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Diffstat (limited to 'contrib/ntp/ntpd/refclock_irig.c')
| -rw-r--r-- | contrib/ntp/ntpd/refclock_irig.c | 1049 |
1 files changed, 0 insertions, 1049 deletions
diff --git a/contrib/ntp/ntpd/refclock_irig.c b/contrib/ntp/ntpd/refclock_irig.c deleted file mode 100644 index 0b35368..0000000 --- a/contrib/ntp/ntpd/refclock_irig.c +++ /dev/null @@ -1,1049 +0,0 @@ -/* - * refclock_irig - audio IRIG-B/E demodulator/decoder - */ -#ifdef HAVE_CONFIG_H -#include <config.h> -#endif - -#if defined(REFCLOCK) && defined(CLOCK_IRIG) - -#include "ntpd.h" -#include "ntp_io.h" -#include "ntp_refclock.h" -#include "ntp_calendar.h" -#include "ntp_stdlib.h" - -#include <stdio.h> -#include <ctype.h> -#include <math.h> -#ifdef HAVE_SYS_IOCTL_H -#include <sys/ioctl.h> -#endif /* HAVE_SYS_IOCTL_H */ - -#include "audio.h" - -/* - * Audio IRIG-B/E demodulator/decoder - * - * This driver receives, demodulates and decodes IRIG-B/E signals when - * connected to the audio codec /dev/audio. The IRIG signal format is an - * amplitude-modulated carrier with pulse-width modulated data bits. For - * IRIG-B, the carrier frequency is 1000 Hz and bit rate 100 b/s; for - * IRIG-E, the carrier frequenchy is 100 Hz and bit rate 10 b/s. The - * driver automatically recognizes which format is in use. - * - * The program processes 8000-Hz mu-law companded samples using separate - * signal filters for IRIG-B and IRIG-E, a comb filter, envelope - * detector and automatic threshold corrector. Cycle crossings relative - * to the corrected slice level determine the width of each pulse and - * its value - zero, one or position identifier. The data encode 20 BCD - * digits which determine the second, minute, hour and day of the year - * and sometimes the year and synchronization condition. The comb filter - * exponentially averages the corresponding samples of successive baud - * intervals in order to reliably identify the reference carrier cycle. - * A type-II phase-lock loop (PLL) performs additional integration and - * interpolation to accurately determine the zero crossing of that - * cycle, which determines the reference timestamp. A pulse-width - * discriminator demodulates the data pulses, which are then encoded as - * the BCD digits of the timecode. - * - * The timecode and reference timestamp are updated once each second - * with IRIG-B (ten seconds with IRIG-E) and local clock offset samples - * saved for later processing. At poll intervals of 64 s, the saved - * samples are processed by a trimmed-mean filter and used to update the - * system clock. - * - * An automatic gain control feature provides protection against - * overdriven or underdriven input signal amplitudes. It is designed to - * maintain adequate demodulator signal amplitude while avoiding - * occasional noise spikes. In order to assure reliable capture, the - * decompanded input signal amplitude must be greater than 100 units and - * the codec sample frequency error less than 250 PPM (.025 percent). - * - * The program performs a number of error checks to protect against - * overdriven or underdriven input signal levels, incorrect signal - * format or improper hardware configuration. Specifically, if any of - * the following errors occur for a time measurement, the data are - * rejected. - * - * o The peak carrier amplitude is less than DRPOUT (100). This usually - * means dead IRIG signal source, broken cable or wrong input port. - * - * o The frequency error is greater than MAXFREQ +-250 PPM (.025%). This - * usually means broken codec hardware or wrong codec configuration. - * - * o The modulation index is less than MODMIN (0.5). This usually means - * overdriven IRIG signal or wrong IRIG format. - * - * o A frame synchronization error has occurred. This usually means - * wrong IRIG signal format or the IRIG signal source has lost - * synchronization (signature control). - * - * o A data decoding error has occurred. This usually means wrong IRIG - * signal format. - * - * o The current second of the day is not exactly one greater than the - * previous one. This usually means a very noisy IRIG signal or - * insufficient CPU resources. - * - * o An audio codec error (overrun) occurred. This usually means - * insufficient CPU resources, as sometimes happens with Sun SPARC - * IPCs when doing something useful. - * - * Note that additional checks are done elsewhere in the reference clock - * interface routines. - * - * Debugging aids - * - * The timecode format used for debugging and data recording includes - * data helpful in diagnosing problems with the IRIG signal and codec - * connections. With debugging enabled (-d on the ntpd command line), - * the driver produces one line for each timecode in the following - * format: - * - * 00 1 98 23 19:26:52 721 143 0.694 20 0.1 66.5 3094572411.00027 - * - * The most recent line is also written to the clockstats file at 64-s - * intervals. - * - * The first field contains the error flags in hex, where the hex bits - * are interpreted as below. This is followed by the IRIG status - * indicator, year of century, day of year and time of day. The status - * indicator and year are not produced by some IRIG devices. Following - * these fields are the signal amplitude (0-8100), codec gain (0-255), - * modulation index (0-1), time constant (2-20), carrier phase error - * (us) and carrier frequency error (PPM). The last field is the on-time - * timestamp in NTP format. - * - * The fraction part of the on-time timestamp is a good indicator of how - * well the driver is doing. With an UltrSPARC 30 and Solaris 2.7, this - * thing can keep the clock within a few tens of microseconds relative - * to the IRIG-B signal. Accuracy with IRIG-E is about ten times worse. - * Unfortunately, Sun broke the 2.7 audio driver in 2.8, which has a - * 10-ms sawtooth modulation. The driver attempts to remove the - * modulation by some clever estimation techniques which mostly work. - * Your experience may vary. - * - * Unlike other drivers, which can have multiple instantiations, this - * one supports only one. It does not seem likely that more than one - * audio codec would be useful in a single machine. More than one would - * probably chew up too much CPU time anyway. - * - * Fudge factors - * - * Fudge flag4 causes the dubugging output described above to be - * recorded in the clockstats file. When the audio driver is compiled, - * fudge flag2 selects the audio input port, where 0 is the mike port - * (default) and 1 is the line-in port. It does not seem useful to - * select the compact disc player port. Fudge flag3 enables audio - * monitoring of the input signal. For this purpose, the monitor gain is - * set to a default value. Fudgetime2 is used as a frequency vernier for - * broken codec sample frequency. - */ -/* - * Interface definitions - */ -#define DEVICE_AUDIO "/dev/audio" /* audio device name */ -#define PRECISION (-17) /* precision assumed (about 10 us) */ -#define REFID "IRIG" /* reference ID */ -#define DESCRIPTION "Generic IRIG Audio Driver" /* WRU */ -#define AUDIO_BUFSIZ 320 /* audio buffer size (40 ms) */ -#define SECOND 8000 /* nominal sample rate (Hz) */ -#define BAUD 80 /* samples per baud interval */ -#define OFFSET 128 /* companded sample offset */ -#define SIZE 256 /* decompanding table size */ -#define CYCLE 8 /* samples per carrier cycle */ -#define SUBFLD 10 /* bits per subfield */ -#define FIELD 10 /* subfields per field */ -#define MINTC 2 /* min PLL time constant */ -#define MAXTC 20 /* max PLL time constant max */ -#define MAXSIG 6000. /* maximum signal level */ -#define MAXCLP 100 /* max clips above reference per s */ -#define DRPOUT 100. /* dropout signal level */ -#define MODMIN 0.5 /* minimum modulation index */ -#define MAXFREQ (250e-6 * SECOND) /* freq tolerance (.025%) */ -#define PI 3.1415926535 /* the real thing */ -#ifdef IRIG_SUCKS -#define WIGGLE 11 /* wiggle filter length */ -#endif /* IRIG_SUCKS */ - -/* - * Experimentally determined filter delays - */ -#define IRIG_B .0019 /* IRIG-B filter delay */ -#define IRIG_E .0019 /* IRIG-E filter delay */ - -/* - * Data bit definitions - */ -#define BIT0 0 /* zero */ -#define BIT1 1 /* one */ -#define BITP 2 /* position identifier */ - -/* - * Error flags (up->errflg) - */ -#define IRIG_ERR_AMP 0x01 /* low carrier amplitude */ -#define IRIG_ERR_FREQ 0x02 /* frequency tolerance exceeded */ -#define IRIG_ERR_MOD 0x04 /* low modulation index */ -#define IRIG_ERR_SYNCH 0x08 /* frame synch error */ -#define IRIG_ERR_DECODE 0x10 /* frame decoding error */ -#define IRIG_ERR_CHECK 0x20 /* second numbering discrepancy */ -#define IRIG_ERR_ERROR 0x40 /* codec error (overrun) */ -#define IRIG_ERR_SIGERR 0x80 /* IRIG status error (Spectracom) */ - -/* - * IRIG unit control structure - */ -struct irigunit { - u_char timecode[21]; /* timecode string */ - l_fp timestamp; /* audio sample timestamp */ - l_fp tick; /* audio sample increment */ - double integ[BAUD]; /* baud integrator */ - double phase, freq; /* logical clock phase and frequency */ - double zxing; /* phase detector integrator */ - double yxing; /* cycle phase */ - double exing; /* envelope phase */ - double modndx; /* modulation index */ - double irig_b; /* IRIG-B signal amplitude */ - double irig_e; /* IRIG-E signal amplitude */ - int errflg; /* error flags */ - /* - * 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 interval counter */ - - /* - * RF variables - */ - double hpf[5]; /* IRIG-B filter shift register */ - double lpf[5]; /* IRIG-E filter shift register */ - double intmin, intmax; /* integrated envelope min and max */ - double envmax; /* peak amplitude */ - double envmin; /* noise amplitude */ - double maxsignal; /* integrated peak amplitude */ - double noise; /* integrated noise amplitude */ - double lastenv[CYCLE]; /* last cycle amplitudes */ - double lastint[CYCLE]; /* last integrated cycle amplitudes */ - double lastsig; /* last carrier sample */ - double fdelay; /* filter delay */ - int decim; /* sample decimation factor */ - int envphase; /* envelope phase */ - int envptr; /* envelope phase pointer */ - int carphase; /* carrier phase */ - int envsw; /* envelope state */ - int envxing; /* envelope slice crossing */ - int tc; /* time constant */ - int tcount; /* time constant counter */ - int badcnt; /* decimation interval counter */ - - /* - * Decoder variables - */ - int pulse; /* cycle counter */ - int cycles; /* carrier cycles */ - int dcycles; /* data cycles */ - int xptr; /* translate table pointer */ - int lastbit; /* last code element length */ - int second; /* previous second */ - int fieldcnt; /* subfield count in field */ - int bits; /* demodulated bits */ - int bitcnt; /* bit count in subfield */ -#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 */ - l_fp wuggle; -}; - -/* - * Function prototypes - */ -static int irig_start P((int, struct peer *)); -static void irig_shutdown P((int, struct peer *)); -static void irig_receive P((struct recvbuf *)); -static void irig_poll P((int, struct peer *)); - -/* - * More function prototypes - */ -static void irig_base P((struct peer *, double)); -static void irig_rf P((struct peer *, double)); -static void irig_decode P((struct peer *, int)); -static void irig_gain P((struct peer *)); - -/* - * Transfer vector - */ -struct refclock refclock_irig = { - irig_start, /* start up driver */ - irig_shutdown, /* shut down driver */ - irig_poll, /* transmit poll message */ - noentry, /* not used (old irig_control) */ - noentry, /* initialize driver (not used) */ - noentry, /* not used (old irig_buginfo) */ - NOFLAGS /* not used */ -}; - -/* - * Global variables - */ -static char hexchar[] = { /* really quick decoding table */ - '0', '8', '4', 'c', /* 0000 0001 0010 0011 */ - '2', 'a', '6', 'e', /* 0100 0101 0110 0111 */ - '1', '9', '5', 'd', /* 1000 1001 1010 1011 */ - '3', 'b', '7', 'f' /* 1100 1101 1110 1111 */ -}; - - -/* - * irig_start - open the devices and initialize data for processing - */ -static int -irig_start( - int unit, /* instance number (used for PCM) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - /* - * 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 irigunit *) - emalloc(sizeof(struct irigunit)))) { - (void) close(fd); - return (0); - } - memset((char *)up, 0, sizeof(struct irigunit)); - pp = peer->procptr; - pp->unitptr = (caddr_t)up; - pp->io.clock_recv = irig_receive; - pp->io.srcclock = (caddr_t)peer; - pp->io.datalen = 0; - pp->io.fd = fd; - if (!io_addclock(&pp->io)) { - (void)close(fd); - free(up); - return (0); - } - - /* - * Initialize miscellaneous variables - */ - peer->precision = PRECISION; - pp->clockdesc = DESCRIPTION; - memcpy((char *)&pp->refid, REFID, 4); - up->tc = MINTC; - up->decim = 1; - up->fdelay = IRIG_B; - up->gain = 127; - - /* - * 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); - return (1); -} - - -/* - * irig_shutdown - shut down the clock - */ -static void -irig_shutdown( - int unit, /* instance number (not used) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - pp = peer->procptr; - up = (struct irigunit *)pp->unitptr; - io_closeclock(&pp->io); - free(up); -} - - -/* - * irig_receive - receive data from the audio device - * - * This routine reads input samples and adjusts the logical clock to - * track the irig clock by dropping or duplicating codec samples. - */ -static void -irig_receive( - struct recvbuf *rbufp /* receive buffer structure pointer */ - ) -{ - struct peer *peer; - struct refclockproc *pp; - struct irigunit *up; - - /* - * Local variables - */ - double sample; /* codec sample */ - u_char *dpt; /* buffer pointer */ - int bufcnt; /* buffer counter */ - l_fp ltemp; /* l_fp temp */ - - peer = (struct peer *)rbufp->recv_srcclock; - pp = peer->procptr; - up = (struct irigunit *)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; - up->phase += pp->fudgetime2 / 1e6; - if (up->phase >= .5) { - up->phase -= 1.; - } else if (up->phase < -.5) { - up->phase += 1.; - irig_rf(peer, sample); - irig_rf(peer, sample); - } else { - irig_rf(peer, sample); - } - L_ADD(&up->timestamp, &up->tick); - - /* - * Once each second, determine the IRIG format and gain. - */ - up->seccnt = (up->seccnt + 1) % SECOND; - if (up->seccnt == 0) { - if (up->irig_b > up->irig_e) { - up->decim = 1; - up->fdelay = IRIG_B; - } else { - up->decim = 10; - up->fdelay = IRIG_E; - } - irig_gain(peer); - up->irig_b = up->irig_e = 0; - } - } - - /* - * 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; -} - -/* - * irig_rf - RF processing - * - * This routine filters the RF signal using a highpass filter for IRIG-B - * and a lowpass filter for IRIG-E. In case of IRIG-E, the samples are - * decimated by a factor of ten. The lowpass filter functions also as a - * decimation filter in this case. Note that the codec filters function - * as roofing filters to attenuate both the high and low ends of the - * passband. IIR filter coefficients were determined using Matlab Signal - * Processing Toolkit. - */ -static void -irig_rf( - struct peer *peer, /* peer structure pointer */ - double sample /* current signal sample */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - /* - * Local variables - */ - double irig_b, irig_e; /* irig filter outputs */ - - pp = peer->procptr; - up = (struct irigunit *)pp->unitptr; - - /* - * IRIG-B filter. 4th-order elliptic, 800-Hz highpass, 0.3 dB - * passband ripple, -50 dB stopband ripple, phase delay .0022 - * s) - */ - irig_b = (up->hpf[4] = up->hpf[3]) * 2.322484e-01; - irig_b += (up->hpf[3] = up->hpf[2]) * -1.103929e+00; - irig_b += (up->hpf[2] = up->hpf[1]) * 2.351081e+00; - irig_b += (up->hpf[1] = up->hpf[0]) * -2.335036e+00; - up->hpf[0] = sample - irig_b; - irig_b = up->hpf[0] * 4.335855e-01 - + up->hpf[1] * -1.695859e+00 - + up->hpf[2] * 2.525004e+00 - + up->hpf[3] * -1.695859e+00 - + up->hpf[4] * 4.335855e-01; - up->irig_b += irig_b * irig_b; - - /* - * IRIG-E filter. 4th-order elliptic, 130-Hz lowpass, 0.3 dB - * passband ripple, -50 dB stopband ripple, phase delay .0219 s. - */ - irig_e = (up->lpf[4] = up->lpf[3]) * 8.694604e-01; - irig_e += (up->lpf[3] = up->lpf[2]) * -3.589893e+00; - irig_e += (up->lpf[2] = up->lpf[1]) * 5.570154e+00; - irig_e += (up->lpf[1] = up->lpf[0]) * -3.849667e+00; - up->lpf[0] = sample - irig_e; - irig_e = up->lpf[0] * 3.215696e-03 - + up->lpf[1] * -1.174951e-02 - + up->lpf[2] * 1.712074e-02 - + up->lpf[3] * -1.174951e-02 - + up->lpf[4] * 3.215696e-03; - up->irig_e += irig_e * irig_e; - - /* - * Decimate by a factor of either 1 (IRIG-B) or 10 (IRIG-E). - */ - up->badcnt = (up->badcnt + 1) % up->decim; - if (up->badcnt == 0) { - if (up->decim == 1) - irig_base(peer, irig_b); - else - irig_base(peer, irig_e); - } -} - -/* - * irig_base - baseband processing - * - * This routine processes the baseband signal and demodulates the AM - * carrier using a synchronous detector. It then synchronizes to the - * data frame at the baud rate and decodes the data pulses. - */ -static void -irig_base( - struct peer *peer, /* peer structure pointer */ - double sample /* current signal sample */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - /* - * Local variables - */ - double xxing; /* phase detector interpolated output */ - double lope; /* integrator output */ - double env; /* envelope detector output */ - double dtemp; /* double temp */ - - pp = peer->procptr; - up = (struct irigunit *)pp->unitptr; - - /* - * Synchronous baud integrator. Corresponding samples of current - * and past baud intervals are integrated to refine the envelope - * amplitude and phase estimate. We keep one cycle of both the - * raw and integrated data for later use. - */ - up->envphase = (up->envphase + 1) % BAUD; - up->carphase = (up->carphase + 1) % CYCLE; - up->integ[up->envphase] += (sample - up->integ[up->envphase]) / - (5 * up->tc); - lope = up->integ[up->envphase]; - up->lastenv[up->carphase] = sample; - up->lastint[up->carphase] = lope; - - /* - * Phase detector. Sample amplitudes are integrated over the - * baud interval. Cycle phase is determined from these - * amplitudes using an eight-sample cyclic buffer. A phase - * change of 360 degrees produces an output change of one unit. - */ - if (up->lastsig > 0 && lope <= 0) { - xxing = lope / (up->lastsig - lope); - up->zxing += (up->carphase - 4 + xxing) / CYCLE; - } - up->lastsig = lope; - - /* - * Update signal/noise estimates and PLL phase/frequency. - */ - if (up->envphase == 0) { - - /* - * Update envelope signal and noise estimates and mess - * with error bits. - */ - up->maxsignal = up->intmax; - up->noise = up->intmin; - if (up->maxsignal < DRPOUT) - up->errflg |= IRIG_ERR_AMP; - if (up->maxsignal > 0) - up->modndx = (up->intmax - up->intmin) / - up->intmax; - else - up->modndx = 0; - if (up->modndx < MODMIN) - up->errflg |= IRIG_ERR_MOD; - up->intmin = 1e6; up->intmax = 0; - if (up->errflg & (IRIG_ERR_AMP | IRIG_ERR_FREQ | - IRIG_ERR_MOD | IRIG_ERR_SYNCH)) { - up->tc = MINTC; - up->tcount = 0; - } - - /* - * Update PLL phase and frequency. The PLL time constant - * is set initially to stabilize the frequency within a - * minute or two, then increases to the maximum. The - * frequency is clamped so that the PLL capture range - * cannot be exceeded. - */ - dtemp = up->zxing * up->decim / BAUD; - up->yxing = dtemp; - up->zxing = 0.; - up->phase += dtemp / up->tc; - up->freq += dtemp / (4. * up->tc * up->tc); - if (up->freq > MAXFREQ) { - up->freq = MAXFREQ; - up->errflg |= IRIG_ERR_FREQ; - } else if (up->freq < -MAXFREQ) { - up->freq = -MAXFREQ; - up->errflg |= IRIG_ERR_FREQ; - } - } - - /* - * Synchronous demodulator. There are eight samples in the cycle - * and ten cycles in the baud interval. The amplitude of each - * cycle is determined at the last sample in the cycle. The - * beginning of the data pulse is determined from the integrated - * samples, while the end of the pulse is determined from the - * raw samples. The raw data bits are demodulated relative to - * the slice level and left-shifted in the decoding register. - */ - if (up->carphase != 7) - return; - env = (up->lastenv[2] - up->lastenv[6]) / 2.; - lope = (up->lastint[2] - up->lastint[6]) / 2.; - if (lope > up->intmax) - up->intmax = lope; - if (lope < up->intmin) - up->intmin = lope; - - /* - * Pulse code demodulator and reference timestamp. The decoder - * looks for a sequence of ten bits; the first two bits must be - * one, the last two bits must be zero. Frame synch is asserted - * when three correct frames have been found. - */ - up->pulse = (up->pulse + 1) % 10; - if (up->pulse == 1) - up->envmax = env; - else if (up->pulse == 9) - up->envmin = env; - up->dcycles <<= 1; - if (env >= (up->envmax + up->envmin) / 2.) - up->dcycles |= 1; - up->cycles <<= 1; - if (lope >= (up->maxsignal + up->noise) / 2.) - up->cycles |= 1; - if ((up->cycles & 0x303c0f03) == 0x300c0300) { - l_fp ltemp; - int bitz; - - /* - * The PLL time constant starts out small, in order to - * sustain a frequency tolerance of 250 PPM. It - * gradually increases as the loop settles down. Note - * that small wiggles are not believed, unless they - * persist for lots of samples. - */ - if (up->pulse != 9) - up->errflg |= IRIG_ERR_SYNCH; - up->pulse = 9; - up->exing = -up->yxing; - if (fabs(up->envxing - up->envphase) <= 1) { - up->tcount++; - if (up->tcount > 50 * up->tc) { - up->tc++; - if (up->tc > MAXTC) - up->tc = MAXTC; - up->tcount = 0; - up->envxing = up->envphase; - } else { - up->exing -= up->envxing - up->envphase; - } - } else { - up->tcount = 0; - up->envxing = up->envphase; - } - - /* - * Determine a reference timestamp, accounting for the - * codec delay and filter delay. Note the timestamp is - * for the previous frame, so we have to backtrack for - * this plus the delay since the last carrier positive - * zero crossing. - */ - dtemp = up->decim * ((up->exing + BAUD) / SECOND + 1.) + - up->fdelay; - DTOLFP(dtemp, <emp); - pp->lastrec = up->timestamp; - L_SUB(&pp->lastrec, <emp); - - /* - * The data bits are collected in ten-bit frames. The - * first two and last two bits are determined by frame - * sync and ignored here; the resulting patterns - * represent zero (0-1 bits), one (2-4 bits) and - * position identifier (5-6 bits). The remaining - * patterns represent errors and are treated as zeros. - */ - bitz = up->dcycles & 0xfc; - switch(bitz) { - - case 0x00: - case 0x80: - irig_decode(peer, BIT0); - break; - - case 0xc0: - case 0xe0: - case 0xf0: - irig_decode(peer, BIT1); - break; - - case 0xf8: - case 0xfc: - irig_decode(peer, BITP); - break; - - default: - irig_decode(peer, 0); - up->errflg |= IRIG_ERR_DECODE; - } - } -} - - -/* - * irig_decode - decode the data - * - * This routine assembles bits into digits, digits into subfields and - * subfields into the timecode field. Bits can have values of zero, one - * or position identifier. There are four bits per digit, two digits per - * subfield and ten subfields per field. The last bit in every subfield - * and the first bit in the first subfield are position identifiers. - */ -static void -irig_decode( - struct peer *peer, /* peer structure pointer */ - int bit /* data bit (0, 1 or 2) */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; -#ifdef IRIG_SUCKS - int i; -#endif /* IRIG_SUCKS */ - - /* - * Local variables - */ - char syncchar; /* sync character (Spectracom) */ - char sbs[6]; /* binary seconds since 0h */ - char spare[2]; /* mulligan digits */ - - pp = peer->procptr; - up = (struct irigunit *)pp->unitptr; - - /* - * Assemble subfield bits. - */ - up->bits <<= 1; - if (bit == BIT1) { - up->bits |= 1; - } else if (bit == BITP && up->lastbit == BITP) { - - /* - * Frame sync - two adjacent position identifiers. - * Monitor the reference timestamp and wiggle the - * clock, but only if no errors have occurred. - */ - up->bitcnt = 1; - up->fieldcnt = 0; - up->lastbit = 0; - if (up->errflg == 0) { -#ifdef IRIG_SUCKS - l_fp ltemp; - - /* - * 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; - up->wuggle = pp->lastrec; - refclock_process(pp); -#else /* IRIG_SUCKS */ - pp->lastref = pp->lastrec; - up->wuggle = pp->lastrec; - refclock_process(pp); -#endif /* IRIG_SUCKS */ - } - up->errflg = 0; - } - up->bitcnt = (up->bitcnt + 1) % SUBFLD; - if (up->bitcnt == 0) { - - /* - * End of subfield. Encode two hexadecimal digits in - * little-endian timecode field. - */ - if (up->fieldcnt == 0) - up->bits <<= 1; - if (up->xptr < 2) - up->xptr = 2 * FIELD; - up->timecode[--up->xptr] = hexchar[(up->bits >> 5) & - 0xf]; - up->timecode[--up->xptr] = hexchar[up->bits & 0xf]; - up->fieldcnt = (up->fieldcnt + 1) % FIELD; - if (up->fieldcnt == 0) { - - /* - * End of field. Decode the timecode and wind - * the clock. Not all IRIG generators have the - * year; if so, it is nonzero after year 2000. - * Not all have the hardware status bit; if so, - * it is lit when the source is okay and dim - * when bad. We watch this only if the year is - * nonzero. Not all are configured for signature - * control. If so, all BCD digits are set to - * zero if the source is bad. In this case the - * refclock_process() will reject the timecode - * as invalid. - */ - up->xptr = 2 * FIELD; - if (sscanf((char *)up->timecode, - "%6s%2d%c%2s%3d%2d%2d%2d", sbs, &pp->year, - &syncchar, spare, &pp->day, &pp->hour, - &pp->minute, &pp->second) != 8) - pp->leap = LEAP_NOTINSYNC; - else - pp->leap = LEAP_NOWARNING; - up->second = (up->second + up->decim) % 60; - if (pp->year > 0) { - pp->year += 2000; - if (syncchar == '0') - up->errflg |= IRIG_ERR_CHECK; - } - if (pp->second != up->second) - up->errflg |= IRIG_ERR_CHECK; - up->second = pp->second; - sprintf(pp->a_lastcode, - "%02x %c %2d %3d %02d:%02d:%02d %4.0f %3d %6.3f %2d %6.1f %6.1f %s", - up->errflg, syncchar, pp->year, pp->day, - pp->hour, pp->minute, pp->second, - up->maxsignal, up->gain, up->modndx, - up->tc, up->exing * 1e6 / SECOND, up->freq * - 1e6 / SECOND, ulfptoa(&up->wuggle, 6)); - pp->lencode = strlen(pp->a_lastcode); - if (pp->sloppyclockflag & CLK_FLAG4) { - record_clock_stats(&peer->srcadr, - pp->a_lastcode); -#ifdef DEBUG - if (debug) - printf("irig: %s\n", - pp->a_lastcode); -#endif /* DEBUG */ - } - } - } - up->lastbit = bit; -} - - -/* - * irig_poll - called by the transmit procedure - * - * This routine sweeps up the timecode updates since the last poll. For - * IRIG-B there should be at least 60 updates; for IRIG-E there should - * be at least 6. If nothing is heard, a timeout event is declared and - * any orphaned timecode updates are sent to foster care. - */ -static void -irig_poll( - int unit, /* instance number (not used) */ - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - pp = peer->procptr; - up = (struct irigunit *)pp->unitptr; - - if (pp->coderecv == pp->codeproc) { - refclock_report(peer, CEVNT_TIMEOUT); - return; - } else { - refclock_receive(peer); - record_clock_stats(&peer->srcadr, pp->a_lastcode); -#ifdef DEBUG - if (debug) - printf("irig: %s\n", pp->a_lastcode); -#endif /* DEBUG */ - } - pp->polls++; - -} - - -/* - * irig_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 - * amplitude, so this crudity works just fine. The input port is set and - * the error flag is cleared, mostly to be ornery. - */ -static void -irig_gain( - struct peer *peer /* peer structure pointer */ - ) -{ - struct refclockproc *pp; - struct irigunit *up; - - pp = peer->procptr; - up = (struct irigunit *)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; -} - -#else -int refclock_irig_bs; -#endif /* REFCLOCK */ |
