All Blog Posts (374)


USES GSTREAMER script for both the SENDER and RECEIVER SEND 4Khz, 12Khz OR 20Khz to RX OP

here is the example using 4Khz

gst-launch-1.0 -v audiotestsrc freq=4000 ! audioconvert ! opusenc ! rtpopuspay ! udpsink host=(ip address of the RX OP) port=9999

RECEIVE OP script: gst-launch-1.0…


Added by Chuck aa0hw on August 27, 2022 at 6:48am — No Comments

QRQ CW REGENERATOR setup for a pi4 iCW/Mumble station: REgenerate both Mumble CW input and CW output

test to see how well a Pi4 MUMBLE iCW setup can handle all the apps it takes to setup up a MUMBLE INPUT and OUTPUT cw audio morse code RE-GENERATOR SYSTEM

80wpm QRQ CW test



Added by Chuck aa0hw on August 26, 2022 at 8:25am — No Comments

QRQ CW over SONOBUS using CARLA in MULTI-CLIENT Mode: key a 555, regen & filter for SonoBus sidetone

Brief Demo for sending QRQ CW over SONOBUS using KXstudio's Carla in "multiple clients" mode on a Raspberry Pi 4 SonoBus is also monitoring its input to be able to monitor the REGEN'd ZamGate CW sidetone in real time at near zero latency

a TLC555 is being keyed by FLdigi's serial port rts pin, TLC555 sending its audio…


Added by Chuck aa0hw on August 17, 2022 at 10:52am — 1 Comment

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…


Added by Chuck aa0hw on August 15, 2022 at 8:30am — 1 Comment

TWIN-T QRQ CW CPO's audio output gets filtered by the HI-PER-MITE Active Audio CW Filter - LIVE demo

to reduce the unwanted harmonics & QRQ CW edge noise generated by a keyed TWIN-T's CW audio output...the HI-PER-MITE active audio cw filter is tested to see how well it cleans it up

Added by Chuck aa0hw on August 11, 2022 at 1:55pm — No Comments

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…


Added by Chuck aa0hw on August 8, 2022 at 11:30am — 2 Comments

HAM RADIO QSO FREQUENCY COORDINATOR /APP\ ~bpsk31~ over ip between OPs by FLdigi & Gstreamer scripts

test using bpsk31 over ip from one op to the other to coordinate frequencies for HF QSO NOTE: NO AUDIO is heard on this video demo....visual only FLdigi provies the ENCODING and DECODING of bpsk31 Gstreamer provides the OPUS codec encoding to convert bpsk31 from and to one OP to the other here are the scripts used in this example…


Added by Chuck aa0hw on August 7, 2022 at 1:36pm — No Comments

Pi4 iAMBIC CW Keyer, QRQ CW Keyboard & Straight Key - using a CW AUDIO to CW MIDI app & 2 key'D CPOs

this video is a follow up to the first video here:

this video adds a CW KEYBOARD, and straight key to the Raspberry PI 4 iambic CW keyer shown in the first video... by using a 2nd keyed CPO at a different PITCH than the 1st keyed CPO in…


Added by Chuck aa0hw on August 7, 2022 at 9:01am — No Comments

pi4 CPO with Raised Cosine Edges: key TLC555 with iambics & FLdigi CW Keyboard - REgenerate CW on pi

TLC555 timer chip square wave oscillator is being 'keyed' (pin 4/pos rail) by a CW KEYER & its iambic paddles AND also being keyed by FLdigi using FLdigi's serial port keying setup via a usb serial port adapter and keying the serial port's RTS PIN Both the CW KEYER and FLDIGI are keying the diode side of an H11F1 FET OPTOisolator chip and…


Added by Chuck aa0hw on August 4, 2022 at 12:38pm — 1 Comment

Morse Code Audio over Mumble: alsa-loopback to interject a CW AUDIO bandpass filter for mumble input


alsa-loopback cable

virtual audio cable

via a Gstreamer TEE SCRIPT to take a keyed oscillator at the mumble sound card input... filter it 1st... and then send it to two places...

1. the mumble USB sound card's output so you can monitor your own…


Added by Chuck aa0hw on August 2, 2022 at 11:45am — No Comments

Full Duplex Fast QSK CW QSO over IP using a multipurpose Gstreamer Script on a Raspberry PI & laptop

the Gstreamer Script used in this video example:


gst-launch-1.0 -v alsasrc device=hw:4 ! "audio/x-raw, format=(string)S16LE, layout=(string)interleaved, rate=(int)48000, channels=(int)2, channel-mask=(bitmask)0x0000000000000003" ! tee name=t !…


Added by Chuck aa0hw on July 30, 2022 at 2:13pm — No Comments

clean up the audio output of your Morse Code Practice Oscillator with this DIY audio BandPass Filter

Near Zero Latency passthrough... using this Gstreamer Script to create a custom CW AUDIO bandpass filter: (CW PITCH of CPO = @700 hertz)

gst-launch-1.0 -v jackaudiosrc ! audiowsincband mode=band-pass lower-frequency=580 upper-frequency=820 length=384 window=3 low-latency=true ! jackaudiosink sync=false…


Added by Chuck aa0hw on July 29, 2022 at 11:16am — 1 Comment

Build your own FREE SDR Receiver APP for Morse Code QSO audio outputs on iCW: Mumble/Discord/Sonobus


several common CW Transmit/RX issues show up on iCW

1. keyclicks/square wave on OP's signal

2. CW pitch/keying too soft on OP's…


Added by Chuck aa0hw on July 29, 2022 at 8:22am — No Comments

High Voltage protection/insulation/isolation between RIG/CW KEYER & a PC sound card input by Pyrex Glass & induction coils

testing using 2 ferrite bobbin core inductor coils inside thick pyrex glass measuring cups to provide high voltage isolation protection between a RIG/cw keyer and a PC soundcard's input

used for sending CW AUDIO over SonoBus by keying a TWIN-T oscillator

the output of the TWIN-T goes to a class D amp…


Added by Chuck aa0hw on July 28, 2022 at 10:30am — 1 Comment

Raspberry Pi 4 - Longwave soundcard SDR CW Transmitter - LIVE demo @ 153Khz, 216Khz & 279Khz

using the dummy sound card JACK set to 800Khz, a Raspberry PI 4 transmitter sends LongWave CW to a laptop receiver over ip using these Gstreamer scripts:


qrq@pi4b:~ $

gst-launch-1.0 -v jackaudiosrc ! "audio/x-raw, channels=1" ! audioconvert ! rtpL24pay ! udpsink…


Added by Chuck aa0hw on July 27, 2022 at 8:24am — No Comments

Key'D TLC555 Square Wave Oscillator to PURE SINE WAVE CW NOTE with Raised Cosine Edges by RECRI SDR

FLdigi is keying a TLC555's pin 4/POS rail to send out a square wave CW NOTE at 1850 hertz - goes to a PI4 usb sound card's LINE INPUT...goes to a HILBERT CELL, then a BANDPASS FILTER(centered at 1850hz) then to a GAIN MODULE(+3db) then to an LO-MIXER that allows you to choose ANY CW PITCH and still keep the bandpass audio filtering bandwidth…


Added by Chuck aa0hw on July 26, 2022 at 8:20am — 1 Comment

KXstudio's CARLA as a standalone APP to conduct QRQ CW over SONOBUS operations - using ALSA on a Pi4

- a Pi4 has a usb sound card with LINE INPUT/line output/headphone output

- fldigi is keying a 555 square wave oscillator(by connecting pin 4 of the 555 to its POS RAIL through an H11F1 OPTOisolator chip) using FLdigi's KEY BY SERIAL PORT RTS PIN feature and sends its audio output to the pi's usb sound card's line…


Added by Chuck aa0hw on July 25, 2022 at 9:09am — No Comments

QRQ CW 'copy by ear' PRACTICE using Mixxx with CW REGENERATION & a tracking CW audio bandpass filter

Mixxx is a VARIABLE SPEED audio player that works great to slow down or speed up a QRQ CW audio file. Mixxx also has a REVIEW/rewind function that allows you to repeat the last word sent as many times as you want(by hitting the keyboard letter 'A' can also repeat while slowing it down... MIXXX will change the cw frequency however....…


Added by Chuck aa0hw on July 23, 2022 at 9:50am — No Comments

High Performance Raspberry Pi4 /midi keyed\ Morse Code Practice Oscillator with a tracking BP filter

this video demo's a RASPBERRY PI 4, SETUP as a high performance morse code practice oscillator using RECRI KEYER CW modules

TEENSY-LC usb midi board with recri midi-keys embed firmware…


Added by Chuck aa0hw on July 20, 2022 at 9:30am — 1 Comment

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