[op25-dev] OP25 Update December 25, 2020

OP25 Update December 25, 2020 ============================= 1. Experimental HTTP Live Streaming These hacks ("OP25-hls hacks") add a new option for audio reception and playback in OP25; namely, via an HTTP live stream to any remote client using a standard Web browser. The web server software used (nginx) is industrial-strength and immediately scalable to dozens or hundreds of simultaneous remote users with zero added effort. More than one upstream source (in parallel) can be served simultaneously. See the file apps/README-hls in the repo for more information. 2. NXDN48/NXDN96 RX and TX The multi_rx and multi_tx apps have been updated accordingly. The "filter_type" JSON keyword for NXDN channels should be set to "nxdn", and the "symbol_rate" keyword should be set to 2400 or 4800 for NXDN48 and NXDN96, respectively. A fair number of trunking and control packets are also currently decoded, although trunked call following for NXDN systems is not currently implemented. I would like to take this opportunity to thank Steve, KB9MWR, whose contribution greatly accelerated the NXDN effort. 3. Graphical (Plotting) Updates The constellation plot appearance has been enhanced and a new plot type "correlation" added. The correlation plot is actually five separate plots (nxdn 48 and 96, p25, dmr, and ysf) and can be used to show at a glance which of the five modulation types is in use. The correlation plot was present in OP25 long ago in scope.py and is now available in both rx.py and multi_rx.py. 4. UDP Linkage Between OP25 TX and RX Prior to these additions, a hardware RF transmitter/radio was always required to utilize the OP25 software TX. The OP25 TX application supports P25, DMR, YSF, NXDN, and DSTAR, and supports both halfrate and fullrate xMBE encoding, in real time, via its built-in software voice encoders. An arbitrary number of channels and modes may be transmitted simultaneously, within the usual spectrum spacing rules. The UDP additions allow the TX and RX to be linked. The example configuration contains two P25 channels, one trunk control channel and one voice channel. This permits rapid testing with no need to wait for a chance to receive a transmission. There is a python utility used to generate the fake P25 control channel data to be broadcast. See the file apps/README-example-udp in the repo for more information. 5. Ubuntu 20.04, Python 3 and GNU Radio 3.8 These are all supported in OP25 but until such time as these versions become more mainstream the changes are applied via a patch located in the TLD of the repo. 6. Experimental Online Web Configuration Interface This is a balky and complex addition and is very experimental. To invoke, run http.py instead of rx.py or multi_rx.py. These latter two are invoked automatically in the backend by http.py. Starting from a "blank" configuration, the details are filled in to a web form and then saved (to a server-side json config). In theory with these additions there is no further need for TSV files, although legacy TSVs can be loaded and then saved as json configs.