RTL-SDR source in GNU-Radio 3.7.1 weird behaivour at 900 ksps

Leif Asbrink leif at sm5bsz.com
Wed Nov 13 16:27:08 UTC 2013


Hello Miguel,

In Linrad I have these defines:
#define MAX_RTL2832_SAMP_RATE_H  2400000
#define MIN_RTL2832_SAMP_RATE_H  900001
#define MAX_RTL2832_SAMP_RATE_L  300000
#define MIN_RTL2832_SAMP_RATE_L  230000

900 kHz does not work, try 900001 Hz.

The range 300001 to 900000 Hz does not work with RTL2832.

73

Leif



 A. Vallejo" <ea4eoz at gmail.com> wrote:

> Hi again.
> 
> I noticed a strange behaivour from RTL-SDR source in GNU-Radio 3.7.1
> 
> When sample rate is set to 900ksps, actual output sample rate is only 300
> ksps.
> 
> You can check this easily connecting a RTL_SDR Source to a WX Gui FFT Sink
> and a RF signal generator.
> 
> For example, on RTL-SDR Source set sample rate to 900000 and frequency to
> 144000000 Hz.
> 
> On the WX GUI FFT Sink, set sample rate to 900000 and base frequency to
> 144000000 Hz.
> 
> Now apply a signal on 144.1 MHz. The FFT Display will show it at 144.3 MHz.
> 
> Apply a signal on 144.05 MHz. The FFT Display will show it at 144.15 MHz.
> 
> Now on the WX GUI FFT Sink, set sample rate to 300000 and repeat the above
> steps. The signal will be displayed at its right places.
> 
> Interestingly, setting sample rate to 1Msps works fine.
> 
> Tested with both E4000 and R820T dongles.
> 
> Any advice?
> 
> Thank you!




More information about the osmocom-sdr mailing list