Is it just me or are the upper and lower beacons unusually low at the Greenhilly WebSDR?
Middle beacon as well as user signals seem OK.
When I receive myself (not WebSDR), signals are also OK
Beacon signal levels low on Greenhilly WebSDR?
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heavy rain in Cornwall......
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Let me re-visit this, because when I ask in a QSO, it turns out that people did monitor their signal levels when setting up, but generally no longer monitor afterwards:
When working over QO100 NB transponder, one's signals are not supposed to be stronger than the lower CW beacon on 10489.500.
And the AMSAT-DL website strongly pushes the Goonhilly WebSDR.
Until recently, the CW beacons (10489.500 and 104900.000) had a signal strength of typically -70dB, and the middle PSK beacon was typically -73dB. Signals raising above that would be yelled at by Leila.
The signal strengths have roughly the same levels on the Italy WebSDR, and my own equipment gives the same (relative) signal levels.
However, recently, the strength of the CW beacons on the Goonhilly WebSDR have dropped significantly and are now -80dB. This only applies for the CW beacons, the PSK beacon as well as user signals have normal signal level.
Signals have normal levels when measured over the Italy WebSDR, or on my own receiver.
Only the CW signals are weaker, and only over the Goonhilly WebSDR!
I have measured over days to make sure it's not a weather issue - it isn't. And to the best of my knowledge all three beacon signals are made from the same earth station. If weather would be obscuring, then I'd expect all signals to be weaker - they aren't, only the CW beacons! - and if the Bochum / Doha ground station would be covered by weather, then all three beacons would be weaker, on all receivers - they aren't, ONLY the CW beacons, and ONLY via the Goonhilly WebSDR.
If people can confirm that would be grand. I've included screenshots of my measurements of 10489.500, 10490.000 and 10489.750; note that the signal history indicates that the signal strength is constant.
Clue appreciated!
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One possible clue is to look at the signal to noise ratio, the SNR, and not the signal in dBm because that could very well be affected by SDR software parameter settings. SNR is much less affected, in SDR console you can get it from the signal history and save it in a CSV file. What I do notice is that the SNRs are GoonHilly are less compared to what I receive at home, no idea why this is the case.
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Ernst, click on [CW] at the CW-beacons
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Ernst, click on [CW] at the CW-beacons
Which gives me the 25+ dB I was looking for
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The QO100 beacon strength might be correlated to relative humidity. All of these measurements take more than two minutes and are done in periods when there is nobody on the NB transponder. The satellite transponder also has an AGC, so if there are strong transmitters it will reduce its gain, keeping my fingers crossed that the transponder beacons are always at the same strength. You can measure the beacon SNR with matlab script readsnr.m which needs signal history files from SDRconsole, see also https://github.com/ejo60/hamradio
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Are thes values from your own RX or Goonhilly? Remember the topic! (I think you mean Goonhilly, not Green ..)
The NB beacon is transmitted from Bochum and is also subject of fluctuatios un the uplink side ...
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Are thes values from your own RX or Goonhilly? Remember the topic! (I think you mean Goonhilly, not Green ..)
The NB beacon is transmitted from Bochum and is also subject of fluctuatios un the uplink side ...
It says JO21fx, and this is not in the UK
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If you add more beacon SNR data and locally observed relative humidity then the relation becomes more clear. Two pictures from an updated article on my blog. https://pa1ejo.wordpress.com/2…3/beacon-signal-strength/
