More Whipping!

It's been cold recently, but also calm and dry, so a good time to test out the PA0RDT mini-whip again - this time, on NDB signals. The whip was suspended about 8m up with a glass fibre pole.

It's much more convenient to record a spectrum captured by SDR and analyse it in the comfort of home, rather than trying to decode weak signals by ear in a cold car, so I did exactly that - though not without hassle, as I've never recorded spectrum for some reason.

SDRUno is not the most intuitive program to use and I was at a loss as to how to make the appropriate spectrum recordings, rather than single-frequency audio recordings. It then dawned on me that using the 'Scheduler' facility, without any schedule (just press record!) is how we go about things. Unfortunately, most of the videos to help people put out by SDRPlay have become outdated; SDRUno is not even being developed any more as they move to a simpler interface alternative.

SDRUno screengrab of some NDB signals, with practically no noise.

 

I recorded about ten minutes of spectrum and then tried processing it using PskovNDB. This is a good program, but seems to be more useful if one is beset by RF noise. I'm lucky in that I have some quiet spots to go to in order to receive and last evening was especially good, with very clean signals. 

Pskov also isn't the most intuitive of programs, mainly through lack of clear directions. There are two parts (and programs) to Pskov: the spectrum builder and the FFT analyser. You run the spectrum WAV file through spectrum builder, which then creates the appropriate files for analysis. 

PskovNDB analysis of a strong NDB signal. On weaker signals, the CW characters can be much more difficult to pick out.

I found Pskov worked quite well, but it isn't always easy to pick-out the patterns of dots and dashes. I actually found it easier and faster to listen back to the recording in order to read the NDB signals. 

Now, it was only early evening when I made by short recording, so there are no spectacular DX NDBs as yet. I also haven't listened to all the recordings I made. But here's the plot thus far, which shows the PA0RDT mini-whip does very well on these, sometimes high power, sometimes very low power signals.

 

With a bit of luck, I might be able to grab a depths-of-night recording, see if any any good DX signals roll in.