Bill and Steve,
Thanks very much for this information...it's clear that I need to do some more
study, but your notes have given me some interesting places to look.
Best regards,
Joe/WB0CDY
On 2/1/19, 5:37 PM, "Bill Somerville" <g4...@classdesign.com> wrote:
On 02/02/2019 00:16, Steven Franke via wsjt-devel wrote:
> Aside from the waterfall display itself, the numbers that are used to
> create it are not available for processing by external programs. The
> Fourier transforms that are displayed in color-coded form on the
> waterfall display are calculated in the Fortran routine
> src/lib/hspec.f90. This routine is called from the C++ code in
> src/widgets/mainwindow.cpp. You’ll be able to find the point where
> hspec is called by searching for the word “hspec” in the
> mainwindow.cpp file.
>
Hi Joe,
further to Steve's points, maybe you have not realized that the
waterfall and 2D spectrum display in WSJT-X are not part of the decoding
process, they are simply a visualization of the received signal in the
frequency domain using just amplitude information from DFT processing of
short chunks of time domain PCM samples as they arrive from the ADC. The
whole Rx period of samples are collected and passed to the decoding
routines at the end of the period where they are sliced and diced in
frequency bins specifically appropriate to the mode being decoded to
find candidate signals and signal extraction of those candidates. This
decoding processing does not use the frequency domain data accumulated
for display on the waterfall and 2D spectrum.
Also a small correction to Steve's points above, lib/hspec.f90 is used
for the horizontal fast mode waterfall analysis. For the slow modes the
vertical waterfall and 2D spectrum plot are derived by the
lib/symspec.f90 routine which does the required DFT transformations.
73
Bill
G4WJS.
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