Thursday, December 18, 2008

Beacons on 28 MHz during the Geminids meteor shower...14th Dec 2008

Back in mid November, I tried a few tests listening to the beacon GB3RAL on 28 MHz during the Leonids meteor shower. For the Geminids, I repeated some of the tests but this time, tried listening for some other beacons as well.

Same as the last time....Kenwood transciever on CW, 500 Hz filter. Antenna....old commercial CB type end fed half wave about 4 metres above ground level. I monitored the received audio using the Sprectrum Lab audio analyzer program.

I tried listening for 4 different beacons on 28 MHz......GB3RAL (~500 kms), LA4TEN (~1,200 kms), F5ZWE (~1,300 kms) and DL0IGI (~1,500 kms). I listened at two different times on the 14th of December.....around 01:00 for GB3RAL and LA4TEN and around 09:00 for all 4 beacons.

Listening around 01:00......
GB3RAL.....I received a few bursts from this beacon. Nothing spectacular but it seemed to be there ok. Due to the fact that it has a faulty keyer, I was not able to get a positive ID. Like before, a lot more shows up on the trace than what I could hear by ear.

LA4TEN......This beacon seemed to be very good. It seemed to be nearly always there and at times, it got strong enough so that I could hear the CW by ear and make a positive ID.

Why was the LA4TEN beacon so consistent?

1) My view in that direction is excellent with no obstructions so that may have helped.
2) Is it the fact that 1,200 kms might be a much better distance for meteor scatter. Certainly for GB3RAL at 500 kms, I would expect that more intense meteor bursts might be required (more ionization) and the bursts would be of shorter duration.
3) Perhaps certain directions are better at different times during the shower??
4) Or perhaps it was the power level? LA4TEN is supposed to have an ERP of 250 watts which is very high for a beacon.
5) Of course, there is always the chance that what I heard was actually weak Sporadic-E rather than just meteor scatter propogation. It's seems unlikely at 1am in the morning in December. Considering that the peak of the shower was around this time, it was probably meteor scatter.

Listening around 09:00....
Conditions were worse. I still got a few pings from GB3RAL. I got very little from DL0IGI and F5ZWE. However, LA4TEN seemed as busy as ever! Looking at other sites, the peak was well over at this stage. In addition, the radiant point for the showers in Gemini may have set below the horizon by that time. I wonder though if the LA4 beacon at this stage was Sporadic-E or or not???

1) I need to find out what times the radiant point is above the horizon for any future shower and what the likely peak time will be.
2) The results show that meteor scater on 28 MHz is pretty impressive. Everything heard here was with an antenna with no gain.

Useful links......
International Meteor Organisation
G7IZU meteor detection page

Next shower is the Ursids on the 22nd of December.

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