Thanks for your help.
I though IQ samples were encoded on 8 bytes.
This explains my error.
Cheers
Frederic
-----Message d'origine-----
De : osmocom-sdr-bounces(a)lists.osmocom.org [mailto:osmocom-sdr-bounces@lists.osmocom.org]
De la part de Leif Asbrink
Envoyé : lundi 17 décembre 2012 14:53
À : osmocom-sdr(a)lists.osmocom.org
Objet : Re: Information about the sampling rate of the RTLSDR driver
Hello Frederic,
Each sample is I and Q with 8 bit each. That is 2 bytes.
When you sample at 2.048 Ms/s you get 4096 bytes/ms so your
observation that it takes 2 ms to fill the buffer is fine:-)
The buffer size is not critical. In my project Linrad it is
a user parameter because small buffers may be useful for
radio amateurs who want a small delay from antenna to
loudspeaker when doing two-way communication while larger
bufers may be helpful on slower computers.
I tried buffers from 2048 bytes to 524288 without errors
on a fast computer.
You are not doing anything wrong:-)
Leif
Hello,
I am testing a DVB-T USB key including the Elonics E4000 chipset and I want to check the
sampling rate of this card.
I set up the sampling rate at 2.048 Ms/s (rtlsdr_set_sample_rate), and my storing buffer
is 8*1024 bytes, so I expect receiving 1024 I/Q samples every 500 microseconds.
I am using the rtlsdr_read_async function to read the samples.
Unfortunately the loop in my program indicates that 8*1024 bytes are read every 2
milliseconds.
I am using the gettimeofday function to measure the time in microseconds.
Does this result mean that the best I can do is to read some samples every 2 ms at 2.048
Ms/s. This would mean that I am missing 1.5 ms of signal.
Is that correct or I am doing something wrong ?
Thanks for your help.
Frederic
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