[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Discuss-gnuradio] Sample size and data rates
From: |
Aadil Volkwin |
Subject: |
[Discuss-gnuradio] Sample size and data rates |
Date: |
Wed, 5 Dec 2007 23:32:09 +0200 |
Hi,
I have modified the usrp_wfm_rc.py script to capture samples of an FM
signal and write them to disk, and a second script to demodulate and
playback the samples.
The scripts are available here: http://rrsg.ee.uct.ac.za/members/aadil/
I have 3 questions:
1) 1 000 000 samples writes a file 8 000 000 bytes (7.6Mb)
This suggests each sample is 8bytes; 4bytes I and 4bytes Q.
Is my assumption correct?
Considering that the ADC produces 12bit samples, I would expect that
each I and Q sample pair would be 4bytes. 2bytes I and 2bytes Q.
Please can someone advise where i've missed some understanding.
2) With reference to the above question, where can I find further
details regarding the function of the gr.sizeof_item identifiers, in
particular gr.sizeof_gr_complex.
3)If my file is 1 000 000 samples and my audio rate is 32KHz( I
understand this to be 32K samples/second) I expect my playback time to
be (1e6/32e3) = approx 30s, however when I play the file I get only
approx 3s playback time.
Im not sure where i've gone wrong.
Thanks for your time, and I look forward to and appreciate your advice.
Aadil
- [Discuss-gnuradio] Sample size and data rates,
Aadil Volkwin <=