Скачать или смотреть Raspberry PI 4 - VLF RECEIVER(RF over IP) TX/RX CW at 21Khz using Gstreamer RTP VORBIS CODEC scripts

BRIEF demo of using a RASPBERRY PI 4 as a VLF RF over IP Receiver
TX/RX CW at 21 Khz using the RECRI KEYER SDR modules
https://github.com/recri/keyer

gstreamer vorbis codec provides the VLF PROPAGATION over IP

NOTE: the PI is only using its NATIVE ANALOGUE sound card output which has just enough capability to output VLF at 22Khz 21 Khz is therefore chosen as the VLF FREQ for this test

NOTE: the TWIN-COIL FERRITE ROD CAGE ANTENNA
has been tuned to resonance for both coils at 21Khz
series resonant cap at the TX COIL , and PARALLEL RESONANT cap at the RX COIL - provides the highest signal strength and S/N ratio by using both methods to get the most 21Khz signal into and from each coil respectively

the RX COIL connects directly to the RX OP's MIC INPUT JACK on the OP's LAPTOP and
from there, the RECRI KEYER SDR apps demodulate & fiter the 21Khz CW VLF incoming -
into a 690 hz CW audio output tone

example of the GSTREAMER 21Khz CW TX SCRIPT - transmit OP is using to send to PI 4 :
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gst-launch-1.0 -v jackaudiosrc ! "audio/x-raw,channels=1" ! audioconvert ! vorbisenc quality=1 ! rtpvorbispay ! rtpstreampay ! tcpserversink port=5678 host=(IP ADDRESS OF THIS TCP SERVER PC)

NOTE: the vorbisenc "QUALITY" setting, has to be set to its highest value in this script to be able to transmit/receive VLF at 21Khz(quality=1)

NOTE: to send 21Khz CW back to the 1st OP, the same AD5DZ, receri keyer CW/SDR apps are used and the same type of gstreamer TX script is used as shown above...so the 2nd OP to send back to the 1st op, uses their laptop to do so etc... the PI 4 is only used as a dedicated VLF RECEIVER