For What it's Worth --
In the HPSDR forum at Dayton, a brief mention was made to Vshaper
(Voice Shaper) I think with respect to the Uwave SDR project. I looked
interesting so I tracked it down ( http://www.dxatlas.com/vshaper/ ).
Written by VE3NEA, it has a 7 band graphic equalizer, graphic display
of noise gate and clipping level, a built in record /play back for
evaluation of mic adjustments w/wo QRN & QRM. Initial I installed in
and selected the D44 mic input 3/4 as the input and the computer sound
card as the output. After playing with it a bit, I reconnected the to
output to VAC Channel 1 ( and thus the VAC input on Power SDR ). After
playing a bit with the levels, it drives the SDR ok.... Except...
Except there is several hundred milliseconds of latency through the
path from the mic , thru the VAC, to the SDR output. Desiring to figure
out where the delay was, I tried several alternate test cases using
Vshaper, VAC, and the Audio Repeater that came with VAC. The Audio
Repeater is the inverse of the VAC.. It connects to two Sound Card like
devices and passes the bit stream through.
The following test conditions had little ( 10's of millisec ) delay.
mic > SC > Vshaper > SC > speaker
mic > SC > Rptr > SC > speaker
mic > SC > Rptr > VAC > Rptr > SC > Speaker
mic > SC > Vshaper > VAC > Rpt > SC > speaker
( The audio repeater is configured with Sampling rate at 48000 to
match the D44 sampling rate and Total Buffer (ms) set to 100 . )
The following test conditions had several hundred millisec of delay
mic > SC > Rptr > VAC > SDR > speaker ( SDR in monitor mode )
mic > SC > Vshaper > VAC >SDR > speaker
I could find nothing on the SDR setup page for VAC that had any
noticeable effect on the Latency thru the SDR. I would seem to me
that the SDR latency thru the VAC path should be less ( not more ) than
the normal mic to SDR output latency.
AL, K0VM
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