-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Interesting. I don't have a logic analyzer handy but after the holiday I may find someone who knows how to use one. More importantly, do you have suspicions about the solution? ;)
As another data point, I've found that performing the second receive at different frequencies can bring the noise floor back to normal. If I transmit at 2.48G and receive at 2.485G the noise floor is normal. With some other RX frequencies, (I think 2.445G) the same problem persists. - -Dan Johnathan Corgan wrote: > Dan Halperin wrote: >> Just-powered on USRP rev 4.2 with RFX2400 rev 2-6-2006. Current SVN. >> >> usrp_rx_cfile.py -f 2.485G -d 8 -s pre.dat >> usrp_siggen.py -i 16 -f 2.485G >> usrp_rx_cfile.py -f 2.485G -d 8 -s post.dat >> >> In the first set of data, the noise level is what I'd expect and >> everything works hunky-dory. After the siggen, however, it all goes >> haywire, the noise floor becomes huge even though an adjacent USRP sees >> nothing. > > I wonder if somehow the USRP transmitter is getting left powered up. > The mixer would be getting random noise and upconverting it to your > passband. This would feed through from the blocked side of the TX/RX > switch (about 30dB of attenuation) into the receiver. > > You'd have to measure the logic level at the mixer chip enable pin to be > sure. > > If this is the case, I have a suspicion about the cause. > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHlOKoy9GYuuMoUJ4RAumXAKCv+cDlNFgGxorc7Wpwc4LNZ7ApWQCgxarx SV6hXvvtbb2Bri+0XsHynHU= =t3l7 -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
