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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] Receive GPS L1 Signal |
Date: | Fri, 24 Jun 2011 07:52:25 -0400 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
On 06/24/2011 03:03 AM, Eddie Sun wrote:
In UHD, you set the sample-rate of the source block, not the decimation. The UHD code determines the appropriate decimation to use based on what it knows about the device. The USRP hardware "stack" arranges for the signal of interest to appear as *complex baseband* signal, in which the signal goes from -bandwidth/2 to +bandwidth/2, which uses the "I" and "Q" signal representation. The "IF" is 0Hz in this case. You shouldn't need to re-sample to process the resulting baseband signal. This baseband "I and Q" signal format is *extremely* common in modern DSP systems for RF. For more background, you should look up the terms "direct conversion receiver", and "quadrature mixer" on Google. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org |
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