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From: | Karan Talasila |
Subject: | Re: [Discuss-gnuradio] Fwd: Problem in uhd_fft |
Date: | Sun, 7 Jul 2013 18:07:28 +0530 |
On 07/04/2013 11:51 PM, Karan Talasila wrote:The BASIC_RX and LF_RX have no downconversion hardware in them at all. They are basically just "buffers" for the ADCs. The BASIC_RX has anHi Josh,can you explain how and why the frequency translation occurs? secondly when the same basic tx chip is used on a usrp N210, the translation occurs at 50Mhz and after. So for USRP N210, the entire range from 0-250 Mhz is represented by alternating between -50Mhz to +50Mhz. Why is it that way?
analog reponse that starts to fall off at about 250Mhz, which is why it's rated to 250Mhz.
In the USRP1/B100/E1XX systems, the sampling clock is at 64MHz by default. That means the first aliases start to show up at the 1st Nyquist
frequency of 32Mhz (half of sample rate). Similarly in the N2XX, which a 100MHz sampling clock, those aliases start to show up at 50Mhz.
My suggestion would be to look into so-called bandpass sampling, and also, importantly, Nyquist Sampling Theorem.
-- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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