CW Transmitter - save even MORE battery power using Pulse Width Modulated CW: LIVE demo of the setup

[Chuck aa0hw]

instead of sending a solid keydown of dits & dahs... when you key down using this method, only the smallest possible pulse width of the minimalist pulses per CW ELEMENT train, at the CW RF frequency of interest, is sent... saving battery power since the PWM key down is a tiny percentage of battery current/power being used when compared to using the normal steady KEY down for each cw element NOTE a special decoder is needed to convert the receive pulse train cw elements back into STEADY CW audio notes... ZAMGATE(sidechain mode) does the PWM encoding and decoding https://www.zamaudio.com/ GSTREAMER script is dialed in so that you can find the smallest pulse width and least amount of pulses per CW ELEMENT this is the script used in this demo: gst-launch-1.0 -v audiotestsrc wave=ticks tick-interval=8000000 sine-periods-per-tick=2 freq=18000 ! audio/x-raw, channels=1 ! audioconvert ! audio/x-raw, channels=1 ! audioconvert ! queue ! jackaudiosink

[Chuck aa0hw]

Pi 4, Through the earth, VLF band, 17Khz, Pulse Width Modulated CW Transmitter - saves battery power

using Pulse Width Modulated CW to save battery power for a "THROUGH THE EARTH", CW VLF 'underground cave to surface' TRANSMITTER this video is a follow up video from the 1st one here: https://youtu.be/seV5ijWRwOc

PWM-CW ENCODER & decoder = ZAMGATE SIDECHAIN GATE

https://www.zamaudio.com/?p=976

PWM-CW

via GSTREAMER & ZAMGATE     

here is the GSTREAMER SCRIPT used:

gst-launch-1.0 -v audiotestsrc wave=ticks tick-interval=8000000 sine-periods-per-tick=2 freq=17321 ! audio/x-raw, channels=1 ! audioconvert ! audio/x-raw, channels=1 ! audioconvert ! queue ! jackaudiosink

[Chuck aa0hw]

1st HF TEST on 80 meters for PWM-CW mode(pulse width modulation CW)

1st test using an SDR WEB RECEIVER with a PWM CW Transmitter

this video is a follow up from the 1st two videos here:

https://youtu.be/seV5ijWRwOc

https://youtu.be/3GIgIIjX7gA

ZAMGATE(sidechain mode) does the PWM encoding and decoding

https://www.zamaudio.com/

SETUP:

2400 hertz pulses were used to save battery power and sent via LSB using AFCW mode on the RIG

RECEIVE by websdr and send it to ZAMGATE decoder

RESULTS are as you hear on this video

PULSE WIDTH MODULATION by Gstreamer script:

gst-launch-1.0 -v audiotestsrc wave=ticks tick-interval=16000000 sine-periods-per-tick=2 freq=2400 ! audio/x-raw, channels=1 ! audioconvert ! audio/x-raw, channels=1 ! audioconvert ! queue ! jackaudiosink

NOTE: these 2.4Khz audio pulses are BANDPASS filtered to limit the HF bandwidth

SCOPE:

GREEN = the pulses as keyed by a cw keyer from the output of the ZAMGATE PWM ENCODER

RED = the pulses after going through a bandpass filter before going to the RIG's line input for transmit

BLUE = the final CW NOTE result of the RX zamgate decoded CW audio note output from websdr browser