DSD demod NXDN support
If you compile from source you will need to checkout the latest version v1.8.3 of dsdcc.
Adds NXDN to the list of digital voice modes supported according to latest dsdcc version. More information can be found in the readme,md file of the plugin: https://github.com/f4exb/sdrangel/blob/master/plugins/channelrx/demoddsd/readme.md
It has been tested only on the 4800 b/s version of the standard (2400 S/s) so it may or may not work on 9600 b/s (4800 S/s) transmissions. In any case the voice full rate decoding (EFR mode) works only if you have a DVSI AMBE dongle (DV serial).
Other changes
- Channel Analyzer: corrected suqared magnitude (power) display in dB
- Scope and channel analyzer: new squared magnitude (linear power) projection mainly for radioastronomy
- Extended scope trace amplification range and trigger minimum step
- DSD demod: enhanced the high pass filter
- DSD demod: use compression on the DV serial audio output to improve voice readability. This can change the correct volume settings
- DATV demod: include it only if FFmpeg > 3.1 is installed
- Fixes for Arch. Manual merge of pull request #183.