Hello everyone,

This was posted to the support group originally, but I don't think that was
the correct venue for it.

I have a GNURadio chart that I run and play audio into my loopback device.
I can run the WSJTX program & decode it just fine. This all runs on Ubuntu
Linux. I am listening to 7.074 MHz USB with a small loop antenna. I receive
stations nearby me frequently and sometimes those from several states away.

I modified my GNURadio flow chart to produce 15 second WAV files that are
output synchronized to the FT8 transmission interval. My hope is I can just
process these files to decode the signals rather than depend on a running
WSJTX session.

I want to decode these using the jt9 command line program. WSJTX has the
option to download the included sample files. So I test again that using
the following

$ jt9 -8 -F 200 -f 1500 210703_133430.wav
133430  15  0.3 2571 ~  W1FC F5BZB -08
133430  -2 -0.8 1197 ~  CQ F5RXL IN94
133430  13 -0.1 2157 ~  WM3PEN EA6VQ -09
133430 -13  0.3  590 ~  K1JT HA0DU KN07
133430  -7  0.1  723 ~  A92EE F5PSR -14
133430  -3 -0.1 2695 ~  K1BZM EA3GP -09
133430 -13  0.3  641 ~  N1JFU EA6EE R-07
133430  -3  0.2  466 ~  N1PJT HB9CQK -10
133430  -7  0.4 2734 ~  W1DIG SV9CVY -14
133430 -16  0.1 1649 ~  K1JT EA3AGB -15
133430 -16  0.3  400 ~  W0RSJ EA3BMU RR73
<DecodeFinished>   0  11        0

This works fine.

I run against my WAV file I created, which I name test.wav

$ jt9 -8 -F 200 -f 1500 test.wav
At line 238 of file /home/bill/wsjtx-prefix/src/lib/jt9.f90
Fortran runtime error: Substring out of bounds: lower bound (0) of 'infile'
is less than one

Error termination. Backtrace:

This crashes. I checked the Fortran source and it looks like it is trying
to parse the command argument file name? So I padded out the file name

$ jt9 -8 -F 200 -f 1500 test0000000000000.wav
 EOF on input file test0000000000000.wav
<DecodeFinished>   0   0        0

This sidesteps whatever that problem is

my test file is 15.335 seconds long. So it is long enough. I looked through
the source code and notice that while the code appears to access the sample
rate of the file, that value isn't used meaningfully. There is no apparent
reference to bit depth.

My file is 8000 Hz sample rate with 8 bit depth. The sample file is 12000
sample rate with 16 bit depth. I converted my file to the same 12000
Hz/16-bit depth

$ sox ./test0000000000000.wav -r 12000 -b 16 ./test0000000000000c.wav
$ jt9 -8 -F 200 -f 1500 test0000000000000c.wav
<DecodeFinished>   0   0        0

At least here the jt9 program completes without any issue.

I have a few questions

1. Is the jt9 program trying to parse the file name? What is the expected
file name format?
2. What sample rate should WAV audio files be in? Is it fixed with no
ability to configure it
3. What bit depth should WAV audio files be in?

Eric KK4KYE
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