Tuesday, December 9, 2008

GB3RAL and the Leonids Meteor Shower...17th Nov 2008

This is a post that I have been meaning to put up for a while. Now that the peak of the Geminids meteor shower is coming up next weekend (13th of Dec), now seems like a good time to put it up.

During the morning of the 17th of November which was supposed to be the peak of the Leonids meteor shower, I tried listening for the GB3RAL beacon in England on 28.215 MHz.

Equipment.....Kenwood TS690s tuned to 28.215.1 MHz on CW (500 Hz filter fitted)
Antenna........Half wave 10 metre vertical at 5 metres AGL
Distance......490 kms due East from here (IO91in<->IO51tu)

As well as listening by ear to the received signals, I put the microphone from the PC next to the rig and monitored the signal with the Spectrum Lab Audio Analyzer program.

After a while, I got a few audible pings that showed on the waterfall dislay so I could see that there was something there around 500 Hz.

At 09:24, I recorded what was the start of a long 5 to 6 minute burst. As you can see above, it started suddenly and after a few minutes, it began to slowly fade away. Listening by ear, I could just about hear that there was something there yet it showed up quite clearly on the waterfall display.

From what I could hear, there was no cw. It was just a constant carrier.

However when I looked at the display closer, I could see that the signal was about 7 Hz wide before finally becoming a narrower signal. I can see from beacon lists that the GB3RAL beacon uses FSK....i.e. the carrier moves in frequency to generate the CW rather than turning on and off. I asked the beacon keeper G0MJW about this and he informed me that the keyer on the beacon has failed and a replacement is under construction.

What I heard and saw was like the beacon keyer was still working (i.e. FSK) except that the frequency shift was now a lot lower than it should be (i.e. 7 Hz instead of say 300 Hz).

Q. Was it GB3RAL that I heard? Probably likely but to be honest, until I can get a positive ID, I will never be 100% sure. I might have a listen again during the Geminids and see how it goes.

(1) The various other lines shown on the above displays are mainly just interference generated by the PC. Even though I can't hear them, they show up quite clearly on the display.

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