Radio and rails...

Once again I managed to receive a few rather poor images from the ISS. I have experimented in the past with various antennas but with them all being indoors results are as expected. Anyway, this is the clearest (so far) of this December event: This was received via a QFH antenna in the loft, Kenwood TS2000X and MMSSTV on Windows.

SAQ was received fine here on the 24th December for their Christmas broadcast at 08:00. This was again using the Airspy HF+ Discover and YouLoop in the loft. I had a bit of time to fiddle with settings in SDR# this time, reducign the bandwidth to 100Hz and trying the HF AGC on and off - leaving it on produces better audio but really not much difference between on and off. The signal from SAQ was showing as -100dBFS vs -110dBFS background. Nothing at all received using vlfrx-tools via the UMC204HD + PA0RDT mini whip. That does show the same large peaks above 19kHz but not the one at about 16.5kHz (see above) nor that smaller peak seen at about 21kHz, so no surprise it did not see SAQ. But never mind, it's still useful. The Youtube recording of the event can be seen at https://www.youtube.com/watch?v=0CQZmW_vE00

I managed to get the endorsements for all 6 bands from 30m to 10m this time. Not as good as last year but the wire is hopeless on 40m (and below) so I am rather wasting my time trying. I am happy with those 6 bands anyway. Of course it is open until the end of February 2025 so there is still plenty of time, especially as I am considering a new family party game for Christmas: "who can get the antenna support highest up the tree" followed by a relay race with 120 foot of wire.

Here is a quick and dirty comparison between the Behringer UMC204HD + PA0RDT mini whip and the Airspy HF+ Discovery and YouLoop looking at a similar amount of spectrum from 0 up to 96kHz or so. First the UMC204HD: And the Airspy: This was not done in any scientific fashion, it's just to show that the soundcard method works ok but is not as good as the Airspy. No surprises there and this is no criticism of either method. I can see the utility of the soundcard method when coupled with the vlfrx-tools package as all manner of analyses become possible. I have only just started reading about that.

Another new toy arrived today. A Behringer UMC204HD "2x4, 24-Bit/192 kHz USB audio/MIDI interface". I had been reading about the use of soudcards for VLF reception and the raves about the UMC202HD - the 204 model has the addition of a MIDI interface as well which may be useful and one came up at the right price (ok, I missed several of the 202 models on eBay so grabbed this 204 one buy-it-now!) I did experiment previously with the built-in soundcard on the Linux PC but got very poor results, quite possibly due to a lack of perseverence (fiddling) on my part. Anyway, I took the advice of the many raves. And it works!I installed the excellent vlfrx-tools package plus an additional package vtlivesgram. Running vtcard and vtcat piped into vtlivesgram results in a very useful display: The trace above shows peaks where I see them using the Airspy HF+ Discovery / YouLoop combination which provided my first ever reception of SAQ. The results are limited when compared to the Airspy but that is to be expected. Here, the Behringer input is simply the output from a PA0RDT mini whip in the loft, plugged directly in via a 1/4" jack.