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Re: [Discuss-gnuradio] High Data rate File Sink dropped data

From: Tom Rondeau
Subject: Re: [Discuss-gnuradio] High Data rate File Sink dropped data
Date: Tue, 2 Aug 2011 20:22:18 -0400

On Tue, Aug 2, 2011 at 8:19 PM, Marcus D. Leech <address@hidden> wrote:
> On 08/02/2011 08:11 PM, Tom Rondeau wrote:
>> On Mon, Aug 1, 2011 at 10:24 AM, Jason Thomas<address@hidden>  wrote:
>>> I am trying to record data directly from a UDP stream to file. I have
>>> four
>>> channels at 1.2MHz sample rate the code is below. Basically it opens a
>>> UDP
>>> source and connects to a file sink. However, It is losing data when
>>> writing
>>> to the file. If I stream a signal with a one second burst the spacing is
>>> not
>>> correct. Also, I have another c++ program that reads the UDP packets and
>>> records directly to file, and there are no lost UDP packets nor lost data
>>> with this program. Also I have checked that the UDP packet size is less
>>> than
>>> 1472, it is currently at 1024 bytes.
>>> Is there a way to see if file_sink is not able to handle that data rate,
>>> or
>>> to see if the UDP source cannot keep up?
>> It's most likely that your disk is not able to keep up. I've used GNU
>> Radio's file sink to save gigabytes of data at 25 MHz float I&Q, but I
>> used a RAID5 device to do it. You probably need more spindles.
>> Tom
> Tom:
> It's not strictly disk-limited, since Jason observes that with a non-Gnu
> Radio program, he can record direct to disk from
>  the raw UDP stream, and not lose anything.

Ah, I misread that. In my mind, he said something else... Still, I've
never had an issue with the file sinks. More data is required.


> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org

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