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From: | Douglas Geiger |
Subject: | Re: [Discuss-gnuradio] USRP2 and external clock (from GPS receiver) |
Date: | Thu, 19 Feb 2009 11:47:56 -0600 |
User-agent: | Thunderbird 2.0.0.19 (Windows/20081209) |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Matt Ettus wrote: > Changkyu Seol wrote: >> Hi! >> >> I am planning to implement multiple synchronized transmitters using >> USRP2 and GPS receiver. Before that I checked whether the USRP2 is >> locked to external clock through following experiment. > > > The easiest way to check for lock is to put the following line in your > firmware: > > clocks_enable_test_clk(true,10); > > This will output a test clock on the middle 2 pins of the 4 pin > connector right near the VCXO on the motherboard. Look at one of those > 2 pins on an oscilloscope at the same time as the 10 MHz reference. You > should see the two clocks don't drift relative to each other. > > Matt > > > _______________________________________________ > Discuss-gnuradio mailing list > address@hidden > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio Is the test clock supposed to be running at 5kHz? I've just tested this on one of my USRP2 - it does appear to be locked with my external clock - - i.e. the 5kHz signal on the pin doesn't drift w.r.t my 10Mhz external source. Thanks, Doug - -- Doug Geiger Research Assistant Communications and Signal Processing Lab Oklahoma State University http://cspl.okstate.edu address@hidden address@hidden -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (Cygwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFJnZtMgfOzzR5bXIgRAlD2AJ4358ZGT8PbPAfp3S6F5LKBEBFG1QCeKy6+ WEBFDTXjvLgtogJazqwQWjE= =bvvj -----END PGP SIGNATURE-----
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