[ntp:hackers] wwv audio report

gnu not unix gnu at wraith.sf.ca.us
Mon Feb 19 11:39:50 PST 2007


Hi Folks--

The ntp-dev-4.2.5p7 code has been working well with wwv audio
here, with the 10MHz Ramsey receiver. The code also picked up
sync with the "tones" wwv generator here very quickly.

Here's an ntpq billboard taken after sync to the tones software.
I was running with no time1 fudge, since there was no prop delay
over the 10 feet of audio cable.

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+SPECTRACOM(0)   .WWVB.           0 l    8   64  377    0.000   -3.323   1.717
*GPS_NMEA(0)     .GPS.            0 l    5   64  377    0.000   -0.001   0.002
+WWV_AUDIO(0)    .WV2.            0 l   10   64  377    0.000    1.504   0.487
-ring.wraith.sf. .GPS.            1 u  137  256  377    0.304    0.006   0.064
-thrall.wraith.s .GPS.            1 u  138  256  377    0.373    0.020   0.012

The host was freebsd 6.2 based K6-2/400.

However, switching the tones from wwv to wwvh caused loss of sync.

Actually I have never seen any version of the wwv audio code grab wwvh.

Here is the log file data, after the 4.2.5p7 locked to wwv
generated by the tones test software, and then switching the
tones to wwvh:

54150 70200.013 127.127.36.0  8 2007 050 19:30:00  S +0 45 0 WH2 71 0 -15.1 256
54150 70202.013 127.127.36.0 wwv5 000d   
      0 3193 1916/3.1 14988/40.0 WV2 0000 0 15/1.8 WH2 d557 71 6145/40.0

The tones program does implement a pll to give better sync,
according to the code comments. The version I'm using can 
be obtained here:

http://www.wraith.sf.ca.us/ntp/tones-wwv.c

Currently you need to recompile for wwv/wwvh versions
(a #define for the 1000/1200 Hz).

../Steven


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