LORAN C reference question
Fri, 23 Jun 2000 09:28:27 -0400
I set up a Loran C frequency reference system some years ago and it
I could not use the RF waveform to check against as I received several
stations in the chain jumbled together and skywave changes over the day
would ruin any attempt to see a stable reference.
Instead, I took an automatic Loran C receiver and poked around inside
and found the master pulse which coincided with the start of the master
station pulse. I brought that pulse out to an external connector. Then
I got a Loran C timing generator, (al a hamfest) which consisted of a
handful of 7400 ICs which took in my 100 kHz frequency standard and
output the Loran C pulse rate for the chain I was on. I then compared
the drift of the local pulses against the off the air pulses. It worked
fine over several days time. You can see skywave shifts during the day
so you have to wait and integrate the errors out.
I now use a GPS receiver with a 1 pps timing pulse output to compare
against a 1 pps generated by my local standard. It is much more stable
and I can adjust the standard much more quickly.
"Paul A. Cianciolo" wrote:
> Hello Folks,
> I finally have a frequency standard here to drive my house system.
> Receivers are a RACAL 6790GSM and a Harris RF 590 both have the ability to
> utilize an external reference.
> My reference has a 100Khz out and I am trying to trigger a scope using the
> 100Khz as
> an input and the Loran C as the trigger signal, so I can see the drift
> overtime, Although it may take days.
> What I cannot seem to do is get a jitter free 100KHZ LORAN signal.
> I am using a LOWRANCE antenna coupler which looks as though it has most of
> the reciever
> elements in it as well as all the bandpass filtering. There is a
> microproceesor on the antenna as well
> 5 or 6 other surface mount chips and a 8 Mhz TCXO.
> Can someone help me locate a point on this thing where I can get a 100Khz
> to lock my source. I have been through this thing with a scope and found
> lots of squarewaves but
> all seem to be derived from the TCXO, and do not change when an antenna is
> In the RF portion of the unit I can see what looks like 3 100Khz signals
> that are time sharing the freq.
> They are all varing amplitudes. Loran is very strong here. I have read that
> most devices that do this
> sort of thing use the 3rd cycle in of the RF pulse.
> Any help would surely be appreciated. Sorry about all the cross posts but
> this email is in an
> effort to get an ultra stable freq. reference for LF, DSP and laser
> Thank you
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