Build a High Performance Morse Code Practice Oscillator with Raised Cosine edges using this setup


this setup uses the following hardware:

1. raspberry pi 4

2. TLC555 that is keyed by a CW KEYER's RIG KEYING jack...(the TLC555 is powered by the PI's own 3.3v power supply via its GPiO pins

3. usb sound card with LINE INPUT - this demo uses a Behringer UCA222 the keyed 555's audio output is a square wave, raspy and unpleasant; no matter, since it will only be used to TRIGGER a software SIDECHAIN GATE that does have a PURE SINE WAVE shaped CW NOTE output

this setup uses the following software APPs

1. ZAMGATE sidechain GATE(stereo)

2. RECRI KEYER's OSCILLATOR module, FILTER module & L0-mixer module

3. CARLA LV2 HOST in alsa audio engine mode the USB SOUND CARD is selected in CARLA as its ALSA sound card CARLA has ADD JACK APPLICATION FEATURE that is how the 3 recri keyer apps/modules are added to the connection bay ie...

for the filter here is the code that goes into ADD JACK APPLICATION

/home/qrq/keyer/bin/./keyer filt -filt-low 11950 -filt-high 12050 -filt-length 384 -grid 1

ZAMGATE is put into SIDECHAIN mode and its attack and release settings will determine how HARD or SOFT your keying will be

ZAMGATE also has a threshold setting, and that will determine how much WEIGHT your cw notes will have from TOO HEAVY to TOO LIGHT etc...

the LO-MIXER determines what the CW PITCH will be, and its tracking bandpass filter setup will keep any CW PITCH exactly the same as far as how you have set the 12Khz BANDPASS FILTER

The first portion of the RECRI MODULEs operate as a 'keyed' 12Khz VLF Carrier... and then it gets mixed down the road by the RECRI LO-MIXER module to its final CW PITCH




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Comment by Chuck aa0hw on August 9, 2022 at 6:32pm

Pi4 - QRQ CW Sidetone Raised Cosine Generator - for a high quality sidetone for Mumble input on iCW

this is a follow up video from the first one here:

please see that video's notes in the description for more info on the Hardware & Software APPs setup that this video is using...

Comment by Chuck aa0hw on August 10, 2022 at 1:38pm

Build a High Performance QRQ CW CPO with Raised Cosine edges using 1 APP: KXstudio CARLA Plugin Host

CARLA is able to SAVE every app inside it that is used to create a raised cosine edge'D - CW NOTE

CARLA also saves the settings...and how each app is connected to the other apps...

CARLA's inside APPS that are used to construct the 'DEVICE' are...

ZAMGATE sidechain GATE, keyed by a 555 osc to passthrough a sine wave

RECRI KEYER - 12khz PURE SINE OSCILLATOR, bandpass filter & LO-mixer

See previous videos on this topic for more info:


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