XCVR2450 Phase Lock Loop, AGC and capture effect

Hi everyone,

First of all thanks a lot for any support!

I am using the XCVR2450 Daughterboard together with the USRP1. My
setup consists of two transmitting nodes and one receiving node, in
which both transmitters send messages in overlapping time slots.

I was wondering how I can access any settings related to the capture
effect when receiving two signals. In my opinion either related to the
Phase Lock Loop or Automatic Gain Control.

Any hints, suggestions or detailed help will be highly appreciated!

best regards and thanks a lot,

B

Last time I looked at the XCVR2450 schematic, there was no AGC. Any
AGC would be implemented in software in the end application, and the
PLLs on the XCVR2450 are used to set the center frequency of the
quadrature downconverter. The hardware doesn’t “know” anything about
whatever modulations you’re using. The USRP family shovel
basebanded-and-filtered RF bandwidth back and forth to your host
computer. What you do with those samples is up to you.

Things to
consider:

o ADC Dynamic range–there’s at least 70dB of dynamic range
available, so you should be able to distinguish the two signals, unless
they’re right on top of each other.

o Analog Dynamic range–if one of
the signals is starting to drive the analog front-end into compression,
it doesn’t matter how much dynamic range you have on the digital side

On Tue, 21 Feb 2012 19:13:42 +0100, [email protected] wrote:

Hi
everyone,

First of all thanks a lot for any support!

I am
using the XCVR2450 Daughterboard together with the USRP1. My
setup
consists of two transmitting nodes and one receiving node, in
which
both transmitters send messages in overlapping time slots.

I was
wondering how I can access any settings related to the capture
effect
when receiving two signals. In my opinion either related to the
Phase
Lock Loop or Automatic Gain Control.

Any hints, suggestions or
detailed help will be highly appreciated!

best regards and thanks a
lot,

B


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