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

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] High Data rate File Sink dropped data
Date: Tue, 02 Aug 2011 20:19:41 -0400
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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.



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.

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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