/* * refclock_wwvb - clock driver for Spectracom WWVB receivers */ #ifdef HAVE_CONFIG_H #include #endif #if defined(REFCLOCK) && defined(WWVB) #include #include #include #include #include "ntpd.h" #include "ntp_io.h" #include "ntp_refclock.h" #include "ntp_stdlib.h" #include "ntp_calendar.h" /* * This driver supports the Spectracom Model 8170 and Netclock/2 WWVB * Synchronized Clock. This clock has proven a reliable source of time, * except in some cases of high ambient conductive RF interference. The * claimed accuracy of the clock is 100 usec relative to the broadcast * signal; however, in most cases the actual accuracy is limited by the * precision of the timecode and the latencies of the serial interface * and operating system. * * The DIPswitches on this clock should be set to 24-hour display, AUTO * DST off, time zone 0 (UTC), data format 0 or 2 (see below) and baud * rate 9600. If this clock is to used as the source for the IRIG Audio * Decoder (refclock_irig.c in this distribution), set the DIPswitches * for AM IRIG output and IRIG format 1 (IRIG B with signature control). * * There are two timecode formats used by these clocks. Format 0, which * is available with both the Netclock/2 and 8170, and format 2, which * is available only with the Netclock/2 and specially modified 8170. * * Format 0 (22 ASCII printing characters): * * i ddd hh:mm:ss TZ=zz * * on-time = first * hh:mm:ss = hours, minutes, seconds * i = synchronization flag (' ' = in synch, '?' = out of synch) * * The alarm condition is indicated by other than ' ' at A, which occurs * during initial synchronization and when received signal is lost for * about ten hours. * * Format 2 (24 ASCII printing characters): * * iqyy ddd hh:mm:ss.fff ld * * on-time = * i = synchronization flag (' ' = in synch, '?' = out of synch) * q = quality indicator (' ' = locked, 'A'...'D' = unlocked) * yy = year (as broadcast) * ddd = day of year * hh:mm:ss.fff = hours, minutes, seconds, milliseconds * * The alarm condition is indicated by other than ' ' at A, which occurs * during initial synchronization and when received signal is lost for * about ten hours. The unlock condition is indicated by other than ' ' * at Q. * * The Q is normally ' ' when the time error is less than 1 ms and a * character in the set 'A'...'D' when the time error is less than 10, * 100, 500 and greater than 500 ms respectively. The L is normally ' ', * but is set to 'L' early in the month of an upcoming UTC leap second * and reset to ' ' on the first day of the following month. The D is * set to 'S' for standard time 'I' on the day preceding a switch to * daylight time, 'D' for daylight time and 'O' on the day preceding a * switch to standard time. The start bit of the first is * synchronized to the indicated time as returned. * * This driver does not need to be told which format is in use - it * figures out which one from the length of the message. A three-stage * median filter is used to reduce jitter and provide a dispersion * measure. The driver makes no attempt to correct for the intrinsic * jitter of the radio itself, which is a known problem with the older * radios. * * Fudge Factors * * This driver can retrieve a table of quality data maintained * internally by the Netclock/2 receiver. If flag4 of the fudge * configuration command is set to 1, the driver will retrieve this * table and write it to the clockstats file on when the first timecode * message of a new day is received. */ /* * Interface definitions */ #define DEVICE "/dev/wwvb%d" /* device name and unit */ #define SPEED232 B9600 /* uart speed (9600 baud) */ #define PRECISION (-10) /* precision assumed (about 1 ms) */ #define REFID "WWVB" /* reference ID */ #define DESCRIPTION "Spectracom WWVB Receiver" /* WRU */ #define NSAMPLES 3 /* stages of median filter */ #define LENWWVB0 22 /* format 0 timecode length */ #define LENWWVB2 24 /* format 2 timecode length */ #define LENWWVB3 29 /* format 3 timecode length */ #define MONLIN 15 /* number of monitoring lines */ /* * Imported from ntp_timer module */ extern u_long current_time; /* current time (s) */ /* * Imported from ntpd module */ extern int debug; /* global debug flag */ /* * WWVB unit control structure */ struct wwvbunit { int pollcnt; /* poll message counter */ u_char tcswitch; /* timecode switch */ l_fp laststamp; /* last receive timestamp */ u_char lasthour; /* last hour (for monitor) */ u_char linect; /* count ignored lines (for monitor */ }; /* * Function prototypes */ static int wwvb_start P((int, struct peer *)); static void wwvb_shutdown P((int, struct peer *)); static void wwvb_receive P((struct recvbuf *)); static void wwvb_poll P((int, struct peer *)); /* * Transfer vector */ struct refclock refclock_wwvb = { wwvb_start, /* start up driver */ wwvb_shutdown, /* shut down driver */ wwvb_poll, /* transmit poll message */ noentry, /* not used (old wwvb_control) */ noentry, /* initialize driver (not used) */ noentry, /* not used (old wwvb_buginfo) */ NOFLAGS /* not used */ }; /* * wwvb_start - open the devices and initialize data for processing */ static int wwvb_start(unit, peer) int unit; struct peer *peer; { register struct wwvbunit *up; struct refclockproc *pp; int fd; char device[20]; #ifdef DEBUG if (debug) printf("inside wwvb_start\n"); #endif /* * Open serial port. Use CLK line discipline, if available. */ (void)sprintf(device, DEVICE, unit); #ifdef TTYCLK if (!(fd = refclock_open(device, SPEED232, LDISC_CLK))) #else if (!(fd = refclock_open(device, SPEED232, 0))) #endif /* TTYCLK */ { #ifdef DEBUG if (debug) printf ("refclock_open barfed\n"); #endif return (0); } /* * Allocate and initialize unit structure */ if (!(up = (struct wwvbunit *) emalloc(sizeof(struct wwvbunit)))) { (void) close(fd); return (0); } memset((char *)up, 0, sizeof(struct wwvbunit)); pp = peer->procptr; pp->io.clock_recv = wwvb_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); } pp->unitptr = (caddr_t)up; /* * Initialize miscellaneous variables */ peer->precision = PRECISION; pp->clockdesc = DESCRIPTION; memcpy((char *)&pp->refid, REFID, 4); up->pollcnt = 2; return (1); } /* * wwvb_shutdown - shut down the clock */ static void wwvb_shutdown(unit, peer) int unit; struct peer *peer; { register struct wwvbunit *up; struct refclockproc *pp; pp = peer->procptr; up = (struct wwvbunit *)pp->unitptr; io_closeclock(&pp->io); free(up); } /* * wwvb_receive - receive data from the serial interface */ static void wwvb_receive(rbufp) struct recvbuf *rbufp; { register struct wwvbunit *up; struct refclockproc *pp; struct peer *peer; l_fp trtmp; u_long ltemp; int temp; char syncchar; /* synchronization indicator */ char qualchar; /* quality indicator */ char leapchar; /* leap indicator */ #ifdef DEBUG if (debug) printf ("in wwvb_receive\n"); #endif /* * Initialize pointers and read the timecode and timestamp */ peer = (struct peer *)rbufp->recv_srcclock; pp = peer->procptr; up = (struct wwvbunit *)pp->unitptr; temp = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp); /* * Note we get a buffer and timestamp for both a and , * but only the timestamp is retained. Note: in format 0 on * a Netclock/2 or upgraded 8170 the start bit is delayed 100 * +-50 us relative to the pps; however, on an unmodified 8170 * the start bit can be delayed up to 10 ms. In format 2 the * reading precision is only to the millisecond. Thus, unless * you have a pps gadget and don't have to have the year, format * 0 provides the lowest jitter. */ if (temp == 0) { if (up->tcswitch == 0) { up->tcswitch = 1; up->laststamp = trtmp; } else up->tcswitch = 0; return; } pp->lencode = temp; pp->lastrec = up->laststamp; up->laststamp = trtmp; up->tcswitch = 1; up->pollcnt = 2; record_clock_stats(&peer->srcadr, pp->a_lastcode); #ifdef DEBUG if (debug) printf("wwvb: timecode %d %s\n", pp->lencode, pp->a_lastcode); #endif /* * We get down to business, check the timecode format and decode * its contents. This code uses the timecode length to determine * whether format 0 or format 2. If the timecode has invalid * length or is not in proper format, we declare bad format and * exit. */ switch (pp->lencode) { int tz = 0; case LENWWVB0: /* * Timecode format 0: "I ddd hh:mm:ss TZ=nn" */ qualchar = leapchar = ' '; if (sscanf(pp->a_lastcode, "%c %3d %2d:%2d:%2d TZ=%2d", &syncchar, &pp->day, &pp->hour, &pp->minute, &pp->second, &tz) == 6) { int hr; hr = pp->hour + tz; pp->day += hr / 24; pp->hour = hr % 24; break; } case LENWWVB2: /* * Timecode format 2: "IQyy ddd hh:mm:ss.mmm LD" */ if (sscanf(pp->a_lastcode, "%c%c %2d %3d %2d:%2d:%2d.%3d %c", &syncchar, &qualchar, &pp->year, &pp->day, &pp->hour, &pp->minute, &pp->second, &pp->msec, &leapchar) == 9) break; case LENWWVB3: /* * Timecode format 3: "0003I yyyymmdd hhmmss+0000SL#" */ { int month,day; int matched; qualchar = ' '; matched = sscanf(pp->a_lastcode,"0003%c %4d%2d%2d %2d%2d%2d%*c%c", &syncchar,&pp->year,&month,&day, &pp->hour,&pp->minute,&pp->second,&leapchar); if (matched==8) { pp->msec = 0; pp->day = 31*(month - 1) + day; if (month > 2) { pp->day = pp->day - (4*month + 23)/10; if (is_leapyear(pp->year)) pp->day++; } break; } #ifdef DEBUG if (debug) printf ("wwvb_receive: Surrender, Dorothy!\n"); #endif } default: if (up->linect > 0) up->linect--; else refclock_report(peer, CEVNT_BADREPLY); return; } /* * Decode synchronization, quality and leap characters. If * unsynchronized, set the leap bits accordingly and exit. * Otherwise, set the leap bits according to the leap character. * Once synchronized, the dispersion depends only on when the * clock was last heard. The first time the clock is heard, the * time last heard is faked based on the quality indicator. The * magic numbers (in seconds) are from the clock specifications. */ switch (qualchar) { case ' ': ltemp = 0; break; case 'A': ltemp = 800; break; case 'B': ltemp = 5300; break; case 'C': ltemp = 25300; break; case 'D': ltemp = NTP_MAXAGE; break; default: refclock_report(peer, CEVNT_BADREPLY); return; } if (syncchar != ' ') pp->leap = LEAP_NOTINSYNC; else { if (leapchar == 'L') pp->leap = LEAP_ADDSECOND; else pp->leap = 0; pp->lasttime = current_time - ltemp; } /* * If the monitor flag is set (flag4), we dump the internal * quality table at the first timecode beginning the day. */ if (pp->sloppyclockflag & CLK_FLAG4 && pp->hour < (int)up->lasthour) up->linect = MONLIN; up->lasthour = pp->hour; /* * Process the new sample in the median filter and determine the * reference clock offset and dispersion. We use lastrec as both * the reference time and receive time in order to avoid being * cute, like setting the reference time later than the receive * time, which may cause a paranoid protocol module to chuck out * the data. */ if (!refclock_process(pp, NSAMPLES, NSAMPLES)) { refclock_report(peer, CEVNT_BADTIME); return; } trtmp = pp->lastrec; trtmp.l_ui -= ltemp; refclock_receive(peer, &pp->offset, 0, pp->dispersion, &trtmp, &pp->lastrec, pp->leap); } /* * wwvb_poll - called by the transmit procedure */ static void wwvb_poll(unit, peer) int unit; struct peer *peer; { register struct wwvbunit *up; struct refclockproc *pp; char poll; /* * Time to poll the clock. The Spectracom clock responds to a * 'T' by returning a timecode in the format(s) specified above. * Note there is no checking on state, since this may not be the * only customer reading the clock. Only one customer need poll * the clock; all others just listen in. If nothing is heard * from the clock for two polls, declare a timeout and keep * going. */ pp = peer->procptr; up = (struct wwvbunit *)pp->unitptr; if (up->pollcnt == 0) refclock_report(peer, CEVNT_TIMEOUT); else up->pollcnt--; if (up->linect > 0) poll = 'R'; else poll = 'T'; if (write(pp->io.fd, &poll, 1) != 1) { refclock_report(peer, CEVNT_FAULT); } else pp->polls++; } #endif