MIDI KEYED - MORSE CODE SINE WAVE OSCILLATOR - with free software

[Chuck Vaughn]

These are our first results from using a hardware MIDI INTERFACE or any other type of MIDI INPUT to key a software code practice oscillator.  From the first experiments, using MIDI to key a CPO shows great promise, and is much more accurate than using a serial port for this purpose.  

A video demonstration of keying a SINE WAVE SOFTWARE CODE PRACTICE OSCILLATOR is here:

https://www.youtube.com/watch?v=h0nmo3FlHxA

NOTE:  Jackrouter is used as the free software base for this setup...please see this video for the JACKROUTER tutorial video here:

https://www.youtube.com/watch?v=h883l3PUJ50

[aa0hw]

I just ran a test on using my LOGIKEY K-1 cw keyer with paddles to send audio from its speaker output to my laptop's microphone input. Then, once the audio reaches the laptop's MIC INPUT,  an AUDIO to MIDI technique was used to REGENERATE the LOGIKEY's original sidetone and convert it to MIDI OUTPUT DATA, (noteON, noteOFF).  This MIDI OUTPUT was used to key a software sinewave oscillator called Bipper. There is an ongoing article on the QRQcw website about this procedure here: http://qrqcwnet.ning.com/profiles/blogs/midi-keyed-morse-code-sine-wave-oscillator-with-free-software.  

The test was very successful, and the accuracy and performance was virtually identical to the original waveform.  Below here is a picture of the the 2 waveforms while a continuous dit stream was sent through this AUDIO to MIDI system.  The top waveform is the original LOGIKEY output audio waveform,  the bottom waveform is the final regenerated AUDIO to MIDI - MIDI to AUDIO cw waveform.   The two waveforms,  are,  for all practical purposes,  a perfect match.

 Using MIDI to key a software CPO, is proving to be superior than using a SERIAL PORT to perform the same function.

Using AUDIO to MIDI to create a MIDI MESSAGE, is very easy,  and since most cw keyers already have a speaker and/or audio output jacks...it makes it very easy to implement this method so you can hook up your cw paddles and cw keyer and generate excellent sinewave shaped cw audio tones with your computer's own soundcard.  You can use an arduino to setup your own HARDWARE MIDI device that you can "key" directly -  some info here : http://shiftmore.blogspot.com/2010/01/quick-and-dirty-arduino-midi-over-usb.html

[aa0hw]

Here is another video that demonstrates how to take any audio oscillator, no matter how rough it sounds, connect the oscillator audio output with an audio cable to your sound card input, MIC or LINE, and convert it to a midi message in order to accurately key a 2nd software code practice oscillator and send that audio to the sound card output so you can hear and monitor your sidetone in near zero latency and high fidelity without any keyclicks,  and also at the same time , send it to the input of mumble.  

 

This method is near perfect in its ability to reproduce the original cw elements in length and exact timing, that are going into the sound card input.      https://www.youtube.com/watch?v=OPeYsPfjPqg 

[aa0hw]

Here is a picture of the basic simple version of this AUDIO to MIDI setup

This gives you the basic simple AUDIO to MIDI function with only 1 post filter stage

 

[aa0hw]

 

I have attached a 30 second video demo of  a basic, simple setup, for this same AUDIO to MIDI method, which also shows the midi noteON and midi noteOFF MESSAGES.  Logikey's K-1 keyer unfiltered audio goes into the MIC JACK of the laptop, to the ReaGate AUDIO to MIDI converter.  ReaGate outputs a MIDI COMMAND to the Bipper SINE WAVE CPO to key a tone at ~780 hertz exactly the same length as the Logikey original cw morse code audio element length that goes into the MIC JACK.  MIDI-OX is used to view these midi messages in real time.  You will be able to hear the cw audio tones from Bipper with only one filter stage and at the same time see the midi messages.  The COLOR CODE of the apps are -  BLUE IS AUDIO.    RED IS MIDI .

 

[aa0hw]

LATENCY OF JACKROUTER for AUDIO to MIDI technique to key a software CPO

This picture shows the inside routing audio delay from a cw sidetone going into the computer sound card MICROPHONE INPUT JACK, then over to the SOUND CARD OUTPUT,  when using JACKROUTER,  measured to be about 17 milliseconds,  this is considered to be - NEAR ZERO LATENCY - 

the first wave is MIC AUDIO from the CW KEYER entering the MIC JACK, the 2nd wave is when that same wave reaches the sound card after going through jackrouter WITHOUT any VST PLUGINS - 17milliseconds

17 milliseconds is just below the human sensory threshold for being able to notice any latency at all

often quoted in the music industry for LIVE PERFORMANCE:

"sounds are perceived as coming from a single source when they occur within 25-35 ms time window"

In this picture, we show the delay between the output of the software CPO - BIPPER - , and the output of the same audio going through all the VST PLUGS, in this example, it only takes another 3 milliseconds to go through 5 VST PLUGINS...to the sound card...the FIRST WAVE on top, is the immediate output of BIPPER, the second waveform on the bottom is the start of the FINAL filtered audio as it outputs from the last VST plugin

When you add these two numbers together, you get a TOTAL OF 20 MILLISECONDS of latency/delay from when the cw keyer sidetone enters the MICROPHONE JACK until it reaches the SOUND CARD OUTPUT.

This is still below the  25 -35 ms human hearing threshold for being able sense any latency at all...

This is outstanding performance from JACKROUTER and ASIO4ALL and the REALTEK HD AUDIO soundcard of this laptop.  Every computer has different soundcards, and drivers, and may have different results than these. Make sure your sound card drivers are up to date for best outcome when using a setup like this for LIVE PERFORMANCE in audio applications.  The jackrouter settings used were 48k sample rate/256 frame buffers.

[aa0hw]

Here is a setup for using audioTOmidi to key a 2nd CPO - for both the MUMBLE INPUT  and MUMBLE OUTPUT

[aa0hw]

    Here is a video demo of the advanced

 

 - AUDIO to MIDI - CW KEYING - of the mumble input and output -  for iCW

 

 - LIVE ACTION -

 https://www.youtube.com/watch?v=FavCoF8IIG4

[aa0hw]

Here is an example of a LOW BIT RATE over mumble[ iCW ] test.  The quality setting on the mumble input settings, was set all the way to the left at 8kbit, which  is as low as the mumble input settings will allow.  A test cw file was sent by FLdigi to the mumble input and on another computer,  an iCW MUMBLE receive station was setup using AUDIO to MIDI conversion technique to regenerate this poor cw audio that was transmitted over mumble/ iCW,  to near perfectly shaped cw notes.  The wave pictured below shows this ...the wave shape on top was the poorly formed original cw captured by the receive mumble iCW station,  and the wave form on the bottom is the regenerated cw tone by the AUDIO to MIDI KEYED CPO technique.

   

[aa0hw]

HERE IS A link to a sound file, that demo's a short clip from this  - LOW BIT RATE over MUMBLE - AUDIO to MIDI TEST -

   The first few morse code tones are from the sound of the very harsh square wave at low bit rate over mumble as it truly sounds,

    then a short pause,  then the last few morse code tones are the AUDIO to MIDI KEYED CPO tones,  recreated from the original.

    https://soundcloud.com/chaseology/audio-to-midi-keying-a