VLF RF over IP IQ CW Transmitter & Receiver: LIVE demo using Gstreamer & the Recri Keyer SDR modules

Gstreamer is for all OS'es MAC, LINUX, WINDOWS 10, Raspberry Pi

https://gstreamer.freedesktop.org/download/

Recri Keyer SDR Modules & CW Keyer, CW Keyboard

https://github.com/recri/keyer

Gstreamer OPUS CODEC IQ VLF RF over IP TRANSMIT SCRIPT:

gst-launch-1.0 -v autoaudiosrc ! audioconvert ! opusenc bitrate=650000 frame-size=2.5 ! rtpopuspay ! udpsink host=(external IP address of recipient) port=7388

Gstreamer OPUS CODEC IQ VLF RF over IP RECEIVE SCRIPT:

gst-launch-1.0 -v udpsrc port=7388 ! "application/x-rtp, media=(string)audio, clock-rate=(int)48000, encoding-name=(string)OPUS, sprop-maxcapturerate=(string)48000, sprop-stereo=(string)1, payload=(int)96, encoding-params=(string)2" ! rtpjitterbuffer ! rtpopusdepay ! opusdec ! audioconvert ! autoaudiosink

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Comment by Chuck aa0hw on March 30, 2021 at 9:39am

Here is a follow up video with the same setup, only on the RECEIVE SIDE, testing adding PINK COMFORT NOISE to the QRQ CW and testing stereo IQ/QI verses MONO for headphone copy of the QRQcw signal

this is a follow up video from the first test setup here:

https://youtu.be/iSIY-pFrjTw

in this video, on the RECEIVE side, adding PINK COMFORT NOISE & switching between MONO and "IQ stereo" and "QI stereo" is tested to see if MONO is truly the "best" way to copy 2 channel IQ QRQ CW with headphones

RECRI KEYER

https://github.com/recri/keyer

SETUP same as in first video test setup:

a LINUX laptop sends 23Khz IQ VLF RF over IP CW to a PI2b and it is transmitted out to two different antennas, a HORIZONTAL INDUCTION LOOP WIRE ANTENNA on the CEILING, and a VERTICAL INDUCTION LOOP WIRE ANTENNA on one of the side walls of the room in the same room is a pi4 with two antennas connected to its USB soundcard STEREO LINE IINPUT - a vertical positioned ferrite rod loopstick antenna and a horizontal positioned ferrite rod loopstick antenna...one connecting to the LEFT LINE INPUT and the other to the RIGHT LINE INPUT.... the 23Khz VLF RF IQ CW antenna signal is sent from the PI4 over a Gstreamer pipeline back to the LAPTOP where the RECRI SDR APPs filter and demod the 23Khz CW from the two ferrite loopstick antennas, and convert it to a 760hz CW IQ signal then... PINK NOISE is added just before the headphones...and also, the IQ(stereo balance) is switched around from iq/qi to mono and tested to see which might sound better for copying "IQ" 2 channel QRQ CW

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