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

[Tommy James Tracy II]

On 10/7/12 6:44 AM, Patrik Tast wrote:
> 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/

Thank you for the reply; I took one of your 8bit samples:
 www.poes-weather.com/~patrik/apt/audio/24_June_2009/090723_213010_NOAA_17.wav

and opened it in the file source, and ran the gnuradio program. If I do
a cat of the output.dat file, I found that there was nothing in it. I
then opened it in VIM and found the following string repeated:

"address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@address@hidden@^@"

I think those aren't valid characters so maybe the float_to_uchar was
unsuccessful.

Did you use a different algorithm? Do I need to multiply the input to
fit it between the 0->1v range before the 255 multiplier?

Sincerely,
Tommy Tracy II

> 
> 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
>>>
>>>
>>>
>>> _______________________________________________
>>> Discuss-gnuradio mailing list
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>>
>>
> 
> 


-- 
  Tommy J. Tracy II
 Computer Engineering
University of Virginia

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