Build ur own Ham Radio Virtual ionosphere with Pi4, gstreamer, QUiSK SDR, 192kHZ sample rate sndCARD

[Chuck aa0hw]

demo of setting up a pi4 to act as an RTSP virtual ham radio ionosphere SERVER that many OPs can connect to for QSO'n or just listening... this setup uses an i/q input above and below ZERO POINT by about 80 Khz worth of RF SPECTRUM - to gather together and QSO uses the gSTREAMER wavpack codec, and a gstreamer GST-RTSP-SERVER

everyone can connect to this pi4 RTSP SERVER and receive the full i/q bandwidth of RF SPECTRUM from -80khz to +80 Khz

this is the Gstreamer RTSP CLIENT SCRIPT used to connect to the pi4 server gst-launch-1.0 rtspsrc location=rtsp://(ip address of the pi4 RTSP SERVER):8554/test latency=0 ! rtpjitterbuffer ! rtpgstdepay ! wavpackdec ! audioconvert ! jackaudiosink(OR autoaudiosink)

to SEND RF to the Pi4 rtsp server....this is an example of the script used: gst-launch-1.0 -v jackaudiosrc ! audioconvert ! wavpackenc ! rtpgstpay ! udpsink host=(ip address of the pi4) port=9999

for each OP sending to the pi4....(using a different port number)... the Pi4 receives each OP's RF/vlf/lf/audio by this script example: gst-launch-1.0 -v udpsrc port=9999 ! "application/x-rtp, media=(string)application, clock-rate=(int)90000, encoding-name=(string)X-GST, caps=(string)YXVkaW8veC13YXZwYWNrLCBjaGFubmVscz0oaW50KTIsIHJhdGU9KGludCkxOTIwMDAsIGRlcHRoPShpbnQpMzIsIGZyYW1lZD0oYm9vbGVhbil0cnVl, capsversion=(string)0, payload=(int)96" ! rtpjitterbuffer ! rtpgstdepay ! wavpackdec ! audioconvert ! jackaudiosink(OR autoaudiosink)

NOTE the RECRI KEYER's SDR APPs can directly send at VLF/LF/RF in addition to typical 20hz to 20kHZ AUDIO https://github.com/recri/keyer

podcast playing is from https://www.qsotoday.com/podcasts/w6obb

[Chuck aa0hw]

Here is another example of setting up a pi4 as a TCP/ip VLF BAND QSO CW SERVER

2 qrq cw nets are operating at the same time on different VLF frequencies in this demo example (NOTE: this operates using i/q phasing so the available band frequencies(at 48khz sound card samplerate) are doubled ie from -23kHZ to -1Khz AND +1Khz to +23Khz

this QUISK SDR and pi4 are only using the ALSA AUDIO ENGINE along with the ALSA virtual audio cables, snd-aloop, to route VLF CW to and from the pi4 QUiSK SDR APPLICATION to and from each connecting over ip CWop

GSTREAMER is used to send and receive VLF CW from the OPs and to the OPs via the VLF BAND operating inside the pi4 QUiSK SDR the gstreamer tee command and audiomixer command allow multiple OPs to send VLF CW via UDP RTPL24 to the pi4 QUiSK SDR QSO SERVER and and RECEIVE all audio from the QUiSK VLF BAND by TCP RTPL24