[chbot] [OT} over the horizon radar, the woodpecker

[Stephen Irons]

I spent a winter at Sanae, the South African base in Antarctica. We could
sometimes hear the woodpecker from there, on 20m and 10m amateur bands (I
think). We did not know where the transmitter was, but it was known to be
caused by 'The Russians' and have something to do with over-the-norizon
radar.

However, we had a far worse local source of interference at the base. One
of the research projects ran an ionospeheric sounder. It transmitted
directly upwards and also at a shallow angle towards the project home base
in South Africa, and they could work out something about the height of the
various layers of the ionosphere by correlating the signal strength
received at the local (Antarctic) receiver and the receiver in South Africa.

This thing would sweep the entire HF band (3MHz to 30MHz) over 15 minutes,
then repeat, 24 hours a day, 365 days per year (except for short periods of
downtime for maintenance). When you were listening on a particular
frequency, you could hear it about 15 seconds before it reached your
frequency, slowly increasing in volume. You had to take off the headphones
or turn down the speakers at it passed through, then you could hear it
fading away for about 15 seconds.

Of course, it only really affected us. Our nearest neighbours were the
Russian about 200 km to the west, and the Germans 250 km to the east.

We called it 'The Beast' .The radio operators hated it, although it was
predictable.

It played havoc with the regular scheduled comms, in 1997, it was either
SSB voice or 50 baud teleprinter, and Morse code for the weather reports. I
experimented with AX25 packet radio type stuff, but found that it was just
not reliable enough. Shorter packets were better, but then throughput
suffered dramatically. We found AMTOR (or was it PACTOR) gave better
results on the noisy HF links we had.

Stephen Irons



On 1 August 2015 at 16:43, Andy Gardner <ceo at andygardner.com> wrote:

>
> They run one down south...
>
> http://www.tiger.latrobe.edu.au/unwin/index.html
>
>
>
> On 1/08/2015, at 9:20 AM, Mark Atherton wrote:
>
> > mainly of interest to the older, northern hemisphere radio ham.
> >
> > https://www.youtube.com/watch?v=xbi6eoh63ZQ
> >
> > So that is what made the infernal noise...
> >
> > -mark
>
>
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