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Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx
From: |
Jason Abele |
Subject: |
Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx |
Date: |
Thu, 28 Oct 2010 14:26:22 -0700 |
> Why do I receive a sine wave when I transmit a constant?
Probably because the 100MHz reference clocks of your two USRP2s are
slightly different
Here are a few suggestions for being sure that you are locking to your
10MHz reference clock:
If you have not modified the generated python code from your GRC
flowgraph, then you are definitely not locked to refclock. The
easiest way to fix this would be:
Use a multi-usrp sink and source from the UHD categorey
Set the number of motherboards and channels to 1 each
Use the Sync to Unknow PPS option
I know that is a strange interface, we will put an option to use
external ref clock in an update coming soon to git repositories near
you.
Finally, be sure your refclock meets the power/amplitude requirements
shown here:
http://www.ettus.com/uhd_docs/manual/html/usrp2.html#ref-clock-10mhz
+5dBm to +20dBm (roughly 1Vpp to 5Vpp)
Jason