Paul the off-air standards I have and another UK make I dont posses divide
the 10MHz standard and the off-air carrier down to 2kHz for locking. It may
not be the best but it is generally adequate for off air LF standard
distribution. My unit will cover 162kHz or 198kHz.
Alan
G3NYK
----- Original Message -----
From: "paul swed" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, March 07, 2017 5:52 PM
Subject: Re: [time-nuts] RFDO - Experience and questions
Gilles
I went back over the starting thread and believe your home brew oscillator
may prevent you from getting all of the accuracy out of TDF.
As I was thinking about a TRF radio and locking the question I arrived at
is how do you turn 162KHz into something useful like 100 KHz 5 MHz or 10
MHz??.
By getting to standard references there are many very good oven
oscillators
available.
Regards
Paul.
On Mon, Mar 6, 2017 at 10:35 PM, paul swed <[email protected]> wrote:
Actually as I think about it from the earlier part of the thread. Locking
to the carrier with a 2-4 second time constant removes the phase
modulation
since its only in the first 200 ms. The 0 Phase is 800 ms in length or
more
for all bits.
Now to find some nice coils for 162 KHz.
Regards
Paul
On Mon, Mar 6, 2017 at 8:30 PM, paul swed <[email protected]> wrote:
A bit more reading if you block the phase comparison from -50ms to 150ms
of the tick you get a 0 carrier phase no modulation. That also explains
why
I thought I could here some sort of phase modulation because there is.
So as an example if you use a GPS tick its really simple to block the
phase changes and only measure the 0 phase carrier. Essentially a 200 ms
carrier gap per second.
Thats quite a clean format you have to work with.
Regards
Paul
WB8TSL
On Mon, Mar 6, 2017 at 8:19 PM, paul swed <[email protected]> wrote:
I checked out 162KHz at 2000 local and now have what I believe to be
TDF
using the 67 ft vertical antenna. I am reading -82 dbm near Boston in
the
US or 3400 miles. A comfortable signal at least in the winter. As a
comparison wwvb at 60 KHz is -77dbm some 2000 miles but also not at a 2
MW
power level like TDF.
Since I had not heard TDF before I listened to Pieters online SDR radio
to see what to listen for. The easiest point to notice is the 59 second
phase. Its funny that also seconds 0-10 should be the same phase but it
did
not seem to be true. Unless what I am hearing is the local oscillator
of
Pieters SDR radio.
So thanks for sharing some new knowledge with Time-nuts.
Regards
Paul
WB8TSL
On Mon, Mar 6, 2017 at 1:46 PM, Pieter-Tjerk de Boer <
[email protected]> wrote:
On Sun, Mar 05, 2017 at 10:42:52PM +0000, Iain Young wrote:
> That's TDF from France. Their equivalent of WWV/MSF/DCF.
> Average phase and frequency deviation is
> zero over 200msec (see link above for details)
This is not quite correct, since the transmitter does not just carry
the
time data (one bit per second, in the first 200 ms of the second), but
also some more data during the next 700 ms of each second.
The latter data is coded in a way which does not guarantee that the
phase
or frequency average is zero other than when averaging over the entire
700 ms block.
Then again, I've been told that although there is a nicely defined
framing
format, in reality it has only ever transmitted idle frames, so in
practice
it's a fixed pattern which repeats every minute and thus could be
cancelled
for use as a frequency reference.
I have a live online decoder for TDF's signal at
http://websdr.ewi.utwente.nl:8901/tdf/
Regards,
Pieter-Tjerk, PA3FWM
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