TRiPLE RESONANT TUNED High "Q" TX & RX Large Ferrite Rod Antennas for VLF CW operations - LiVE DEMO

[Chuck aa0hw]

FERRITE TX ANTENNA is max tuned for PEAK SIGNAL OUTPUT on 30Khz VLF CW input windings of ferrite rod TX antenna is SERIES TUNED by CAPs and output windinws of ferrite rod TX antenna is PARALLEL TUNED by CAPs FERRITE

RECEIVE ANTENNA is max tuned for PEAK SIGNAL RECEIVE signal on 30Khz VLF CW by a .1uF cap and the BEST coil TAP for MAX signal getting to a sound card's LINE INPUT then to a sound card SDR for mixing 30khz down to normal CW AUDIO pitch..(recri keyer provides the SDR MODULES for this conversion - https://github.com/recri/keyer -

distance between TX & RX antennas is 10 FEET - output power of TRANSMITTER is only what the usb sound card Line OUTPUT jack is capable of putting out....(less than its headphone jack)

[Chuck aa0hw]

Pulse Density Modulation battery powered 30Khz CW VLF Transmitter - 1/10th power drain of A1-MODE CW

using the same RESONANT FERRITE ANTENNA setups

This Pulse Density Modulated CW MODE is 1/10 the power drain of the normal CW MODE with full duration CW elements, since the PDM-CW transmitter is only "ON" for just 1ms per every 10ms for the duration of each CW ELEMENT...

ie for a (30 wpm dit) = 40 ms, typical A1 CW MODE DiT, the PDM-CW transmitter is only on for a TOTAL of only 4ms...

....four.... 1ms batches of 10 cycles of 30Khz sine wave goes out to be transmitted to a 30Khz tuned FERRITE ROD antenna

the TRANSMIT PDM-CW encoder uses ZAMGATE, and GSTREAMER

gSTREAMER provides the pulse train, 10 cycles of 30Khz every 10 milliseconds using this script:

gst-launch-1.0 -v audiotestsrc wave=ticks tick-interval=10000000 sine-periods-per-tick=30 freq=30000 volume=.9 ! audio/x-raw, channels=1, rate=96000 ! audioconvert ! autoaudiosink

this pulse train is held back by the ZAMGATE APP until ZAMGATE's sidechain port is KEYED by a CW KEYER's audio output... allowing the 30Khz PDM-CW to go through only for the duration of each CW ELEMENT according to the SPEED of the CW KEYER

to DECODE the PDM-CW TRIGGER MIDI MONO app is used.... an audio TO midi cw app.. TMM analyzes the PEAKS/ and averages them out and creates a MIDI CW KEYING DATA OUTPUT which then goes over to KEY the MIDI INPUT Port of a CW KEYER CPO by RECRI KEYER

https://github.com/recri/keyer