KiwiSDR support
Many thanks to Vort for bringing us support for KiwiSDR! This plugin is designed to enable connection to publicly available KiwiSDR receivers.
I met KiwiSDR a few years ago on their stand in Friedrichshafen Hamradio. The hardware looked pretty good with a 14 bit ADC but I realized that the interface was only web based and then did not give it more attention. This is only when Vort opened a few issues to iron out parts of code that were not much exercised to support interpolation on some audio demodulators. It turned out that interpolation was needed to step up sample rate from 12 kS/s to the audio device at 48 kS/s and this was needed to support input from the 12 kS/s I/Q stream coming from the Kiwi. In one of the comments from Vort there was a pointer to the code so I decided to have a look.
I must say I had a lot of fun trying various receivers and frequencies to see how things were received here and there. I have never been in favor of TCP and even more websockets to carry I/Q streams or any kind of live stream and would favor UDP. However customer experience had the better of me and I became convinced that it had to be supported in SDRangel. In fact UDP makes sense in a private network but when you want to broadcast your stream over the wild internet websockets do have a decisive advantage: it makes it easier to pass the multiple routers along the way and ultimately firewalls. I have not tried it yet but reverse proxying should be possible also.
So do like I did: have fun! Please have a look at the readme of the plugin for more information: https://github.com/f4exb/sdrangel/tree/master/plugins/samplesource/kiwisdr
Other changes and fixes
- FreeDV demod: implemented interpolator/decimator (yes this is also because of KiwiSDR)
- SSB demod: reworked AGC to handle the threshold gate properly
- Enlarge text box of splash screen so that the tallest characters display correctly