-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hey all,
Sorry to bring up painful memories :). I did some calculations to work out frequency drift of the USRPs, and I wanted to know where I'm going wrong. The crystals in the RFX 2400 are spec'ed at 50ppm error, which is to say that the maximum frequency offset between the sender and receiver is then 2 * 50 ppm * 2.462 GHz (802.11b Channel 11) = 246.2 kHz. 246.2 kHz sampled at 64 MHz is 246.2 kHz * 2pi / 64 MHz which is approximately 0.02417 radians / sample. At, say, DBPSK 250kbps, oversampled by a factor of 2, that means we decimate by 128 (500 ksamples per second), to then get at most ~3.094 radians per sample drift. With DBPSK this could flip all of our bits! Does that mean we in fact do need to worry about the case where the complement of the access code is detected? Is my understanding of the meaning of ppm error wrong? Does the distribution we assume for the frequency offset make this possibility negligible? Thanks! - -Dan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGN+uOy9GYuuMoUJ4RAoGqAKDQEPs1o5BtCEsfMo4PLm9zLh09CwCeIi/8 9wr0qg+XJ2dexNuIRPr0tgw= =8wIA -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
