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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] Bandwidth of XCVR 2450 Daugtherboard |
Date: | Wed, 28 Sep 2011 14:36:10 -0400 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0) Gecko/20110922 Thunderbird/7.0 |
On 28/09/2011 2:32 PM, Konstantinos wrote:
Most of the daughtercards convert to/from complex-baseband to/from real RF. The analog filters operate at baseband, and are thereforeThanks for your reply. However, I am a little bit confused since in your reply you mention that these are programmable low-pass filters which operate at baseband, while in the code the associated comment says that this is the bandwidth of the bandpass filter on the board. Secondly, why are these baseband filters? These are on the daughterboard so I would expect them to operate on the intermediate band, since the daughterboard converts complex IF to Real RF. Please let me know where I get this wrong. Thank you for your time again. BR, Konstantinos
low-pass filters.There are exceptions--the TVRX and TVRX2 use a non-zero IF. But all the other daughtercards use complex-baseband.
So, in complex baseband, if you want a total bandwidth of 40MHz, what you're actually asking for is -20Mhz to +20Mhz. Which means that
I and Q are both low-pass filtered to 20MHz.
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