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[Discuss-gnuradio] DBSRX AGC?
From: |
Robert Miller |
Subject: |
[Discuss-gnuradio] DBSRX AGC? |
Date: |
Sun, 14 Jun 2009 06:14:20 -0700 (PDT) |
Hi,
I am running an experiment where I would like to monitor the magnitudes of a
bursty, constant-envelope signal using the USRP and a DBSRX receiver. I am
seeing some quasi-periodic amplitude transitions and wanted to know if this
could be related to an AGC. Why I believe it is AGC-related is because the
amplitude transitions occur ONLY on leading-edge boundaries (and never
intra-burst). What I see magnitude-wise in Matlab based on data from
usrp_rx_cfile.py is something like:
_---_---_---_|||_|||_|||_|||_|||_---_---_---_|||_|||_|||_|||_---_---_|||_|||_|||_---
... (magnitude vs. time --- please excuse my ascii art:)
where there are really only two magnitude levels ( ||| and --- , and
interburst 'silence' is denoted as _ ). Furthermore, I ran another
experiment using the same bursty, constant envelope signal using 2 DBSRX
receivers in a single USRP (with the proper mux of 0x3210). Both receivers
experienced the same phenomenon, however there was some more 'interesting'
behavior. When the DBSRX on side A transitioned from high to low, the DBSRX
on side B transitioned from low to high. This was the case for multiple
runs, and again the transitions only occured at leading edge times. In
summary my questions are as follows:
1) Is there an AGC in the DBSRX?
2) If yes, can I turn it off?
Thanks in advance for any ideas, recommendations, or comments!
Rob
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- [Discuss-gnuradio] DBSRX AGC?,
Robert Miller <=