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Re: [Discuss-gnuradio] GRC FFT Block Question
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From: |
Marcus D. Leech |
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Subject: |
Re: [Discuss-gnuradio] GRC FFT Block Question |
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Date: |
Wed, 11 May 2011 08:16:30 -0400 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.39.b3pre.fc14 Thunderbird/3.1.9 |
On 05/11/2011 07:57 AM, Tom Rondeau wrote:
Mehmet,
You are seeing the frequency drift of the oscillator in both the
transmitter and receiver. They will never be perfectly accurate. You
should probably test your block using a simulation setup. That is, tie
the transmitted signal straight to the receiver in GRC and bypass the
USRPs altogether to make sure your block is correct.
If you are looking for a symmetrical signal, you could then use your
calculation as the error value in a control loop to correct your
frequency offset :)
Tom
With the range of observed values given by Mehmet, it looks like a total
frequency error of about 12.5PPM, which is pretty darned good.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org