On Wed, 2025-04-09 at 15:56:32 +0300, Hans Summers via groups.io wrote:
What would be a simpler way of arranging it? I can alter it...
Hans and Braden,
I think I need to explain my proposal a little bit further to avoid
misunderstanding. I attach a PDF outlining the present design and my
alternative.
In the present design a BANDPASS filter is used, nominally with a center
around the sidetone frequency of 700 Hz. In my sketch it also includes
the Hilbert transform. I guess that the present filter is of order 10 or
so according to the graphs in the manual.
My proposal is to use ZERO BEAT of the received signal and use a LOWPASS
filter. To get similar performance as above, two filters (for I and Q)
of order 5 or so will be needed. The side tone is mixed after the filter
just in front of the DAC feeding the speaker/phones. An optional offset
(OF) can be added to adjust the center of the CW filter up and down.
This will mean two settings: bandwidth and center. These can be adjusted
independently.
The Goertzel algorithm can be replaced by an moving average to feed the
CW decoder.
Regards Anders
