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Diffstat (limited to 'contrib/ntp/ntpd/refclock_wwv.c')
| -rw-r--r-- | contrib/ntp/ntpd/refclock_wwv.c | 2859 |
1 files changed, 0 insertions, 2859 deletions
diff --git a/contrib/ntp/ntpd/refclock_wwv.c b/contrib/ntp/ntpd/refclock_wwv.c deleted file mode 100644 index 11aae7f..0000000 --- a/contrib/ntp/ntpd/refclock_wwv.c +++ /dev/null @@ -1,2859 +0,0 @@ -/* - * refclock_wwv - clock driver for NIST WWV/H time/frequency station - */ -#ifdef HAVE_CONFIG_H -#include <config.h> -#endif - -#if defined(REFCLOCK) && defined(CLOCK_WWV) - -#include "ntpd.h" -#include "ntp_io.h" -#include "ntp_refclock.h" -#include "ntp_calendar.h" -#include "ntp_stdlib.h" -#include "audio.h" - -#include <stdio.h> -#include <ctype.h> -#include <math.h> -#ifdef HAVE_SYS_IOCTL_H -# include <sys/ioctl.h> -#endif /* HAVE_SYS_IOCTL_H */ - -#define ICOM 1 - -#ifdef ICOM -#include "icom.h" -#endif /* ICOM */ - -/* - * Audio WWV/H demodulator/decoder - * - * 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. 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 - * program as propagation conditions change throughout the day and - * night. - * - * The driver receives, demodulates and decodes the radio signals when - * 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 - * 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 - * identification feature. - * - * The ICOM code is normally compiled in the driver. It isn't used, - * unless the mode keyword on the server configuration command specifies - * a nonzero ICOM ID select code. The C-IV trace is turned on if the - * debug level is greater than one. - */ -/* - * 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 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. /* 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 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 MAXERR 30 /* max data bit errors in minute */ -#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) - * - * 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 and BGATE is set if a BCD digit - * bit is invalid. SFLAG is set when during seconds 59, 0 and 1 while - * 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 FGATE 0x0010 /* frequency gate */ -#define DGATE 0x0020 /* data bit error */ -#define BGATE 0x0040 /* BCD digit bit error */ -#define SFLAG 0x1000 /* probe flag */ -#define LEPDAY 0x2000 /* leap second day */ -#define LEPSEC 0x4000 /* leap second minute */ - -/* - * Station scoreboard bits - * - * These are used to establish the signal quality for each of the five - * frequencies and two stations. - */ -#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 */ - -/* - * Alarm status bits (alarm) - * - * These bits indicate various alarm conditions, which are decoded to - * 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 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 */ - -/* - * 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 /* station acquisition timeout */ -#define DIGIT 30 /* minute unit digit 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 driver. The values defined here may be on the - * adventurous side in the interest of the highest sensitivity. - */ -#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. /* 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. The increments are for 4.5-deg sine - * 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 */ -#define MAXAVG 1024 /* max time constant */ -#define TCONST 16 /* data bit/digit time constant */ - -/* - * Miscellaneous status bits (misc) - * - * These bits correspond to designated bits in the WWV/H timecode. The - * bit probabilities are exponentially averaged over several minutes and - * processed by a integrator and threshold. - */ -#define DUT1 0x01 /* 56 DUT .1 */ -#define DUT2 0x02 /* 57 DUT .2 */ -#define DUT4 0x04 /* 58 DUT .4 */ -#define DUTS 0x08 /* 50 DUT sign */ -#define DST1 0x10 /* 55 DST1 leap warning */ -#define DST2 0x20 /* 2 DST2 DST1 delayed one day */ -#define SECWAR 0x40 /* 3 leap second warning */ - -/* - * 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 (.0011 + .0047 + .0002) /* net system delay (s) */ - -/* - * Table of sine values at 4.5-degree increments. This is used by the - * synchronous matched filter demodulators. The integral of sine-squared - * over one complete cycle is PI, so the table is normallized by 1 / PI. - */ -double sintab[] = { - 0.000000e+00, 2.497431e-02, 4.979464e-02, 7.430797e-02, /* 0-3 */ - 9.836316e-02, 1.218119e-01, 1.445097e-01, 1.663165e-01, /* 4-7 */ - 1.870979e-01, 2.067257e-01, 2.250791e-01, 2.420447e-01, /* 8-11 */ - 2.575181e-01, 2.714038e-01, 2.836162e-01, 2.940800e-01, /* 12-15 */ - 3.027307e-01, 3.095150e-01, 3.143910e-01, 3.173286e-01, /* 16-19 */ - 3.183099e-01, 3.173286e-01, 3.143910e-01, 3.095150e-01, /* 20-23 */ - 3.027307e-01, 2.940800e-01, 2.836162e-01, 2.714038e-01, /* 24-27 */ - 2.575181e-01, 2.420447e-01, 2.250791e-01, 2.067257e-01, /* 28-31 */ - 1.870979e-01, 1.663165e-01, 1.445097e-01, 1.218119e-01, /* 32-35 */ - 9.836316e-02, 7.430797e-02, 4.979464e-02, 2.497431e-02, /* 36-39 */ --0.000000e+00, -2.497431e-02, -4.979464e-02, -7.430797e-02, /* 40-43 */ --9.836316e-02, -1.218119e-01, -1.445097e-01, -1.663165e-01, /* 44-47 */ --1.870979e-01, -2.067257e-01, -2.250791e-01, -2.420447e-01, /* 48-51 */ --2.575181e-01, -2.714038e-01, -2.836162e-01, -2.940800e-01, /* 52-55 */ --3.027307e-01, -3.095150e-01, -3.143910e-01, -3.173286e-01, /* 56-59 */ --3.183099e-01, -3.173286e-01, -3.143910e-01, -3.095150e-01, /* 60-63 */ --3.027307e-01, -2.940800e-01, -2.836162e-01, -2.714038e-01, /* 64-67 */ --2.575181e-01, -2.420447e-01, -2.250791e-01, -2.067257e-01, /* 68-71 */ --1.870979e-01, -1.663165e-01, -1.445097e-01, -1.218119e-01, /* 72-75 */ --9.836316e-02, -7.430797e-02, -4.979464e-02, -2.497431e-02, /* 76-79 */ - 0.000000e+00}; /* 80 */ - -/* - * Decoder operations at the end of each second are driven by a state - * machine. The transition matrix consists of a dispatch table indexed - * by second number. Each entry in the table contains a case switch - * number and argument. - */ -struct progx { - int sw; /* case switch number */ - int arg; /* argument */ -}; - -/* - * Case switch numbers - */ -#define IDLE 0 /* no operation */ -#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 - */ -#define MN 0 /* minute digits (2) */ -#define HR 2 /* hour digits (2) */ -#define DA 4 /* day digits (3) */ -#define YR 7 /* year digits (2) */ - -struct progx progx[] = { - {SYNC2, 0}, /* 0 latch sync max */ - {SYNC3, 0}, /* 1 QSY data channel */ - {MSCBIT, DST2}, /* 2 dst2 */ - {MSCBIT, SECWAR}, /* 3 lw */ - {COEF, 0}, /* 4 1 year units */ - {COEF, 1}, /* 5 2 */ - {COEF, 2}, /* 6 4 */ - {COEF, 3}, /* 7 8 */ - {DECIM9, YR}, /* 8 */ - {IDLE, 0}, /* 9 p1 */ - {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 */ - {COEF, 2}, /* 17 40 */ - {COEF2, 3}, /* 18 80 (not used) */ - {DECIM6, MN + 1}, /* 19 p2 */ - {COEF, 0}, /* 20 1 hour units */ - {COEF, 1}, /* 21 2 */ - {COEF, 2}, /* 22 4 */ - {COEF, 3}, /* 23 8 */ - {DECIM9, HR}, /* 24 */ - {COEF, 0}, /* 25 10 hour tens */ - {COEF, 1}, /* 26 20 */ - {COEF2, 2}, /* 27 40 (not used) */ - {COEF2, 3}, /* 28 80 (not used) */ - {DECIM2, HR + 1}, /* 29 p3 */ - {COEF, 0}, /* 30 1 day units */ - {COEF, 1}, /* 31 2 */ - {COEF, 2}, /* 32 4 */ - {COEF, 3}, /* 33 8 */ - {DECIM9, DA}, /* 34 */ - {COEF, 0}, /* 35 10 day tens */ - {COEF, 1}, /* 36 20 */ - {COEF, 2}, /* 37 40 */ - {COEF, 3}, /* 38 80 */ - {DECIM9, DA + 1}, /* 39 p4 */ - {COEF, 0}, /* 40 100 day hundreds */ - {COEF, 1}, /* 41 200 */ - {COEF2, 2}, /* 42 400 (not used) */ - {COEF2, 3}, /* 43 800 (not used) */ - {DECIM3, DA + 2}, /* 44 */ - {IDLE, 0}, /* 45 */ - {IDLE, 0}, /* 46 */ - {IDLE, 0}, /* 47 */ - {IDLE, 0}, /* 48 */ - {IDLE, 0}, /* 49 p5 */ - {MSCBIT, DUTS}, /* 50 dut+- */ - {COEF, 0}, /* 51 10 year tens */ - {COEF, 1}, /* 52 20 */ - {COEF, 2}, /* 53 40 */ - {COEF, 3}, /* 54 80 */ - {MSC20, DST1}, /* 55 dst1 */ - {MSCBIT, DUT1}, /* 56 0.1 dut */ - {MSCBIT, DUT2}, /* 57 0.2 */ - {MSC21, DUT4}, /* 58 0.4 QSY probe channel */ - {MIN1, 0}, /* 59 p6 latch sync min */ - {MIN2, 0} /* 60 leap second */ -}; - -/* - * BCD coefficients for maximum likelihood digit decode - */ -#define P15 1. /* max positive number */ -#define N15 -1. /* max negative number */ - -/* - * Digits 0-9 - */ -#define P9 (P15 / 4) /* mark (+1) */ -#define N9 (N15 / 4) /* space (-1) */ - -double bcd9[][4] = { - {N9, N9, N9, N9}, /* 0 */ - {P9, N9, N9, N9}, /* 1 */ - {N9, P9, N9, N9}, /* 2 */ - {P9, P9, N9, N9}, /* 3 */ - {N9, N9, P9, N9}, /* 4 */ - {P9, N9, P9, N9}, /* 5 */ - {N9, P9, P9, N9}, /* 6 */ - {P9, P9, P9, N9}, /* 7 */ - {N9, N9, N9, P9}, /* 8 */ - {P9, N9, N9, P9}, /* 9 */ - {0, 0, 0, 0} /* backstop */ -}; - -/* - * Digits 0-6 (minute tens) - */ -#define P6 (P15 / 3) /* mark (+1) */ -#define N6 (N15 / 3) /* space (-1) */ - -double bcd6[][4] = { - {N6, N6, N6, 0}, /* 0 */ - {P6, N6, N6, 0}, /* 1 */ - {N6, P6, N6, 0}, /* 2 */ - {P6, P6, N6, 0}, /* 3 */ - {N6, N6, P6, 0}, /* 4 */ - {P6, N6, P6, 0}, /* 5 */ - {N6, P6, P6, 0}, /* 6 */ - {0, 0, 0, 0} /* backstop */ -}; - -/* - * Digits 0-3 (day hundreds) - */ -#define P3 (P15 / 2) /* mark (+1) */ -#define N3 (N15 / 2) /* space (-1) */ - -double bcd3[][4] = { - {N3, N3, 0, 0}, /* 0 */ - {P3, N3, 0, 0}, /* 1 */ - {N3, P3, 0, 0}, /* 2 */ - {P3, P3, 0, 0}, /* 3 */ - {0, 0, 0, 0} /* backstop */ -}; - -/* - * Digits 0-2 (hour tens) - */ -#define P2 (P15 / 2) /* mark (+1) */ -#define N2 (N15 / 2) /* space (-1) */ - -double bcd2[][4] = { - {N2, N2, 0, 0}, /* 0 */ - {P2, N2, 0, 0}, /* 1 */ - {N2, P2, 0, 0}, /* 2 */ - {0, 0, 0, 0} /* backstop */ -}; - -/* - * DST decode (DST2 DST1) for prettyprint - */ -char dstcod[] = { - 'S', /* 00 standard time */ - 'I', /* 01 set clock ahead at 0200 local */ - 'O', /* 10 set clock back at 0200 local */ - 'D' /* 11 daylight time */ -}; - -/* - * The decoding matrix consists of nine row vectors, one for each digit - * of the timecode. The digits are stored from least to most significant - * order. The maximum likelihood timecode is formed from the digits - * corresponding to the maximum likelihood values reading in the - * opposite order: yy ddd hh:mm. - */ -struct decvec { - int radix; /* radix (3, 4, 6, 10) */ - int digit; /* current clock digit */ - int mldigit; /* maximum likelihood digit */ - int phase; /* maximum likelihood digit phase */ - int count; /* match count */ - double digprb; /* max digit probability */ - double digsnr; /* likelihood function (dB) */ - double like[10]; /* likelihood integrator 0-9 */ -}; - -/* - * The station structure is used to acquire the minute pulse from WWV - * and/or WWVH. These stations are distinguished by the frequency used - * for the second and minute sync pulses, 1000 Hz for WWV and 1200 Hz - * for WWVH. Other than frequency, the format is the same. - */ -struct sync { - 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; /* sync envelope at 59, 1 s */ - double synsnr; /* sync signal SNR */ - int count; /* bit counter */ - char refid[5]; /* reference identifier */ - int select; /* select bits */ - int reach; /* reachability register */ -}; - -/* - * The channel structure is used to mitigate between channels. - */ -struct chan { - int gain; /* audio gain */ - 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 */ -}; - -/* - * WWV unit control structure - */ -struct wwvunit { - l_fp timestamp; /* audio sample timestamp */ - l_fp tick; /* audio sample increment */ - double phase, freq; /* logical clock phase and frequency */ - double monitor; /* audio monitor point */ - int fd_icom; /* ICOM file descriptor */ - int errflg; /* error flags */ - 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 */ -#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; /* 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; /* second sample counter */ - long mphase; /* minute sample counter */ - - /* - * Variables used to mitigate which channel to use - */ - struct chan mitig[NCHAN]; /* channel data */ - struct sync *sptr; /* station pointer */ - int dchan; /* data channel */ - int schan; /* probe channel */ - int achan; /* active channel */ - - /* - * Variables used by the clock state machine - */ - struct decvec decvec[9]; /* decoding matrix */ - int rsec; /* seconds counter */ - int digcnt; /* count of digits synchronized */ - - /* - * Variables used to estimate signal levels and bit/digit - * probabilities - */ - double sigsig; /* data max signal */ - double sigamp; /* data max envelope (square) */ - double noiamp; /* data noise envelope (square) */ - double datsnr; /* data SNR (dB) */ - - /* - * Variables used to establish status and alarm conditions - */ - int status; /* status bits */ - int alarm; /* alarm flashers */ - int misc; /* miscellaneous timecode bits */ - int errcnt; /* data bit error counter */ - int errbit; /* data bit errors in minute */ -}; - -/* - * Function prototypes - */ -static int wwv_start P((int, struct peer *)); -static void wwv_shutdown P((int, struct peer *)); -static void wwv_receive P((struct recvbuf *)); -static void wwv_poll P((int, struct peer *)); - -/* - * More function prototypes - */ -static void wwv_epoch P((struct peer *)); -static void wwv_rf P((struct peer *, double)); -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, int)); -static void wwv_corr4 P((struct peer *, struct decvec *, - double [], double [][4])); -static void wwv_gain P((struct peer *)); -static void wwv_tsec P((struct wwvunit *)); -static double wwv_data P((struct wwvunit *, double)); -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) */ - -/* - * Transfer vector - */ -struct refclock refclock_wwv = { - wwv_start, /* start up driver */ - wwv_shutdown, /* shut down driver */ - wwv_poll, /* transmit poll message */ - noentry, /* not used (old wwv_control) */ - noentry, /* initialize driver (not used) */ - noentry, /* not used (old wwv_buginfo) */ - NOFLAGS /* not used */ -}; - - -/* - * wwv_start - open the devices and initialize data for processing - */ -static int -wwv_start( - int unit, /* instance number (used by PCM) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; -#ifdef ICOM - int temp; -#endif /* ICOM */ - - /* - * Local variables - */ - int fd; /* file descriptor */ - int i; /* index */ - double step; /* codec adjustment */ - - /* - * Open audio device - */ - fd = audio_init(DEVICE_AUDIO, AUDIO_BUFSIZ, unit); - if (fd < 0) - return (0); -#ifdef DEBUG - if (debug) - audio_show(); -#endif - - /* - * Allocate and initialize unit structure - */ - if (!(up = (struct wwvunit *)emalloc(sizeof(struct wwvunit)))) { - close(fd); - return (0); - } - memset(up, 0, sizeof(struct wwvunit)); - pp = peer->procptr; - pp->unitptr = (caddr_t)up; - pp->io.clock_recv = wwv_receive; - pp->io.srcclock = (caddr_t)peer; - pp->io.datalen = 0; - pp->io.fd = fd; - if (!io_addclock(&pp->io)) { - close(fd); - free(up); - return (0); - } - - /* - * Initialize miscellaneous variables - */ - peer->precision = PRECISION; - pp->clockdesc = DESCRIPTION; - - /* - * The companded samples are encoded sign-magnitude. The table - * contains all the 256 values in the interest of speed. - */ - up->comp[0] = up->comp[OFFSET] = 0.; - up->comp[1] = 1; up->comp[OFFSET + 1] = -1.; - up->comp[2] = 3; up->comp[OFFSET + 2] = -3.; - step = 2.; - for (i = 3; i < OFFSET; i++) { - up->comp[i] = up->comp[i - 1] + step; - up->comp[OFFSET + i] = -up->comp[i]; - if (i % 16 == 0) - step *= 2.; - } - DTOLFP(1. / SECOND, &up->tick); - - /* - * Initialize the decoding matrix with the radix for each digit - * position. - */ - up->decvec[MN].radix = 10; /* minutes */ - up->decvec[MN + 1].radix = 6; - up->decvec[HR].radix = 10; /* hours */ - up->decvec[HR + 1].radix = 3; - up->decvec[DA].radix = 10; /* days */ - up->decvec[DA + 1].radix = 10; - up->decvec[DA + 2].radix = 4; - up->decvec[YR].radix = 10; /* years */ - up->decvec[YR + 1].radix = 10; - wwv_newgame(peer); - up->schan = up->achan = 3; - - /* - * Initialize autotune if available. Start out at 15 MHz. Note - * that the ICOM select code must be less than 128, so the high - * order bit can be used to select the line speed. - */ -#ifdef ICOM - temp = 0; -#ifdef DEBUG - if (debug > 1) - temp = P_TRACE; -#endif - if (peer->ttl != 0) { - if (peer->ttl & 0x80) - up->fd_icom = icom_init("/dev/icom", B1200, - temp); - else - up->fd_icom = icom_init("/dev/icom", B9600, - temp); - } - if (up->fd_icom > 0) { - if ((temp = wwv_qsy(peer, up->schan)) != 0) { - NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) - 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 */ - return (1); -} - - -/* - * wwv_shutdown - shut down the clock - */ -static void -wwv_shutdown( - int unit, /* instance number (not used) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - io_closeclock(&pp->io); - if (up->fd_icom > 0) - close(up->fd_icom); - free(up); -} - - -/* - * wwv_receive - receive data from the audio device - * - * This routine reads input samples and adjusts the logical clock to - * track the A/D sample clock by dropping or duplicating codec samples. - * It also controls the A/D signal level with an AGC loop to mimimize - * quantization noise and avoid overload. - */ -static void -wwv_receive( - struct recvbuf *rbufp /* receive buffer structure pointer */ - ) -{ - struct peer *peer; - struct refclockproc *pp; - struct wwvunit *up; - - /* - * Local variables - */ - double sample; /* codec sample */ - u_char *dpt; /* buffer pointer */ - int bufcnt; /* buffer counter */ - l_fp ltemp; - - peer = (struct peer *)rbufp->recv_srcclock; - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * Main loop - read until there ain't no more. Note codec - * samples are bit-inverted. - */ - DTOLFP((double)rbufp->recv_length / SECOND, <emp); - L_SUB(&rbufp->recv_time, <emp); - up->timestamp = rbufp->recv_time; - dpt = rbufp->recv_buffer; - for (bufcnt = 0; bufcnt < rbufp->recv_length; bufcnt++) { - sample = up->comp[~*dpt++ & 0xff]; - - /* - * Clip noise spikes greater than MAXSIG. If no clips, - * increase the gain a tad; if the clips are too high, - * decrease a tad. - */ - if (sample > MAXSIG) { - sample = MAXSIG; - up->clipcnt++; - } else if (sample < -MAXSIG) { - sample = -MAXSIG; - up->clipcnt++; - } - - /* - * 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) { - up->phase += 1.; - wwv_rf(peer, sample); - wwv_rf(peer, sample); - } else { - wwv_rf(peer, sample); - } - L_ADD(&up->timestamp, &up->tick); - } - - /* - * 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) - up->mongain = MONGAIN; - else - up->mongain = 0; -} - - -/* - * wwv_poll - called by the transmit procedure - * - * 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( - int unit, /* instance number (not used) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - if (pp->coderecv == pp->codeproc) - up->errflg = CEVNT_TIMEOUT; - if (up->errflg) - refclock_report(peer, up->errflg); - up->errflg = 0; - pp->polls++; -} - - -/* - * wwv_rf - process signals and demodulate to baseband - * - * This routine grooms and filters decompanded raw audio samples. The - * output signals include the 100-Hz baseband data signal in quadrature - * form, plus the epoch index of the second sync signal and the second - * index of the minute sync signal. - * - * 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. - * - * 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 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( - struct peer *peer, /* peerstructure pointer */ - double isig /* input signal */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - struct sync *sp; - - static double lpf[5]; /* 150-Hz lpf delay line */ - double data; /* lpf output */ - static double bpf[9]; /* 1000/1200-Hz bpf delay line */ - double syncx; /* bpf output */ - static double mf[41]; /* 1000/1200-Hz mf delay line */ - double mfsync; /* mf output */ - - static int iptr; /* data channel pointer */ - static double ibuf[DATSIZ]; /* data I channel delay line */ - static double qbuf[DATSIZ]; /* data Q channel delay line */ - - static int jptr; /* sync channel pointer */ - static double cibuf[SYNSIZ]; /* wwv I channel delay line */ - static double cqbuf[SYNSIZ]; /* wwv Q channel delay line */ - static double ciamp; /* wwv I channel amplitude */ - static double cqamp; /* wwv Q channel amplitude */ - static int csinptr; /* wwv channel phase */ - static double hibuf[SYNSIZ]; /* wwvh I channel delay line */ - static double hqbuf[SYNSIZ]; /* wwvh Q channel delay line */ - static double hiamp; /* wwvh I channel amplitude */ - static double hqamp; /* wwvh Q channel amplitude */ - static int hsinptr; /* wwvh channels phase */ - - static double epobuf[SECOND]; /* epoch sync comb filter */ - static double epomax; /* epoch sync amplitude buffer */ - static int epopos; /* epoch sync position buffer */ - - static int iniflg; /* initialization flag */ - 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)); - memset((char *)bpf, 0, sizeof(bpf)); - memset((char *)mf, 0, sizeof(mf)); - memset((char *)ibuf, 0, sizeof(ibuf)); - memset((char *)qbuf, 0, sizeof(qbuf)); - memset((char *)cibuf, 0, sizeof(cibuf)); - memset((char *)cqbuf, 0, sizeof(cqbuf)); - memset((char *)hibuf, 0, sizeof(hibuf)); - memset((char *)hqbuf, 0, sizeof(hqbuf)); - memset((char *)epobuf, 0, sizeof(epobuf)); - } - - /* - * Baseband data demodulation. The 100-Hz subcarrier is - * extracted using a 150-Hz IIR lowpass filter. This attenuates - * the 1000/1200-Hz sync signals, as well as the 440-Hz and - * 600-Hz tones and most of the noise and voice modulation - * components. - * - * Matlab IIR 4th-order IIR elliptic, 150 Hz lowpass, 0.2 dB - * passband ripple, -50 dB stopband ripple. - */ - data = (lpf[4] = lpf[3]) * 8.360961e-01; - data += (lpf[3] = lpf[2]) * -3.481740e+00; - data += (lpf[2] = lpf[1]) * 5.452988e+00; - data += (lpf[1] = lpf[0]) * -3.807229e+00; - lpf[0] = isig - data; - data = lpf[0] * 3.281435e-03 - + lpf[1] * -1.149947e-02 - + lpf[2] * 1.654858e-02 - + lpf[3] * -1.149947e-02 - + lpf[4] * 3.281435e-03; - - /* - * The I and Q quadrature data signals are produced by - * 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. - */ - i = up->datapt; - up->datapt = (up->datapt + IN100) % 80; - dtemp = sintab[i] * data / DATSIZ * DGAIN; - up->irig -= ibuf[iptr]; - ibuf[iptr] = dtemp; - up->irig += dtemp; - i = (i + 20) % 80; - dtemp = sintab[i] * data / DATSIZ * DGAIN; - up->qrig -= qbuf[iptr]; - qbuf[iptr] = dtemp; - up->qrig += dtemp; - iptr = (iptr + 1) % DATSIZ; - - /* - * Baseband sync demodulation. The 1000/1200 sync signals are - * extracted using a 600-Hz IIR bandpass filter. This removes - * the 100-Hz data subcarrier, as well as the 440-Hz and 600-Hz - * tones and most of the noise and voice modulation components. - * - * Matlab 4th-order IIR elliptic, 800-1400 Hz bandpass, 0.2 dB - * passband ripple, -50 dB stopband ripple. - */ - syncx = (bpf[8] = bpf[7]) * 4.897278e-01; - syncx += (bpf[7] = bpf[6]) * -2.765914e+00; - syncx += (bpf[6] = bpf[5]) * 8.110921e+00; - syncx += (bpf[5] = bpf[4]) * -1.517732e+01; - syncx += (bpf[4] = bpf[3]) * 1.975197e+01; - syncx += (bpf[3] = bpf[2]) * -1.814365e+01; - syncx += (bpf[2] = bpf[1]) * 1.159783e+01; - syncx += (bpf[1] = bpf[0]) * -4.735040e+00; - bpf[0] = isig - syncx; - syncx = bpf[0] * 8.203628e-03 - + bpf[1] * -2.375732e-02 - + bpf[2] * 3.353214e-02 - + bpf[3] * -4.080258e-02 - + bpf[4] * 4.605479e-02 - + bpf[5] * -4.080258e-02 - + bpf[6] * 3.353214e-02 - + bpf[7] * -2.375732e-02 - + bpf[8] * 8.203628e-03; - - /* - * The I and Q quadrature minute sync signals are produced by - * multiplying the filtered signal by 1000-Hz (WWV) and 1200-Hz - * (WWVH) sine and cosine signals, respectively. The resulting - * 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; - ciamp = ciamp - cibuf[jptr] + dtemp; - cibuf[jptr] = dtemp; - i = (i + 20) % 80; - 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; - 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; - hiamp = hiamp - hibuf[jptr] + dtemp; - hibuf[jptr] = dtemp; - i = (i + 20) % 80; - 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; - 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) { - up->watch++; - 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. - */ - 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); - } -#endif /* ICOM */ - } - } else { - - /* - * If the leap bit is set, set the minute epoch - * back one second so the station processes - * don't miss a beat. - */ - if (up->status & LEPSEC) { - up->mphase -= SECOND; - if (up->mphase < 0) - up->mphase += MINUTE; - } - } - } - - /* - * 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->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 (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) { - pdelay = (int)(pp->fudgetime1 * SECOND); - - /* - * WWV FIR matched filter, five cycles of 1000-Hz - * sinewave. - */ - mf[40] = mf[39]; - mfsync = (mf[39] = mf[38]) * 4.224514e-02; - mfsync += (mf[38] = mf[37]) * 5.974365e-02; - mfsync += (mf[37] = mf[36]) * 4.224514e-02; - mf[36] = mf[35]; - mfsync += (mf[35] = mf[34]) * -4.224514e-02; - mfsync += (mf[34] = mf[33]) * -5.974365e-02; - mfsync += (mf[33] = mf[32]) * -4.224514e-02; - mf[32] = mf[31]; - mfsync += (mf[31] = mf[30]) * 4.224514e-02; - mfsync += (mf[30] = mf[29]) * 5.974365e-02; - mfsync += (mf[29] = mf[28]) * 4.224514e-02; - mf[28] = mf[27]; - mfsync += (mf[27] = mf[26]) * -4.224514e-02; - mfsync += (mf[26] = mf[25]) * -5.974365e-02; - mfsync += (mf[25] = mf[24]) * -4.224514e-02; - mf[24] = mf[23]; - mfsync += (mf[23] = mf[22]) * 4.224514e-02; - mfsync += (mf[22] = mf[21]) * 5.974365e-02; - mfsync += (mf[21] = mf[20]) * 4.224514e-02; - mf[20] = mf[19]; - mfsync += (mf[19] = mf[18]) * -4.224514e-02; - mfsync += (mf[18] = mf[17]) * -5.974365e-02; - mfsync += (mf[17] = mf[16]) * -4.224514e-02; - mf[16] = mf[15]; - mfsync += (mf[15] = mf[14]) * 4.224514e-02; - mfsync += (mf[14] = mf[13]) * 5.974365e-02; - mfsync += (mf[13] = mf[12]) * 4.224514e-02; - mf[12] = mf[11]; - mfsync += (mf[11] = mf[10]) * -4.224514e-02; - mfsync += (mf[10] = mf[9]) * -5.974365e-02; - mfsync += (mf[9] = mf[8]) * -4.224514e-02; - mf[8] = mf[7]; - mfsync += (mf[7] = mf[6]) * 4.224514e-02; - mfsync += (mf[6] = mf[5]) * 5.974365e-02; - mfsync += (mf[5] = mf[4]) * 4.224514e-02; - mf[4] = mf[3]; - mfsync += (mf[3] = mf[2]) * -4.224514e-02; - mfsync += (mf[2] = mf[1]) * -5.974365e-02; - mfsync += (mf[1] = mf[0]) * -4.224514e-02; - mf[0] = syncx; - } else if (up->status & SELH) { - pdelay = (int)(pp->fudgetime2 * SECOND); - - /* - * WWVH FIR matched filter, six cycles of 1200-Hz - * sinewave. - */ - mf[40] = mf[39]; - mfsync = (mf[39] = mf[38]) * 4.833363e-02; - mfsync += (mf[38] = mf[37]) * 5.681959e-02; - mfsync += (mf[37] = mf[36]) * 1.846180e-02; - mfsync += (mf[36] = mf[35]) * -3.511644e-02; - mfsync += (mf[35] = mf[34]) * -5.974365e-02; - mfsync += (mf[34] = mf[33]) * -3.511644e-02; - mfsync += (mf[33] = mf[32]) * 1.846180e-02; - mfsync += (mf[32] = mf[31]) * 5.681959e-02; - mfsync += (mf[31] = mf[30]) * 4.833363e-02; - mf[30] = mf[29]; - mfsync += (mf[29] = mf[28]) * -4.833363e-02; - mfsync += (mf[28] = mf[27]) * -5.681959e-02; - mfsync += (mf[27] = mf[26]) * -1.846180e-02; - mfsync += (mf[26] = mf[25]) * 3.511644e-02; - mfsync += (mf[25] = mf[24]) * 5.974365e-02; - mfsync += (mf[24] = mf[23]) * 3.511644e-02; - mfsync += (mf[23] = mf[22]) * -1.846180e-02; - mfsync += (mf[22] = mf[21]) * -5.681959e-02; - mfsync += (mf[21] = mf[20]) * -4.833363e-02; - mf[20] = mf[19]; - mfsync += (mf[19] = mf[18]) * 4.833363e-02; - mfsync += (mf[18] = mf[17]) * 5.681959e-02; - mfsync += (mf[17] = mf[16]) * 1.846180e-02; - mfsync += (mf[16] = mf[15]) * -3.511644e-02; - mfsync += (mf[15] = mf[14]) * -5.974365e-02; - mfsync += (mf[14] = mf[13]) * -3.511644e-02; - mfsync += (mf[13] = mf[12]) * 1.846180e-02; - mfsync += (mf[12] = mf[11]) * 5.681959e-02; - mfsync += (mf[11] = mf[10]) * 4.833363e-02; - mf[10] = mf[9]; - mfsync += (mf[9] = mf[8]) * -4.833363e-02; - mfsync += (mf[8] = mf[7]) * -5.681959e-02; - mfsync += (mf[7] = mf[6]) * -1.846180e-02; - mfsync += (mf[6] = mf[5]) * 3.511644e-02; - mfsync += (mf[5] = mf[4]) * 5.974365e-02; - mfsync += (mf[4] = mf[3]) * 3.511644e-02; - mfsync += (mf[3] = mf[2]) * -1.846180e-02; - mfsync += (mf[2] = mf[1]) * -5.681959e-02; - mfsync += (mf[1] = mf[0]) * -4.833363e-02; - mf[0] = syncx; - } else { - mfsync = 0; - pdelay = 0; - } - - /* - * 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. - */ - dtemp = (epobuf[epoch] += (mfsync - epobuf[epoch]) / - up->avgint); - if (dtemp > epomax) { - epomax = dtemp; - 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); - } -} - - -/* - * wwv_qrz - identify and acquire WWV/WWVH minute sync pulse - * - * 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 - * frequency in turn for the minute pulse from either station, which - * 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. 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, /* peer structure pointer */ - struct sync *sp, /* sync channel structure */ - 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, fpoch; - int isgood; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * Find the sample with peak energy, which defines the minute - * 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; - - /* - * 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->synmax, sp->synmin); - isgood = isgood && sp->synmax > ATHR && snr > ASNR; - 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 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 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 %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->lastpos = sp->pos; - sp->maxamp = sp->noiamp = 0; - } -} - - -/* - * wwv_endpoc - identify and acquire second sync pulse - * - * 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). - * - * 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 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 */ - int epopos /* epoch max position */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - static int epoch_mf[3]; /* epoch median filter */ - static int xepoch; /* last second epoch */ - static int zepoch; /* last averaging interval epoch */ - 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; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - if (!iniflg) { - iniflg = 1; - memset((char *)epoch_mf, 0, sizeof(epoch_mf)); - } - - /* - * A three-stage median filter is used to help denoise the - * 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]) - 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]) - 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 signal amplitude or SNR fall below thresholds or if no - * stations are heard, dim the second sync lamp and start over. - */ - 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 { - if (maxrun > 0 && mepoch == xepoch) { - maxrun += syncnt; - } else if (syncnt > maxrun) { - maxrun = syncnt; - mepoch = xepoch; - } - syncnt = 0; - } - if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & (SSYNC | - MSYNC))) { - sprintf(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); -#endif /* DEBUG */ - } - - /* - * 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 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 codec clock - * loop. It also affects the 100-Hz subcarrier loop and the bit - * and digit comparison counter thresholds. - */ - 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; - } - } - } - } - 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); -#endif /* DEBUG */ - } - up->status |= FGATE; - zepoch = mepoch; - avgcnt = syncnt = maxrun = 0; -} - - -/* - * wwv_epoch - epoch scanner - * - * 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 - * sync pulses. Therefore, the data subcarrier reference phase is - * disciplined using the hardlimited quadrature-phase signal sampled at - * the same time as the in-phase signal. The phase tracking loop uses - * phase adjustments of plus-minus one sample (125 us). - */ -static void -wwv_epoch( - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - struct chan *cp; - static double dpulse; /* data pulse length */ - double dtemp; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * Sample the minute sync pulse envelopes at epoch 800 for both - * the WWV and WWVH stations. This will be used later for - * 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. - */ - if (up->rphase == 800 * MS) { - up->repoch = up->yepoch; - cp = &up->mitig[up->achan]; - cp->wwv.synamp = cp->wwv.amp; - cp->wwvh.synamp = cp->wwvh.amp; - } - - /* - * 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; - - /* - * 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; - - /* - * 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. - */ - } 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 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->mphase % SECOND == up->repoch) { - up->datsnr = wwv_snr(up->sigsig, sqrt(up->noiamp)); - wwv_rsec(peer, dpulse); - wwv_gain(peer); - up->rphase = dpulse = 0; - } -} - - -/* - * wwv_rsec - process receiver second - * - * This routine is called at the end of each receiver second to - * implement the per-second state machine. The machine assembles BCD - * digit bits, decodes miscellaneous bits and dances the leap seconds. - * - * Normally, the minute has 60 seconds numbered 0-59. If the leap - * warning bit is set, the last minute (1439) of 30 June (day 181 or 182 - * 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. - */ -static void -wwv_rsec( - struct peer *peer, /* peer structure pointer */ - double dpulse - ) -{ - static int iniflg; /* initialization flag */ - static double bcddld[4]; /* BCD data bits */ - static double bitvec[61]; /* bit integrator for misc bits */ - struct refclockproc *pp; - 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; - if (!iniflg) { - iniflg = 1; - memset((char *)bitvec, 0, sizeof(bitvec)); - } - - /* - * The bit represents the probability of a hit on zero (negative - * values), a hit on one (positive values) or a miss (zero - * value). The likelihood vector is the exponential average of - * these probabilities. Only the bits of this vector - * corresponding to the miscellaneous bits of the timecode are - * used, but it's easier to do them all. After that, crank the - * seconds state machine. - */ - nsec = up->rsec + 1; - bit = wwv_data(up, dpulse); - bitvec[up->rsec] += (bit - bitvec[up->rsec]) / TCONST; - sw = progx[up->rsec].sw; - arg = progx[up->rsec].arg; - switch (sw) { - - /* - * Ignore this second. - */ - case IDLE: /* 9, 45-49 */ - break; - - /* - * Probe channel stuff - * - * The WWV/H format contains data pulses in second 59 (position - * 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]; - cp->wwv.synmax = sqrt(cp->wwv.synamp); - cp->wwvh.synmax = sqrt(cp->wwvh.synamp); - break; - - /* - * 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]; - 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 = sqrt((sp->synmin + sp->synamp) / 2.); - sp->synsnr = wwv_snr(sp->synmax, sp->synmin); - sp->select &= ~(SYNCNG | DATANG | ERRRNG); - if (sp->synmax < QTHR || sp->synsnr < QSNR) - sp->select |= SYNCNG; - 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 = sqrt((rp->synmin + rp->synamp) / 2.); - rp->synsnr = wwv_snr(rp->synmax, rp->synmin); - rp->select &= ~(SYNCNG | DATANG | ERRRNG); - if (rp->synmax < QTHR || rp->synsnr < QSNR) - rp->select |= SYNCNG; - 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++; - } - - /* - * 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); -#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; - - /* - * Save the bit probability in the BCD data vector at the index - * given by the argument. Note that all bits of the vector have - * to be above the data gate threshold for the digit to be - * considered valid. Bits not used in the digit are forced to - * zero and not checked for errors. - */ - 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; - break; - - case COEF2: /* 18, 27-28, 42-43 */ - bcddld[arg] = 0; - break; - - /* - * Correlate coefficient vector with each valid digit vector and - * save in decoding matrix. We step through the decoding matrix - * digits correlating each with the coefficients and saving the - * greatest and the next lower for later SNR calculation. - */ - case DECIM2: /* 29 */ - wwv_corr4(peer, &up->decvec[arg], bcddld, bcd2); - break; - - case DECIM3: /* 44 */ - wwv_corr4(peer, &up->decvec[arg], bcddld, bcd3); - break; - - case DECIM6: /* 19 */ - wwv_corr4(peer, &up->decvec[arg], bcddld, bcd6); - break; - - case DECIM9: /* 8, 14, 24, 34, 39 */ - wwv_corr4(peer, &up->decvec[arg], bcddld, bcd9); - break; - - /* - * 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. 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 */ - if (bitvec[up->rsec] > BTHR) - up->misc |= arg; - else if (bitvec[up->rsec] < -BTHR) - up->misc &= ~arg; - else - 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 |= 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 - * - * 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]; - cp->wwv.synmin = cp->wwv.synamp; - cp->wwvh.synmin = cp->wwvh.synamp; - - /* - * 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->status & SSYNC && up->digcnt >= 9) - up->status |= INSYNC; - if (up->status & LEPDAY) { - pp->leap = LEAP_ADDSECOND; - } else { - pp->leap = LEAP_NOWARNING; - 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; - - /* - * 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 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(<emp, &pp->lastref); - if (ltemp.l_f < 0) - ltemp.l_i = -1; - else - ltemp.l_i = 0; - pp->lastref = pp->lastrec; - if (!L_ISNEG(<emp)) - L_CLR(&up->wigwag); - else - L_ADD(&up->wigwag, <emp); - 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 %5.1f %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 */ - } -} - - -/* - * wwv_data - calculate bit probability - * - * This routine is called at the end of the receiver second to calculate - * the probabilities that the previous second contained a zero (P0), one - * (P1) or position indicator (P2) pulse. If not in sync or if the data - * 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. - * - * 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( - struct wwvunit *up, /* driver unit pointer */ - double pulse /* pulse length (sample units) */ - ) -{ - double p0, p1, p2; /* probabilities */ - double dpulse; /* pulse length in ms */ - - p0 = p1 = p2 = 0; - dpulse = pulse - DATSIZ / 2; - - /* - * 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->status & (SELV | SELH)) || up->sigsig < DTHR || - up->datsnr < DSNR || dpulse < DATSIZ) { - up->status |= DGATE; - up->errcnt++; - if (up->errcnt > MAXERR) - up->alarm |= MODERR; - return (0); - } - - /* - * The probability of P0 is one below 200 ms falling to zero at - * 500 ms. The probability of P1 is zero below 200 ms rising to - * one at 500 ms and falling to zero at 800 ms. The probability - * of P2 is zero below 500 ms, rising to one above 800 ms. - */ - up->status &= ~DGATE; - if (dpulse < (200 * MS)) { - p0 = 1; - } else if (dpulse < 500 * MS) { - dpulse -= 200 * MS; - p1 = dpulse / (300 * MS); - p0 = 1 - p1; - } else if (dpulse < 800 * MS) { - dpulse -= 500 * MS; - p2 = dpulse / (300 * MS); - p1 = 1 - p2; - } else { - p2 = 1; - } - - /* - * The ouput is a metric that ranges from -1 (P0), to +1 (P1) - * scaled for convenience. An output of zero represents an - * erasure, either because of a data error or pulse length - * greater than 500 ms. At the moment, we don't use P2. - */ - return ((p1 - p0) * MAXSIG); -} - - -/* - * wwv_corr4 - determine maximum likelihood digit - * - * This routine correlates the received digit vector with the BCD - * coefficient vectors corresponding to all valid digits at the given - * position in the decoding matrix. The maximum value corresponds to the - * maximum likelihood digit, while the ratio of this value to the next - * lower value determines the likelihood function. Note that, if the - * digit is invalid, the likelihood vector is averaged toward a miss. - */ -static void -wwv_corr4( - struct peer *peer, /* peer unit pointer */ - struct decvec *vp, /* decoding table pointer */ - double data[], /* received data vector */ - double tab[][4] /* correlation vector array */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - - double topmax, nxtmax; /* metrics */ - double acc; /* accumulator */ - char tbuf[80]; /* monitor buffer */ - int mldigit; /* max likelihood digit */ - int diff; /* decoding difference */ - int i, j; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * Correlate digit vector with each BCD coefficient vector. If - * any BCD digit bit is bad, consider all bits a miss. - */ - mldigit = 0; - topmax = nxtmax = -MAXSIG; - for (i = 0; tab[i][0] != 0; i++) { - acc = 0; - for (j = 0; j < 4; j++) { - if (!(up->status & BGATE)) - acc += data[j] * tab[i][j]; - } - acc = (vp->like[i] += (acc - vp->like[i]) / TCONST); - if (acc > topmax) { - nxtmax = topmax; - topmax = acc; - mldigit = i; - } else if (acc > nxtmax) { - nxtmax = acc; - } - } - vp->mldigit = mldigit; - vp->digprb = topmax; - vp->digsnr = wwv_snr(topmax, nxtmax); - - /* - * The maximum likelihood digit is compared with the current - * clock digit. The difference represents the decoding phase - * 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->count = 0; - vp->phase = diff; - } - if (vp->digsnr < BSNR) { - vp->count = 0; - 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 |= 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, - vp->digit, vp->mldigit, vp->phase, vp->count, - vp->digprb, vp->digsnr); - record_clock_stats(&peer->srcadr, tbuf); -#ifdef DEBUG - if (debug) - printf("%s\n", tbuf); -#endif /* DEBUG */ - } - up->status &= ~BGATE; -} - - -/* - * wwv_tsec - transmitter minute processing - * - * 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. - */ -static void -wwv_tsec( - struct wwvunit *up /* driver structure pointer */ - ) -{ - int minute, day, isleap; - int temp; - - /* - * Advance minute unit of the day. - */ - temp = carry(&up->decvec[MN]); /* minute units */ - - /* - * Propagate carries through the day. - */ - if (temp == 0) /* carry minutes */ - temp = carry(&up->decvec[MN + 1]); - if (temp == 0) /* carry hours */ - temp = carry(&up->decvec[HR]); - if (temp == 0) - temp = carry(&up->decvec[HR + 1]); - - /* - * 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 + - 1].digit * 600; - 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 (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 - * through the year. - */ - if (minute != 1440) - return; - minute = 0; - while (carry(&up->decvec[HR]) != 0); /* advance to minute 0 */ - while (carry(&up->decvec[HR + 1]) != 0); - day++; - temp = carry(&up->decvec[DA]); /* carry days */ - if (temp == 0) - temp = carry(&up->decvec[DA + 1]); - if (temp == 0) - temp = carry(&up->decvec[DA + 2]); - - /* - * Roll the year if this the first day and propagate carries - * through the century. - */ - if (day != (isleap ? 365 : 366)) - return; - day = 1; - while (carry(&up->decvec[DA]) != 1); /* advance to day 1 */ - while (carry(&up->decvec[DA + 1]) != 0); - while (carry(&up->decvec[DA + 2]) != 0); - temp = carry(&up->decvec[YR]); /* carry years */ - if (temp) - carry(&up->decvec[YR + 1]); -} - - -/* - * 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 or - * zero if a carry occurred. Once synchronized, the clock digit will - * match the maximum likelihood digit corresponding to that position. - */ -static int -carry( - struct decvec *dp /* decoding table pointer */ - ) -{ - int temp; - int j; - - dp->digit++; /* advance clock digit */ - if (dp->digit == dp->radix) { /* modulo radix */ - dp->digit = 0; - } - temp = dp->like[dp->radix - 1]; /* rotate likelihood vector */ - for (j = dp->radix - 1; j > 0; j--) - dp->like[j] = dp->like[j - 1]; - dp->like[0] = temp; - return (dp->digit); -} - - -/* - * wwv_snr - compute SNR or likelihood function - */ -static double -wwv_snr( - double signal, /* signal */ - double noise /* noise */ - ) -{ - double rval; - - /* - * This is a little tricky. Due to the way things are measured, - * either or both the signal or noise amplitude can be negative - * or zero. The intent is that, if the signal is negative or - * zero, the SNR must always be zero. This can happen with the - * subcarrier SNR before the phase has been aligned. On the - * other hand, in the likelihood function the "noise" is the - * next maximum down from the peak and this could be negative. - * However, in this case the SNR is truly stupendous, so we - * simply cap at MAXSNR dB. - */ - if (signal <= 0) { - rval = 0; - } else if (noise <= 0) { - rval = MAXSNR; - } else { - rval = 20 * log10(signal / noise); - if (rval > MAXSNR) - rval = MAXSNR; - } - return (rval); -} - - -/* - * wwv_newchan - change to new data channel - * - * 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( - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - struct sync *sp, *rp; - double rank, dtemp; - int i, j; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * 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 = NULL; - rank = 0; - for (i = 0; i < NCHAN; i++) { - rp = &up->mitig[i].wwvh; - dtemp = wwv_metric(rp); - if (dtemp >= rank) { - rank = dtemp; - sp = rp; - j = i; - } - rp = &up->mitig[i].wwv; - dtemp = wwv_metric(rp); - if (dtemp >= rank) { - rank = dtemp; - sp = rp; - 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; - - /* - * Initialize strategic values. Note we set the leap bits - * NOTINSYNC and the refid "NONE". - */ - 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 - * - * This routine saves the AGC for the current channel, switches to a new - * channel and restores the AGC for that channel. If a tunable receiver - * is not available, just fake it. - */ -static int -wwv_qsy( - struct peer *peer, /* peer structure pointer */ - int chan /* channel */ - ) -{ - int rval = 0; - struct refclockproc *pp; - struct wwvunit *up; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - if (up->fd_icom > 0) { - up->mitig[up->achan].gain = up->gain; - rval = icom_freq(up->fd_icom, peer->ttl & 0x7f, - qsy[chan]); - up->achan = chan; - up->gain = up->mitig[up->achan].gain; - } - return (rval); -} -#endif /* ICOM */ - - -/* - * timecode - assemble timecode string and length - * - * Prettytime format - similar to Spectracom - * - * sq yy ddd hh:mm:ss ld dut lset agc iden sig errs freq avgt - * - * s sync indicator ('?' or ' ') - * q error bits (hex 0-F) - * yyyy year of century - * ddd day of year - * hh hour of day - * mm minute of hour - * 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 reference identifier (station and frequency) - * sig signal quality (0-100) - * errs bit errors in last minute - * freq frequency offset (PPM) - * avgt averaging time (s) - */ -static int -timecode( - struct wwvunit *up, /* driver structure pointer */ - char *ptr /* target string */ - ) -{ - struct sync *sp; - int year, day, hour, minute, second, dut; - char synchar, leapchar, dst; - char cptr[50]; - - - /* - * Common fixed-format fields - */ - synchar = (up->status & INSYNC) ? ' ' : '?'; - 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, 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; - 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)); -} - - -/* - * wwv_gain - adjust codec gain - * - * 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. - */ -static void -wwv_gain( - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct wwvunit *up; - - pp = peer->procptr; - up = (struct wwvunit *)pp->unitptr; - - /* - * Apparently, the codec uses only the high order bits of the - * gain control field. Thus, it may take awhile for changes to - * wiggle the hardware bits. - */ - if (up->clipcnt == 0) { - up->gain += 4; - 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->mongain, up->port); - up->clipcnt = 0; -#if DEBUG - if (debug > 1) - audio_show(); -#endif -} - - -#else -int refclock_wwv_bs; -#endif /* REFCLOCK */ |
