2 Generic Reference Driver
3 </TITLE></HEAD><BODY><H3>
4 Generic Reference Driver
9 Address: 127.127.8.<I>u</I>
10 <BR>Reference ID: <TT>PARSE</TT>
11 <BR>Driver ID: <TT>GENERIC</TT>
12 <BR>Serial Port: <TT>/dev/refclock-<I>u</I></TT>; TTY mode according to
17 The timecode of these receivers is sampled via a STREAMS module in the
18 kernel (The STREAMS module has been designed for use with SUN Systems
19 under SunOS 4.1.x or Solaris 2.3 - 2.6. It can be linked directly into
20 the kernel or loaded via the loadable driver mechanism). This STREAMS
21 module can be adapted to be able to convert different time code formats.
22 If the daemon is compiled without the STREAM definition synchronization
23 will work without the Sun streams module, though accuracy is
24 significantly degraded. This feature allows to use PARSE also on non Sun
27 <P>The actual receiver status is mapped into various synchronization
28 states generally used by receivers. The STREAMS module is configured to
29 interpret the time codes of DCF C51, PZF535, PZF509, GPS166, Trimble SV6
30 GPS, ELV DCF7000, Schmid, Wharton 400A and low cost receivers (see list
33 <P>The reference clock support in ntp contains the necessary
34 configuration tables for those receivers. In addition to supporting
35 several different clock types and 4 devices, the generation a a PPS
36 signal is also provided as an configuration option. The PPS
37 configuration option uses the receiver generated time stamps for feeding
38 the PPS loopfilter control for much finer clock synchronization.
40 <P>CAUTION: The PPS configuration option is different from the hardware
41 PPS signal, which is also supported (see below), as it controls the way
42 ntpd is synchronized to the reference clock, while the hardware PPS
43 signal controls the way time offsets are determined.
45 <P>The use of the PPS option requires receivers with an accuracy of
50 <P>Only two fudge factors are utilized. The time1 fudge factor defines
51 the phase offset of the synchronization character to the actual time. On
52 the availability of PPS information the time2 fudge factor defines the
53 skew between the PPS time stamp and the receiver timestamp of the PPS
54 signal. This parameter is usually zero, as usually the PPS signal is
55 believed in time and OS delays should be corrected in the machine
56 specific section of the kernel driver. time2 needs only be set when the
57 actual PPS signal is delayed for some reason. The flag1 enables input
58 filtering. This a median filter with continuous sampling. The flag2
59 selects averaging of the samples remaining after the filtering. Leap
60 second-handling is controlled with the flag3. When set a leap second
61 will be deleted on receipt of a leap second indication from the
62 receiver. Otherwise the leap second will be added, (which is the
63 default). flag3 should never be set. PPS handling is enabled by adding
64 128 to the mode parameter in the server/peer command.
69 <P>The ntpq program can read clock variables command list several
71 These hold the following information: refclock_time is the local time
73 the offset to UTC (format HHMM). The currently active receiver flags are
74 listed in refclock_status. Additional feature flags of the receiver are
75 optionally listed in parentheses. The actual time code is listed in
77 A qualification of the decoded time code format is following in
78 refclock_format. The last piece of information is the overall running
79 time and the accumulated times for the clock event states in
80 refclock_states. When PPS information is present additional variable are
81 available. refclock_ppstime lists then the PPS timestamp and
82 refclock_ppsskew lists the difference between RS232
83 derived timestamp and the PPS timestamp.
85 <P>Currently, eighteen clock types (devices /dev/refclock-0 -
86 /dev/refclock-3) are supported by the PARSE driver.
87 <BR>A note on the implementations:
88 <UL><li>These implementations where mainly done <B><I>WITHOUT</I></B>
89 actual access to the hardware. Thus not all implementations provide full
90 support. The development was done with the help of many souls who had
91 the hardware and where so kind to borrow me their time an patience
92 during the development and debugging cycle. Thus for continued support
93 and quality direct access to the receivers is a big help. Nevertheless i
94 am not prepared to buy these reference clocks - donations to <A
95 HREF="http://www4.informatik.uni-erlangen.de/~kardel">me</A>
96 (<A HREF="mailto: kardel@acm.org">kardel@acm.org</A>) are welcome as
97 long as they work within Europe 8-).
99 <P>Verified implementations are:
104 <p>These variants are tested for the decoding with my own homegrown
105 receivers. Interfacing with specific commercial products may involve
106 some fiddeling with cables. Especially commericial RAWDCF receivers have
107 a seemingly unlimited number of ways to draw power from the RS232 port
108 and to encode the DCF77 datastream. You are mainly on your own here
109 unless i have a sample of the receiver.
111 <A HREF="http://www.meinberg.de">Meinberg clocks</A>
113 <p>These implementations are verified by the Meinberg people themselves
114 and i have access to one of these clocks.</UL>
116 The pictures below refer to the respective clock and where taken from
117 the vendors web pages. They are linked to the respective vendors.
120 <B><TT>server 127.127.8.0-3 mode 0</TT></B>
122 <p><B><TT><A HREF="http://www.meinberg.de">Meinberg </A>PZF535/<A
123 HREF="http://www.meinberg.de/english/products/pzf509.htm">PZF509 receiver</A> (FM
124 demodulation/TCXO / 50us)</TT></B>
127 <B><TT>server 127.127.8.0-3 mode 1</TT></B>
129 <p><B><TT><A HREF="http://www.meinberg.de">Meinberg </A> PZF535/<A
130 HREF="http://www.meinberg.de/english/products/pzf509.htm">PZF509
131 receiver</A> (FM demodulation/OCXO / 50us)</TT></B>
132 <BR><A HREF="http://www.meinberg.de/english/products/pzf509.htm"><IMG
133 SRC="pic/pzf509.jpg" ALT="BILD PZF509" HEIGHT=300 WIDTH=260
137 <B><TT>server 127.127.8.0-3 mode 2</TT></B>
139 <p><B><TT><A HREF="http://www.meinberg.de">Meinberg </A> DCF U/A
140 31/<A HREF="http://www.meinberg.de/english/products/c51.htm">DCF C51 receiver</A>
141 (AM demodulation / 4ms)</TT></B>
142 <BR><A HREF="http://www.meinberg.de/english/products/c51.htm"><IMG
143 SRC="pic/c51.jpg" ALT="BILD C51" HEIGHT=180 WIDTH=330 ALIGN=TEXTTOP></A>
146 <B><TT>server 127.127.8.0-3 mode 3</TT></B>
148 <p><B><TT><A HREF="http://www.elv.de">ELV</A> DCF7000 (sloppy AM
153 <B><TT>server 127.127.8.0-3 mode 4</TT></B>
155 <p><B><TT>Walter Schmid DCF receiver Kit (AM demodulation /
159 <B><TT>server 127.127.8.0-3 mode 5</TT></B>
161 <p><B><TT>RAW DCF77 100/200ms pulses (Conrad DCF77 receiver module /
165 <B><TT>server 127.127.8.0-3 mode 6</TT></B>
167 <p><B><TT>RAW DCF77 100/200ms pulses (TimeBrick DCF77 receiver module
171 <B><TT>server 127.127.8.0-3 mode 7</TT></B>
173 <p><B><TT><A HREF="http://www.meinberg.de">Meinberg </A> <A
174 HREF="http://www.meinberg.de/english/products/gps167.htm">GPS166/GPS167
175 receiver</A> (GPS / <<1us)</TT></B>
176 <BR><A HREF="http://www.meinberg.de/english/products/gps167.htm"><IMG
177 SRC="pic/gps167.jpg" ALT="BILD GPS167" HEIGHT=300 WIDTH=280
181 <B><TT>server 127.127.8.0-3 mode 8</TT></B>
182 <p><B><TT><A HREF="http://www.igel.de">IGEL</A> <A
183 HREF="http://www.igel.de/eigelmn.htm">clock</A></TT></B>
184 <BR><A HREF="http://www.igel.de/eigelmn.htm"><IMG SRC="pic/igclock.gif"
185 HEIGHT=174 WIDTH=200></A>
188 <B><TT>server 127.127.8.0-3 mode 9</TT></B>
190 <p><B><TT><A HREF="http://www.trimble.com">Trimble</A> <A
191 HREF="http://www.trimble.com/cgi/omprod.cgi/pd_om011.htm">SVeeSix
192 GPS receiver</A>TAIP protocol (GPS / <<1us)</TT></B>
195 <B><TT>server 127.127.8.0-3 mode 10</TT></B>
197 <p><B><TT><A HREF="http://www.trimble.com">Trimble</A> <A
198 HREF="http://www.trimble.com/cgi/omprod.cgi/pd_om011.htm">SVeeSix
199 GPS receiver</A> TSIP protocol (GPS / <<1us) (no kernel support
201 <BR><A HREF="http://www.trimble.com/cgi/omprod.cgi/pd_om011.htm"><IMG
202 SRC="pic/pd_om011.gif" ALT="SVeeSix-CM3" BORDER=0 HEIGHT=100 WIDTH=420
204 <BR><A HREF="http://www.trimble.com/cgi/omprod.cgi/pd_om006.htm"><IMG
205 SRC="pic/pd_om006.gif" ALT="Lassen-SK8" BORDER=0 HEIGHT=100
209 <B><TT>server 127.127.8.0-3 mode 11</TT></B>
211 <p><B><TT>Radiocode Clocks Ltd RCC 8000 Intelligent Off-Air Master
216 <B><TT>server 127.127.8.0-3 mode 12</TT></B>
218 <p><B><TT><A HREF="http://www.hopf-time.com">HOPF</A> <A
219 HREF="http://www.hopf-time.com/kart6021.htm">Funkuhr
221 <BR><A HREF="http://www.hopf-time.com/engl/kart6021.htm"><IMG
222 SRC="pic/fg6021.gif" ALT="DCF77-Interface Board" HEIGHT=207 WIDTH=238
226 <B><TT>server 127.127.8.0-3 mode 13</TT></B>
228 <p><B><TT>Diem's Computime Radio Clock</TT></B>
231 <B><TT>server 127.127.8.0-3 mode 14</TT></B>
233 <p><B><TT>RAWDCF receiver (DTR=high/RTS=low)</TT></B>
236 <B><TT>server 127.127.8.0-3 mode 15</TT></B>
238 <p><B><TT>WHARTON 400A Series Clocks with a 404.2 Serial
241 <B><TT>server 127.127.8.0-3 mode 16</TT></B>
243 <p><B><TT>RAWDCF receiver (DTR=low/RTS=high)
246 <B><TT>server 127.127.8.0-3 mode 17</TT></B>
248 <p><B><TT>VARITEXT Receiver (MSF)
252 Actual data formats and set-up requirements of the various clocks can be
253 found in <A HREF="parsedata.htm">NTP PARSE clock data formats</A>.
255 <P>The reference clock support carefully monitors the state transitions
256 of the receiver. All state changes and exceptional events such as loss
257 of time code transmission are logged via the syslog facility. Every hour
258 a summary of the accumulated times for the clock states is listed via
261 <P>PPS support is only available when the receiver is completely
262 synchronized. The receiver is believed to deliver correct time for an
263 additional period of time after losing synchronizations, unless a
264 disruption in time code transmission is detected (possible power loss).
265 The trust period is dependent on the receiver oscillator and thus a
266 function of clock type. This is one of the parameters in the clockinfo
267 field of the reference clock implementation. This parameter cannot be
270 <P>In addition to the PPS loopfilter control a true PPS hardware signal
271 can be applied on Sun Sparc stations via the CPU serial ports on the CD
272 pin. This signal is automatically detected and will be used for offset
273 calculation. The input signal must be the time mark for the following
274 time code. (The edge sensitivity can be selected - look into the
275 appropriate kernel/parsestreams.c for details). Meinberg receivers can
276 be connected by feeding the PPS pulse of the receiver via a 1488 level
277 converter to Pin 8 (CD) of a Sun serial zs-port. To select PPS support
278 the STREAMS driver for PARSE must be loaded and the mode parameter ist
279 the mode value of above plus 128. If 128 is not added to the mode value
280 PPS will be detected to be available but it will not be used. For PPS to
281 be used you MUST add 128 to the mode parameter.
283 <P>For the Meinberg GPS166/GPS167 receiver is also a special firmware
284 release available (Uni-Erlangen). This release should be used for proper
287 <P>The raw DCF77 pulses can be fed via a level converter directly into
288 Pin 3 (Rx) of the Sun. The telegrams will be decoded an used for
289 synchronization. AM DCF77 receivers are running as low as $25. The
290 accuracy is dependent on the receiver and is somewhere between 2ms
291 (expensive) to 10ms (cheap). Upon bad signal reception of DCF77
292 synchronizations will cease as no backup oscillator is available as
293 usually found in other reference clock receivers. So it is important to
294 have a good place for the DCF77 antenna. For transmitter shutdowns you
295 are out of luck unless you have other NTP servers with alternate time
298 <H4>Monitor Data</H4>
300 Clock states statistics are written hourly the the syslog service.
301 Online information can be found by examining the clock variable via the
304 <H4>Fudge Factors</H4>
308 <DT><TT>time1 <I>time</I></TT></DT>
309 <DD>Specifies the time offset calibration factor, in seconds and
310 fraction, with default depending on clock type.</DD>
312 <DT><TT>time2 <I>time</I></TT></DT>
313 <DD>Specifies the offset if the PPS signal to the actual time. (PPS fine
316 <DT><TT>stratum <I>number</I></TT></DT>
317 <DD>Specifies the driver stratum, in decimal from 0 to 15, with default
320 <DT><TT>refid <I>string</I></TT></DT>
321 <DD>Specifies the driver reference identifier, an ASCII string from one
322 to four characters, with default according to current clock type.</DD>
324 <DT><TT>flag1 0 | 1</TT></DT>
325 <DD>Not used by this driver.</DD>
327 <DT><TT>flag2 0 | 1</TT></DT>
328 <DD>Not used by this driver.</DD>
330 <DT><TT>flag3 0 | 1</TT></DT>
331 <DD>delete next leap second instead of adding it.</DD>
334 <TT>flag4 0 | 1</TT></DT>
335 <DD>Delete next leap second instead of adding it - flag will be re-
336 defined soon - so don't use it. Statistics are provided by more common
337 means (syslog, clock variable via ntpq)</DD>
341 <H4>Making your own PARSE clocks</H4>
343 The parse clock mechanismis deviated from the way other ntp reference
344 clocks work. For a short description how to build parse reference clocks
345 see <A HREF="parsenew.htm">making PARSE clocks</A>
347 <P>Additional Information
349 <P><A HREF="refclock.htm">Reference Clock Drivers</A>
351 <hr><a href=index.htm><img align=left src=pic/home.gif></a><address><a
352 href="mailto:mills@udel.edu"> David L. Mills <mills@udel.edu></a>
353 </address></body></html>