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Re: [Discuss-gnuradio] DBSRx set gain code
From: |
Matt Ettus |
Subject: |
Re: [Discuss-gnuradio] DBSRx set gain code |
Date: |
Thu, 22 Dec 2005 10:07:11 -0800 |
User-agent: |
Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) |
Lee Patton wrote:
>
> After looking at the data sheets for all components on the DBSRX, I
> gather that the RF LNA and IF low-pass filter gain control, both of
> which are in the MAX2118, are the two variable gain amps to which you
> are referring. Is that correct?
Yes
> daughterboard gain (79dB) + PGA gain (20dB) = 99dB. The DBSRX returns
> 104dB. Where does the extra 5dB of programmable gain come from? (It
> looks like it is the "dl" variable in your code, but I don't know what
> that corresponds to. Please see below)
Yes, it comes from dl. dl turns on a 5dB gain amp in the chip.
>
> To minimize noise, I would assume that when setting the gain it is
> preferable to fist max out the RF LNA, then the IF gain control, and
> finally the PGA. Is that correct?
Yes
Matt