QRQ CW Transmit Audio Filtering - to reduce drastically your RIG from transmitting RF CW EDGE NOISE Harmonics

Even at 8.3 ms RISE and FALL time, as was used in this test setup,  which is even more than the usual COMMERCIAL RIG's  RAISED COSINE WAVE SHAPE, the amount of CW EDGE NOISE harmonic energy that you will still transmit above and below the actual CW PITCH, when sending at QRQ CW - say at 90 wpm,  is shown here in this Spectrum Analyzer view below:

However, if you filter your CW NOTE before it goes to TRANSMIT, you can virtually eliminate ALL of the HARMONICs above and below your CW PITCH as shown below:  and transmit a "purer" CW NOTE

as, you can see, virtual all of the harmonics above and below the CW PITCH(808 hertz) in this example has been eliminated by the CW AUDIO FILTER CHAIN as will be shown below...there are 3 filters...HP, LP, BP

1.    HIGH PASS FILTER 

2.  LOW PASS FILTER

3. BANDPASS FILTER

This also assists in getting rid of virtually all of the CW EDGE PERCUSSIVE AUDIO NOISE QRM that you would otherwise hear when listening at 90 wpm

NOTE:  this is designed for AFCW MODE(A2 mode), since you usually can not alter your RIG's CW NOTE before it goes to TRANSMIT in the typical A1 MODE of sending CW

Here is what the FINAL 90 wpm DIT looks like on the AUDIO SCOPE

Here is an example of what QRQ CW sounds like at 90 wpm using this cw audio filtering scheme 

CALF STUDIO GEAR

https://calf-studio-gear.org/

Views: 31

Comment

You need to be a member of QRQcw to add comments!

Join QRQcw

Please consider making a donation today to help us pay for this website and keep QRQcw alive and growing
BALANCE:

We have received  $130 of the $250 needed for the Ning website fee due 8-1-2019

  *  THANKS FOR

   YOUR SUPPORT  * 

© 2019   Created by Chuck aa0hw.   Powered by

Badges  |  Report an Issue  |  Terms of Service

Offline

Live Video