Re: Info needed on Spectracom 8171A clock... Help

From: Tim Shoppa (shoppa_at_trailing-edge.com)
Date: 08/14/04 

Date: 14 Aug 2004 05:13:01 -0700

Dennis <Dennis_The_Menace@no_spam.net> wrote in message news:<10hnmbgs2042aac@corp.supernews.com>...
> --
>
> I have a Spectracom 8171A WWVB Synchronized clock.
> Need a manual on this clock, or some good operating
> information. Much appreciated.

I believe that it uses the same protocols as the Spectracom
8170, which is well documented in many places including the NTP
source code. From refclock_wwvb.c:

 * This driver supports the Spectracom Model 8170 and Netclock/2 WWVB
 * Synchronized Clocks and the Netclock/GPS Master Clock. Both the WWVB
 * and GPS clocks have proven reliable sources of time; however, the
 * WWVB clocks have proven vulnerable to high ambient conductive RF
 * interference. The claimed accuracy of the WWVB clocks is 100 us
 * relative to the broadcast signal, while the claimed accuracy of the
 * GPS clock is 50 ns; however, in most cases the actual accuracy is
 * limited by the resolution of the timecode and the latencies of the
 * serial interface and operating system.
 *
 * The WWVB and GPS clocks should be configured for 24-hour display,
 * AUTO DST off, time zone 0 (UTC), data format 0 or 2 (see below) and
 * baud rate 9600. If the clock is to used as the source for the IRIG
 * Audio Decoder (refclock_irig.c in this distribution), it should be
 * configured for AM IRIG output and IRIG format 1 (IRIG B with
 * signature control). The GPS clock can be configured either to respond
 * to a 'T' poll character or left running continuously.
 *
 * 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, specially modified 8170 and
 * GPS.
 *
 * Format 0 (22 ASCII printing characters):
 *
 * <cr><lf>i ddd hh:mm:ss TZ=zz<cr><lf>
 *
 * on-time = first <cr>
 * 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):
 *
 * <cr><lf>iqyy ddd hh:mm:ss.fff ld
 *
 * on-time = <cr>
 * 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 <cr> is
 * synchronized to the indicated time as returned.

Tim.

Relevant Pages

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  • Re: Info needed on Spectracom 8171A clock... Help
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