2 * refclock_wwvb - clock driver for Spectracom WWVB and GPS receivers
9 #if defined(REFCLOCK) && defined(CLOCK_SPECTRACOM)
13 #include "ntp_refclock.h"
14 #include "ntp_calendar.h"
15 #include "ntp_stdlib.h"
21 * This driver supports the Spectracom Model 8170 and Netclock/2 WWVB
22 * Synchronized Clocks and the Netclock/GPS Master Clock. Both the WWVB
23 * and GPS clocks have proven reliable sources of time; however, the
24 * WWVB clocks have proven vulnerable to high ambient conductive RF
25 * interference. The claimed accuracy of the WWVB clocks is 100 us
26 * relative to the broadcast signal, while the claimed accuracy of the
27 * GPS clock is 50 ns; however, in most cases the actual accuracy is
28 * limited by the resolution of the timecode and the latencies of the
29 * serial interface and operating system.
31 * The WWVB and GPS clocks should be configured for 24-hour display,
32 * AUTO DST off, time zone 0 (UTC), data format 0 or 2 (see below) and
33 * baud rate 9600. If the clock is to used as the source for the IRIG
34 * Audio Decoder (refclock_irig.c in this distribution), it should be
35 * configured for AM IRIG output and IRIG format 1 (IRIG B with
36 * signature control). The GPS clock can be configured either to respond
37 * to a 'T' poll character or left running continuously.
39 * There are two timecode formats used by these clocks. Format 0, which
40 * is available with both the Netclock/2 and 8170, and format 2, which
41 * is available only with the Netclock/2, specially modified 8170 and
44 * Format 0 (22 ASCII printing characters):
46 * <cr><lf>i ddd hh:mm:ss TZ=zz<cr><lf>
48 * on-time = first <cr>
49 * hh:mm:ss = hours, minutes, seconds
50 * i = synchronization flag (' ' = in synch, '?' = out of synch)
52 * The alarm condition is indicated by other than ' ' at a, which occurs
53 * during initial synchronization and when received signal is lost for
56 * Format 2 (24 ASCII printing characters):
58 * <cr><lf>iqyy ddd hh:mm:ss.fff ld
61 * i = synchronization flag (' ' = in synch, '?' = out of synch)
62 * q = quality indicator (' ' = locked, 'A'...'D' = unlocked)
63 * yy = year (as broadcast)
65 * hh:mm:ss.fff = hours, minutes, seconds, milliseconds
67 * The alarm condition is indicated by other than ' ' at a, which occurs
68 * during initial synchronization and when received signal is lost for
69 * about ten hours. The unlock condition is indicated by other than ' '
72 * The q is normally ' ' when the time error is less than 1 ms and a
73 * character in the set 'A'...'D' when the time error is less than 10,
74 * 100, 500 and greater than 500 ms respectively. The l is normally ' ',
75 * but is set to 'L' early in the month of an upcoming UTC leap second
76 * and reset to ' ' on the first day of the following month. The d is
77 * set to 'S' for standard time 'I' on the day preceding a switch to
78 * daylight time, 'D' for daylight time and 'O' on the day preceding a
79 * switch to standard time. The start bit of the first <cr> is
80 * synchronized to the indicated time as returned.
82 * This driver does not need to be told which format is in use - it
83 * figures out which one from the length of the message. The driver
84 * makes no attempt to correct for the intrinsic jitter of the radio
85 * itself, which is a known problem with the older radios.
89 * This driver can retrieve a table of quality data maintained
90 * internally by the Netclock/2 clock. If flag4 of the fudge
91 * configuration command is set to 1, the driver will retrieve this
92 * table and write it to the clockstats file when the first timecode
93 * message of a new day is received.
95 * PPS calibration fudge time 1: format 0 .003134, format 2 .004034
98 * Interface definitions
100 #define DEVICE "/dev/wwvb%d" /* device name and unit */
101 #define SPEED232 B9600 /* uart speed (9600 baud) */
102 #define PRECISION (-13) /* precision assumed (about 100 us) */
103 #define REFID "WWVB" /* reference ID */
104 #define DESCRIPTION "Spectracom WWVB/GPS Receiver" /* WRU */
106 #define LENWWVB0 22 /* format 0 timecode length */
107 #define LENWWVB1 22 /* format 1 timecode length */
108 #define LENWWVB2 24 /* format 2 timecode length */
109 #define LENWWVB3 29 /* format 3 timecode length */
110 #define MONLIN 15 /* number of monitoring lines */
113 * WWVB unit control structure
116 l_fp laststamp; /* last receive timestamp */
117 u_char lasthour; /* last hour (for monitor) */
118 u_char linect; /* count ignored lines (for monitor */
122 * Function prototypes
124 static int wwvb_start P((int, struct peer *));
125 static void wwvb_shutdown P((int, struct peer *));
126 static void wwvb_receive P((struct recvbuf *));
127 static void wwvb_poll P((int, struct peer *));
128 static void wwvb_timer P((int, struct peer *));
133 struct refclock refclock_wwvb = {
134 wwvb_start, /* start up driver */
135 wwvb_shutdown, /* shut down driver */
136 wwvb_poll, /* transmit poll message */
137 noentry, /* not used (old wwvb_control) */
138 noentry, /* initialize driver (not used) */
139 noentry, /* not used (old wwvb_buginfo) */
140 wwvb_timer /* called once per second */
145 * wwvb_start - open the devices and initialize data for processing
153 register struct wwvbunit *up;
154 struct refclockproc *pp;
159 * Open serial port. Use CLK line discipline, if available.
161 sprintf(device, DEVICE, unit);
162 if (!(fd = refclock_open(device, SPEED232, LDISC_CLK)))
166 * Allocate and initialize unit structure
168 if (!(up = (struct wwvbunit *)
169 emalloc(sizeof(struct wwvbunit)))) {
173 memset((char *)up, 0, sizeof(struct wwvbunit));
175 pp->unitptr = (caddr_t)up;
176 pp->io.clock_recv = wwvb_receive;
177 pp->io.srcclock = (caddr_t)peer;
180 if (!io_addclock(&pp->io)) {
187 * Initialize miscellaneous variables
189 peer->precision = PRECISION;
190 pp->clockdesc = DESCRIPTION;
191 memcpy((char *)&pp->refid, REFID, 4);
197 * wwvb_shutdown - shut down the clock
205 register struct wwvbunit *up;
206 struct refclockproc *pp;
209 up = (struct wwvbunit *)pp->unitptr;
210 io_closeclock(&pp->io);
216 * wwvb_receive - receive data from the serial interface
220 struct recvbuf *rbufp
224 struct refclockproc *pp;
227 l_fp trtmp; /* arrival timestamp */
228 int tz; /* time zone */
229 int day, month; /* ddd conversion */
230 int temp; /* int temp */
231 char syncchar; /* synchronization indicator */
232 char qualchar; /* quality indicator */
233 char leapchar; /* leap indicator */
234 char dstchar; /* daylight/standard indicator */
235 char tmpchar; /* trashbin */
238 * Initialize pointers and read the timecode and timestamp
240 peer = (struct peer *)rbufp->recv_srcclock;
242 up = (struct wwvbunit *)pp->unitptr;
243 temp = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp);
246 * Note we get a buffer and timestamp for both a <cr> and <lf>,
247 * but only the <cr> timestamp is retained. Note: in format 0 on
248 * a Netclock/2 or upgraded 8170 the start bit is delayed 100
249 * +-50 us relative to the pps; however, on an unmodified 8170
250 * the start bit can be delayed up to 10 ms. In format 2 the
251 * reading precision is only to the millisecond. Thus, unless
252 * you have a PPS gadget and don't have to have the year, format
253 * 0 provides the lowest jitter.
256 up->laststamp = trtmp;
260 pp->lastrec = up->laststamp;
263 * We get down to business, check the timecode format and decode
264 * its contents. This code uses the timecode length to determine
265 * format 0, 2 or 3. If the timecode has invalid length or is
266 * not in proper format, we declare bad format and exit.
268 syncchar = qualchar = leapchar = dstchar = ' ';
270 switch (pp->lencode) {
275 * Timecode format 0: "I ddd hh:mm:ss DTZ=nn"
277 if (sscanf(pp->a_lastcode,
278 "%c %3d %2d:%2d:%2d%c%cTZ=%2d",
279 &syncchar, &pp->day, &pp->hour, &pp->minute,
280 &pp->second, &tmpchar, &dstchar, &tz) == 8)
287 * Timecode format 2: "IQyy ddd hh:mm:ss.mmm LD" */
288 if (sscanf(pp->a_lastcode,
289 "%c%c %2d %3d %2d:%2d:%2d.%3ld %c",
290 &syncchar, &qualchar, &pp->year, &pp->day,
291 &pp->hour, &pp->minute, &pp->second, &pp->nsec,
299 * Timecode format 3: "0003I yyyymmdd hhmmss+0000SL#"
301 if (sscanf(pp->a_lastcode,
302 "0003%c %4d%2d%2d %2d%2d%2d+0000%c%c",
303 &syncchar, &pp->year, &month, &day, &pp->hour,
304 &pp->minute, &pp->second, &dstchar, &leapchar) == 8)
306 pp->day = ymd2yd(pp->year, month, day);
314 * Unknown format: If dumping internal table, record
315 * stats; otherwise, declare bad format.
317 if (up->linect > 0) {
319 record_clock_stats(&peer->srcadr,
322 refclock_report(peer, CEVNT_BADREPLY);
328 * Decode synchronization, quality and leap characters. If
329 * unsynchronized, set the leap bits accordingly and exit.
330 * Otherwise, set the leap bits according to the leap character.
331 * Once synchronized, the dispersion depends only on the
338 pp->lastref = pp->lastrec;
354 pp->disp = MAXDISPERSE;
358 pp->disp = MAXDISPERSE;
359 refclock_report(peer, CEVNT_BADREPLY);
363 pp->leap = LEAP_NOTINSYNC;
364 else if (leapchar == 'L')
365 pp->leap = LEAP_ADDSECOND;
367 pp->leap = LEAP_NOWARNING;
370 * Process the new sample in the median filter and determine the
371 * timecode timestamp.
373 if (!refclock_process(pp))
374 refclock_report(peer, CEVNT_BADTIME);
375 if (peer->disp > MAXDISTANCE)
376 refclock_receive(peer);
381 * wwvb_timer - called once per second by the transmit procedure
389 register struct wwvbunit *up;
390 struct refclockproc *pp;
391 char pollchar; /* character sent to clock */
394 * Time to poll the clock. The Spectracom clock responds to a
395 * 'T' by returning a timecode in the format(s) specified above.
396 * Note there is no checking on state, since this may not be the
397 * only customer reading the clock. Only one customer need poll
398 * the clock; all others just listen in.
401 up = (struct wwvbunit *)pp->unitptr;
406 if (write(pp->io.fd, &pollchar, 1) != 1)
407 refclock_report(peer, CEVNT_FAULT);
412 * wwvb_poll - called by the transmit procedure
420 register struct wwvbunit *up;
421 struct refclockproc *pp;
424 * Sweep up the samples received since the last poll. If none
425 * are received, declare a timeout and keep going.
428 up = (struct wwvbunit *)pp->unitptr;
432 * If the monitor flag is set (flag4), we dump the internal
433 * quality table at the first timecode beginning the day.
435 if (pp->sloppyclockflag & CLK_FLAG4 && pp->hour <
438 up->lasthour = pp->hour;
441 * Process median filter samples. If none received, declare a
442 * timeout and keep going.
444 if (pp->coderecv == pp->codeproc) {
445 refclock_report(peer, CEVNT_TIMEOUT);
448 refclock_receive(peer);
449 record_clock_stats(&peer->srcadr, pp->a_lastcode);
452 printf("wwvb: timecode %d %s\n", pp->lencode,
458 int refclock_wwvb_bs;
459 #endif /* REFCLOCK */