#define DEVICE_AUDIO "/dev/audio" /* audio device name */
#define AUDIO_BUFSIZ 320 /* audio buffer size (50 ms) */
#define PRECISION (-10) /* precision assumed (about 1 ms) */
-#define REFID "NONE" /* reference ID */
#define DESCRIPTION "WWV/H Audio Demodulator/Decoder" /* WRU */
#define SECOND 8000 /* second epoch (sample rate) (Hz) */
#define MINUTE (SECOND * 60) /* minute epoch */
#define MAXSNR 30. /* max SNR reference */
#define DGAIN 20. /* data channel gain reference */
#define SGAIN 10. /* sync channel gain reference */
-#define MAXFREQ 1. /* freq tolerance (125 PPM) */
+#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 channels */
-#define AUDIO_PHI 5e-6 /* max frequency error */
+#define NCHAN 5 /* number of radio channels */
+#define AUDIO_PHI 5e-6 /* dispersion growth factor */
#ifdef IRIG_SUCKS
#define WIGGLE 11 /* wiggle filter length */
#endif /* IRIG_SUCKS */
/*
* General purpose status bits (status)
*
- * Notes: SELV and/or SELH are set when 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 or timeout. 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.
+ * 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 for alternate frequencies. LEPSEC is set when the SECWAR of
- * the timecode is set on the last second of 30 June or 31 December. At
- * the end of this minute the driver inserts second 60 in the seconds
- * state machine and the minute sync slips a second.
+ * probing alternate frequencies. LEPDAY is set when SECWAR of the
+ * timecode is set on 30 June or 31 December. LEPSEC is set during the
+ * last minute of the day when LEPDAY is set. At the end of this minute
+ * the driver inserts second 60 in the seconds state machine and the
+ * minute sync slips a second. The SLOSS and SJITR bits are for monitor
+ * only.
*/
#define MSYNC 0x0001 /* minute epoch sync */
#define SSYNC 0x0002 /* second epoch sync */
#define DSYNC 0x0004 /* minute units sync */
#define INSYNC 0x0008 /* clock synchronized */
-#define SLOSS 0x0010 /* minute sync signal lost */
-#define SJITR 0x0020 /* minute sync excessive jitter */
+#define SLOSS 0x0010 /* seconds sync signal lost */
+#define SJITR 0x0020 /* seconds sync excessive jitter */
#define DGATE 0x0040 /* data bit error */
#define BGATE 0x0080 /* BCD digit bit error */
#define SFLAG 0x1000 /* probe flag */
-#define LEPSEC 0x2000 /* leap second in progress */
+#define LEPDAY 0x2000 /* leap second day */
+#define LEPSEC 0x4000 /* leap second minute */
/*
* Station scoreboard bits
* developed in future. All these are in minutes.
*/
#define ACQSN 5 /* station acquisition timeout */
-#define HSPEC 15 /* second sync timeout */
#define DIGIT 30 /* minute unit digit timeout */
+#define HOLD 30 /* reachable timeout */
#define PANIC (2 * 1440) /* panic timeout */
-#define HOLD 30 /* reach hold */
+
/*
* Thresholds. These establish the minimum signal level, minimum SNR and
* maximum jitter thresholds which establish the error and false alarm
#define DUT2 0x02 /* 57 DUT .2 */
#define DUT4 0x04 /* 58 DUT .4 */
#define DUTS 0x08 /* 50 DUT sign */
-#define DST1 0x10 /* 55 DST1 DST in progress */
-#define DST2 0x20 /* 2 DST2 DST change warning */
+#define DST1 0x10 /* 55 DST1 leap warning */
+#define DST2 0x20 /* 2 DST2 DST1 delayed one day */
#define SECWAR 0x40 /* 3 leap second warning */
/*
*/
char dstcod[] = {
'S', /* 00 standard time */
- 'I', /* 01 daylight warning */
- 'O', /* 10 standard warning */
+ 'I', /* 01 set clock ahead at 0200 local */
+ 'O', /* 10 set clock back at 0200 local */
'D' /* 11 daylight time */
};
int fd_icom; /* ICOM file descriptor */
int errflg; /* error flags */
int watch; /* watchcat */
- int swatch; /* second sync watchcat */
/*
* Audio codec variables
*/
peer->precision = PRECISION;
pp->clockdesc = DESCRIPTION;
- memcpy(&pp->refid, REFID, 4);
/*
* The companded samples are encoded sign-magnitude. The table
*/
if (up->mphase == 0) {
up->watch++;
- up->swatch++;
- if (up->status & LEPSEC) {
-
- /*
- * If the leap bit is set, set the minute epoch
- * back one second so the station processes
- * don't miss a beat.
- */
- up->mphase -= SECOND;
- if (up->mphase < 0)
- up->mphase += MINUTE;
- } else if (!(up->status & MSYNC)) {
+ if (!(up->status & MSYNC)) {
/*
* If minute sync has not been acquired before
} else {
/*
- * If digit sync has not been acquired before
- * timeout, game over and restart from scratch.
- * If the second sync times out, dim the second
- * sync lamp and raise an alarm.
+ * If the leap bit is set, set the minute epoch
+ * back one second so the station processes
+ * don't miss a beat.
*/
- if (up->swatch > HSPEC)
- up->status &= ~SSYNC;
- if (!(up->status & SSYNC))
- up->alarm |= 1 << SYNERR;
- if (up->watch > DIGIT && !(up->status & DSYNC))
- wwv_newgame(peer);
+ if (up->status & LEPSEC) {
+ up->mphase -= SECOND;
+ if (up->mphase < 0)
+ up->mphase += MINUTE;
+ }
}
}
* 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 second phase is zero. Note that
- * the minute search has determined an approximate frequency
- * offset as wedll.
+ * next minute epoch, while the second phase is zero.
*/
if (up->status & MSYNC) {
wwv_epoch(peer);
static int epoch_mf[3]; /* epoch median filter */
static int xepoch; /* last second epoch */
static int zepoch; /* last averaging interval epoch */
- static int syncnt; /* second epoch run length counter */
+ static int syncnt; /* run length counter */
+ static int maxrun; /* longest run length */
+ static int mepoch; /* longest run epoch */
static int jitcnt; /* jitter holdoff counter */
static int avgcnt; /* averaging interval counter */
static int avginc; /* averaging ratchet */
* frequency averaging interval, the new candidate replaces the
* old one anyway. The compare counter is incremented if the new
* candidate is identical to the last one; otherwise, it is
- * forced to zero. If the compare counter increments to 10, the
- * epoch buffer is reset and the second sync lamp is lit.
+ * forced to zero.
*
* Careful attention to detail here. If the signal amplitude
* falls below the threshold or if no stations are heard or the
up->eposnr < SSNR) {
up->status |= SLOSS;
up->status &= ~SSYNC;
- jitcnt = syncnt = avgcnt = 0;
+ jitcnt = avgcnt = syncnt = maxrun = 0;
return;
}
avgcnt++;
if (abs(tmp2) <= MS || jitcnt >= up->avgint) {
jitcnt = 0;
if (tmp2 != 0) {
- xepoch = up->tepoch;
+ if (syncnt > maxrun) {
+ maxrun = syncnt;
+ mepoch = xepoch;
+ }
syncnt = 0;
} else {
- if (syncnt < SCMP) {
- syncnt++;
- } else {
- up->status |= SSYNC;
- up->swatch = 0;
- up->yepoch = up->tepoch;
- }
+ syncnt++;
}
+ xepoch = up->tepoch;
} else {
- up->status |= SJITR;
- jitcnt++;
+ if (syncnt > maxrun) {
+ maxrun = syncnt;
+ mepoch = xepoch;
+ }
syncnt = 0;
+ jitcnt++;
+ up->status |= SJITR;
}
if ((pp->sloppyclockflag & CLK_FLAG4) && !(up->status & (SSYNC |
MSYNC))) {
* 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. If
- * the epoch change over the interval is 1 ms or less, the
- * frequency is adjusted, but clamped at +-125 PPM. In this case
- * the wiggle counter is incremented; otherwise, it is
- * decremented. If the counter increments to +3, the averaging
- * interval is doubled; if it decrements to -3, the interval is
- * halved.
- *
+ * 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.
+ *
+ * The best averaging interval epoches are when the jitter
+ * counter is zero, but in any case the epoches cannot be more
+ * than twice the averaging interval. This avoids lockup,
+ * especially when first starting up when the interval is small.
+ */
+ if ((jitcnt == 0 && avgcnt < up->avgint) || (jitcnt != 0 &&
+ avgcnt < 2 * up->avgint))
+ 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 ((avgcnt >= up->avgint && jitcnt == 0) || avgcnt > 2 *
- up->avgint) {
- dtemp = (up->tepoch - zepoch) % SECOND;
- if (abs(dtemp) < MAXFREQ * MINAVG) {
+ if (syncnt > maxrun) {
+ maxrun = syncnt;
+ mepoch = xepoch;
+ }
+ if (maxrun > SCMP) {
+ up->yepoch = mepoch;
+ up->status |= SSYNC;
+ } 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.
+ */
+ dtemp = (up->tepoch - zepoch) % SECOND;
+ if (abs(dtemp) < MAXFREQ * MINAVG) {
+ if (maxrun * abs(up->tepoch - zepoch) < avgcnt) {
up->freq += dtemp / avgcnt;
- if (up->freq > MAXFREQ) {
+ if (up->freq > MAXFREQ)
up->freq = MAXFREQ;
- } else if (up->freq < -MAXFREQ) {
+ else if (up->freq < -MAXFREQ)
up->freq = -MAXFREQ;
- } else 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--;
+ }
+ if (abs(dtemp) < MAXFREQ * MINAVG / 2.) {
+ if (avginc < 3) {
+ avginc++;
} else {
- if (up->avgint > MINAVG) {
- up->avgint >>= 1;
+ if (up->avgint < MAXAVG) {
+ up->avgint <<= 1;
avginc = 0;
}
}
}
- if (pp->sloppyclockflag & CLK_FLAG4) {
- sprintf(tbuf,
- "wwv2 %04x %5.0f %4d %4d %4d %4d %4.0f %6.1f",
- up->status, up->epomax, up->tepoch, jitcnt,
- avginc, avgcnt, dtemp, up->freq * 1e6 /
- SECOND);
- record_clock_stats(&peer->srcadr, tbuf);
+ } 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 %4d %+2d %4d %4.0f %6.1f",
+ up->status, up->epomax, up->tepoch, maxrun, jitcnt,
+ avginc, avgcnt, dtemp, up->freq * 1e6 / SECOND);
+ record_clock_stats(&peer->srcadr, tbuf);
#ifdef DEBUG
- if (debug)
- printf("%s\n", tbuf);
+ if (debug)
+ printf("%s\n", tbuf);
#endif /* DEBUG */
- zepoch = up->tepoch;
- avgcnt = 0;
- }
}
+ zepoch = up->tepoch;
+ avgcnt = syncnt = maxrun = 0;
}
/*
* 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.
+ * 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;
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->tepoch,
+ 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,
* Miscellaneous bits. If above the positive threshold, declare
* 1; if below the negative threshold, declare 0; otherwise
* raise the SYMERR alarm. At the end of second 58, QSY to the
- * probe channel.
+ * probe channel. The design is intended to preserve the bits
+ * over periods of signal loss.
*/
case MSC20: /* 55 */
wwv_corr4(peer, &up->decvec[YR + 1], bcddld, bcd9);
* kernel is armed one second before the actual leap is
* scheduled.
*/
- if (up->status & LEPSEC) {
+ if (up->status & LEPDAY) {
pp->leap = LEAP_ADDSECOND;
} else {
pp->leap = LEAP_NOWARNING;
break;
/*
- * If SECWAR is set on the last minute of 30 June or 31
+ * 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
}
/*
- * If all nine digits have been found and compared correctly,
- * declare victory.
+ * If digit sync has not been acquired before timeout, game over
+ * and restart from scratch.
+ */
+ if (!(up->status & DSYNC) && up->watch > DIGIT) {
+ wwv_newgame(peer);
+ return;
+ }
+
+ /*
+ * If tracking second sync and all nine digits have been found
+ * and compared correctly, declare victory.
*/
- if (up->digcnt >= 9)
- up->status |= INSYNC;
+ if (up->status & SSYNC) {
+ if (up->digcnt >= 9)
+ up->status |= INSYNC;
+ } else {
+ up->alarm |= 1 << SYNERR;
+ }
pp->disp += AUDIO_PHI;
up->rsec = nsec;
-#ifdef IRIG_SUCKS
+#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
#endif /* IRIG_SUCKS */
/*
- * If victory has been declared and seconds sync has been lit
- * for a couple of minutes, wind the system clock. 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 victory has been declared and seconds sync is lit, wind
+ * the system clock. 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->alarm & (3 << SYNERR)) == 0) {
+ if (up->status & INSYNC && up->status & SSYNC) {
pp->second = up->rsec;
pp->minute = up->decvec[MN].digit + up->decvec[MN +
1].digit * 10;
* 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(
temp = carry(&up->decvec[HR + 1]);
/*
- * Decode the current minute and day. Set the leap second enable
- * bit on the last minute of 30 June and 31 December.
+ * Decode the current minute and day. Set leap day if the
+ * timecode leap bit is set on 30 June or 31 December. Set leap
+ * minute if the last minute on leap day. This code fails in
+ * 2400 AD.
*/
minute = up->decvec[MN].digit + up->decvec[MN + 1].digit *
10 + up->decvec[HR].digit * 60 + up->decvec[HR +
day = up->decvec[DA].digit + up->decvec[DA + 1].digit * 10 +
up->decvec[DA + 2].digit * 100;
isleap = (up->decvec[YR].digit & 0x3) == 0;
- if (minute == 1439 && (day == (isleap ? 182 : 183) || day ==
- (isleap ? 365 : 366)) && up->misc & SECWAR)
+ if (up->misc & SECWAR && (day == (isleap ? 182 : 183) || day ==
+ (isleap ? 365 : 366)) && up->status & INSYNC && up->status &
+ SSYNC)
+ up->status |= LEPDAY;
+ else
+ up->status &= ~LEPDAY;
+ if (up->status & LEPDAY && minute == 1439)
up->status |= LEPSEC;
else
up->status &= ~LEPSEC;
* on 25 MHz.
*
* This routine selects the best channel using a metric computed from
- * the reachability shift register and minute pulse amplitude. The high
- * order bits of the metric show the number of reachability register 1
- * bits in the last six probes, while the low order bits hold the minute
- * sync pulse amplitude. Normally, the award goes to the the channel
- * with the highest metric; but, case of ties, the award goes to the
- * channel with the highest minute sync pulse amplitude and then to the
- * highest frequency.
+ * 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
struct refclockproc *pp;
struct wwvunit *up;
struct sync *sp, *rp;
- double rank,dtemp;
+ double rank, dtemp;
int i, j;
pp = peer->procptr;
/*
* Search all five station pairs looking for the channel with
- * maximum metric, where the metric is defined as the high order
- * bits the bit count and the low order bits the minute sync
- * pulse amplitude. If no station is found above thresholds, the
+ * maximum metric. If no station is found above thresholds, the
* reference ID is set to NONE and we wait for hotter ions.
*/
j = 0;
up = (struct wwvunit *)pp->unitptr;
/*
- * Initialize strategic values.
+ * 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;
/*
* 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(
*
* Prettytime format - similar to Spectracom
*
- * sq yy ddd hh:mm:ss.fff ld dut lset agc stn comp errs freq avgt
+ * sq yy ddd hh:mm:ss ld dut lset agc iden sig errs freq avgt
*
* s sync indicator ('?' or ' ')
- * q quality character (hex 0-F)
+ * q error bits (hex 0-F)
* yyyy year of century
* ddd day of year
* hh hour of day
* mm minute of hour
- * ss minute of hour
- * fff millisecond of second
- * l leap second warning ' ' or 'L'
- * d DST state 'S', 'D', 'I', or 'O'
- * dut DUT sign and magnitude in deciseconds
+ * ss second of minute)
+ * l leap second warning (' ' or 'L')
+ * d DST state ('S', 'D', 'I', or 'O')
+ * dut DUT sign and magnitude (0.1 s)
* lset minutes since last clock update
* agc audio gain (0-255)
* iden reference identifier (station and frequency)
- * comp channel bit counter
+ * sig signal quality (0-100)
* errs bit errors in last minute
* freq frequency offset (PPM)
* avgt averaging time (s)
projects / thirdparty / ntp.git / commitdiff
