460 lines
12 KiB
C
460 lines
12 KiB
C
/*
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* refclock_wwvb - clock driver for Spectracom WWVB and GPS receivers
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#if defined(REFCLOCK) && defined(CLOCK_SPECTRACOM)
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#include "ntpd.h"
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#include "ntp_io.h"
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#include "ntp_refclock.h"
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#include "ntp_calendar.h"
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#include "ntp_stdlib.h"
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#include <stdio.h>
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#include <ctype.h>
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/*
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* This driver supports the Spectracom Model 8170 and Netclock/2 WWVB
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* Synchronized Clocks and the Netclock/GPS Master Clock. Both the WWVB
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* and GPS clocks have proven reliable sources of time; however, the
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* WWVB clocks have proven vulnerable to high ambient conductive RF
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* interference. The claimed accuracy of the WWVB clocks is 100 us
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* relative to the broadcast signal, while the claimed accuracy of the
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* GPS clock is 50 ns; however, in most cases the actual accuracy is
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* limited by the resolution of the timecode and the latencies of the
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* serial interface and operating system.
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*
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* The WWVB and GPS clocks should be configured for 24-hour display,
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* AUTO DST off, time zone 0 (UTC), data format 0 or 2 (see below) and
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* baud rate 9600. If the clock is to used as the source for the IRIG
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* Audio Decoder (refclock_irig.c in this distribution), it should be
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* configured for AM IRIG output and IRIG format 1 (IRIG B with
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* signature control). The GPS clock can be configured either to respond
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* to a 'T' poll character or left running continuously.
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*
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* There are two timecode formats used by these clocks. Format 0, which
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* is available with both the Netclock/2 and 8170, and format 2, which
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* is available only with the Netclock/2, specially modified 8170 and
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* GPS.
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*
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* Format 0 (22 ASCII printing characters):
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*
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* <cr><lf>i ddd hh:mm:ss TZ=zz<cr><lf>
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*
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* on-time = first <cr>
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* hh:mm:ss = hours, minutes, seconds
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* i = synchronization flag (' ' = in synch, '?' = out of synch)
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*
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* The alarm condition is indicated by other than ' ' at a, which occurs
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* during initial synchronization and when received signal is lost for
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* about ten hours.
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*
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* Format 2 (24 ASCII printing characters):
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*
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* <cr><lf>iqyy ddd hh:mm:ss.fff ld
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*
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* on-time = <cr>
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* i = synchronization flag (' ' = in synch, '?' = out of synch)
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* q = quality indicator (' ' = locked, 'A'...'D' = unlocked)
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* yy = year (as broadcast)
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* ddd = day of year
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* hh:mm:ss.fff = hours, minutes, seconds, milliseconds
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*
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* The alarm condition is indicated by other than ' ' at a, which occurs
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* during initial synchronization and when received signal is lost for
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* about ten hours. The unlock condition is indicated by other than ' '
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* at q.
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*
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* The q is normally ' ' when the time error is less than 1 ms and a
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* character in the set 'A'...'D' when the time error is less than 10,
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* 100, 500 and greater than 500 ms respectively. The l is normally ' ',
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* but is set to 'L' early in the month of an upcoming UTC leap second
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* and reset to ' ' on the first day of the following month. The d is
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* set to 'S' for standard time 'I' on the day preceding a switch to
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* daylight time, 'D' for daylight time and 'O' on the day preceding a
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* switch to standard time. The start bit of the first <cr> is
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* synchronized to the indicated time as returned.
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*
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* This driver does not need to be told which format is in use - it
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* figures out which one from the length of the message. The driver
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* makes no attempt to correct for the intrinsic jitter of the radio
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* itself, which is a known problem with the older radios.
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*
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* Fudge Factors
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*
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* This driver can retrieve a table of quality data maintained
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* internally by the Netclock/2 clock. If flag4 of the fudge
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* configuration command is set to 1, the driver will retrieve this
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* table and write it to the clockstats file when the first timecode
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* message of a new day is received.
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*
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* PPS calibration fudge time 1: format 0 .003134, format 2 .004034
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*/
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/*
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* Interface definitions
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*/
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#define DEVICE "/dev/wwvb%d" /* device name and unit */
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#define SPEED232 B9600 /* uart speed (9600 baud) */
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#define PRECISION (-13) /* precision assumed (about 100 us) */
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#define REFID "WWVB" /* reference ID */
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#define DESCRIPTION "Spectracom WWVB/GPS Receiver" /* WRU */
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#define LENWWVB0 22 /* format 0 timecode length */
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#define LENWWVB1 22 /* format 1 timecode length */
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#define LENWWVB2 24 /* format 2 timecode length */
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#define LENWWVB3 29 /* format 3 timecode length */
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#define MONLIN 15 /* number of monitoring lines */
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/*
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* WWVB unit control structure
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*/
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struct wwvbunit {
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l_fp laststamp; /* last receive timestamp */
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u_char lasthour; /* last hour (for monitor) */
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u_char linect; /* count ignored lines (for monitor */
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};
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/*
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* Function prototypes
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*/
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static int wwvb_start P((int, struct peer *));
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static void wwvb_shutdown P((int, struct peer *));
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static void wwvb_receive P((struct recvbuf *));
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static void wwvb_poll P((int, struct peer *));
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static void wwvb_timer P((int, struct peer *));
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/*
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* Transfer vector
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*/
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struct refclock refclock_wwvb = {
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wwvb_start, /* start up driver */
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wwvb_shutdown, /* shut down driver */
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wwvb_poll, /* transmit poll message */
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noentry, /* not used (old wwvb_control) */
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noentry, /* initialize driver (not used) */
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noentry, /* not used (old wwvb_buginfo) */
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wwvb_timer /* called once per second */
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};
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/*
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* wwvb_start - open the devices and initialize data for processing
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*/
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static int
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wwvb_start(
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int unit,
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struct peer *peer
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)
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{
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register struct wwvbunit *up;
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struct refclockproc *pp;
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int fd;
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char device[20];
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/*
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* Open serial port. Use CLK line discipline, if available.
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*/
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sprintf(device, DEVICE, unit);
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if (!(fd = refclock_open(device, SPEED232, LDISC_CLK)))
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return (0);
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/*
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* Allocate and initialize unit structure
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*/
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if (!(up = (struct wwvbunit *)
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emalloc(sizeof(struct wwvbunit)))) {
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close(fd);
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return (0);
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}
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memset((char *)up, 0, sizeof(struct wwvbunit));
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pp = peer->procptr;
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pp->unitptr = (caddr_t)up;
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pp->io.clock_recv = wwvb_receive;
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pp->io.srcclock = (caddr_t)peer;
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pp->io.datalen = 0;
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pp->io.fd = fd;
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if (!io_addclock(&pp->io)) {
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close(fd);
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free(up);
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return (0);
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}
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/*
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* Initialize miscellaneous variables
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*/
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peer->precision = PRECISION;
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pp->clockdesc = DESCRIPTION;
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memcpy((char *)&pp->refid, REFID, 4);
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return (1);
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}
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/*
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* wwvb_shutdown - shut down the clock
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*/
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static void
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wwvb_shutdown(
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int unit,
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struct peer *peer
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)
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{
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register struct wwvbunit *up;
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struct refclockproc *pp;
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pp = peer->procptr;
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up = (struct wwvbunit *)pp->unitptr;
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io_closeclock(&pp->io);
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free(up);
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}
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/*
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* wwvb_receive - receive data from the serial interface
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*/
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static void
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wwvb_receive(
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struct recvbuf *rbufp
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)
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{
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struct wwvbunit *up;
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struct refclockproc *pp;
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struct peer *peer;
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l_fp trtmp; /* arrival timestamp */
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int tz; /* time zone */
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int day, month; /* ddd conversion */
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int temp; /* int temp */
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char syncchar; /* synchronization indicator */
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char qualchar; /* quality indicator */
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char leapchar; /* leap indicator */
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char dstchar; /* daylight/standard indicator */
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char tmpchar; /* trashbin */
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/*
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* Initialize pointers and read the timecode and timestamp
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*/
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peer = (struct peer *)rbufp->recv_srcclock;
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pp = peer->procptr;
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up = (struct wwvbunit *)pp->unitptr;
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temp = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp);
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/*
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* Note we get a buffer and timestamp for both a <cr> and <lf>,
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* but only the <cr> timestamp is retained. Note: in format 0 on
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* a Netclock/2 or upgraded 8170 the start bit is delayed 100
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* +-50 us relative to the pps; however, on an unmodified 8170
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* the start bit can be delayed up to 10 ms. In format 2 the
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* reading precision is only to the millisecond. Thus, unless
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* you have a PPS gadget and don't have to have the year, format
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* 0 provides the lowest jitter.
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*/
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if (temp == 0) {
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up->laststamp = trtmp;
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return;
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}
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pp->lencode = temp;
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pp->lastrec = up->laststamp;
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/*
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* We get down to business, check the timecode format and decode
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* its contents. This code uses the timecode length to determine
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* format 0, 2 or 3. If the timecode has invalid length or is
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* not in proper format, we declare bad format and exit.
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*/
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syncchar = qualchar = leapchar = dstchar = ' ';
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tz = 0;
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switch (pp->lencode) {
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case LENWWVB0:
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/*
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* Timecode format 0: "I ddd hh:mm:ss DTZ=nn"
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*/
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if (sscanf(pp->a_lastcode,
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"%c %3d %2d:%2d:%2d%c%cTZ=%2d",
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&syncchar, &pp->day, &pp->hour, &pp->minute,
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&pp->second, &tmpchar, &dstchar, &tz) == 8)
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pp->nsec = 0;
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break;
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case LENWWVB2:
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/*
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* Timecode format 2: "IQyy ddd hh:mm:ss.mmm LD" */
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if (sscanf(pp->a_lastcode,
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"%c%c %2d %3d %2d:%2d:%2d.%3ld %c",
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&syncchar, &qualchar, &pp->year, &pp->day,
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&pp->hour, &pp->minute, &pp->second, &pp->nsec,
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&leapchar) == 9)
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pp->nsec *= 1000000;
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break;
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case LENWWVB3:
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/*
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* Timecode format 3: "0003I yyyymmdd hhmmss+0000SL#"
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*/
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if (sscanf(pp->a_lastcode,
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"0003%c %4d%2d%2d %2d%2d%2d+0000%c%c",
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&syncchar, &pp->year, &month, &day, &pp->hour,
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&pp->minute, &pp->second, &dstchar, &leapchar) == 8)
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{
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pp->day = ymd2yd(pp->year, month, day);
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pp->nsec = 0;
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break;
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}
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default:
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/*
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* Unknown format: If dumping internal table, record
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* stats; otherwise, declare bad format.
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*/
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if (up->linect > 0) {
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up->linect--;
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record_clock_stats(&peer->srcadr,
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pp->a_lastcode);
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} else {
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refclock_report(peer, CEVNT_BADREPLY);
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}
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return;
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}
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/*
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* Decode synchronization, quality and leap characters. If
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* unsynchronized, set the leap bits accordingly and exit.
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* Otherwise, set the leap bits according to the leap character.
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* Once synchronized, the dispersion depends only on the
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* quality character.
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*/
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switch (qualchar) {
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case ' ':
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pp->disp = .001;
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pp->lastref = pp->lastrec;
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break;
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case 'A':
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pp->disp = .01;
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break;
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case 'B':
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pp->disp = .1;
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break;
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case 'C':
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pp->disp = .5;
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break;
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case 'D':
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pp->disp = MAXDISPERSE;
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break;
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default:
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pp->disp = MAXDISPERSE;
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refclock_report(peer, CEVNT_BADREPLY);
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break;
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}
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if (syncchar != ' ')
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pp->leap = LEAP_NOTINSYNC;
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else if (leapchar == 'L')
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pp->leap = LEAP_ADDSECOND;
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else
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pp->leap = LEAP_NOWARNING;
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/*
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* Process the new sample in the median filter and determine the
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* timecode timestamp.
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*/
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if (!refclock_process(pp))
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refclock_report(peer, CEVNT_BADTIME);
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if (peer->disp > MAXDISTANCE)
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refclock_receive(peer);
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}
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/*
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* wwvb_timer - called once per second by the transmit procedure
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*/
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static void
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wwvb_timer(
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int unit,
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struct peer *peer
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)
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{
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register struct wwvbunit *up;
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struct refclockproc *pp;
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char pollchar; /* character sent to clock */
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/*
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* Time to poll the clock. The Spectracom clock responds to a
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* 'T' by returning a timecode in the format(s) specified above.
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* Note there is no checking on state, since this may not be the
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* only customer reading the clock. Only one customer need poll
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* the clock; all others just listen in.
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*/
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pp = peer->procptr;
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up = (struct wwvbunit *)pp->unitptr;
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if (up->linect > 0)
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pollchar = 'R';
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else
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pollchar = 'T';
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if (write(pp->io.fd, &pollchar, 1) != 1)
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refclock_report(peer, CEVNT_FAULT);
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}
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/*
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* wwvb_poll - called by the transmit procedure
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*/
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static void
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wwvb_poll(
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int unit,
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struct peer *peer
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)
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{
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register struct wwvbunit *up;
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struct refclockproc *pp;
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/*
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* Sweep up the samples received since the last poll. If none
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* are received, declare a timeout and keep going.
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*/
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pp = peer->procptr;
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up = (struct wwvbunit *)pp->unitptr;
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pp->polls++;
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/*
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* If the monitor flag is set (flag4), we dump the internal
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* quality table at the first timecode beginning the day.
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*/
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if (pp->sloppyclockflag & CLK_FLAG4 && pp->hour <
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(int)up->lasthour)
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up->linect = MONLIN;
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up->lasthour = pp->hour;
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/*
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* Process median filter samples. If none received, declare a
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* timeout and keep going.
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*/
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if (pp->coderecv == pp->codeproc) {
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refclock_report(peer, CEVNT_TIMEOUT);
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return;
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}
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refclock_receive(peer);
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record_clock_stats(&peer->srcadr, pp->a_lastcode);
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#ifdef DEBUG
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if (debug)
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printf("wwvb: timecode %d %s\n", pp->lencode,
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pp->a_lastcode);
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#endif
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}
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#else
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int refclock_wwvb_bs;
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#endif /* REFCLOCK */
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