Raspberry Pi - Jumping in at the deep end
I'm plugging away unsuccessfully trying to get spots from my old raspberry pi but still enjoying the journey.
I think I made the mistake of jumping in at the deep end. I was trying wspr on my raspberry pi before I ever had a radio or had a good grasp on antennas.
Since the summer I have become the proud owner of an old Kenwood TS-820s which has taught me a lot. I now know how to replace the fuse in a TS-820s
and that the valves in these radios weren't designed for digimodes :-)
The TS-820s also confirmed something I had suspected, my raspberry pi's transmit signal is out by a whopping +7MHz. I had an SDR dongle before the
radio so at the time wasn't sure if it was the pi or the dongle which was the problem. Now I know my pi is not behaving itself. The signal doesn't seem to drift,
it's just not were expected. Having addressed the transmit frequency I'm still not getting decodes on my sdr setup 30m away.
Oddly enough I am getting decodes on the sdr setup when I use rpitx to transmit a wav file of a wspr signal recording from the same raspberry pi. I'm trying
to address the fact the modulated wav file I created using rpitx is optimised for voice using a 2.5KHz low pass filter. In my limited radio mind I imagine this means
I'm trying to send a big fat signal rather than a lean one. Someone just kindly told me about SimJT so I will see if I can create a better audio file to transmit.
My other gut feeling is that being in located in Belfast my wspr signals have a lot to compete with. I often have a police helicopter over head and goodness knows
what other band activity going on around me.
I have appreciated the support of the users of this site. I refer back to comments on previous blog posts as old suggestions are a good reference as my understanding grows.
I've ordered another lpf from Hans Summers for 40m so I'll see how that goes. There's a lot more life on my TS-820s on 40m than 20m at the moment.