Monday 23 August 2010


I put the new WSPR beacon to use over the weekend, concentrating on the over-night period (I want to use the station antenna at other times!).

I was up ridiculously early on Sunday morning (the result of drinking too much on Saturday evening) and I noticed the beacon wasn't getting spotted. I checked that it was indeed working - which it was - and I resolved to watch the "start-up" of spots. What I saw was an interesting pattern of fading reception in the evening, silence through the night and a re-awakening with the dawn.

I decided to count the number of spots reported for each "flash" from the beacon. Each flash is 112 seconds long and (at 50mW) that is 5.6 Joules of energy.

I present the counts for the last two nights as a graph - The night of Saturday 21st in blue and the night of Sunday 22nd in red...

The additional "authority" which graphing confers to the data isn't to be taken seriously... I realise that this is at best a pseudo-scientific statistic! However, the number of times my five-and-a-bit Joules are reported is interesting - even if it doesn't account for relative location of the reporting station, the received SNR, etc., etc..

Also, it doesn't account for any differences in WSPR operating practice - I wonder if there are just more WSPR stations active on a Saturday evening than on a Sunday (explaining the peak just after sunset on Saturday)?

Whatever the shortcomings of the "data", it does suggest some patterns of 30m propagation from my QTH...
  • First, there's an orderly fade down to overnight "Quiet" (see the postscript below) and a more abrupt fade up with the dawn.
  • Second - and more interestingly - there's a chance of some DX overnight. Douglas, w3hh, in Ocala, FL (who has spotted my emissions before) heard the new beacon at almost exactly the same time during both the last two nights. He's hearing me at the end of a path achieving 85000 miles per Watt (with reported receiving SNR of -24 dB).
Those (many) of you who know more about propagation than I can comment on how ordinary (or otherwise) these observations are.

I'll try and collect some more overnight data to make this study (slightly) more meaningful.

...-.- de m0xpd

p.s. "Corcovado" is the name of the mountain on which stands the famous statue of "Christ the Redeemer" above Rio de Janeiro. It is also the name of a song by Antonio Carlos ("Tom") Jobim. The song was made famous by a number of artists who've recorded the English version, the lyrics of which were contributed by Canadian writer Gene Lees.

That version is entitled "Quiet Nights of Quiet Stars".

1 comment:

  1. That's interesting. Running my 30m APRS gateway I notice a fade-out between late morning and mid-afternoon. I don't leave it running overnight but quite a few stations are still coming in when I shut down at bedtime. I wonder if you have noticed a mid-day fade-out?