[Discuss-gnuradio] corrupted points when writing to file

[ematlis]

Hi-

I have a python app which seems to corrupt points when I use it to 
demodulate a data stream stored in a file and write the de-modulated 
result back to a file.  I've attached the python code, and an image of 
the problem can be seen at

www.nd.edu/~ematlis/z.gnuradio/waveform.jpg

The modulated waveform is shown in the top plot and the demodulated output 
in the bottom plot.

The signal was acquired with a Lecroy digital oscilloscope; it's a 100 kHz 
sine AM modulated at 10 kHz.

As you can see from the image, while the original modulated data shows no 
corruption in 10002 points, the demodulated data has the first 875-900 
points incorrectly set to close to zero.  This is repeatable.

Could it have anything to do with the fact that I'm generating a gui? 
Could the time it takes to generate the gui window interfere with the 
operation of the demodulation?  If I were to make this just a script, ie 
with no scope or fft sink, and no gui box, would it affect things?  (And 
p.s., how would I do that?)

thanks,
eric

************************************
Eric H. Matlis, Ph.D.
Aerospace & Mechanical Engineering Dept.
120 Hessert Center for Aerospace Research
University of Notre Dame
Notre Dame, IN 46556-5684
Phone: (574) 631-6054
Fax:   (574) 631-8355

demodulate_file.py
Description: Text document