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Old 29th Dec 2016, 2:29 pm   #21
Stylo N M
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Default Re: Allouis 162kHz long wave.

The signals vary a lot anyway at this time of the year, whether on full power or not.

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Old 29th Dec 2016, 6:12 pm   #22
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Default Re: Allouis 162kHz long wave.

The Wikipaedia article is interesting- I was aware that it had shifted to 163.84kHz from the previous 164kHz before the final shift to the Geneva band-plan multiples-of-9 162kHz, but hadn't spotted that that was the fifth harmonic of the 32.768kHz timebase standard, or 2 to the power 16. The current 162kHz transmission uses a once per second phase "hic" in the carrier to provide a reference to slaved users.

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Old 29th Dec 2016, 7:59 pm   #23
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Default Re: Allouis 162kHz long wave.

Interesting data on the 162KHz Allouis Transmitter, running 2 Megawatts with an average range of 3500Km and a timesignal (TDF) similar to MSF (UK) and DCF (Germany) but which used much less power and consequently had a smaller range.

I have never seen or heard of a clock with a TDF receiver in it whereas MSF and DCF clocks are readily available, I guess the fact that MSF and DCF use a simple amplitude modulated time code as the carrier was not used for continuous transmission of information, whereas the TDF transmitter was used to broadcast France Inter programming and uses phase modulation for this purpose which requires a more complex (read: expensive) receiver design.

Does anyone know any more about the use of the TDF timesignal, it is logical that the massive range would have made it more likely to be used in areas of the old French Empire... There must be many users (probably military as well) of the signal, otherwise why implement and maintain it up to now?

I suspect that the timesignal is to be preserved as a service (as was MSF with it's move to Cumbria) even though the France Inter program transmission is terminated. Perhaps they are continuing the signal from Allouis until a suitable replacement site can be found?
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Old 29th Dec 2016, 9:48 pm   #24
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Default Re: Allouis 162kHz long wave.

There was a feature on this LW close down at the end of the Radio 4 PM program today [last item before 6pm]. Worth a listen just for the woman reading the Shipping Forecast in french!
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Old 30th Dec 2016, 9:04 am   #25
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Default Re: Allouis 162kHz long wave.

The data format for the TDF time signal is the same as DCF which is different to the MSF data format. I have a timer which can accept a TDF input from an external receiver but, not having a receiver, I've connected a DCF receiver which works well.

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Old 30th Dec 2016, 4:25 pm   #26
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Default Re: Allouis 162kHz long wave.

I've long toyed with the idea of a variable propagation emulator which adds the imperfections of radio to a 'perfect' interweb radio stream. You know - a bit of fading, the occasional CRACK!! as someone turns off something inductive, heterodynes, distant stations in the background...
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Old 1st Jan 2017, 12:10 am   #27
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Default Re: Allouis 162kHz long wave.

So the plug was (sort of) pulled at 23:00 UTC on the dot...

The TDF time signal remains on the air. All I get on the radios here in Ely is a slight quietening of the static due to the remaining carrier, but the Twente SDR receiver clearly shows that the signal is still being AM modulated with the France Inter audio, albeit somewhat distorted and with a bandwidth C. 3 Khz. With filters set appropriately it is still a listenable signal. I assume you could still hear it in the vicinity of the transmitter.

So, a station notionally off the air yet with the feed still connected to a transmitter that remains powered into a mast that still needs to be maintained...

I'm struggling to see where the economic savings are here. Would it not have been easier just to reduce the output power?


I've got a recording of it's last 20 minutes (including the post-closure signal) that I'll try and upload tomorrow.

Rob B

Edit:

I've just gone back over the audio in the recording and it is apparent that the modulation is not that of the France Inter signal, but rather that of the RTL transmitter on 234 khz - arising I assume from the Luxembourg effect.
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Old 1st Jan 2017, 12:55 am   #28
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Default Re: Allouis 162kHz long wave.

Yep- plenty of quieting and eye deflection on Marconi 559 and Eddystone 670 here, just no mod! It does seem odd just to continue the carrier.
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Old 1st Jan 2017, 1:12 am   #29
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Default Re: Allouis 162kHz long wave.

For those who have never experienced "The Luxemburg Effect" you can do so now.
The modulation of RTL on 236kHz can be heard very faintly on 162kHz.
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Old 1st Jan 2017, 2:40 am   #30
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Default Re: Allouis 162kHz long wave.

Yes I can hear it here now (Faintly). What causes it?
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Old 1st Jan 2017, 9:25 am   #31
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Default Re: Allouis 162kHz long wave.

It was a sad moment. They were broadcasting normally and counted down the seconds to midnight, then just silence. No welcome to the New Year. Just the background interference noise.

Edward
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Old 1st Jan 2017, 10:17 am   #32
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Default Re: Allouis 162kHz long wave.

I forgot to listen-in, but LW seemed quite empty when I tuned in at midnight UK time.

This is quite nice....

https://www.youtube.com/watch?v=FOOm760EYJc

Happy New Year!
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Old 1st Jan 2017, 1:15 pm   #33
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Default Re: Allouis 162kHz long wave.

The carrier wave is still there and with the BFO turned on it's possible to hear the time signals it carries.

Listening to it whilst watching my PC's clock I can clearly hear the modulation change at the minute transitions.
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Old 1st Jan 2017, 2:08 pm   #34
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Default Re: Allouis 162kHz long wave.

Does seem something of a waste of a powerful carrier in a long-established broadcasting channel allocation not to modulate it with something more interesting than a time signal, especially given modern efficient modulation techniques. Perhaps the near future will be revealing of what is likely to be done with it.
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Old 1st Jan 2017, 3:09 pm   #35
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Default Re: Allouis 162kHz long wave.

Quote:
Originally Posted by linescan87 View Post
Yes I can hear it here now (Faintly). What causes it?
Essentially, it's due to the non-linearity of the reflective layers between the transmitter and the receiver: think of it as a form of cross-modulation, where the signal from the one transmitter modulates the characteristics of the reflective layers slightly, and this modulation is then superimposed on other signals reflected off those layers.

Generally only happens with *very* powerful transmitters!
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Old 2nd Jan 2017, 6:49 pm   #36
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Default Re: Allouis 162kHz long wave.

I had a listen to the 162 Kc/s carrier with the BFO on and there is an obvious wobble of its frequency which must be the time clock data.

Next I tried Europe 1 and their carrier was steady as a rock, BBC Radio 4 carrier has a sort of wobble to it, Luxembourg was steady and RTE on 252 Kc/s was steady as well. Finally as night came on I could here Romania from Brasov that also seemed steady. I have such a high noise level here I couldn't hear Czechoslovakia on 270 Kc/s or the pirate on 260 kc/s.

Can anyone else confirm if the Czechoslovak station is still on?
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Old 2nd Jan 2017, 9:40 pm   #37
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Default Re: Allouis 162kHz long wave.

The Czech station is still there on 270kHz. I logged it on 272kHz in the dim and distant past, so I guess it's changed frequency to fit in with the band plan.

There's an unintelligible transmission on 260kHz.
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