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Re: [Discuss-gnuradio] Lost samples from RTL2832 dongle
From: |
CEL |
Subject: |
Re: [Discuss-gnuradio] Lost samples from RTL2832 dongle |
Date: |
Tue, 23 Jan 2018 12:44:14 +0000 |
Hi John,
my experience, indeed, is that USB passthrough support in VMs is
suboptimal. So, this could very well be a virtual USB host controller
problem.
I'd actually recommend circumventing the issue, e.g. by running rtl_tcp
on the host machine, and using the appropriate source string in the gr-
osmosdr source.
Best regards,
Marcus
On Tue, 2018-01-23 at 12:40 +0000, john cooper wrote:
> Hello GNU people, some help greatly appreciated.
>
> I am a newbie to GNU Radio and have a lost samples problem, lost from the
> USB 2 RF device, seemingly not in the Flowgraph signal chain.
>
> Although I have no hard evidence I am coming to the point of suspecting the
> problem lies with the running of GNU under Oracle VM, hosted by Win 10.
>
> Physical RF device is a DVB-T+DAB+FM USB dongle, with Realtek RTL2832U and
> the R820 device.
>
> System is GNU Radio ( latest version ) running as a guest under Oracle VM,
> hosted by Win 10 Pro on a machine with significant system resources.
>
> Oracle version is VM 5.2.6r
>
> Problem is *always* dropped samples from a DVB-T+DAB+FM USB dongle, tens to
> hundreds of lost samples.
>
> I have done the following :-
>
> Added my name to the virtualbox users list.
>
> added the Virtual Box Extension Pack 5.2.6 to allow USB 2 support in
> the VM
>
> Selected USB2 in the Oracle VM machine.
>
> Blacklisted the RTL2338 DVB-T driver via
> /etc/modprobe.d/blacklist-rtl.conf etc.
>
> Tested with rtl_test with sample speeds from 2.4e6 down to 0.25 e6
>
> Several Flowgraphs of various example FM broadcast receivers all have
> choppy audio, believed to be due to lost sample from the RF device via USB2
> and not seemingly due to mismatch of audio sing sample rates.
>
>
> Using only the RTL_SDR source block and Low Pass Filter, plus the WX GUI FFT
> Sink and the WX GUI Scope Sink, in a FlowGraph produces spikes in the Audio
> which coincide with the suggested sample losses from the physical dongle.
>
>
> Under any and all tests and sample rates the result of rtl_test when ran in
> the terminal is a continual stream of lost samples.
>
>
> Other information;
>
> running SDR# via the host system ( Win 10 Pro ) is faultless at 2.4e6 sample
> speed and all lower speeds.
>
> I have also installed Gqrx in the VM and this system stalls with the
> Terminal screen failing to enter the initial set up dialogue screen but does
> list in the terminal screen the list of parameters, then hangs.
>
> If anyone has input to the problem, I would be very pleased to hear back and
> offer my thanks in advance.
>
> John
>
>
> Virus-free. www.avg.com
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> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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