Inf/Sup frequency shift fixes
Firstly the decimator for inf/sup decimation with shift was not working properly just missing the FIR filter causing possible massive ghost images problems. I am wondering why this was not found before maybe it is not so much used. Anyway thaks to beta-tester for having incidentally pointed me on this important bug. The original finding (issue #172) was that PlutoSDR was not showing the appropriate frequency shift on the spectrum. In order to fix that the calculation was moved in a single place thus it is the same for all plugins implementing the inf/sup feature. The shifting scheme has been changed also to have the baseband as close as possible to the device center frequency. This optimizes the device RF filtering not requiring exaggeratedly large bandwidths. See the plugins documentation for details. Some slight performance improvements to the decimators were made also.
Fixes after Ubuntu 18.04 and Qt 5.9.5 upgrade
My main development platform was updated from Ubuntu 16.04 to 18.04 which is the new LTS. Consequently the Qt version was bumped to 5.9.5 and a few adjustments and fixes were required:
- SDRdaemonsource plugin fixes with UDP sink signal handling changes. See issue #173
- The default governor in 18.04 is powersave (ondemand was dropped) and this makes some cosmetic changes to the CPU load you can observe in
topfor example. Overall this is fine as it optimizes power and heat but it ruins any benchmarking. It is unknown if high throughput operation is affected. A paragraph was added to documentation to avoid surprises as it occured to me. See issue #174 - The dialogs (file and color) now use the native (GTK3) dialogs systematically. This breaks the overall look and feel so the option to use Qt dialogs instead was added to all dialog calls.
Other changes and fixes
- Changed default name of the record file avoiding collision on repeated operation by having a timestamp as part of the name. Fixes issue #170 A custom name can be specified using the Web API (no GUI support presently). An empty file name triggers the timestamped default name.
- Fixed keyboard input for negative values on relative integer value dials. Fixes issue #168
- NFM demod: fixed squelch indicator being always off when audio is muted
- Benchmarking: added inf/sup decimators test
- BladeRF library upgrade to 1.9.0