107 lines
3.6 KiB
HTML
107 lines
3.6 KiB
HTML
<!-- $NetBSD: driver19.html,v 1.1 1998/12/30 20:20:34 mcr Exp $ -->
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Strict//EN">
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<html><head><title>
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Heath WWV/WWVH Receiver
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</title></head><body><h3>
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Heath WWV/WWVH Receiver
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</h3><hr>
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<p><h4>Synopsis</h4>
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<p>Address: 127.127.19.<var>u</var>
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<br>Reference ID: WWV
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<br>Driver ID: WWV_HEATH
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<br>Serial Port: <code>/dev/heath<var>u</var></code>; 1200 baud, 8-bits,
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no parity
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<br>Features: <code>tty_clk</code>
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<br>Requires: <code>/usr/include/sys/termios.h</code> header file with
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modem control
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<p><h4>Description</h4>
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<p>This driver supports the Heath GC-1000 Most Accurate Clock, with
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RS232C Output Accessory. This is a WWV/WWVH receiver somewhat less
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robust than other supported receivers. Its claimed accuracy is 100 ms
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when actually synchronized to the broadcast signal, but this doesn't
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happen even most of the time, due to propagation conditions, ambient
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noise sources, etc. When not synchronized, the accuracy is at the whim
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of the internal clock oscillator, which can wander into the sunset
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without warning. Since the indicated precision is 100 ms, expect a host
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synchronized only to this thing to wander to and fro, occasionally being
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rudely stepped when the offset exceeds the default CLOCK_MAX of 128 ms.
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<p>The internal DIPswitches should be set to operate at 1200 baud in
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MANUAL mode and the current year. The external DIPswitches should be set
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to GMT and 24-hour format. It is very important that the year be set
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correctly in the DIPswitches; otherwise, the day of year will be
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incorrect after 28 April of a normal or leap year.
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<p>In MANUAL mode the clock responds to a rising edge of the request to
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send (RTS) modem control line by sending the timecode. Therefore, it is
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necessary that the operating system implement the <code>TIOCMBIC</code>
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and <code>TIOCMBIS</code> ioctl system calls and <code>TIOCM_RTS</code>
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control bit. Present restrictions require the use of a POSIX-compatible
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programming interface, although other interfaces may work as well.
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<p>The clock message consists of 23 ASCII printing characters in the
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following format:
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<pre>
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hh:mm:ss.f dd/mm/yr<cr>
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hh:mm:ss.f = hours, minutes, seconds
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f = deciseconds ('?' when out of spec)
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dd/mm/yr = day, month, year
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</pre>
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<p>The alarm condition is indicated by '?', rather than a digit, at A.
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Note that 0?:??:??.? is displayed before synchronization is first
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established and hh:mm:ss.? once synchronization is established and then
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lost again for about a day.
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<p>A fudge time1 value of .07 s appears to center the clock offset
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residuals.
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<p><h4>Monitor Data</h4>
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<p>When enabled by the <code>flag4</code> fudge flag, every received
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timecode is written as-is to the <code>clockstats</code> file.
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<p><h4>Fudge Factors</h4>
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<dl>
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<dt><code>time1 <i>time</i></code>
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<dd>Specifies the time offset calibration factor, in seconds and
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fraction, with default 0.0.
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<p><dt><code>time2 <i>time</i></code>
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<dd>Not used by this driver.
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<p><dt><code>stratum <i>number</i></code>
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<dd>Specifies the driver stratum, in decimal from 0 to 15, with default
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0.
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<p><dt><code>refid <i>string</i></code>
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<dd>Specifies the driver reference identifier, an ASCII string from one
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to four characters, with default <code>WWV</code>.
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<p><dt><code>flag1 0 | 1</code>
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<dd>Not used by this driver.
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<p><dt><code>flag2 0 | 1</code>
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<dd>Not used by this driver.
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<p><dt><code>flag3 0 | 1</code>
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<dd>Enable <code>ppsclock</code> line discipline/streams module if set.
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<p><dt><code>flag4 0 | 1</code>
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<dd>Enable <code>clockstats</code> recording if set.
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</dl>
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<p>Additional Information
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<p><a href="refclock.html"> Reference Clock Drivers</a>
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<hr><address>David L. Mills (mills@udel.edu)</address></body></html>
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