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Re: [Discuss-gnuradio] Hardware "jitter", particularly USB
From: |
Martin Braun |
Subject: |
Re: [Discuss-gnuradio] Hardware "jitter", particularly USB |
Date: |
Mon, 14 Mar 2016 12:57:18 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 |
We call this the two-clock problem, and yeah, it's quite common.
Cheers,
M
On 03/14/2016 11:14 AM, Gregory W. Ratcliff wrote:
> GnuRadio community,
>
> I have been using various hardware interfaces to gnuradio lately.
> In the simplest example, I noticed an issue with Funcube Pro Plus with
> broadcast wideband FM (about 4 GRC blocks) whereby it would consistently
> underflow, even though every rate appeared to be perfect. A crude but
> effective fix has been to interpolate by 500, decimate by 499.
>
> I occasionally notice a similar problem with DVB modules, never with Hermes.
>
> This has caused me to wonder if some subtle error has crept into OSMOCOM
> or the Funcube module has a timing error (that had been masked
> previously by OSMOCOM).
>
> Am I alone in this (in which case I will look closely at usb/audio/pc
> hardware)?
>
> Thanks in advance,
>
> Greg
> NZ8R
>
> Gregory W. Ratcliff
>
>
>
>
>
>
>
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