Watchcat timeouts (watch)
*
* If these timeouts expire, the status bits are mashed to zero and the
* driver starts from scratch. Suitably more refined procedures may be
* developed in future. All these are in minutes.
*/
-#define ACQSN 5 /* acquisition timeout */
-#define HSPEC 15 /* second sync timeout */
+#define ACQSN 5 /* station acquisition timeout */
#define DIGIT 30 /* minute unit digit timeout */
-#define PANIC (4 * 1440) /* panic timeout */
+#define HOLD 30 /* reachable timeout */
+#define PANIC (2 * 1440) /* panic timeout */
/*
* Thresholds. These establish the minimum signal level, minimum SNR and
* maximum jitter thresholds which establish the error and false alarm
- * rates of the receiver. The values defined here may be on the
+ * rates of the driver. The values defined here may be on the
* adventurous side in the interest of the highest sensitivity.
*/
-#define ATHR 2000 /* acquisition amplitude threshold */
-#define ASNR 6.0 /* acquisition SNR threshold (dB) */
-#define AWND 50 /* acquisition window threshold (ms) */
-#define AMIN 3 /* acquisition min compare count */
-#define AMAX 6 /* max compare count */
-#define QTHR 2000 /* QSY amplitude threshold */
-#define QSNR 20.0 /* QSY SNR threshold (dB) */
+#define MTHR 13. /* acquisition signal gate (percent) */
+#define TTHR 50. /* tracking signal gate (percent) */
+#define ATHR 2000. /* acquisition amplitude threshold */
+#define ASNR 6. /* acquisition SNR threshold (dB) */
+#define AWND 20. /* acquisition jitter threshold (ms) */
+#define AMIN 3 /* min bit count */
+#define AMAX 6 /* max bit count */
+#define QTHR 2000 /* QSY sync threshold */
+#define QSNR 20. /* QSY sync SNR threshold (dB) */
+#define XTHR 1000. /* QSY data threshold */
+#define XSNR 10. /* QSY data SNR threshold (dB) */
#define STHR 500 /* second sync amplitude threshold */
+#define SSNR 10. /* second sync SNR threshold */
#define SCMP 10 /* second sync compare threshold */
#define DTHR 1000 /* bit amplitude threshold */
-#define DSNR 10.0 /* bit SNR threshold (dB) */
-#define BTHR 1000 /* digit probability threshold */
-#define BSNR 3.0 /* digit likelihood threshold (dB) */
-#define BCMP 5 /* digit compare threshold (dB) */
+#define DSNR 10. /* bit SNR threshold (dB) */
+#define BTHR 1000 /* digit amplitude threshold */
+#define BSNR 3. /* digit likelihood threshold (dB) */
+#define BCMP 5 /* digit compare threshold */
/*
- * Tone frequency definitions.
+ * Tone frequency definitions. The increments are for 4.5-deg sine
+ * table.
*/
-#define MS 8 /* samples per millisecond */
-#define IN100 1 /* 100 Hz 4.5-deg sin table */
-#define IN1000 10 /* 1000 Hz 4.5-deg sin table */
-#define IN1200 12 /* 1200 Hz 4.5-deg sin table */
+#define MS (SECOND / 1000) /* samples per millisecond */
+#define IN100 ((100 * 80) / SECOND) /* 100 Hz increment */
+#define IN1000 ((1000 * 80) / SECOND) /* 1000 Hz increment */
+#define IN1200 ((1200 * 80) / SECOND) /* 1200 Hz increment */
/*
* Acquisition and tracking time constants. Usually powers of 2.
*/
-#define MINAVG 8 /* min time constant (s) */
-#define MAXAVG 7 /* max time constant (log2 s) */
-#define TCONST 16 /* minute time constant (s) */
-#define SYNCTC (1024 / (1 << MAXAVG)) /* FLL constant (s) */
+#define MINAVG 8 /* min time constant */
+#define MAXAVG 1024 /* max time constant */
+#define TCONST 16 /* data bit/digit time constant */
/*
* Miscellaneous status bits (misc)
@@ -212,30 +212,20 @@
#define DUT2 0x02 /* 57 DUT .2 */
#define DUT4 0x04 /* 58 DUT .4 */
#define DUTS 0x08 /* 50 DUT sign */
-#define DST1 0x10 /* 55 DST1 DST in progress */
-#define DST2 0x20 /* 2 DST2 DST change warning */
+#define DST1 0x10 /* 55 DST1 leap warning */
+#define DST2 0x20 /* 2 DST2 DST1 delayed one day */
#define SECWAR 0x40 /* 3 leap second warning */
/*
- * The total system delay with the DSP93 program is at 22.5 ms,
- * including the propagation delay from Ft. Collins, CO, to Newark, DE
- * (8.9 ms), the communications receiver delay and the delay of the
- * DSP93 program itself. The DSP93 program delay is due mainly to the
- * 400-Hz FIR bandpass filter (5 ms) and second sync matched filter (5
- * ms), leaving about 3.6 ms for the receiver delay and strays.
- *
- * The total system delay with this program is estimated at 27.1 ms by
- * comparison with another PPS-synchronized NTP server over a 10-Mb/s
- * Ethernet. The propagation and receiver delays are the same as with
- * the DSP93 program. The program delay is due only to the 600-Hz
- * IIR bandpass filter (1.1 ms), since other delays have been removed.
- * Assuming 4.7 ms for the receiver, program and strays, this leaves
- * 13.5 ms for the audio codec and operating system latencies for a
- * total of 18.2 ms. as the systematic delay. The additional propagation
- * delay specific to each receiver location can be programmed in the
- * fudge time1 and time2 values for WWV and WWVH, respectively.
+ * The on-time synchronization point for the driver is the second epoch
+ * sync pulse produced by the FIR matched filters. As the 5-ms delay of
+ * these filters is compensated, the program delay is 1.1 ms due to the
+ * 600-Hz IIR bandpass filter. The measured receiver delay is 4.7 ms and
+ * the codec delay less than 0.2 ms. The additional propagation delay
+ * specific to each receiver location can be programmed in the fudge
+ * time1 and time2 values for WWV and WWVH, respectively.
*/
-#define PDELAY (.0036 + .0011 + .0135) /* net system delay (s) */
+#define PDELAY (.0011 + .0047 + .0002) /* net system delay (s) */
/*
* Table of sine values at 4.5-degree increments. This is used by the
@@ -280,20 +270,19 @@ struct progx {
* Case switch numbers
*/
#define IDLE 0 /* no operation */
-#define COEF 1 /* BCD bit conditioned on DSYNC */
-#define COEF1 2 /* BCD bit */
-#define COEF2 3 /* BCD bit ignored */
-#define DECIM9 4 /* BCD digit 0-9 */
-#define DECIM6 5 /* BCD digit 0-6 */
-#define DECIM3 6 /* BCD digit 0-3 */
-#define DECIM2 7 /* BCD digit 0-2 */
-#define MSCBIT 8 /* miscellaneous bit */
-#define MSC20 9 /* miscellaneous bit */
-#define MSC21 10 /* QSY probe channel */
-#define MIN1 11 /* minute */
-#define MIN2 12 /* leap second */
-#define SYNC2 13 /* QSY data channel */
-#define SYNC3 14 /* QSY data channel */
+#define COEF 1 /* BCD bit */
+#define COEF2 2 /* BCD bit ignored */
+#define DECIM9 3 /* BCD digit 0-9 */
+#define DECIM6 4 /* BCD digit 0-6 */
+#define DECIM3 5 /* BCD digit 0-3 */
+#define DECIM2 6 /* BCD digit 0-2 */
+#define MSCBIT 7 /* miscellaneous bit */
+#define MSC20 8 /* miscellaneous bit */
+#define MSC21 9 /* QSY probe channel */
+#define MIN1 10 /* minute */
+#define MIN2 11 /* leap second */
+#define SYNC2 12 /* QSY data channel */
+#define SYNC3 13 /* QSY data channel */
/*
* Offsets in decoding matrix
@@ -314,10 +303,10 @@ struct progx progx[] = {
{COEF, 3}, /* 7 8 */
{DECIM9, YR}, /* 8 */
{IDLE, 0}, /* 9 p1 */
- {COEF1, 0}, /* 10 1 minute units */
- {COEF1, 1}, /* 11 2 */
- {COEF1, 2}, /* 12 4 */
- {COEF1, 3}, /* 13 8 */
+ {COEF, 0}, /* 10 1 minute units */
+ {COEF, 1}, /* 11 2 */
+ {COEF, 2}, /* 12 4 */
+ {COEF, 3}, /* 13 8 */
{DECIM9, MN}, /* 14 */
{COEF, 0}, /* 15 10 minute tens */
{COEF, 1}, /* 16 20 */
@@ -442,8 +431,8 @@ double bcd2[][4] = {
*/
char dstcod[] = {
'S', /* 00 standard time */
- 'I', /* 01 daylight warning */
- 'O', /* 10 standard warning */
+ 'I', /* 01 set clock ahead at 0200 local */
+ 'O', /* 10 set clock back at 0200 local */
'D' /* 11 daylight time */
};
@@ -472,32 +461,32 @@ struct decvec {
* for WWVH. Other than frequency, the format is the same.
*/
struct sync {
- double amp; /* sync amplitude (I, Q square) */
- double synamp; /* sync envelope at 800 ms */
+ double epoch; /* accumulated epoch differences */
+ double maxamp; /* sync max envelope (square) */
+ double noiamp; /* sync noise envelope (square) */
+ long pos; /* max amplitude position */
+ long lastpos; /* last max position */
+ long mepoch; /* minute synch epoch */
+
+ double amp; /* sync amplitude (I, Q squares) */
+ double synamp; /* sync max envelope at 800 ms */
double synmax; /* sync envelope at 0 s */
- double synmin; /* avg sync envelope at 59 s, 1 s */
+ double synmin; /* sync envelope at 59, 1 s */
double synsnr; /* sync signal SNR */
- double noise; /* max amplitude off pulse */
- double sigmax; /* max amplitude on pulse */
- double lastmax; /* last max amplitude on pulse */
- long pos; /* position at maximum amplitude */
- long lastpos; /* last position at maximum amplitude */
- long jitter; /* shake, wiggle and waggle */
- long mepoch; /* minute synch epoch */
- int count; /* compare counter */
+ int count; /* bit counter */
char refid[5]; /* reference identifier */
- char ident[4]; /* station identifier */
int select; /* select bits */
+ int reach; /* reachability register */
};
/*
- * The channel structure is used to mitigate between channels. At this
- * point we have already decided which station to use.
+ * The channel structure is used to mitigate between channels.
*/
struct chan {
int gain; /* audio gain */
- int errcnt; /* data bit error counter */
- double noiamp; /* I-channel average noise amplitude */
+ double sigamp; /* data max envelope (square) */
+ double noiamp; /* data noise envelope (square) */
+ double datsnr; /* data signal SNR */
struct sync wwv; /* wwv station */
struct sync wwvh; /* wwvh station */
};
@@ -508,37 +497,42 @@ struct chan {
struct wwvunit {
l_fp timestamp; /* audio sample timestamp */
l_fp tick; /* audio sample increment */
- double comp[SIZE]; /* decompanding table */
double phase, freq; /* logical clock phase and frequency */
double monitor; /* audio monitor point */
int fd_icom; /* ICOM file descriptor */
int errflg; /* error flags */
- int bufcnt; /* samples in buffer */
- int bufptr; /* buffer index pointer */
+ int watch; /* watchcat */
+
+ /*
+ * Audio codec variables
+ */
+ double comp[SIZE]; /* decompanding table */
int port; /* codec port */
int gain; /* codec gain */
+ int mongain; /* codec monitor gain */
int clipcnt; /* sample clipped count */
- int seccnt; /* second countdown */
- int minset; /* minutes since last clock set */
- int watch; /* watchcat */
- int swatch; /* second sync watchcat */
+#ifdef IRIG_SUCKS
+ l_fp wigwag; /* wiggle accumulator */
+ int wp; /* wiggle filter pointer */
+ l_fp wiggle[WIGGLE]; /* wiggle filter */
+ l_fp wigbot[WIGGLE]; /* wiggle bottom fisher*/
+#endif /* IRIG_SUCKS */
/*
* Variables used to establish basic system timing
*/
- int avgint; /* log2 master time constant (s) */
- int epoch; /* second epoch ramp */
- int repoch; /* receiver sync epoch */
- int yepoch; /* transmitter sync epoch */
+ int avgint; /* master time constant */
+ int tepoch; /* sync epoch median */
+ int yepoch; /* sync epoch */
+ int repoch; /* buffered sync epoch */
double epomax; /* second sync amplitude */
+ double eposnr; /* second sync SNR */
double irig; /* data I channel amplitude */
double qrig; /* data Q channel amplitude */
int datapt; /* 100 Hz ramp */
double datpha; /* 100 Hz VFO control */
- int rphase; /* receiver sample counter */
- int rsec; /* receiver seconds counter */
+ int rphase; /* second sample counter */
long mphase; /* minute sample counter */
- long nepoch; /* minute epoch index */
/*
* Variables used to mitigate which channel to use
@@ -553,19 +547,16 @@ struct wwvunit {
* Variables used by the clock state machine
*/
struct decvec decvec[9]; /* decoding matrix */
- int cdelay; /* WWV propagation delay (samples) */
- int hdelay; /* WVVH propagation delay (samples) */
- int pdelay; /* propagation delay (samples) */
- int tphase; /* transmitter sample counter */
- int tsec; /* transmitter seconds counter */
+ int rsec; /* seconds counter */
int digcnt; /* count of digits synchronized */
/*
* Variables used to estimate signal levels and bit/digit
* probabilities
*/
- double sigamp; /* I-channel peak signal amplitude */
- double noiamp; /* I-channel average noise amplitude */
+ double sigsig; /* data max signal */
+ double sigamp; /* data max envelope (square) */
+ double noiamp; /* data noise envelope (square) */
double datsnr; /* data SNR (dB) */
/*
@@ -575,6 +566,7 @@ struct wwvunit {
int alarm; /* alarm flashers */
int misc; /* miscellaneous timecode bits */
int errcnt; /* data bit error counter */
+ int errbit; /* data bit errors in minute */
};
/*
@@ -590,10 +582,10 @@ static void wwv_poll P((int, struct peer *));
*/
static void wwv_epoch P((struct peer *));
static void wwv_rf P((struct peer *, double));
-static void wwv_endpoc P((struct peer *, double, int));
+static void wwv_endpoc P((struct peer *, int));
static void wwv_rsec P((struct peer *, double));
static void wwv_qrz P((struct peer *, struct sync *,
- double));
+ double, int));
static void wwv_corr4 P((struct peer *, struct decvec *,
double [], double [][4]));
static void wwv_gain P((struct peer *));
@@ -603,7 +595,12 @@ static int timecode P((struct wwvunit *, char *));
static double wwv_snr P((double, double));
static int carry P((struct decvec *));
static void wwv_newchan P((struct peer *));
+static void wwv_newgame P((struct peer *));
+static double wwv_metric P((struct sync *));
+#ifdef ICOM
static int wwv_qsy P((struct peer *, int));
+#endif /* ICOM */
+
static double qsy[NCHAN] = {2.5, 5, 10, 15, 20}; /* frequencies (MHz) */
/*
@@ -625,13 +622,12 @@ struct refclock refclock_wwv = {
*/
static int
wwv_start(
- int unit, /* instance number (not used) */
+ int unit, /* instance number (used by PCM) */
struct peer *peer /* peer structure pointer */
)
{
struct refclockproc *pp;
struct wwvunit *up;
- struct chan *cp;
#ifdef ICOM
int temp;
#endif /* ICOM */
@@ -646,7 +642,7 @@ wwv_start(
/*
* Open audio device
*/
- fd = audio_init(DEVICE_AUDIO);
+ fd = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit);
if (fd < 0)
return (0);
#ifdef DEBUG
@@ -657,12 +653,11 @@ wwv_start(
/*
* Allocate and initialize unit structure
*/
- if (!(up = (struct wwvunit *)
- emalloc(sizeof(struct wwvunit)))) {
- (void) close(fd);
+ if (!(up = (struct wwvunit *)emalloc(sizeof(struct wwvunit)))) {
+ close(fd);
return (0);
}
- memset((char *)up, 0, sizeof(struct wwvunit));
+ memset(up, 0, sizeof(struct wwvunit));
pp = peer->procptr;
pp->unitptr = (caddr_t)up;
pp->io.clock_recv = wwv_receive;
@@ -670,7 +665,7 @@ wwv_start(
pp->io.datalen = 0;
pp->io.fd = fd;
if (!io_addclock(&pp->io)) {
- (void)close(fd);
+ close(fd);
free(up);
return (0);
}
@@ -680,8 +675,6 @@ wwv_start(
*/
peer->precision = PRECISION;
pp->clockdesc = DESCRIPTION;
- memcpy((char *)&pp->refid, REFID, 4);
- DTOLFP(1. / SECOND, &up->tick);
/*
* The companded samples are encoded sign-magnitude. The table
@@ -697,6 +690,7 @@ wwv_start(
if (i % 16 == 0)
step *= 2.;
}
+ DTOLFP(1. / SECOND, &up->tick);
/*
* Initialize the decoding matrix with the radix for each digit
@@ -711,22 +705,8 @@ wwv_start(
up->decvec[DA + 2].radix = 4;
up->decvec[YR].radix = 10; /* years */
up->decvec[YR + 1].radix = 10;
-
- /*
- * Initialize the station processes for audio gain, select bit,
- * station/frequency identifier and reference identifier.
- */
- up->gain = 127;
- for (i = 0; i < NCHAN; i++) {
- cp = &up->mitig[i];
- cp->gain = up->gain;
- cp->wwv.select = SELV;
- strcpy(cp->wwv.refid, "WWV ");
- sprintf(cp->wwv.ident,"C%.0f", floor(qsy[i]));
- cp->wwvh.select = SELH;
- strcpy(cp->wwvh.refid, "WWVH");
- sprintf(cp->wwvh.ident, "H%.0f", floor(qsy[i]));
- }
+ wwv_newgame(peer);
+ up->schan = up->achan = 3;
/*
* Initialize autotune if available. Start out at 15 MHz. Note
@@ -739,8 +719,8 @@ wwv_start(
if (debug > 1)
temp = P_TRACE;
#endif
- if (peer->ttlmax != 0) {
- if (peer->ttlmax & 0x80)
+ if (peer->ttl != 0) {
+ if (peer->ttl & 0x80)
up->fd_icom = icom_init("/dev/icom", B1200,
temp);
else
@@ -748,14 +728,17 @@ wwv_start(
temp);
}
if (up->fd_icom > 0) {
- up->schan = 3;
- if ((temp = wwv_qsy(peer, up->schan)) < 0) {
+ if ((temp = wwv_qsy(peer, up->schan)) != 0) {
NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
- msyslog(LOG_ERR,
- "ICOM bus error; autotune disabled");
+ msyslog(LOG_NOTICE,
+ "icom: radio not found");
up->errflg = CEVNT_FAULT;
close(up->fd_icom);
up->fd_icom = 0;
+ } else {
+ NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
+ msyslog(LOG_NOTICE,
+ "icom: autotune enabled");
}
}
#endif /* ICOM */
@@ -806,10 +789,8 @@ wwv_receive(
*/
double sample; /* codec sample */
u_char *dpt; /* buffer pointer */
+ int bufcnt; /* buffer counter */
l_fp ltemp;
- int isneg;
- double dtemp;
- int i, j;
peer = (struct peer *)rbufp->recv_srcclock;
pp = peer->procptr;
@@ -819,13 +800,12 @@ wwv_receive(
* Main loop - read until there ain't no more. Note codec
* samples are bit-inverted.
*/
+ DTOLFP((double)rbufp->recv_length / SECOND, &ltemp);
+ L_SUB(&rbufp->recv_time, &ltemp);
up->timestamp = rbufp->recv_time;
- up->bufcnt = rbufp->recv_length;
- DTOLFP((double)up->bufcnt / SECOND, &ltemp);
- L_SUB(&up->timestamp, &ltemp);
dpt = rbufp->recv_buffer;
- for (up->bufptr = 0; up->bufptr < up->bufcnt; up->bufptr++) {
- sample = up->comp[~*dpt & 0xff];
+ for (bufcnt = 0; bufcnt < rbufp->recv_length; bufcnt++) {
+ sample = up->comp[~*dpt++ & 0xff];
/*
* Clip noise spikes greater than MAXSIG. If no clips,
@@ -841,14 +821,17 @@ wwv_receive(
}
/*
- * Variable frequency oscillator. A phase change of one
- * unit produces a change of 360 degrees; a frequency
- * change of one unit produces a change of 1 Hz.
+ * Variable frequency oscillator. The codec oscillator
+ * runs at the nominal rate of 8000 samples per second,
+ * or 125 us per sample. A frequency change of one unit
+ * results in either duplicating or deleting one sample
+ * per second, which results in a frequency change of
+ * 125 PPM.
*/
up->phase += up->freq / SECOND;
if (up->phase >= .5) {
up->phase -= 1.;
- } else if (up->phase < - .5) {
+ } else if (up->phase < -.5) {
up->phase += 1.;
wwv_rf(peer, sample);
wwv_rf(peer, sample);
@@ -856,71 +839,30 @@ wwv_receive(
wwv_rf(peer, sample);
}
L_ADD(&up->timestamp, &up->tick);
-
- /*
- * Once each second adjust the codec port and gain.
- * While at it, initialize the propagation delay for
- * both WWV and WWVH. Don't forget to correct for the
- * receiver phase delay, mostly due to the 600-Hz
- * IIR bandpass filter used for the sync signals.
- */
- up->cdelay = (int)(SECOND * (pp->fudgetime1 + PDELAY));
- up->hdelay = (int)(SECOND * (pp->fudgetime2 + PDELAY));
- up->seccnt = (up->seccnt + 1) % SECOND;
- if (up->seccnt == 0) {
- if (pp->sloppyclockflag & CLK_FLAG2)
- up->port = 2;
- else
- up->port = 1;
- }
-
- /*
- * During development, it is handy to have an audio
- * monitor that can be switched to various signals. This
- * code converts the linear signal left in up->monitor
- * to codec format.
- */
- isneg = 0;
- dtemp = up->monitor;
- if (sample < 0) {
- isneg = 1;
- dtemp -= dtemp;
- }
- i = 0;
- j = OFFSET >> 1;
- while (j != 0) {
- if (dtemp > up->comp[i])
- i += j;
- else if (dtemp < up->comp[i])
- i -= j;
- else
- break;
- j >>= 1;
- }
- if (isneg)
- *dpt = ~(i + OFFSET);
- else
- *dpt = ~i;
- dpt++;
}
/*
- * Squawk to the monitor speaker if enabled.
+ * Set the input port and monitor gain for the next buffer.
*/
+ if (pp->sloppyclockflag & CLK_FLAG2)
+ up->port = 2;
+ else
+ up->port = 1;
if (pp->sloppyclockflag & CLK_FLAG3)
- if (write(pp->io.fd, (u_char *)&rbufp->recv_space,
- (u_int)up->bufcnt) < 0)
- perror("wwv:");
+ up->mongain = MONGAIN;
+ else
+ up->mongain = 0;
}
/*
* wwv_poll - called by the transmit procedure
*
- * This routine keeps track of status. If nothing is heard for two
- * successive poll intervals, a timeout event is declared and any
- * orphaned timecode updates are sent to foster care. Once the clock is
- * set, it always appears reachable, unless reset by watchdog timeout.
+ * This routine keeps track of status. If no offset samples have been
+ * processed during a poll interval, a timeout event is declared. If
+ * errors have have occurred during the interval, they are reported as
+ * well. Once the clock is set, it always appears reachable, unless
+ * reset by watchdog timeout.
*/
static void
wwv_poll(
@@ -935,13 +877,10 @@ wwv_poll(
up = (struct wwvunit *)pp->unitptr;
if (pp->coderecv == pp->codeproc)
up->errflg = CEVNT_TIMEOUT;
- else
- pp->polls++;
- if (up->status & INSYNC)
- peer->reach |= 1;
if (up->errflg)
refclock_report(peer, up->errflg);
up->errflg = 0;
+ pp->polls++;
}
@@ -953,36 +892,27 @@ wwv_poll(
* form, plus the epoch index of the second sync signal and the second
* index of the minute sync signal.
*
- * There are three 1-s ramps used by this program, all spanning the
- * range 0-7999 logical samples for exactly one second, as determined by
- * the logical clock. The first drives the second epoch and runs
- * continuously. The second determines the receiver phase and the third
- * the transmitter phase within the second. The receiver second begins
- * upon arrival of the 5-ms second sync pulse which begins the second;
- * while the transmitter second begins before it by the specified
- * propagation delay.
- *
- * There are three 1-m ramps spanning the range 0-59 seconds. The first
- * drives the minute epoch in samples and runs continuously. The second
- * determines the receiver second and the third the transmitter second.
- * The receiver second begins upon arrival of the 800-ms sync pulse sent
- * during the first second of the minute; while the transmitter second
- * begins before it by the specified propagation delay.
+ * There are two 1-s ramps used by this program. Both count the 8000
+ * logical clock samples spanning exactly one second. The epoch ramp
+ * counts the samples starting at an arbitrary time. The rphase ramp
+ * counts the samples starting at the 5-ms second sync pulse found
+ * during the epoch ramp.
*
- * The output signals include the epoch maximum and phase and second
- * maximum and index. The epoch phase provides the master reference for
- * all signal and timing functions, while the second index identifies
- * the first second of the minute. The epoch and second maxima are used
- * to calculate SNR for gating functions.
+ * There are two 1-m ramps used by this program. The mphase ramp counts
+ * the 480,000 logical clock samples spanning exactly one minute and
+ * starting at an arbitrary time. The rsec ramp counts the 60 seconds of
+ * the minute starting at the 800-ms minute sync pulse found during the
+ * mphase ramp. The rsec ramp drives the seconds state machine to
+ * determine the bits and digits of the timecode.
*
* Demodulation operations are based on three synthesized quadrature
- * sinusoids: 100 Hz for the data subcarrier, 1000 Hz for the WWV sync
- * signals and 1200 Hz for the WWVH sync signal. These drive synchronous
- * matched filters for the data subcarrier (170 ms at 100 Hz), WWV
- * minute sync signal (800 ms at 1000 Hz) and WWVH minute sync signal
- * (800 ms at 1200 Hz). Two additional matched filters are switched in
- * as required for the WWV seconds sync signal (5 ms at 1000 Hz) and
- * WWVH seconds sync signal (5 ms at 1200 Hz).
+ * sinusoids: 100 Hz for the data signal, 1000 Hz for the WWV sync
+ * signal and 1200 Hz for the WWVH sync signal. These drive synchronous
+ * matched filters for the data signal (170 ms at 100 Hz), WWV minute
+ * sync signal (800 ms at 1000 Hz) and WWVH minute sync signal (800 ms
+ * at 1200 Hz). Two additional matched filters are switched in
+ * as required for the WWV second sync signal (5 ms at 1000 Hz) and
+ * WWVH second sync signal (5 ms at 1200 Hz).
*/
static void
wwv_rf(
@@ -992,6 +922,7 @@ wwv_rf(
{
struct refclockproc *pp;
struct wwvunit *up;
+ struct sync *sp;
static double lpf[5]; /* 150-Hz lpf delay line */
double data; /* lpf output */
@@ -1021,13 +952,14 @@ wwv_rf(
static int epopos; /* epoch sync position buffer */
static int iniflg; /* initialization flag */
- struct sync *sp;
- double dtemp;
- long ltemp;
- int i;
+ int epoch; /* comb filter index */
+ int pdelay; /* propagation delay (samples) */
+ double dtemp;
+ int i;
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
+
if (!iniflg) {
iniflg = 1;
memset((char *)lpf, 0, sizeof(lpf));
@@ -1041,7 +973,6 @@ wwv_rf(
memset((char *)hqbuf, 0, sizeof(hqbuf));
memset((char *)epobuf, 0, sizeof(epobuf));
}
- up->monitor = isig; /* change for debug */
/*
* Baseband data demodulation. The 100-Hz subcarrier is
@@ -1069,13 +1000,9 @@ wwv_rf(
* multiplying the filtered signal by 100-Hz sine and cosine
* signals, respectively. The data signals are demodulated by
* 170-ms synchronous matched filters to produce the amplitude
- * and phase signals used by the decoder. Note the correction
- * due to the propagation delay is necessary for seamless
- * handover between WWV and WWVH.
+ * and phase signals used by the decoder.
*/
- i = up->datapt - up->pdelay % 80;
- if (i < 0)
- i += 80;
+ i = up->datapt;
up->datapt = (up->datapt + IN100) % 80;
dtemp = sintab[i] * data / DATSIZ * DGAIN;
up->irig -= ibuf[iptr];
@@ -1123,9 +1050,14 @@ wwv_rf(
* signals are demodulated by 800-ms synchronous matched filters
* to synchronize the second and minute and to detect which one
* (or both) the WWV or WWVH signal is present.
+ *
+ * Note the master timing ramps, which run continuously. The
+ * minute counter (mphase) counts the samples in the minute,
+ * while the second counter (epoch) counts the samples in the
+ * second.
*/
up->mphase = (up->mphase + 1) % MINUTE;
-
+ epoch = up->mphase % SECOND;
i = csinptr;
csinptr = (csinptr + IN1000) % 80;
dtemp = sintab[i] * syncx / SYNSIZ * SGAIN;
@@ -1135,9 +1067,12 @@ wwv_rf(
dtemp = sintab[i] * syncx / SYNSIZ * SGAIN;
cqamp = cqamp - cqbuf[jptr] + dtemp;
cqbuf[jptr] = dtemp;
+ sp = &up->mitig[up->schan].wwv;
dtemp = ciamp * ciamp + cqamp * cqamp;
- wwv_qrz(peer, &up->mitig[up->schan].wwv, dtemp);
-
+ sp->amp = dtemp;
+ if (!(up->status & MSYNC))
+ wwv_qrz(peer, sp, dtemp, (int)(pp->fudgetime1 *
+ SECOND));
i = hsinptr;
hsinptr = (hsinptr + IN1200) % 80;
dtemp = sintab[i] * syncx / SYNSIZ * SGAIN;
@@ -1147,98 +1082,95 @@ wwv_rf(
dtemp = sintab[i] * syncx / SYNSIZ * SGAIN;
hqamp = hqamp - hqbuf[jptr] + dtemp;
hqbuf[jptr] = dtemp;
+ sp = &up->mitig[up->schan].wwvh;
dtemp = hiamp * hiamp + hqamp * hqamp;
- wwv_qrz(peer, &up->mitig[up->schan].wwvh, dtemp);
-
+ sp->amp = dtemp;
+ if (!(up->status & MSYNC))
+ wwv_qrz(peer, sp, dtemp, (int)(pp->fudgetime2 *
+ SECOND));
jptr = (jptr + 1) % SYNSIZ;
+ /*
+ * The following section is called once per minute. It does
+ * housekeeping and timeout functions and empties the dustbins.
+ */
if (up->mphase == 0) {
-
- /*
- * This section is called once per minute at the minute
- * epoch independently of the transmitter or receiver
- * minute. If the leap bit is set, set the minute epoch
- * back one second so the station processes don't miss a
- * beat. Then, increment the watchdog counter and test
- * for two sets of conditions depending on whether
- * minute sync has been acquired or not.
- */
up->watch++;
- if (up->rsec == 60) {
- up->mphase -= SECOND;
- if (up->mphase < 0)
- up->mphase += MINUTE;
- } else if (!(up->status & MSYNC)) {
-
- /*
- * If minute sync has not been acquired, the
- * program listens for minute sync pulses from
- * both WWV and WWVH. The station with the
- * greater compare count is selected, with ties
- * broken by WWV, but only if the count is at
- * least three. Once a station has been
- * acquired, it is initialized and begins
- * tracking the signal.
+ if (!(up->status & MSYNC)) {
+
+ /*
+ * If minute sync has not been acquired before
+ * timeout, or if no signal is heard, the
+ * program cycles to the next frequency and
+ * tries again.
*/
- if (up->mitig[up->achan].wwv.count >=
- up->mitig[up->achan].wwvh.count)
- sp = &up->mitig[up->achan].wwv;
- else
- sp = &up->mitig[up->achan].wwvh;
- if (sp->count >= AMIN) {
- up->watch = up->swatch = 0;
- up->status |= MSYNC;
- ltemp = sp->mepoch - SYNSIZ;
- if (ltemp < 0)
- ltemp += MINUTE;
- up->rsec = (MINUTE - ltemp) / SECOND;
- if (!(up->status & SSYNC)) {
- up->repoch = ltemp % SECOND;
- up->yepoch = up->repoch -
- up->pdelay;
- if (up->yepoch < 0)
- up->yepoch += SECOND;
+ wwv_newchan(peer);
+ if (!(up->status & (SELV | SELH)) || up->watch >
+ ACQSN) {
+ wwv_newgame(peer);
+#ifdef ICOM
+ if (up->fd_icom > 0) {
+ up->schan = (up->schan + 1) %
+ NCHAN;
+ wwv_qsy(peer, up->schan);
}
- wwv_newchan(peer);
- } else if (sp->count == 0 || up->watch >= ACQSN)
- {
- up->watch = sp->count = 0;
- up->schan = (up->schan + 1) % NCHAN;
- wwv_qsy(peer, up->schan);
+#endif /* ICOM */
}
} else {
/*
- * If minute sync has been acquired, the program
- * watches for timeout. The timeout is reset
- * when the clock is set or verified. If a
- * timeout occurs and the minute units digit has
- * not synchronized, reset the program and start
- * over.
+ * If the leap bit is set, set the minute epoch
+ * back one second so the station processes
+ * don't miss a beat.
*/
- if (up->watch > DIGIT && !(up->status & DSYNC))
- up->watch = up->status = 0;
+ if (up->status & LEPSEC) {
+ up->mphase -= SECOND;
+ if (up->mphase < 0)
+ up->mphase += MINUTE;
+ }
+ }
+ }
- /*
- * If the second sync times out, dim the sync
- * lamp and raise an alarm.
- */
- up->swatch++;
- if (up->swatch > HSPEC)
- up->status &= ~SSYNC;
+ /*
+ * When the channel metric reaches threshold and the second
+ * counter matches the minute epoch within the second, the
+ * driver has synchronized to the station. The second number is
+ * the remaining seconds until the next minute epoch, while the
+ * sync epoch is zero. Watch out for the first second; if
+ * already synchronized to the second, the buffered sync epoch
+ * must be set.
+ */
+ if (up->status & MSYNC) {
+ wwv_epoch(peer);
+ } else if ((sp = up->sptr) != NULL) {
+ struct chan *cp;
+
+ if (sp->count >= AMIN && epoch == sp->mepoch % SECOND) {
+ up->rsec = 60 - sp->mepoch / SECOND;
+ up->rphase = 0;
+ up->status |= MSYNC;
+ up->watch = 0;
if (!(up->status & SSYNC))
- up->alarm |= 1 << SYNERR;
+ up->repoch = up->yepoch = epoch;
+ else
+ up->repoch = up->yepoch;
+ for (i = 0; i < NCHAN; i++) {
+ cp = &up->mitig[i];
+ cp->wwv.count = cp->wwv.reach = 0;
+ cp->wwvh.count = cp->wwvh.reach = 0;
+ }
}
}
/*
- * The second sync pulse is extracted using 5-ms FIR matched
- * filters at 1000 Hz for WWV or 1200 Hz for WWVH. This pulse is
- * used for the most precise synchronization, since if provides
- * a resolution of one sample (125 us).
+ * The second sync pulse is extracted using 5-ms (40 sample) FIR
+ * matched filters at 1000 Hz for WWV or 1200 Hz for WWVH. This
+ * pulse is used for the most precise synchronization, since if
+ * provides a resolution of one sample (125 us). The filters run
+ * only if the station has been reliably determined.
*/
if (up->status & SELV) {
- up->pdelay = up->cdelay;
+ pdelay = (int)(pp->fudgetime1 * SECOND);
/*
* WWV FIR matched filter, five cycles of 1000-Hz
@@ -1286,7 +1218,7 @@ wwv_rf(
mfsync += (mf[1] = mf[0]) * -4.224514e-02;
mf[0] = syncx;
} else if (up->status & SELH) {
- up->pdelay = up->hdelay;
+ pdelay = (int)(pp->fudgetime2 * SECOND);
/*
* WWVH FIR matched filter, six cycles of 1200-Hz
@@ -1335,32 +1267,47 @@ wwv_rf(
mf[0] = syncx;
} else {
mfsync = 0;
+ pdelay = 0;
}
/*
- * Extract the seconds sync pulse using a 1-s comb filter at
- * baseband. Correct for the FIR matched filter delay, which is
- * 5 ms for both the WWV and WWVH filters. Blank the signal when
- * probing.
+ * Enhance the seconds sync pulse using a 1-s (8000-sample) comb
+ * filter. Correct for the FIR matched filter delay, which is 5
+ * ms for both the WWV and WWVH filters, and also for the
+ * propagation delay. Once each second look for second sync. If
+ * not in minute sync, fiddle the codec gain. Note the SNR is
+ * computed from the maximum sample and the two samples 6 ms
+ * before and 6 ms after it, so if we slip more than a cycle the
+ * SNR should plummet.
*/
- up->epoch = (up->epoch + 1) % SECOND;
- if (up->epoch == 0) {
- wwv_endpoc(peer, epomax, epopos);
- up->epomax = epomax;
- epomax = 0;
- if (!(up->status & MSYNC))
- wwv_gain(peer);
- }
- dtemp = (epobuf[up->epoch] += (mfsync - epobuf[up->epoch]) /
- (MINAVG << up->avgint));
+ dtemp = (epobuf[epoch] += (mfsync - epobuf[epoch]) /
+ up->avgint);
if (dtemp > epomax) {
epomax = dtemp;
- epopos = up->epoch - up->pdelay - 5 * MS;
+ epopos = epoch;
+ }
+ if (epoch == 0) {
+ int k, j;
+
+ up->epomax = epomax;
+ k = epopos - 6 * MS;
+ if (k < 0)
+ k += SECOND;
+ j = epopos + 6 * MS;
+ if (j >= SECOND)
+ i -= SECOND;
+ up->eposnr = wwv_snr(epomax, max(abs(epobuf[k]),
+ abs(epobuf[j])));
+ epopos -= pdelay + 5 * MS;
if (epopos < 0)
epopos += SECOND;
+ wwv_endpoc(peer, epopos);
+ if (!(up->status & SSYNC))
+ up->alarm |= SYNERR;
+ epomax = 0;
+ if (!(up->status & MSYNC))
+ wwv_gain(peer);
}
- if (up->status & MSYNC)
- wwv_epoch(peer);
}
@@ -1369,39 +1316,41 @@ wwv_rf(
*
* This routine implements a virtual station process used to acquire
* minute sync and to mitigate among the ten frequency and station
- * combinations. During minute sync acquisition, the process probes each
+ * combinations. During minute sync acquisition the process probes each
* frequency in turn for the minute pulse from either station, which
- * involves searching through the entire epoch minute of samples. After
- * minute sync acquisition, the process searches only during the probe
- * window, which occupies seconds 59, 0 and 1, to construct a metric
- * used to determine which frequency and station provides the best
- * signal.
- *
- * The pulse discriminator requires that (a) the peak on-pulse sample
- * amplitude must be above 2000, (b) the SNR relative to the peak
- * off-pulse sample amplitude must be reduced 6 dB or more below the
- * peak and (c) the maximum difference between the current and previous
- * epoch indices must be less than 50 ms. A compare counter keeps track
- * of the number of successive intervals which satisfy these criteria.
+ * involves searching through the entire minute of samples. After
+ * finding a candidate, the process searches only the seconds before and
+ * after the candidate for the signal and all other seconds for the
+ * noise.
*
* Students of radar receiver technology will discover this algorithm
- * amounts to a range gate discriminator. In practice, the performance
- * of this gadget is amazing. Once setting teeth in a station, it hangs
- * on until the minute beep can barely be heard and long after the
- * second tick and comb filter have given up.
+ * amounts to a range gate discriminator. The discriminator requires
+ * that the peak minute pulse amplitude be at least 2000 and the SNR be
+ * at least 6 dB. In addition after finding a candidate, The peak second
+ * pulse amplitude must be at least 2000, the SNR at least 6 dB and the
+ * difference between the current and previous epoch must be less than
+ * 7.5 ms, which corresponds to a frequency error of 125 PPM.. A compare
+ * counter keeps track of the number of successive intervals which
+ * satisfy these criteria.
+ *
+ * Note that, while the minute pulse is found by by the discriminator,
+ * the actual value is determined from the second epoch. The assumption
+ * is that the discriminator peak occurs about 800 ms into the second,
+ * so the timing is retarted to the previous second epoch.
*/
static void
wwv_qrz(
- struct peer *peer, /* peerstructure pointer */
+ struct peer *peer, /* peer structure pointer */
struct sync *sp, /* sync channel structure */
- double syncx /* bandpass filtered sync signal */
+ double syncx, /* bandpass filtered sync signal */
+ int pdelay /* propagation delay (samples) */
)
{
struct refclockproc *pp;
struct wwvunit *up;
char tbuf[80]; /* monitor buffer */
double snr; /* on-pulse/off-pulse ratio (dB) */
- long epoch;
+ long epoch, fpoch;
int isgood;
pp = peer->procptr;
@@ -1409,171 +1358,147 @@ wwv_qrz(
/*
* Find the sample with peak energy, which defines the minute
- * epoch. If minute sync has been acquired, search only the
- * probe window; otherwise, search the entire minute. If a
- * maximum has been found with good amplitude, search only the
- * second before and after that position for the next maximum
- * and the rest of the window for the noise.
- */
- if (!(up->status & MSYNC) || up->status & SFLAG) {
- sp->amp = syncx;
- if (up->status & MSYNC)
- epoch = up->nepoch;
- else if (sp->count > 1)
- epoch = sp->mepoch;
- else
- epoch = sp->lastpos;
- if (syncx > sp->sigmax) {
- sp->sigmax = syncx;
- sp->pos = up->mphase;
- }
- if (abs(MOD(up->mphase - epoch, MINUTE)) > SYNSIZ &&
- syncx > sp->noise) {
- sp->noise = syncx;
- }
+ * epoch. If a sample has been found with good amplitude,
+ * accumulate the noise squares for all except the second before
+ * and after that position.
+ */
+ isgood = up->epomax > STHR && up->eposnr > SSNR;
+ if (isgood) {
+ fpoch = up->mphase % SECOND - up->tepoch;
+ if (fpoch < 0)
+ fpoch += SECOND;
+ } else {
+ fpoch = pdelay + SYNSIZ;
+ }
+ epoch = up->mphase - fpoch;
+ if (epoch < 0)
+ epoch += MINUTE;
+ if (syncx > sp->maxamp) {
+ sp->maxamp = syncx;
+ sp->pos = epoch;
}
+ if (abs((epoch - sp->lastpos) % MINUTE) > SECOND)
+ sp->noiamp += syncx;
+
+ /*
+ * At the end of the minute, determine the epoch of the
+ * sync pulse, as well as the SNR and difference between
+ * the current and previous epoch, which represents the
+ * intrinsic frequency error plus jitter.
+ */
if (up->mphase == 0) {
+ sp->synmax = sqrt(sp->maxamp);
+ sp->synmin = sqrt(sp->noiamp / (MINUTE - 2 * SECOND));
+ epoch = (sp->pos - sp->lastpos) % MINUTE;
/*
- * At the end of the minute, determine the epoch of the
- * sync pulse, as well as the SNR and difference between
- * the current and previous epoch (jitter).
+ * If not yet in minute sync, we have to do a little
+ * dance to find a valid minute sync pulse, emphasis
+ * valid.
*/
- sp->jitter = MOD(sp->pos - sp->lastpos, MINUTE);
- sp->select &= ~JITRNG;
- if (abs(sp->jitter) > AWND * MS)
- sp->select |= JITRNG;
- sp->sigmax = SQRT(sp->sigmax);
- sp->noise = SQRT(sp->noise);
- if (up->status & MSYNC) {
-
- /*
- * If in minute sync, just count the runs up and
- * down.
- */
- if (sp->select & (DATANG | SYNCNG | JITRNG)) {
- if (sp->count > 0)
- sp->count--;
- } else {
- if (sp->count < AMAX)
- sp->count++;
- }
- } else {
+ snr = wwv_snr(sp->synmax, sp->synmin);
+ isgood = isgood && sp->synmax > ATHR && snr > ASNR;
+ switch (sp->count) {
- /*
- * If not yet in minute sync, we have to do a
- * little dance to find a valid minute sync
- * pulse, emphasis valid.
- */
- snr = wwv_snr(sp->sigmax, sp->noise);
- isgood = sp->sigmax > ATHR && snr > ASNR &&
- !(sp->select & JITRNG);
- switch (sp->count) {
+ /*
+ * In state 0 the station was not heard during the
+ * previous probe. Look for the biggest blip greater
+ * than the amplitude threshold in the minute and assume
+ * that the minute sync pulse. We're fishing here, since
+ * the range gate has not yet been determined. If found,
+ * bump to state 1.
+ */
+ case 0:
+ if (sp->synmax >= ATHR)
+ sp->count++;
+ break;
- /*
- * In state 0 the station was not heard during
- * the previous probe. Look for the biggest blip
- * greater than the amplitude threshold in the
- * minute and assume that the minute sync pulse.
- * If found, bump to state 1.
- */
- case 0:
- if (sp->sigmax >= ATHR)
- sp->count++;
+ /*
+ * In state 1 a candidate blip has been found and the
+ * next minute has been searched for another blip. If
+ * none are found acceptable, drop back to state 0 and
+ * hunt some more. Otherwise, a legitimate minute pulse
+ * may have been found, so bump to state 2.
+ */
+ case 1:
+ if (!isgood) {
+ sp->count = 0;
break;
+ }
+ sp->count++;
+ break;
- /*
- * In state 1 a candidate blip has been found
- * and the next minute has been searched for
- * another blip. If none are found greater than
- * the threshold, or if the biggest blip outside
- * the candidate pulse is less than 6 dB below
- * the biggest blip, drop back to state 0 and
- * hunt some more. Otherwise, a legitimate
- * minute pulse may have been found, so bump to
- * state 2.
- */
- case 1:
- if (sp->sigmax < ATHR) {
- sp->count--;
- break;
- } else if (!isgood) {
- break;
- }
- /* fall through */
-
- /*
- * In states 2 and above, continue to groom
- * samples as before and drop back to the
- * previous state if the groom fails. If it
- * succeeds, bump to the next state until
- * reaching the clamp, if ever.
- */
- default:
- if (!isgood) {
- sp->count--;
- break;
- }
- sp->mepoch = sp->pos;
- if (sp->count < AMAX)
- sp->count++;
- break;
+ /*
+ * In states 2 and above, continue to groom samples as
+ * before and drop back to state 0 if the groom fails.
+ * If it succeeds, set the epoch and bump to the next
+ * state until reaching the threshold, if ever.
+ */
+ default:
+ if (!isgood || abs(epoch) > AWND * MS) {
+ sp->count = 0;
+ break;
}
+ sp->mepoch = sp->pos;
+ sp->count++;
+ break;
+ }
+ if (pp->sloppyclockflag & CLK_FLAG4) {
sprintf(tbuf,
- "wwv8 %d %3d %-3s %d %5.0f %5.1f %7ld %7ld %7ld",
- up->port, up->gain, sp->ident, sp->count,
- sp->sigmax, snr, sp->pos, sp->jitter,
- MOD(sp->pos - up->nepoch - SYNSIZ, MINUTE));
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
+ "wwv8 %d %3d %s %d %5.0f %5.1f %5ld %5d %ld",
+ up->port, up->gain, sp->refid, sp->count,
+ sp->synmax, snr, sp->pos, up->tepoch,
+ epoch);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
if (debug)
printf("%s\n", tbuf);
#endif
}
- sp->lastmax = sp->sigmax;
sp->lastpos = sp->pos;
- sp->sigmax = sp->noise = 0;
+ sp->maxamp = sp->noiamp = 0;
}
}
/*
- * wwv_endpoc - process receiver epoch
+ * wwv_endpoc - identify and acquire second sync pulse
*
- * This routine is called at the end of the receiver epoch. It
- * determines the epoch position within the second and disciplines the
- * sample clock using a frequency-lock loop (FLL).
+ * This routine is called at the end of the second sync interval. It
+ * determines the second sync epoch position within the interval and
+ * disciplines the sample clock using a frequency-lock loop (FLL).
*
- * Seconds sync is determined in the RF input routine as the maximum
+ * Second sync is determined in the RF input routine as the maximum
* over all 8000 samples in the second comb filter. To assure accurate
* and reliable time and frequency discipline, this routine performs a
- * great deal of heavy-handed data filtering and grooming.
+ * great deal of heavy-handed heuristic data filtering and grooming.
+ *
+ * Note that, since the minute sync pulse is very wide (800 ms), precise
+ * minute sync epoch acquisition requires at least a rough estimate of
+ * the second sync pulse (5 ms). This becomes more important in choppy
+ * conditions at the lower frequencies at night, since sferics and
+ * cochannel crude can badly distort the minute pulse.
*/
static void
wwv_endpoc(
struct peer *peer, /* peer structure pointer */
- double epomax, /* epoch max */
int epopos /* epoch max position */
)
{
struct refclockproc *pp;
struct wwvunit *up;
-
static int epoch_mf[3]; /* epoch median filter */
- static int tepoch; /* median filter epoch */
- static int tspan; /* median filter span */
static int xepoch; /* last second epoch */
static int zepoch; /* last averaging interval epoch */
- static int syncnt; /* second epoch run length counter */
- static int jitcnt; /* jitter holdoff counter */
+ static int syncnt; /* run length counter */
+ static int maxrun; /* longest run length */
+ static int mepoch; /* longest run epoch */
static int avgcnt; /* averaging interval counter */
static int avginc; /* averaging ratchet */
-
static int iniflg; /* initialization flag */
char tbuf[80]; /* monitor buffer */
double dtemp;
- int tmp2, tmp3;
+ int tmp2;
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
@@ -1584,86 +1509,64 @@ wwv_endpoc(
/*
* A three-stage median filter is used to help denoise the
- * seconds sync pulse. The median sample becomes the candidate
- * epoch; the difference between the other two samples becomes
- * the span, which is used currently only for debugging.
+ * second sync pulse. The median sample becomes the candidate
+ * epoch.
*/
epoch_mf[2] = epoch_mf[1];
epoch_mf[1] = epoch_mf[0];
epoch_mf[0] = epopos;
if (epoch_mf[0] > epoch_mf[1]) {
- if (epoch_mf[1] > epoch_mf[2]) {
- tepoch = epoch_mf[1]; /* 0 1 2 */
- tspan = epoch_mf[0] - epoch_mf[2];
- } else if (epoch_mf[2] > epoch_mf[0]) {
- tepoch = epoch_mf[0]; /* 2 0 1 */
- tspan = epoch_mf[2] - epoch_mf[1];
- } else {
- tepoch = epoch_mf[2]; /* 0 2 1 */
- tspan = epoch_mf[0] - epoch_mf[1];
- }
+ if (epoch_mf[1] > epoch_mf[2])
+ up->tepoch = epoch_mf[1]; /* 0 1 2 */
+ else if (epoch_mf[2] > epoch_mf[0])
+ up->tepoch = epoch_mf[0]; /* 2 0 1 */
+ else
+ up->tepoch = epoch_mf[2]; /* 0 2 1 */
} else {
- if (epoch_mf[1] < epoch_mf[2]) {
- tepoch = epoch_mf[1]; /* 2 1 0 */
- tspan = epoch_mf[2] - epoch_mf[0];
- } else if (epoch_mf[2] < epoch_mf[0]) {
- tepoch = epoch_mf[0]; /* 1 0 2 */
- tspan = epoch_mf[1] - epoch_mf[2];
- } else {
- tepoch = epoch_mf[2]; /* 1 2 0 */
- tspan = epoch_mf[1] - epoch_mf[0];
- }
+ if (epoch_mf[1] < epoch_mf[2])
+ up->tepoch = epoch_mf[1]; /* 2 1 0 */
+ else if (epoch_mf[2] < epoch_mf[0])
+ up->tepoch = epoch_mf[0]; /* 1 0 2 */
+ else
+ up->tepoch = epoch_mf[2]; /* 1 2 0 */
}
/*
- * If the epoch candidate is within 1 ms of the last one, the
- * new candidate replaces the last one and the jitter counter is
- * reset; otherwise, the candidate is ignored and the jitter
- * counter is incremented. If the jitter counter exceeds the
- * frequency averaging interval, the new candidate replaces the
- * old one anyway. The compare counter is incremented if the new
- * candidate is identical to the last one; otherwise, it is
- * forced to zero. If the compare counter increments to 10, the
- * epoch is reset and the receiver second epoch is set.
- *
- * Careful attention to detail here. If the signal amplitude
- * falls below the threshold or if no stations are heard, we
- * certainly cannot be in sync.
+ * If the signal amplitude or SNR fall below thresholds or if no
+ * stations are heard, dim the second sync lamp and start over.
*/
- tmp2 = MOD(tepoch - xepoch, SECOND);
- if (up->epomax < STHR || !(up->status & (SELV | SELH))) {
- up->status &= ~SSYNC;
- jitcnt = syncnt = avgcnt = 0;
- } else if (abs(tmp2) <= MS || jitcnt >= (MINAVG << up->avgint))
- {
- jitcnt = 0;
- if (tmp2 != 0) {
- xepoch = tepoch;
- syncnt = 0;
- } else {
- if (syncnt < SCMP) {
- syncnt++;
- } else {
- up->status |= SSYNC;
- up->swatch = 0;
- up->repoch = tepoch;
- up->yepoch = up->repoch;
- if (up->yepoch < 0)
- up->yepoch += SECOND;
- }
- }
- avgcnt++;
+ if (!(up->status & (SELV | SELH)) || up->epomax < STHR ||
+ up->eposnr < SSNR) {
+ up->status &= ~(SSYNC | FGATE);
+ avgcnt = syncnt = maxrun = 0;
+ return;
+ }
+ avgcnt++;
+
+ /*
+ * If the epoch candidate is the same as the last one, increment
+ * the compare counter. If not, save the length and epoch of the
+ * current run for use later and reset the counter.
+ */
+ tmp2 = (up->tepoch - xepoch) % SECOND;
+ if (tmp2 == 0) {
+ syncnt++;
} else {
- jitcnt++;
- syncnt = avgcnt = 0;
+ if (maxrun > 0 && mepoch == xepoch) {
+ maxrun += syncnt;
+ } else if (syncnt > maxrun) {
+ maxrun = syncnt;
+ mepoch = xepoch;
+ }
+ syncnt = 0;
}
- if (!(up->status & SSYNC) && 0) {
+ if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & (SSYNC |
+ MSYNC))) {
sprintf(tbuf,
- "wwv1 %2d %04x %5.0f %2d %5.0f %5d %5d %5d %2d %4d",
- up->rsec, up->status, up->epomax, avgcnt, epomax,
- tepoch, tspan, tmp2, syncnt, jitcnt);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
+ "wwv1 %04x %5.0f %5.1f %5d %5d %4d %4d",
+ up->status, up->epomax, up->eposnr, up->tepoch,
+ tmp2, avgcnt, syncnt);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
if (debug)
printf("%s\n", tbuf);
@@ -1671,72 +1574,122 @@ wwv_endpoc(
}
/*
- * The sample clock frequency is disciplined using a first-order
+ * The sample clock frequency is disciplined using a first order
* feedback loop with time constant consistent with the Allan
- * intercept of typical computer clocks. The loop update is
- * calculated each averaging interval from the epoch change in
- * 125-us units and interval length in seconds. The interval is
- * doubled after four intervals where epoch change is not more
- * than one sample.
+ * intercept of typical computer clocks.
*
+ * The frequency update is calculated from the epoch change in
+ * 125-us units divided by the averaging interval in seconds.
* The averaging interval affects other receiver functions,
- * including the the 1000/1200-Hz comb filter and sample clock
+ * including the the 1000/1200-Hz comb filter and codec clock
* loop. It also affects the 100-Hz subcarrier loop and the bit
* and digit comparison counter thresholds.
*/
- tmp3 = MOD(tepoch - zepoch, SECOND);
- if (avgcnt >= (MINAVG << up->avgint)) {
- if (abs(tmp3) < MS) {
- dtemp = (double)tmp3 / avgcnt;
- up->freq += dtemp / SYNCTC;
- if (up->freq > MAXFREQ)
- up->freq = MAXFREQ;
- else if (up->freq < -MAXFREQ)
- up->freq = -MAXFREQ;
- if (abs(tmp3) <= 1 && up->avgint < MAXAVG) {
- if (avginc < 4) {
+ if (avgcnt < up->avgint) {
+ xepoch = up->tepoch;
+ return;
+ }
+
+ /*
+ * During the averaging interval the longest run of identical
+ * epoches is determined. If the longest run is at least 10
+ * seconds, the SSYNC bit is lit and the value becomes the
+ * reference epoch for the next interval. If not, the second
+ * synd lamp is dark and flashers set.
+ */
+ if (maxrun > 0 && mepoch == xepoch) {
+ maxrun += syncnt;
+ } else if (syncnt > maxrun) {
+ maxrun = syncnt;
+ mepoch = xepoch;
+ }
+ xepoch = up->tepoch;
+ if (maxrun > SCMP) {
+ up->status |= SSYNC;
+ up->yepoch = mepoch;
+ } else {
+ up->status &= ~SSYNC;
+ }
+
+ /*
+ * If the epoch change over the averaging interval is less than
+ * 1 ms, the frequency is adjusted, but clamped at +-125 PPM. If
+ * greater than 1 ms, the counter is decremented. If the epoch
+ * change is less than 0.5 ms, the counter is incremented. If
+ * the counter increments to +3, the averaging interval is
+ * doubled and the counter set to zero; if it increments to -3,
+ * the interval is halved and the counter set to zero.
+ *
+ * Here be spooks. From careful observations, the epoch
+ * sometimes makes a long run of identical samples, then takes a
+ * lurch due apparently to lost interrupts or spooks. If this
+ * happens, the epoch change times the maximum run length will
+ * be greater than the averaging interval, so the lurch should
+ * be believed but the frequency left alone. Really intricate
+ * here.
+ */
+ if (maxrun == 0)
+ mepoch = up->tepoch;
+ dtemp = (mepoch - zepoch) % SECOND;
+ if (up->status & FGATE) {
+ if (abs(dtemp) < MAXFREQ * MINAVG) {
+ if (maxrun * abs(mepoch - zepoch) <
+ avgcnt) {
+ up->freq += dtemp / avgcnt;
+ if (up->freq > MAXFREQ)
+ up->freq = MAXFREQ;
+ else if (up->freq < -MAXFREQ)
+ up->freq = -MAXFREQ;
+ }
+ if (abs(dtemp) < MAXFREQ * MINAVG / 2) {
+ if (avginc < 3) {
avginc++;
} else {
+ if (up->avgint < MAXAVG) {
+ up->avgint <<= 1;
+ avginc = 0;
+ }
+ }
+ }
+ } else {
+ if (avginc > -3) {
+ avginc--;
+ } else {
+ if (up->avgint > MINAVG) {
+ up->avgint >>= 1;
avginc = 0;
- up->avgint++;
}
}
- if (up->avgint < MAXAVG) {
- sprintf(tbuf,
- "wwv2 %2d %04x %5.0f %5d %5d %2d %2d %6.1f %6.1f",
- up->rsec, up->status, up->epomax,
- MINAVG << up->avgint, avgcnt,
- avginc, tmp3, dtemp / SECOND * 1e6,
- up->freq / SECOND * 1e6);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(
- &peer->srcadr, tbuf);
+ }
+ }
+ if (pp->sloppyclockflag & CLK_FLAG4) {
+ sprintf(tbuf,
+ "wwv2 %04x %4.0f %4d %4d %2d %4d %4.0f %6.1f",
+ up->status, up->epomax, mepoch, maxrun, avginc,
+ avgcnt, dtemp, up->freq * 1e6 / SECOND);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
+ if (debug)
+ printf("%s\n", tbuf);
#endif /* DEBUG */
- }
- }
- zepoch = tepoch;
- avgcnt = 0;
}
+ up->status |= FGATE;
+ zepoch = mepoch;
+ avgcnt = syncnt = maxrun = 0;
}
/*
- * wwv_epoch - main loop
+ * wwv_epoch - epoch scanner
*
- * This routine establishes receiver and transmitter epoch
- * synchronization and determines the data subcarrier pulse length.
- * Receiver synchronization is determined by the minute sync pulse
- * detected in the wwv_rf() routine and the second sync pulse detected
- * in the wwv_epoch() routine. This establishes when to sample the data
- * subcarrier in-phase signal for the maximum level and noise level and
- * when to determine the pulse length. The transmitter second leads the
- * receiver second by the propagation delay, receiver delay and filter
- * delay of this program. It establishes the clock time and implements
- * the sometimes idiosyncratic conventional clock time and civil
- * calendar.
+ * This routine scans the receiver second epoch to determine the signal
+ * amplitudes and pulse timings. Receiver synchronization is determined
+ * by the minute sync pulse detected in the wwv_rf() routine and the
+ * second sync pulse detected in the wwv_epoch() routine. A pulse width
+ * discriminator extracts data signals from the 100-Hz subcarrier. The
+ * transmitted signals are delayed by the propagation delay, receiver
+ * delay and filter delay of this program. Delay corrections are
+ * introduced separately for WWV and WWVH.
*
* Most communications radios use a highpass filter in the audio stages,
* which can do nasty things to the subcarrier phase relative to the
@@ -1750,152 +1703,96 @@ wwv_epoch(
struct peer *peer /* peer structure pointer */
)
{
- static double dpulse; /* data pulse length */
struct refclockproc *pp;
struct wwvunit *up;
struct chan *cp;
- struct sync *sp;
- l_fp offset; /* NTP format offset */
+ static double dpulse; /* data pulse length */
double dtemp;
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
/*
- * Sample the minute sync pulse amplitude at epoch 800 for both
+ * Sample the minute sync pulse envelopes at epoch 800 for both
* the WWV and WWVH stations. This will be used later for
- * channel mitigation.
+ * channel and station mitigation. Note that the seconds epoch
+ * is set here well before the end of the second to make sure we
+ * never seet the epoch backwards.
*/
- cp = &up->mitig[up->achan];
if (up->rphase == 800 * MS) {
- sp = &cp->wwv;
- sp->synamp = SQRT(sp->amp);
- sp = &cp->wwvh;
- sp->synamp = SQRT(sp->amp);
+ up->repoch = up->yepoch;
+ cp = &up->mitig[up->achan];
+ cp->wwv.synamp = cp->wwv.amp;
+ cp->wwvh.synamp = cp->wwvh.amp;
}
- if (up->rsec == 0) {
- up->sigamp = up->datsnr = 0;
- } else {
-
- /*
- * Estimate the noise level by integrating the I-channel
- * energy at epoch 30 ms.
- */
- if (up->rphase == 30 * MS) {
- if (!(up->status & SFLAG))
- up->noiamp += (up->irig - up->noiamp) /
- (MINAVG << up->avgint);
- else
- cp->noiamp += (SQRT(up->irig *
- up->irig + up->qrig * up->qrig) -
- cp->noiamp) / 8;
-
- /*
- * Strobe the peak I-channel data signal at epoch 200
- * ms. Compute the SNR and adjust the 100-Hz reference
- * oscillator phase using the Q-channel data signal at
- * that epoch. Save the envelope amplitude for the probe
- * channel.
- */
- } else if (up->rphase == 200 * MS) {
- if (!(up->status & SFLAG)) {
- up->sigamp = up->irig;
- if (up->sigamp < 0)
- up->sigamp = 0;
- up->datsnr = wwv_snr(up->sigamp,
- up->noiamp);
- up->datpha = up->qrig / (MINAVG <<
- up->avgint);
- if (up->datpha >= 0) {
- up->datapt++;
- if (up->datapt >= 80)
- up->datapt -= 80;
- } else {
- up->datapt--;
- if (up->datapt < 0)
- up->datapt += 80;
- }
- } else {
- up->sigamp = SQRT(up->irig * up->irig +
- up->qrig * up->qrig);
- up->datsnr = wwv_snr(up->sigamp,
- cp->noiamp);
- }
+ /*
+ * Sample the data subcarrier at epoch 15 ms, giving a guard
+ * time of +-15 ms from the beginning of the second until the
+ * pulse rises at 30 ms. The I-channel amplitude is used to
+ * calculate the slice level. The envelope amplitude is used
+ * during the probe seconds to determine the SNR. There is a
+ * compromise here; we want to delay the sample as long as
+ * possible to give the radio time to change frequency and the
+ * AGC to stabilize, but as early as possible if the second
+ * epoch is not exact.
+ */
+ if (up->rphase == 15 * MS) {
+ up->noiamp = up->irig * up->irig + up->qrig * up->qrig;
- /*
- * The slice level is set half way between the peak
- * signal and noise levels. Strobe the negative zero
- * crossing after epoch 200 ms and record the epoch at
- * that time. This defines the length of the data pulse,
- * which will later be converted into scaled bit
- * probabilities.
- */
- } else if (up->rphase > 200 * MS) {
- dtemp = (up->sigamp + up->noiamp) / 2;
- if (up->irig < dtemp && dpulse == 0)
- dpulse = up->rphase;
+ /*
+ * Sample the data subcarrier at epoch 215 ms, giving a guard
+ * time of +-15 ms from the earliest the pulse peak can be
+ * reached to the earliest it can begin to fall. For the data
+ * channel latch the I-channel amplitude for all except the
+ * probe seconds and adjust the 100-Hz reference oscillator
+ * phase using the Q-channel amplitude at this epoch. For the
+ * probe channel latch the envelope amplitude.
+ */
+ } else if (up->rphase == 215 * MS) {
+ up->sigsig = up->irig;
+ if (up->sigsig < 0)
+ up->sigsig = 0;
+ up->datpha = up->qrig / up->avgint;
+ if (up->datpha >= 0) {
+ up->datapt++;
+ if (up->datapt >= 80)
+ up->datapt -= 80;
+ } else {
+ up->datapt--;
+ if (up->datapt < 0)
+ up->datapt += 80;
}
- }
+ up->sigamp = up->irig * up->irig + up->qrig * up->qrig;
/*
- * At the end of the transmitter second, crank the clock state
- * machine. Note we have to be careful to set the transmitter
- * epoch at the same time as the receiver epoch to be sure the
- * right propagation delay is used. We don't bother the heavy
- * machinery unless the clock is set.
+ * The slice level is set half way between the peak signal and
+ * noise levels. Sample the negative zero crossing after epoch
+ * 200 ms and record the epoch at that time. This defines the
+ * length of the data pulse, which will later be converted into
+ * scaled bit probabilities.
*/
- up->tphase++;
- if (up->epoch == up->yepoch) {
- wwv_tsec(up);
- up->tphase = 0;
-
- /*
- * Determine the current offset from the time of century
- * and the sample timestamp, but only if the SYNERR
- * alarm has not been raised in the present or previous
- * minute.
- */
- if (!(up->status & SFLAG) && up->status & INSYNC &&
- (up->alarm & (3 << SYNERR)) == 0) {
- pp->second = up->tsec;
- pp->minute = up->decvec[MN].digit +
- up->decvec[MN + 1].digit * 10;
- pp->hour = up->decvec[HR].digit +
- up->decvec[HR + 1].digit * 10;
- pp->day = up->decvec[DA].digit + up->decvec[DA +
- 1].digit * 10 + up->decvec[DA + 2].digit *
- 100;
- pp->year = up->decvec[YR].digit +
- up->decvec[YR + 1].digit * 10;
- if (pp->year < UTCYEAR)
- pp->year += 2000;
- else
- pp->year += 1900;
-
- /*
- * We have to simulate refclock_process() here,
- * since the fudgetime gets added much earlier
- * than this.
- */
- pp->lastrec = up->timestamp;
- L_CLR(&offset);
- if (!clocktime(pp->day, pp->hour, pp->minute,
- pp->second, GMT, pp->lastrec.l_ui,
- &pp->yearstart, &offset.l_ui))
- up->errflg = CEVNT_BADTIME;
- else
- refclock_process_offset(pp, offset,
- pp->lastrec, 0.);
- }
+ } else if (up->rphase > 200 * MS) {
+ dtemp = (up->sigsig + sqrt(up->noiamp)) / 2;
+ if (up->irig < dtemp && dpulse == 0)
+ dpulse = up->rphase;
}
/*
- * At the end of the receiver second, process the data bit and
- * update the decoding matrix probabilities.
+ * At the end of the second crank the clock state machine and
+ * adjust the codec gain. Note the epoch is buffered from the
+ * center of the second in order to avoid jitter while the
+ * seconds synch is diddling the epoch. Then, determine the true
+ * offset and update the median filter in the driver interface.
+ *
+ * Sample the data subcarrier envelope at the end of the second
+ * to determine the SNR for the pulse. This gives a guard time
+ * of +-30 ms from the decay of the longest pulse to the rise of
+ * the next pulse.
*/
up->rphase++;
- if (up->epoch == up->repoch) {
+ if (up->mphase % SECOND == up->repoch) {
+ up->datsnr = wwv_snr(up->sigsig, sqrt(up->noiamp));
wwv_rsec(peer, dpulse);
wwv_gain(peer);
up->rphase = dpulse = 0;
@@ -1915,9 +1812,7 @@ wwv_epoch(
* for leap years) or 31 December (day 365 or 366 for leap years) is
* augmented by one second numbered 60. This is accomplished by
* extending the minute interval by one second and teaching the state
- * machine to ignore it. BTW, stations WWV/WWVH cowardly kill the
- * transmitter carrier for a few seconds around the leap to avoid icky
- * details of transmission format during the leap.
+ * machine to ignore it.
*/
static void
wwv_rsec(
@@ -1932,9 +1827,14 @@ wwv_rsec(
struct wwvunit *up;
struct chan *cp;
struct sync *sp, *rp;
+ l_fp offset; /* offset in NTP seconds */
double bit; /* bit likelihood */
char tbuf[80]; /* monitor buffer */
int sw, arg, nsec;
+#ifdef IRIG_SUCKS
+ int i;
+ l_fp ltemp;
+#endif /* IRIG_SUCKS */
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
@@ -1969,65 +1869,105 @@ wwv_rsec(
* Probe channel stuff
*
* The WWV/H format contains data pulses in second 59 (position
- * identifier) and second 1 (not used), and the minute sync
- * pulse in second 0. At the end of second 58, we QSYed to the
- * probe channel, which rotates over all WWV/H frequencies. At
- * the end of second 59, we latched the sync noise and tested
- * for data bit error. At the end of second 0, we now latch the
- * sync peak.
+ * identifier), second 1 (not used) and the minute sync pulse in
+ * second 0. At the end of second 58, QSY to the probe channel,
+ * which rotates over all WWV/H frequencies. At the end of
+ * second 1 QSY back to the data channel.
+ *
+ * At the end of second 0 save the minute sync pulse peak value
+ * previously latched at 800 ms.
*/
case SYNC2: /* 0 */
cp = &up->mitig[up->achan];
- sp = &cp->wwv;
- sp->synmax = sp->synamp;
- sp = &cp->wwvh;
- sp->synmax = sp->synamp;
+ cp->wwv.synmax = sqrt(cp->wwv.synamp);
+ cp->wwvh.synmax = sqrt(cp->wwvh.synamp);
break;
/*
- * At the end of second 1, latch and average the sync noise and
- * test for data bit error. Set SYNCNG if the sync pulse
- * amplitude and SNR are not above thresholds. Set DATANG if
- * data error occured on both second 59 and second 1. Finally,
- * QSY back to the data channel.
+ * At the end of second 1 determine the minute sync pulse
+ * amplitude and SNR and set SYNCNG if these values are below
+ * thresholds. Determine the data pulse amplitude and SNR and
+ * set DATANG if these values are below thresholds. Set ERRRNG
+ * if data pulses in second 59 and second 1 are decoded in
+ * error. Shift a 1 into the reachability register if SYNCNG and
+ * DATANG are both lit; otherwise shift a 0. Ignore ERRRNG for
+ * the present. The number of 1 bits in the last six intervals
+ * represents the channel metric used by the mitigation routine.
+ * Finally, QSY back to the data channel.
*/
case SYNC3: /* 1 */
cp = &up->mitig[up->achan];
- if (up->sigamp < DTHR || up->datsnr < DSNR)
- cp->errcnt++;
+ cp->sigamp = sqrt(up->sigamp);
+ cp->noiamp = sqrt(up->noiamp);
+ cp->datsnr = wwv_snr(cp->sigamp, cp->noiamp);
+ /*
+ * WWV station
+ */
sp = &cp->wwv;
- sp->synmin = (sp->synmin + sp->synamp) / 2;
+ sp->synmin = sqrt((sp->synmin + sp->synamp) / 2.);
sp->synsnr = wwv_snr(sp->synmax, sp->synmin);
- sp->select &= ~(DATANG | SYNCNG);
+ sp->select &= ~(SYNCNG | DATANG | ERRRNG);
if (sp->synmax < QTHR || sp->synsnr < QSNR)
sp->select |= SYNCNG;
- if (cp->errcnt > 1)
+ if (cp->sigamp < XTHR || cp->datsnr < XSNR)
sp->select |= DATANG;
+ if (up->errcnt > 2)
+ sp->select |= ERRRNG;
+ sp->reach <<= 1;
+ if (sp->reach & (1 << AMAX))
+ sp->count--;
+ if (!(sp->select & (SYNCNG | DATANG))) {
+ sp->reach |= 1;
+ sp->count++;
+ }
+ /*
+ * WWVH station
+ */
rp = &cp->wwvh;
- rp->synmin = (rp->synmin + rp->synamp) / 2;
+ rp->synmin = sqrt((rp->synmin + rp->synamp) / 2.);
rp->synsnr = wwv_snr(rp->synmax, rp->synmin);
- rp->select &= ~(DATANG | SYNCNG);
+ rp->select &= ~(SYNCNG | DATANG | ERRRNG);
if (rp->synmax < QTHR || rp->synsnr < QSNR)
rp->select |= SYNCNG;
- if (cp->errcnt > 1)
+ if (cp->sigamp < XTHR || cp->datsnr < XSNR)
rp->select |= DATANG;
+ if (up->errcnt > 2)
+ rp->select |= ERRRNG;
+ rp->reach <<= 1;
+ if (rp->reach & (1 << AMAX))
+ rp->count--;
+ if (!(rp->select & (SYNCNG | DATANG | ERRRNG))) {
+ rp->reach |= 1;
+ rp->count++;
+ }
- cp->errcnt = 0;
- sprintf(tbuf,
- "wwv5 %d %3d %-3s %04x %d %.0f/%.1f/%ld %s %04x %d %.0f/%.1f/%ld",
- up->port, up->gain, sp->ident, sp->select,
- sp->count, sp->synmax, sp->synsnr, sp->jitter,
- rp->ident, rp->select, rp->count, rp->synmax,
- rp->synsnr, rp->jitter);
- if (pp->sloppyclockflag & CLK_FLAG4)
+ /*
+ * Set up for next minute.
+ */
+ if (pp->sloppyclockflag & CLK_FLAG4) {
+ sprintf(tbuf,
+ "wwv5 %2d %04x %3d %4d %d %.0f/%.1f %s %04x %.0f %.0f/%.1f %s %04x %.0f %.0f/%.1f",
+ up->port, up->status, up->gain, up->yepoch,
+ up->errcnt, cp->sigamp, cp->datsnr,
+ sp->refid, sp->reach & 0xffff,
+ wwv_metric(sp), sp->synmax, sp->synsnr,
+ rp->refid, rp->reach & 0xffff,
+ wwv_metric(rp), rp->synmax, rp->synsnr);
record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
+ if (debug)
+ printf("%s\n", tbuf);
#endif /* DEBUG */
+ }
+#ifdef ICOM
+ if (up->fd_icom > 0)
+ wwv_qsy(peer, up->dchan);
+#endif /* ICOM */
up->status &= ~SFLAG;
+ up->errcnt = 0;
+ up->alarm = 0;
wwv_newchan(peer);
break;
@@ -2038,7 +1978,9 @@ wwv_rsec(
* considered valid. Bits not used in the digit are forced to
* zero and not checked for errors.
*/
- case COEF1: /* 10-13 */
+ case COEF: /* 4-7, 10-13, 15-17, 20-23,
+ 25-26, 30-33, 35-38, 40-41,
+ 51-54 */
if (up->status & DGATE)
up->status |= BGATE;
bcddld[arg] = bit;
@@ -2048,13 +1990,6 @@ wwv_rsec(
bcddld[arg] = 0;
break;
- case COEF: /* 4-7, 15-17, 20-23, 25-26,
- 30-33, 35-38, 40-41, 51-54 */
- if (up->status & DGATE || !(up->status & DSYNC))
- up->status |= BGATE;
- bcddld[arg] = bit;
- break;
-
/*
* Correlate coefficient vector with each valid digit vector and
* save in decoding matrix. We step through the decoding matrix
@@ -2081,122 +2016,207 @@ wwv_rsec(
* Miscellaneous bits. If above the positive threshold, declare
* 1; if below the negative threshold, declare 0; otherwise
* raise the SYMERR alarm. At the end of second 58, QSY to the
- * probe channel.
+ * probe channel. The design is intended to preserve the bits
+ * over periods of signal loss.
*/
case MSC20: /* 55 */
wwv_corr4(peer, &up->decvec[YR + 1], bcddld, bcd9);
/* fall through */
- case MSCBIT: /* 2, 3, 50, 56-57 */
+ case MSCBIT: /* 2-3, 50, 56-57 */
if (bitvec[up->rsec] > BTHR)
up->misc |= arg;
else if (bitvec[up->rsec] < -BTHR)
up->misc &= ~arg;
else
- up->alarm |= 1 << SYMERR;
+ up->alarm |= SYMERR;
break;
+ /*
+ * Save the data channel gain, then QSY to the probe channel.
+ */
case MSC21: /* 58 */
if (bitvec[up->rsec] > BTHR)
up->misc |= arg;
else if (bitvec[up->rsec] < -BTHR)
up->misc &= ~arg;
else
- up->alarm |= 1 << SYMERR;
- up->schan = (up->schan + 1) % NCHAN;
- wwv_qsy(peer, up->schan);
- up->status |= SFLAG;
+ up->alarm |= SYMERR;
+ up->mitig[up->dchan].gain = up->gain;
+#ifdef ICOM
+ if (up->fd_icom > 0) {
+ up->schan = (up->schan + 1) % NCHAN;
+ wwv_qsy(peer, up->schan);
+ }
+#endif /* ICOM */
+ up->status |= SFLAG | SELV | SELH;
+ up->errbit = up->errcnt;
+ up->errcnt = 0;
break;
/*
* The endgames
*
- * Second 59 contains the first data pulse of the probe
- * sequence. Check it for validity and establish the noise floor
- * for the minute sync SNR.
+ * During second 59 the receiver and codec AGC are settling
+ * down, so the data pulse is unusable. At the end of this
+ * second, latch the minute sync pulse noise floor. Then do the
+ * minute processing and update the system clock. If a leap
+ * second sail on to the next second (60); otherwise, set up for
+ * the next minute.
*/
case MIN1: /* 59 */
cp = &up->mitig[up->achan];
- if (up->sigamp < DTHR || up->datsnr < DSNR)
- cp->errcnt++;
- sp = &cp->wwv;
- sp->synmin = sp->synamp;
- sp = &cp->wwvh;
- sp->synmin = sp->synamp;
+ cp->wwv.synmin = cp->wwv.synamp;
+ cp->wwvh.synmin = cp->wwvh.synamp;
/*
- * If SECWARN is set on the last minute of 30 June or 31
- * December, LEPSEC bit is set. At the end of the minute
- * in which LEPSEC is set the transmitter and receiver
- * insert an extra second (60) in the timescale and the
- * minute sync skips a second. We only get to test this
- * wrinkle at intervals of about 18 months, the actual
- * mileage may vary.
+ * Dance the leap if necessary and the kernel has the
+ * right stuff. Then, wind up the clock and initialize
+ * for the following minute. If the leap dance, note the
+ * kernel is armed one second before the actual leap is
+ * scheduled.
*/
- if (up->tsec == 60) {
- up->status &= ~LEPSEC;
- break;
- }
- /* fall through */
-
- /*
- * If all nine clock digits are valid and the SYNERR alarm is
- * not raised in the current or previous second, the clock is
- * set or validated. If at least one digit is set, which by
- * design must be the minute units digit, the clock state
- * machine begins to count the minutes.
- */
- case MIN2: /* 59/60 */
- up->minset = ((current_time - peer->update) + 30) / 60;
- if (up->digcnt > 0)
- up->status |= DSYNC;
- if (up->digcnt >= 9 && (up->alarm & (3 << SYNERR)) == 0)
- {
+ if (up->status & SSYNC && up->digcnt >= 9)
up->status |= INSYNC;
- up->watch = 0;
- }
- pp->lencode = timecode(up, pp->a_lastcode);
- if (up->misc & SECWAR)
+ if (up->status & LEPDAY) {
pp->leap = LEAP_ADDSECOND;
- else
+ } else {
pp->leap = LEAP_NOWARNING;
- refclock_receive(peer);
+ wwv_tsec(up);
+ nsec = up->digcnt = 0;
+ }
+ pp->lencode = timecode(up, pp->a_lastcode);
record_clock_stats(&peer->srcadr, pp->a_lastcode);
#ifdef DEBUG
if (debug)
printf("wwv: timecode %d %s\n", pp->lencode,
pp->a_lastcode);
#endif /* DEBUG */
+ if (up->status & INSYNC && up->watch < HOLD)
+ refclock_receive(peer);
+ break;
- /*
- * The ultimate watchdog is the interval since the
- * reference clock interface code last received an
- * update from this driver. If the interval is greater
- * than a couple of days, manual intervention is
- * probably required, so the program resets and tries to
- * resynchronized from scratch.
- */
- if (up->minset > PANIC)
- up->status = 0;
- up->alarm = (up->alarm & ~0x8888) << 1;
- up->nepoch = (up->mphase + SYNSIZ) % MINUTE;
- up->errcnt = up->digcnt = nsec = 0;
+ /*
+ * If LEPDAY is set on the last minute of 30 June or 31
+ * December, the LEPSEC bit is set. At the end of the minute in
+ * which LEPSEC is set the transmitter and receiver insert an
+ * extra second (60) in the timescale and the minute sync skips
+ * a second. We only get to test this wrinkle at intervals of
+ * about 18 months; the actual mileage may vary.
+ */
+ case MIN2: /* 60 */
+ wwv_tsec(up);
+ nsec = up->digcnt = 0;
break;
}
- if (!(up->status & DSYNC)) {
+
+ /*
+ * If digit sync has not been acquired before timeout or if no
+ * station has been heard, game over and restart from scratch.
+ */
+ if (!(up->status & DSYNC) && (!(up->status & (SELV | SELH)) ||
+ up->watch > DIGIT)) {
+ wwv_newgame(peer);
+ return;
+ }
+
+ /*
+ * If no timestamps have been struck before timeout, game over
+ * and restart from scratch.
+ */
+ if (up->watch > PANIC) {
+ wwv_newgame(peer);
+ return;
+ }
+ pp->disp += AUDIO_PHI;
+ up->rsec = nsec;
+
+#ifdef IRIG_SUCKS
+ /*
+ * You really don't wanna know what comes down here. Leave it to
+ * say Solaris 2.8 broke the nice clean audio stream, apparently
+ * affected by a 5-ms sawtooth jitter. Sundown on Solaris. This
+ * leaves a little twilight.
+ *
+ * The scheme involves differentiation, forward learning and
+ * integration. The sawtooth has a period of 11 seconds. The
+ * timestamp differences are integrated and subtracted from the
+ * signal.
+ */
+ ltemp = pp->lastrec;
+ L_SUB(&ltemp, &pp->lastref);
+ if (ltemp.l_f < 0)
+ ltemp.l_i = -1;
+ else
+ ltemp.l_i = 0;
+ pp->lastref = pp->lastrec;
+ if (!L_ISNEG(&ltemp))
+ L_CLR(&up->wigwag);
+ else
+ L_ADD(&up->wigwag, &ltemp);
+ L_SUB(&pp->lastrec, &up->wigwag);
+ up->wiggle[up->wp] = ltemp;
+
+ /*
+ * Bottom fisher. To understand this, you have to know about
+ * velocity microphones and AM transmitters. No further
+ * explanation is offered, as this is truly a black art.
+ */
+ up->wigbot[up->wp] = pp->lastrec;
+ for (i = 0; i < WIGGLE; i++) {
+ if (i != up->wp)
+ up->wigbot[i].l_ui++;
+ L_SUB(&pp->lastrec, &up->wigbot[i]);
+ if (L_ISNEG(&pp->lastrec))
+ L_ADD(&pp->lastrec, &up->wigbot[i]);
+ else
+ pp->lastrec = up->wigbot[i];
+ }
+ up->wp++;
+ up->wp %= WIGGLE;
+#endif /* IRIG_SUCKS */
+
+ /*
+ * If victory has been declared and seconds sync is lit, strike
+ * a timestamp. It should not be a surprise, especially if the
+ * radio is not tunable, that sometimes no stations are above
+ * the noise and the reference ID set to NONE.
+ */
+ if (up->status & INSYNC && up->status & SSYNC) {
+ pp->second = up->rsec;
+ pp->minute = up->decvec[MN].digit + up->decvec[MN +
+ 1].digit * 10;
+ pp->hour = up->decvec[HR].digit + up->decvec[HR +
+ 1].digit * 10;
+ pp->day = up->decvec[DA].digit + up->decvec[DA +
+ 1].digit * 10 + up->decvec[DA + 2].digit * 100;
+ pp->year = up->decvec[YR].digit + up->decvec[YR +
+ 1].digit * 10;
+ pp->year += 2000;
+ L_CLR(&offset);
+ if (!clocktime(pp->day, pp->hour, pp->minute,
+ pp->second, GMT, up->timestamp.l_ui,
+ &pp->yearstart, &offset.l_ui)) {
+ up->errflg = CEVNT_BADTIME;
+ } else {
+ up->watch = 0;
+ pp->disp = 0;
+ refclock_process_offset(pp, offset,
+ up->timestamp, PDELAY);
+ }
+ }
+ if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status &
+ DSYNC)) {
sprintf(tbuf,
- "wwv3 %2d %04x %5.0f %5.0f %5.0f %5.1f %5.0f %5.0f",
- up->rsec, up->status, up->epomax, up->sigamp,
- up->datpha, up->datsnr, bit, bitvec[up->rsec]);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
+ "wwv3 %2d %04x %5.0f %5.1f %5.0f %5.1f %5.0f",
+ up->rsec, up->status, up->epomax, up->eposnr,
+ up->sigsig, up->datsnr, bit);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
if (debug)
printf("%s\n", tbuf);
#endif /* DEBUG */
- }
- up->rsec = up->tsec = nsec;
- return;
+ }
}
@@ -2209,7 +2229,12 @@ wwv_rsec(
* bit is bad, a bit error is declared and the probabilities are forced
* to zero. Otherwise, the data gate is enabled and the probabilities
* are calculated. Note that the data matched filter contributes half
- * the pulse width, or 85 ms..
+ * the pulse width, or 85 ms.
+ *
+ * It's important to observe that there are three conditions to
+ * determine: average to +1 (hit), average to -1 (miss) or average to
+ * zero (erasure). The erasure condition results from insufficient
+ * signal (noise) and has no bias toward either a hit or miss.
*/
static double
wwv_data(
@@ -2224,14 +2249,16 @@ wwv_data(
dpulse = pulse - DATSIZ / 2;
/*
- * If the data amplitude or SNR are below threshold or if the
- * pulse length is less than 170 ms, declare an erasure.
+ * If no station is being tracked, if either the data amplitude
+ * or SNR are below threshold or if the pulse length is less
+ * than 170 ms, declare an erasure.
*/
- if (up->sigamp < DTHR || up->datsnr < DSNR || dpulse < DATSIZ) {
+ if (!(up->status & (SELV | SELH)) || up->sigsig < DTHR ||
+ up->datsnr < DSNR || dpulse < DATSIZ) {
up->status |= DGATE;
up->errcnt++;
if (up->errcnt > MAXERR)
- up->alarm |= 1 << MODERR;
+ up->alarm |= MODERR;
return (0);
}
@@ -2325,44 +2352,59 @@ wwv_corr4(
/*
* The maximum likelihood digit is compared with the current
* clock digit. The difference represents the decoding phase
- * error. If the digit probability and likelihood are good and
- * the difference stays the same for a number of comparisons,
- * the clock digit is reset to the maximum likelihood digit.
+ * error. If the clock is not yet synchronized, the phase error
+ * is corrected even of the digit probability and likelihood are
+ * below thresholds. This avoids lengthy averaging times should
+ * a carry mistake occur. However, the digit is not declared
+ * synchronized until these values are above thresholds and the
+ * last five decoded values are identical. If the clock is
+ * synchronized, the phase error is not corrected unless the
+ * last five digits are all above thresholds and identical. This
+ * avoids mistakes when the signal is coming out of the noise
+ * and the SNR is very marginal.
*/
diff = mldigit - vp->digit;
if (diff < 0)
diff += vp->radix;
if (diff != vp->phase) {
- vp->phase = diff;
vp->count = 0;
+ vp->phase = diff;
}
- if (vp->digprb < BTHR || vp->digsnr < BSNR) {
+ if (vp->digsnr < BSNR) {
vp->count = 0;
- up->alarm |= 1 << SYMERR;
- } else if (vp->count < BCMP) {
+ up->alarm |= SYMERR;
+ } else if (vp->digprb < BTHR) {
+ vp->count = 0;
+ up->alarm |= SYMERR;
if (!(up->status & INSYNC)) {
vp->phase = 0;
vp->digit = mldigit;
}
+ } else if (vp->count < BCMP) {
vp->count++;
+ up->status |= DSYNC;
+ if (!(up->status & INSYNC)) {
+ vp->phase = 0;
+ vp->digit = mldigit;
+ }
} else {
vp->phase = 0;
vp->digit = mldigit;
up->digcnt++;
}
if (vp->digit != mldigit)
- up->alarm |= 1 << DECERR;
- if (!(up->status & INSYNC)) {
+ up->alarm |= DECERR;
+ if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status &
+ INSYNC)) {
sprintf(tbuf,
"wwv4 %2d %04x %5.0f %2d %d %d %d %d %5.0f %5.1f",
- up->rsec, up->status, up->epomax, vp->radix,
+ up->rsec, up->status, up->epomax, vp->radix,
vp->digit, vp->mldigit, vp->phase, vp->count,
vp->digprb, vp->digsnr);
- if (pp->sloppyclockflag & CLK_FLAG4)
- record_clock_stats(&peer->srcadr, tbuf);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
+ if (debug)
+ printf("%s\n", tbuf);
#endif /* DEBUG */
}
up->status &= ~BGATE;
@@ -2370,13 +2412,11 @@ wwv_corr4(
/*
- * wwv_tsec - transmitter second processing
+ * wwv_tsec - transmitter minute processing
*
- * This routine is called at the end of the transmitter second. It
+ * This routine is called at the end of the transmitter minute. It
* implements a state machine that advances the logical clock subject to
- * the funny rules that govern the conventional clock and calendar. Note
- * that carries from the least significant (minutes) digit are inhibited
- * until that digit is synchronized.
+ * the funny rules that govern the conventional clock and calendar.
*/
static void
wwv_tsec(
@@ -2386,18 +2426,10 @@ wwv_tsec(
int minute, day, isleap;
int temp;
- up->tsec++;
- if (up->tsec < 60 || up->status & LEPSEC)
- return;
- up->tsec = 0;
-
/*
- * Advance minute unit of the day. If the minute unit is not
- * synchronized, go no further.
+ * Advance minute unit of the day.
*/
temp = carry(&up->decvec[MN]); /* minute units */
- if (!(up->status & DSYNC))
- return;
/*
* Propagate carries through the day.
@@ -2410,8 +2442,10 @@ wwv_tsec(
temp = carry(&up->decvec[HR + 1]);
/*
- * Decode the current minute and day. Set the leap second enable
- * bit on the last minute of 30 June and 31 December.
+ * Decode the current minute and day. Set leap day if the
+ * timecode leap bit is set on 30 June or 31 December. Set leap
+ * minute if the last minute on leap day. This code fails in
+ * 2400 AD.
*/
minute = up->decvec[MN].digit + up->decvec[MN + 1].digit *
10 + up->decvec[HR].digit * 60 + up->decvec[HR +
@@ -2419,9 +2453,16 @@ wwv_tsec(
day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 +
up->decvec[DA + 2].digit * 100;
isleap = (up->decvec[YR].digit & 0x3) == 0;
- if (minute == 1439 && (day == (isleap ? 182 : 183) || day ==
- (isleap ? 365 : 366)) && up->misc & SECWAR)
+ if (up->misc & SECWAR && (day == (isleap ? 182 : 183) || day ==
+ (isleap ? 365 : 366)) && up->status & INSYNC && up->status &
+ SSYNC)
+ up->status |= LEPDAY;
+ else
+ up->status &= ~LEPDAY;
+ if (up->status & LEPDAY && minute == 1439)
up->status |= LEPSEC;
+ else
+ up->status &= ~LEPSEC;
/*
* Roll the day if this the first minute and propagate carries
@@ -2459,8 +2500,8 @@ wwv_tsec(
* carry - process digit
*
* This routine rotates a likelihood vector one position and increments
- * the clock digit modulo the radix. It returns the new clock digit -
- * zero if a carry occured. Once synchronized, the clock digit will
+ * the clock digit modulo the radix. It returns the new clock digit or
+ * zero if a carry occurred. Once synchronized, the clock digit will
* match the maximum likelihood digit corresponding to that position.
*/
static int
@@ -2517,19 +2558,36 @@ wwv_snr(
return (rval);
}
+
/*
* wwv_newchan - change to new data channel
*
- * Assuming the radio can be tuned by this program, it actually appears
- * as a 10-channel receiver, one channel for each of WWV and WWVH on
- * each of five frequencies. While the radio is tuned to the working
- * data channel (frequency and station) for most of the minute, during
- * seconds 59, 0 and 1 the radio is tuned to a probe channel, in order
- * to pick up minute sync and data pulses. The search for WWV and WWVH
- * stations operates simultaneously, with WWV on 1000 Hz and WWVH on
- * 1200 Hz. The probe channel rotates for each minute over the five
- * frequencies. At the end of each rotation, this routine mitigates over
- * all channels and chooses the best frequency and station.
+ * The radio actually appears to have ten channels, one channel for each
+ * of five frequencies and each of two stations (WWV and WWVH), although
+ * if not tunable only the 15 MHz channels appear live. While the radio
+ * is tuned to the working data channel frequency and station for most
+ * of the minute, during seconds 59, 0 and 1 the radio is tuned to a
+ * probe frequency in order to search for minute sync pulse and data
+ * subcarrier from other transmitters.
+ *
+ * The search for WWV and WWVH operates simultaneously, with WWV minute
+ * sync pulse at 1000 Hz and WWVH at 1200 Hz. The probe frequency
+ * rotates each minute over 2.5, 5, 10, 15 and 20 MHz in order and yes,
+ * we all know WWVH is dark on 20 MHz, but few remember when WWV was lit
+ * on 25 MHz.
+ *
+ * This routine selects the best channel using a metric computed from
+ * the reachability register and minute pulse amplitude. Normally, the
+ * award goes to the the channel with the highest metric; but, in case
+ * of ties, the award goes to the channel with the highest minute sync
+ * pulse amplitude and then to the highest frequency.
+ *
+ * The routine performs an important squelch function to keep dirty data
+ * from polluting the integrators. During acquisition and until the
+ * clock is synchronized, the signal metric must be at least MTR (13);
+ * after that the metrict must be at least TTHR (50). If either of these
+ * is not true, the station select bits are cleared so the second sync
+ * is disabled and the data bit integrators averaged to a miss.
*/
static void
wwv_newchan(
@@ -2538,61 +2596,119 @@ wwv_newchan(
{
struct refclockproc *pp;
struct wwvunit *up;
- struct chan *cp;
struct sync *sp, *rp;
- int rank;
+ double rank, dtemp;
int i, j;
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
/*
- * Reset the matched filter selector and station pointer to
- * avoid fooling around should we lose this game.
- */
- up->sptr = 0;
- up->status &= ~(SELV | SELH);
-
- /*
- * Search all five station pairs looking for the station with
- * the maximum compare counter. Ties go to the highest frequency
- * and then to WWV.
+ * Search all five station pairs looking for the channel with
+ * maximum metric. If no station is found above thresholds, the
+ * reference ID is set to NONE and we wait for hotter ions.
*/
j = 0;
- sp = (struct sync *)0;
+ sp = NULL;
rank = 0;
for (i = 0; i < NCHAN; i++) {
- cp = &up->mitig[i];
- rp = &cp->wwvh;
- if (rp->count >= rank) {
+ rp = &up->mitig[i].wwvh;
+ dtemp = wwv_metric(rp);
+ if (dtemp >= rank) {
+ rank = dtemp;
sp = rp;
- rank = rp->count;
j = i;
}
- rp = &cp->wwv;
- if (rp->count >= rank) {
+ rp = &up->mitig[i].wwv;
+ dtemp = wwv_metric(rp);
+ if (dtemp >= rank) {
+ rank = dtemp;
sp = rp;
- rank = rp->count;
j = i;
}
}
+ up->dchan = j;
+ up->sptr = sp;
+ up->status &= ~(SELV | SELH);
+ memcpy(&pp->refid, "NONE", 4);
+ if ((!(up->status & INSYNC) && rank >= MTHR) || ((up->status &
+ INSYNC) && rank >= TTHR)) {
+ up->status |= sp->select & (SELV | SELH);
+ memcpy(&pp->refid, sp->refid, 4);
+ }
+ if (peer->stratum <= 1)
+ memcpy(&peer->refid, &pp->refid, 4);
+}
+
+
+/*
+ * www_newgame - reset and start over
+ */
+static void
+wwv_newgame(
+ struct peer *peer /* peer structure pointer */
+ )
+{
+ struct refclockproc *pp;
+ struct wwvunit *up;
+ struct chan *cp;
+ int i;
+
+ pp = peer->procptr;
+ up = (struct wwvunit *)pp->unitptr;
/*
- * If we find a station, continue to track it. If not, X marks
- * the spot and we wait for better ions.
+ * Initialize strategic values. Note we set the leap bits
+ * NOTINSYNC and the refid "NONE".
*/
- if (rank > 0) {
- up->dchan = j;
- up->sptr = sp;
- up->status |= sp->select & (SELV | SELH);
- memcpy((char *)&pp->refid, sp->refid, 4);
- if (peer->stratum <= 1)
- memcpy((char *)&peer->refid, sp->refid, 4);
- wwv_qsy(peer, up->dchan);
+ peer->leap = LEAP_NOTINSYNC;
+ up->watch = up->status = up->alarm = 0;
+ up->avgint = MINAVG;
+ up->freq = 0;
+ up->sptr = NULL;
+ up->gain = MAXGAIN / 2;
+
+ /*
+ * Initialize the station processes for audio gain, select bit,
+ * station/frequency identifier and reference identifier.
+ */
+ memset(up->mitig, 0, sizeof(up->mitig));
+ for (i = 0; i < NCHAN; i++) {
+ cp = &up->mitig[i];
+ cp->gain = up->gain;
+ cp->wwv.select = SELV;
+ sprintf(cp->wwv.refid, "WV%.0f", floor(qsy[i]));
+ cp->wwvh.select = SELH;
+ sprintf(cp->wwvh.refid, "WH%.0f", floor(qsy[i]));
}
+ wwv_newchan(peer);
+}
+
+/*
+ * wwv_metric - compute station metric
+ *
+ * The most significant bits represent the number of ones in the
+ * reachability register. The least significant bits represent the
+ * minute sync pulse amplitude. The combined value is scaled 0-100.
+ */
+double
+wwv_metric(
+ struct sync *sp /* station pointer */
+ )
+{
+ double dtemp;
+
+ dtemp = sp->count * MAXSIG;
+ if (sp->synmax < MAXSIG)
+ dtemp += sp->synmax;
+ else
+ dtemp += MAXSIG - 1;
+ dtemp /= (AMAX + 1) * MAXSIG;
+ return (dtemp * 100.);
}
+#ifdef ICOM
/*
* wwv_qsy - Tune ICOM receiver
*
@@ -2606,22 +2722,22 @@ wwv_qsy(
int chan /* channel */
)
{
+ int rval = 0;
struct refclockproc *pp;
struct wwvunit *up;
- int rval = 0;
pp = peer->procptr;
up = (struct wwvunit *)pp->unitptr;
- up->mitig[up->achan].gain = up->gain;
-#ifdef ICOM
- if (up->fd_icom > 0)
- rval = icom_freq(up->fd_icom, peer->ttlmax & 0x7f,
+ if (up->fd_icom > 0) {
+ up->mitig[up->achan].gain = up->gain;
+ rval = icom_freq(up->fd_icom, peer->ttl & 0x7f,
qsy[chan]);
-#endif /* ICOM */
- up->achan = chan;
- up->gain = up->mitig[up->achan].gain;
+ up->achan = chan;
+ up->gain = up->mitig[up->achan].gain;
+ }
return (rval);
}
+#endif /* ICOM */
/*
@@ -2629,23 +2745,22 @@ wwv_qsy(
*
* Prettytime format - similar to Spectracom
*
- * sq yy ddd hh:mm:ss.fff ld dut lset agc stn comp errs freq avgt
+ * sq yy ddd hh:mm:ss ld dut lset agc iden sig errs freq avgt
*
* s sync indicator ('?' or ' ')
- * q quality character (hex 0-F)
+ * q error bits (hex 0-F)
* yyyy year of century
* ddd day of year
* hh hour of day
* mm minute of hour
- * ss minute of hour
- * fff millisecond of second
- * l leap second warning ' ' or 'L'
- * d DST state 'S', 'D', 'I', or 'O'
- * dut DUT sign and magnitude in deciseconds
+ * ss second of minute)
+ * l leap second warning (' ' or 'L')
+ * d DST state ('S', 'D', 'I', or 'O')
+ * dut DUT sign and magnitude (0.1 s)
* lset minutes since last clock update
* agc audio gain (0-255)
- * iden station identifier (station and frequency)
- * comp minute sync compare counter
+ * iden reference identifier (station and frequency)
+ * sig signal quality (0-100)
* errs bit errors in last minute
* freq frequency offset (PPM)
* avgt averaging time (s)
@@ -2657,8 +2772,8 @@ timecode(
)
{
struct sync *sp;
- int year, day, hour, minute, second, frac, dut;
- char synchar, qual, leapchar, dst;
+ int year, day, hour, minute, second, dut;
+ char synchar, leapchar, dst;
char cptr[50];
@@ -2666,49 +2781,30 @@ timecode(
* Common fixed-format fields
*/
synchar = (up->status & INSYNC) ? ' ' : '?';
- qual = 0;
- if (up->alarm & (3 << DECERR))
- qual |= 0x1;
- if (up->alarm & (3 << SYMERR))
- qual |= 0x2;
- if (up->alarm & (3 << MODERR))
- qual |= 0x4;
- if (up->alarm & (3 << SYNERR))
- qual |= 0x8;
- year = up->decvec[7].digit + up->decvec[7].digit * 10;
- if (year < UTCYEAR)
- year += 2000;
- else
- year += 1900;
- day = up->decvec[4].digit + up->decvec[5].digit * 10 +
- up->decvec[6].digit * 100;
- hour = up->decvec[2].digit + up->decvec[3].digit * 10;
- minute = up->decvec[0].digit + up->decvec[1].digit * 10;
- second = up->tsec;
- frac = (up->tphase * 1000) / SECOND;
+ year = up->decvec[YR].digit + up->decvec[YR + 1].digit * 10 +
+ 2000;
+ day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 +
+ up->decvec[DA + 2].digit * 100;
+ hour = up->decvec[HR].digit + up->decvec[HR + 1].digit * 10;
+ minute = up->decvec[MN].digit + up->decvec[MN + 1].digit * 10;
+ second = 0;
leapchar = (up->misc & SECWAR) ? 'L' : ' ';
dst = dstcod[(up->misc >> 4) & 0x3];
dut = up->misc & 0x7;
if (!(up->misc & DUTS))
dut = -dut;
- sprintf(ptr, "%c%1X", synchar, qual);
- sprintf(cptr, " %4d %03d %02d:%02d:%02d.%.03d %c%c %+d",
- year, day, hour, minute, second, frac, leapchar, dst, dut);
+ sprintf(ptr, "%c%1X", synchar, up->alarm);
+ sprintf(cptr, " %4d %03d %02d:%02d:%02d %c%c %+d",
+ year, day, hour, minute, second, leapchar, dst, dut);
strcat(ptr, cptr);
/*
* Specific variable-format fields
*/
sp = up->sptr;
- if (sp != 0)
- sprintf(cptr, " %d %d %s %d %d %.1f %d", up->minset,
- up->mitig[up->dchan].gain, sp->ident, sp->count,
- up->errcnt, up->freq / SECOND * 1e6, MINAVG <<
- up->avgint);
- else
- sprintf(cptr, " %d %d X 0 %d %.1f %d", up->minset,
- up->mitig[up->dchan].gain, up->errcnt, up->freq /
- SECOND * 1e6, MINAVG << up->avgint);
+ sprintf(cptr, " %d %d %s %.0f %d %.1f %d", up->watch,
+ up->mitig[up->dchan].gain, sp->refid, wwv_metric(sp),
+ up->errbit, up->freq / SECOND * 1e6, up->avgint);
strcat(ptr, cptr);
return (strlen(ptr));
}
@@ -2717,9 +2813,10 @@ timecode(
/*
* wwv_gain - adjust codec gain
*
- * This routine is called once each second. If the signal envelope
- * amplitude is too low, the codec gain is bumped up by four units; if
- * too high, it is bumped down. The decoder is relatively insensitive to
+ * This routine is called at the end of each second. It counts the
+ * number of signal clips above the MAXSIG threshold during the previous
+ * second. If there are no clips, the gain is bumped up; if too many
+ * clips, it is bumped down. The decoder is relatively insensitive to
* amplitude, so this crudity works just fine. The input port is set and
* the error flag is cleared, mostly to be ornery.
*/
@@ -2741,15 +2838,19 @@ wwv_gain(
*/
if (up->clipcnt == 0) {
up->gain += 4;
- if (up->gain > 255)
- up->gain = 255;
- } else if (up->clipcnt > SECOND / 100) {
+ if (up->gain > MAXGAIN)
+ up->gain = MAXGAIN;
+ } else if (up->clipcnt > MAXCLP) {
up->gain -= 4;
if (up->gain < 0)
up->gain = 0;
}
- audio_gain(up->gain, up->port);
+ audio_gain(up->gain, up->mongain, up->port);
up->clipcnt = 0;
+#if DEBUG
+ if (debug > 1)
+ audio_show();
+#endif
}
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