Message-ID: <004401c09507$38893640$0d0e0805@globocabo.com.br>
From: "PY3CRX PY2PLL" <py2pll@py.qsl.br>
To: rsgb_lf_group@blacksheep.org
References: <5.0.2.1.2.20010212090705.00a69aa0@mail.pncl.co.uk> <3A87DD0F.AAF4D15E@virgin.net>
Subject: Re: LF: GPS-Disciplined BPSK
Date: Mon, 12 Feb 2001 12:19:33 -0300
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> This would seem to need much less engineering than
> processing the output of a GPS.
>
> Stewart G3YSX

I can detect 60KHz from WWVB, but useless to lock anything ... so ... I use
a Furuno OEM module, that has only 1pps + NMEA outputs. But the 1pps is good
enough to lock a DSP56002EVM board to G3PLX chirp sounder monitoring
project. Around the world RF trip is 55 ... 60 ms maximum + multipath
variations.

For a 24h period, for example, the Cyprus transmitter or Inskip transmitter
are plotted from here within 100 miles.

This Furuno GPS is a 8 in view class but a cheap module. Other participants
uses other brands/cheap, common ones too (Garmin, Oncore, etc).

Seems that even having something like 100ns tolerance on 1pps pulses (my
case) this will not be enough to match phase because the propagation delay
from my place to England is +/- 24ms, to Greece +/- 36ms, and so on. May be
if we schedule the contacts we can enter lat/log data somewhere to "predict"
the prop. time delay.

For a simple application like QRSS, if a station matches its dots/traces to
a 1pps pulses will be a must. At least I'll know on what time slot I can
find a signal. And in this case some ms will not be important on a 60 second
dot :o).

Sorry to mixed those subjects but it's part of my efforts to catch some
signal from above the Equator. This weekend I locked a 100KHz oscilator to
the 1pps pulse. This locking process took more than one hour :o)

BTW, a question about GPSs: what signals fequencies can I expect to find
inside a "sample" GPS module? Some have 5 / 10 MHz outputs besides 1pps.
Others have 2048 / 1554 to EU/US data networks. But there's no guarantee
that this signals are locked to GPS constelation. So is there any clock that
run free on a "none-in-view" condition and locked otherwise? On mine I found
16.6666MHz (seems the internal clock oscilator), 11.605MHz (free or
locked???) and 1KHz on some testpoints. I'll be happy if one of this
frequencies are locked to the source :o/

NIST has some material about GPS X NIST traceable specs ...

73
Marcus
PY3CRX/PY2PLL
S. B. do Campo - GG66rf
http://py.qsl.br
Active from "DC" to 24GHz