Re: [Discuss-gnuradio] Having issues getting APT-DECODER Sample working

[Patrik Tast]

Hi Tommy,

>What do you mean by source file sink?
I thought you were using GRC and if the file was downloaded from me I
know it is (recorded) in 8bit 2.4kHz carrier.

You will find a lot of hits regarding APT when googling and be very
objective, most are copy -> copy....

Sure we can/could convert it to 16, 32, 64, 128 bit etc.
The fact is that APT is 8bit so why change it to 32bit?
The result will be a 4x bigger file almost full of zeroes since again
only 8 bits are used (gray scale). If recorded as 16bit it will be of
course 2x bigger than required since max is again 0x0000 ffff.
In this case you wont win if more bits are used.

APT bandwidth is ~30kHz @ 137Mhz

Some samples here, don't convert:
http://www.poes-weather.com/~patrik/apt/audio/24_June_2009/
Images & tests:
http://www.poes-weather.com/index.php?view=article&id=100%
3Asunday-6th-july-2008&Itemid=73&option=com_content

24/7 images:
http://www.poes-weather.com/~patrik/apt/logs/daily/

Patrik

On Sat, 2012-10-06 at 22:43 -0400, Tommy James Tracy II wrote:
> On 10/6/12 5:37 PM, Patrik Tast wrote:
> > Hi Tommy,
> > 
> > Most likely the file (wav) you have found is in 8bit.
> > Try to adjust your source file sink.
> > 
> > Patrik
> > 
> Dear Patrik,
> 
>       What do you mean by source file sink?
> I used soundconverter to convert the WAV file to mp3, and then back to a
> 32-bit sampled WAV. I tried it, and it failed with the same error.
> 
> I also tried to use FFT with byte input, but that doesn't exist. The
> only options are float or complex.
> 
> Again thank you!
> 
> Tom
> 
> > On Sat, 2012-10-06 at 16:51 -0400, Tommy James Tracy II wrote:
> >> Dear Gnuradio,
> >>
> >>    I'm trying to run the following gnuradio program:
> >> http://www.oz9aec.net/index.php/gnu-radio/gnu-radio-blog/440-simple-apt-decoder-prototype
> >>
> >> I found a WAV file online to use as the input to the APT-Decoder, so I
> >> fed it in. Unfortunately, the output file resulted in a bunch of '^@'
> >> characters instead of the expected ASCII(0) through ASCII(255).
> >>
> >> To make sure that the Audio file source was actually producing an
> >> output, I hooked up an AUDIO_SINK block between the File Source and the
> >> Band Pass Filter. I heard the expected APT sound.
> >>
> >> I then proceeded to drop in a WX GUI FFT Sink, and kept getting the
> >> following error:
> >>
> >> Has anyone seen this?
> >> -----
> >>
> >> Traceback (most recent call last):
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/plotter_base.py",
> >> line 187, in _on_paint
> >>     for fcn in self._draw_fcns: fcn[1]()
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/plotter_base.py",
> >> line 59, in draw
> >>     self._draw()
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/grid_plotter_base.py",
> >> line 407, in _draw_point_label
> >>     label_str = self._populate_point_label(x_val, y_val)
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/channel_plotter.py",
> >> line 151, in _populate_point_label
> >>     label_str += '\n%s: %s'%(channel, common.eng_format(y_value,
> >> self.y_units))
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/common.py",
> >> line 82, in eng_format
> >>     coeff, exp, prefix = get_si_components(num)
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/common.py",
> >> line 48, in get_si_components
> >>     exp = get_exp(num)
> >>   File
> >> "/usr/local/lib/python2.7/dist-packages/gnuradio/wxgui/plotter/common.py",
> >> line 37, in get_exp
> >>     return int(math.floor(math.log10(abs(num))))
> >> ValueError: cannot convert float NaN to integer
> >>
> >> -----
> >>
> >> I think this means that the WAV file (float output) is producing NAN
> >> outputs. Is there any way that I can remove those? Anyone have any
> >> success doing this before?
> >>
> >> Thanks in advance!
> >> _______________________________________________
> >> Discuss-gnuradio mailing list
> >> address@hidden
> >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > 
> > 
> > 
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> > 
> 
>