[ntp:questions] Re: CHU time source?

Ross rwa at aukward.bogons
Fri Dec 31 06:47:22 UTC 2004


shoppa at trailing-edge.com writes:

> You're in Toronto, the CHU transmitters in Ottawa, only 250 or 300
> miles away.  You'd probably get pretty good reception continuously on
> either 3.33MHz or 7.335MHz.

I lived in Trenton, Ont. in the 60's.  CHU is a ton of bricks all over
southern Ontario.

> I don't have any experience with audio refclocks under FreeBSD, but it
> "oughta work".  It took me a little bit of tinkering to make it work
> with Linux, see

I've run both the CHU and WWV clocks from my present QTH of Edmonton, and
FreeBSD is very happy with them.  I did some butchery in the PCM code to
get better control over the audio source and AVC, but that was pretty much
cosmetic.  CHU turns out to be quite jittery and I've elected to go with
WWV since I've only got one (non-agile) receiver that I can dedicate.

Right now, on the radio clock machine (aubey.bogons)

   ntpq> lpeer
        remote           refid      st t when poll reach   delay   offset  jitter
   ==============================================================================
   *WWV_AUDIO(1)    .WV20.           0 l   15   64  377    0.000   -0.098   0.069

   ntpq> cl
   status=0101 clk_noreply, last_clk_noreply,
   device="WWV/H Audio Demodulator/Decoder",
   timecode=" 4 2004 366 06:26:59  S -5 0 255 WV20 6 38 78.6 1024",
   poll=1611, noreply=547, badformat=0, baddata=0, fudgetime1=5.220,
   stratum=0, refid=WV20, flags=14

   ntpq> rl
   status=0284 leap_none, sync_lf_clock, 8 events, event_peer/strat_chg,
   version="ntpd 4.1.73 at 1.982-r Sat Apr 17 22:52:07 MDT 2004 (1)",
   processor="i386", system="FreeBSD/5.2.1-RELEASE-p8", leap=00, stratum=1,
   precision=-20, rootdelay=0.000, rootdispersion=2.832, peer=61580,
   refid=WV20, reftime=c57f6f78.03e4d4a2  Thu, Dec 30 2004 23:26:00.015,
   poll=6, clock=c57f6faf.6ad491df  Thu, Dec 30 2004 23:26:55.417, state=4,
   offset=-0.098, frequency=-46.083, jitter=0.052, stability=0.000

(although it's 23:30 local and the 19 meter propagation is marginal right now);
and from a neighbour on the same LAN,

   % ntpq -c lpee

        remote           refid      st t when poll reach   delay   offset  jitter
   ==============================================================================
   *aubey.bogons    .WV20.           1 u    4   64  377    0.307   -0.036   0.001
   -dense.utcc.utor 128.100.96.226   2 u  174  256  377   47.375   -2.935   0.122
   -ensb.cpsc.ucalg 18.26.4.105      2 u  115  256  377   17.361   -2.296   0.328
   -ntp.ubc.ca      140.142.16.34    2 u   45  256  335   26.238   -0.666   0.880
   -f02s01.tac.net  204.34.198.41    2 u  140  256  377   15.621   -1.595   0.495
   -time1.chu.nrc.c 209.87.233.50    2 u  125  256  377   95.124  -10.064   5.311

Not bad for home-entertainment-grade ADSL and a garage-sale sw receiver.

regards,
Ross



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