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Low Frequency Radio Transmission

AncientMariner
The annual Christmas Eve message will be transmitted in Morse code on December 24th at 08:00 utc (UK Time) on 17.2 kHz. Tuning up commences at about 07:30 utc.

If interested and you do not have a suitable receiver in the conventional sense, you can use the sound card in your pc and this software https://sites.google.com/site/sm6lkm/saqrx/ together with a decent length of wire.

The transmission will be screened live at  YouTube Channel.

Clive

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    Many thanks for the translation.

    Merry Christmas to all.

    Alasdair
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    mapj1:

    1967, the BBC split the Light Programme into a pop music and entertainment network. The Light Programme became BBC Radio 1 and BBC Radio 2 long wave. The BBC Third Programme became BBC Radio 3,  Home Service was renamed BBC Radio 4.

    In 1978  radio 4 moved to a longwave channel  on 198khz, and radio 2 moved back to medium wave.




    Does Radio 4 continue on longwave for strategic reasons?


    1. The shipping forecast - moved from Radio 2 in 1978.

    2. For Royal Navy submarines to detect if the UK (probably) still exists and hasn't been blasted off the face of the earth!


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    Yes, radio 4 is still broadcast on long wave, and it is reported that these long wave transmissions can be received by HM submarines even whilst submerged. It is said that brief messages for HM forces can be concealed within the normal programme content. The absence of the long wave signal would be a cause for concern.
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    Not I suspect while deeply submerged - the "skin depth" at 200KHz will be around a metre, in typical sea water, and as you lose nearly 9dB per skin depth,  a mere 10m of seawater cover is a 90dB loss - a lot even for an ultra narrowband system to recover a signal from. Mind you, if you only want to know if the carrier is still there or not, then you do not need much bandwidth. Systems are a little more sophisticated than just assume a nuclear war has started if you cannot listen to The Archers,  but even so anything with any bandwidth of mention, needs something, even if it is only the antenna part, to go up to the surface.

    The VLF navigation systems were VLF for a good reason like the US Omega system used 14kHz for example.
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    You are a bit on the high side with 14 kHz Mike!


    Omega main frequency was 10.2 kHz with 11.05 kHz 11.3recurring kHz and 13.6 kHz Secondary frequencies used for lane identification. Each of the eight stations also had a unique frequency (11.8 kHz 12.0 kHz 12.1 kHz 12.3 kHz 12.8 kHz 12.9 kHz 13.0 kHz 13.1 kHz) as a station identifier, but the receivers I had dealings with were either Redifon which just received 10.2 kHz or the JRC set which used 10.2 kHz and the Secondary frequencies.


    14.881091 kHz was used by the USSR and then Russia for their navigation system along with some other odd-ball frequencies (13.28125 kHz, 12.648809 kHz and 11.904761 kHz).  The Omega frequencies having a nice mathematical relationship.


    Whilst currently I cannot hear or see and of these frequencies on my SpectraVue display, that does not mean that the system has been closed down. It has gone quiet before. Omega closed in 1997 and Decca Navigator which used frequencies between 70 and 129 kHz closed down in spring 2000.


    Re Radio 4 - Back in 2011 it was reported that the station life was down to the remaining life of the output valves. https://www.theguardian.com/media/2011/oct/09/bbc-radio4-long-wave-goodbye they must have found some more perhaps?  There was also a discussion here. 

     https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=43741&STARTPAGE=1&FTVAR_FORUMVIEWTMP=Linear


    Clive
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    I stand corrected on the details of the frequencies. I do know there have been attempts to raise funding for a re-start of a modern LORAN like system (circa 100KHz ), as a back up for critical navigation at sea, as GPS has proved to be rather too vulnerable to  jamming for comfort. For that matter there are plenty of land based systems that rely on GPS for both positioning and timing, that some might consider to be quite critical. So far however nothing significant has been built.
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    mapj1:

    . . . I do know there have been attempts to raise funding for a re-start of a modern LORAN like system (circa 100KHz ), as a back up for critical navigation at sea, as GPS has proved to be rather too vulnerable to  jamming for comfort . . .




    There were trials of eLORAN in Europe in 2014 / 2015. The last I heard about it was that the trials were being discontinued at the end of 2015 and I've not heard anything about it since!

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    Sorry Mike for coming on a bit strong in my last post.


    I have a bit of a soft spot for Omega and VLF, which likely commenced when back in 1976 I visited the Decca Navigator Green Slave at Neston, about 7 miles north of where we live. Standing in the ATU hut at the base of the Tee Aerial, you could hear the clacking of the relays as the aerial was retuned for each frequency in the sequence and also feel or sense the transmission keying. A strange sensation.  Te ATU hut for the MSF 60 kHZ service was a No Entry when transmitting at Rugby Radio, although likely at higher power than Decca Navigator.


    When I visited Rugby Radio in 2007 just after MSF closed down, GBR on 15.975 kHz had been closed for some time and in its place an eLoran transmitter feeding a Tee aerial supported on two of the 820 foot masts. 

    Besides Neston to the north, we also had Criggion 32 miles to the south.  Criggion, now closed with GBR, provided the UK Navy's GBZ service on 19.6 kHZ or more likely 19.575 kHz with MSK,

    Criggion played a part in the development of Omega, a good guide to which is J A Pierce's Memoirs, a copy of which I found on the net before they were edited and depersonalised.


    The eLoran service I mentioned at Rugby, transferred to Anthorn in I think 2014, but I am not sure of the current state since other transmitters in that chain have been switched off. That said, I can see a transmission centred on 100 kHZ, but where from I do no know. The signal being less than half of Anthorn's MSF on 60.0 kHz.

    Cheers!

    Clive


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    AncientMariner:


    . . . back in 1976 I visited the Decca Navigator Green Slave at Neston, about 7 miles north of where we live. 

     






    Sometime in the late 1990s, just before the shut-down, I peered through the wire at the Decca Navigator Red Slave (North British Chain) located at Clanrolla, Northern Ireland.


    You won't find Clanrolla on Google Maps (I think it might be a townland) but if you find Castor Bay Road and follow it north of of the M1 towards the lough, then you are in the right sort of area. I can't actually remember exactly where it was myself!


    Unfortunatley I don't have any photographs of the station. It was dismantled and removed sometime in the early 2000s and as far as I am aware, nothing remains on site.


    As for the eLORAN trials, the general story from beginning to end seems to be summarised in the following Notices to Mariners from the Comissioners of Irish Lights. The trials actually go back a lot further than I initally thought!

    https://www.irishlights.ie/safety-navigation/notices-to-mariners/2007-04-eloran-transmissions.aspx

    https://www.irishlights.ie/safety-navigation/notices-to-mariners/2007-06-eloran-transmissions.aspx

    https://www.irishlights.ie/safety-navigation/notices-to-mariners/2008-02-eloran-transmissions.aspx

    https://www.irishlights.ie/safety-navigation/notices-to-mariners/2012-13-eloran.aspx

    https://www.irishlights.ie/safety-navigation/notices-to-mariners/2015-11-eloran-trial-discontinued.aspx




     


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