12 CW Signals on the virtual VLF BAND: created using i/q quadrature encoding and LYSDR I/Q decoding

i/q encoding of CW Signals from -3kHZ to -30kHZ & +3kHZ to +30kHZ was done with 12 CW KEYBOARD from RECRI KEYER

NOTE:

A 3 minute recording of all 12 CW signals in FLAC format is available for download here: https://u.pcloud.link/publink/show?code=XZPy4YVZW3EIRFGzQMhdvapPy2m...

if you would like to test & try & decode these VLF signals with your own SDR...

(sample rate of your soundcard needs to be at least 63Khz)

Comment by Chuck aa0hw on August 15, 2022 at 12:01pm: QSO CW over the Virtual VLF BAND using a Pi4 JackTrip HUB Sever & multiple JackTrip HUB clients

this example is demo'iNG a CW QSO OVER the VLF BAND between 2 CW OPs, with sound cards set to 63Khz sample rate, in order to be able to send CW directly up to a VLF frequency of 30Khz

RECRI KEYER's CW KEYBOARDs can send directly at VLF frequencies... https://github.com/recri/keyer

for RECEIVE, a sound card SDR is used.... to demodulate the VLF CW down to AUDIO CW ... in this DEMO, LYSDR is being used for that purpose: https://github.com/gordonjcp/lysdr

JACKTRIP provides the MEDIUM for SENDING VLF RF over IP and the JACKTRIP HUB SERVER system allows a pi4 JACKTRIP HUB SERVER to automatically make all incoming and outgoing connections possible without any manual intervention in wiring up all the connections yourself manually...

see these links for more info on JackTrip

https://github.com/jacktrip/jacktrip/releases

https://www.jacktrip.com/

https://www.jacktrip.org/

https://ccrma.stanford.edu/software/jacktrip/

https://jacktrip.github.io/jacktrip/index.html

to set up a sample rate of 63000 (could have also used 96Khz or 192Khz) a JACK DUMMY VIRTUAL SOUND CARD was used, and then alsa_out was loaded into the jack connection bay to connect audio from the JACK BAY to the 'real' hardware sound card