Filtering QRQcw audio tones with free software

[Chuck aa0hw]

The following Video demonstrates a method to filter QRQ CW morse code audio tones with free software:

 

If you are interested in trying this setup please see this video RE: JACKROUTER SETUP for WINDOWS 7

 

LINKS MENTIONED IN THIS VIDEO:

 

VST PLUGINS THAT FILTER THE QRQ CW

1.  REAGATE from reaplugs by REAPER

2.  Engineers Filter

3.  Mequalizer

VSTi CPO cw tone generators

1.  bipper

2.  TAL

3.  Polygon

 

HERE IS A MIDI NOTE CHART to help you select the closest preferred cw audio frequency - to write the correct number in the REAGATE send midi note box -

[Chuck aa0hw]

Here is a picture of some cw being transmitted at 80 wpm from FLdigi  and at the same time it is being regenerated with the Bipper sine wave VSTi CPO and post-filtered by the Bessel function bandpass filter in the Engineers Filter VST plugin.  Bipper plus the Bessel come pretty close to duplicating the exact length and wave shape of the original FLdigi cw tone.  (FLdigi on bottom Bipper on top)

 

The other excellent feature of this REGENERATIVE CW method, is the process is almost at near zero latency, the time difference between the start of the FLdigi cw note and the REGENERATED BIPPER CPO cw note is less than 5 milliseconds.

 

HERE IS AN EXAMPLE OF REGENERATING LOW BIT RATE OVER THE INTERNET CW

The wave form on top is from a morse code audio tone transmitted over mumble with an audio quality of transmission setting of 8k bit rate.  This is a very poor quality wave form, and yet the AUDIO to MIDI process is able to regenerate the cw audio tone/wave to its near perfect original condition.(bottom)

HERE IS A SHORT EXAMPLE OF WHAT THIS SOUNDS LIKE

The first few seconds of audio is a harsh square wave, the 2nd is the same audio, but this time it is only used to activate the AUDIO to MIDI system to key a 2nd sCPO, software code practice oscillator.

[Chuck aa0hw]

Here is a very short video / audio demonstration of the MEqualizer plugin filtering out the percussive edge noise from a QRQ CW file being sent by FLdigi at 80 wpm.

MEqualizer does a great job of getting rid of this edge noise.

This video demonstrates the excellent filtering qualities of MEqualizer on getting rid of the percussive noise generated by an audio QRQ CW file being sent at 80 wpm. Even though the RAISED COSINE EDGE's - rise and fall time - are @ 6 milliseconds, the inherit audio characteristics of QRQ CW at this high speed always generates percussive QRN from the rapid, repetitive, onslaught of the cw element edges, irrespective of their rise/fall time settings.

NOTE: you will probably need to use headphones in order to hear these filtering changes. The video starts out in the FILTER ON state. Then the BYPASS button is toggled OFF and then back ON - a couple of times. An audio spectrum analyzer is also on display so you can view the spectrum bandwidth changes between FILTER ON and FILTER OFF.

for more information on MEqualizer, see here:
http://www.meldaproduction.com/plugin...

[Chuck aa0hw]

Here is another example showing the free Engineers Filter turning a harsh square wave cw sidetone into a very nicely shaped cw note with Rasied Cosine edges:

short demo of the ENGINEERS FILTER VST PLUGIN taking a very harsh sounding morse code audio square wave sidetone and filtering it into a very nice sounding - raised cosine shaped - cw note...

ENGINEERS FILTER:
http://www.rs-met.com/freebies.html

VST HOST used is MINI HOST MODULAR:
http://www.image-line.com/documents/news.php?entry_id=1391136116
https://www.image-line.com/support/flstudio_online_manual/html/plug...
http://www.image-line.com/documents/news.php?tag=minihost+modular