Stuttered processing with OsmoSDR and DVB-T Stick

GNU Radio
1

Hello,

I run gnuradio latest stable installation on a 64bit Ubuntu Installation
with Pentium 977 + 8GB RAM. I use the DVB-T Hama Nano DVB-T-Stick which
is one of the RTL-Chip derivates. I tried to create a FM-Radio reception
which only consists of the OsmoSDR-Srouce, A WBFM Receive PLL and the
Audio Sink (see attached png)

What I get is a stuttered signal processing of the recepition. I can
here the radio signal, but it is interrupted at a rate of approximately
3 Hz. I checked the CPU load but it is well below 100%. Does anyone have
an idea what I did wrong? I would appreciate any sort of suggestions.
Thanks!

Additional experiment: when I make a chain of sine-wave →
WBFM-Transmitter → WBFM-Receiver → Audio Sink, with the sample rates
as shown in the original fm receiver, there is continuous playback.
Therefore I expect that it has something to do with the OsmoSDR, libusb,
rtl-driver, rtl-chip.

Any suggestions?

Regards,

Markus

m48/m48+ by Markus Gonser

Internet: http://www.mksg.de
m48 on the AppStore: Connecting to the iTunes Store.
m48+ on the AppStore: http://itunes.apple.com/app/m48/id341541461?mt=8
E-Mail: [email protected]

2

On 24/11/12 06:55 AM, Markus Gonser wrote:

approximately 3 Hz. I checked the CPU load but it is well below 100%.

[email protected]
Discuss-gnuradio Info Page
705.6k is likely not a supported sample rate on the RTLSDR.

It’s fairly rare that sample rates on any SDR are exactly multiples of
audio rates, so you have to use
rational resamplers, or fractional interpolators to match rates.

3

Hey Marcus,

thank you for your feedback. That must have been it! I also tried the
simple_fm_rcv exmample on Rtl-sdr - rtl-sdr - Open Source Mobile Communications and
it actually works wonderfully. Sorry for this premature queastion.
Regards,

Markus

Am 24.11.2012 um 14:32 schrieb “Marcus D. Leech” [email protected]: