> Tuning is done to the best of the receiver's (synthesizer/PLL) > ability. Please reference what a superheterodyne receiver is: > > http://en.wikipedia.org/wiki/Superheterodyne > > Now, knowing that there is a 64MHz local oscillator reference on the > board, that must somehow get "multiplied up" using a PLL to generate > your 2.4GHz signal. Some simple math follows: > > Multiplier = 2.4e9 / 64e6 > Multiplier = 37.5 > > So a 64MHz signal must be multiplied up by 37.5x to generate the > desired frequency. Now, lets imagine that our crystal oscillator is > off by 320Hz. I believe this is a crystal oscillator rating of 5ppm. > For more information on PPM, see: > > http://en.wikipedia.org/wiki/Parts_per_million > > Establishing we have an oscillator with a 5ppm offset, and a > multiplier of 37.5, we can then calculate what our frequency offset > will be: > > Foffset = multiplier * LOoffset > Foffset = 37.5 * 320Hz > Foffset = 12kHz > > By only being off by 5 cycles for every 64 million, we have created a > 12kHz offset only at the transmitter. This may be added or subtracted > based on how the receiver is sampling as well.
Thanks again! Actually, the major problem for me was there is no data sheet/manual about the XCVR2450 tranceiver. The only information on the manufacturer website, www.ettus.com , is the operating frequency range and the maximum transmit power. So, i didn't know to what IF frequency the tranceiver downconverts the RF signal;how much gain it provides and to what extent the oscillator of the XCVR2450 is accurate. So Dear : Matt Ettus, Do you have any data sheet, description or manual for this tranceiver ? If yes, where can i get it? If no, I think it is really important to prepare a data sheet and a manual for each USRP Daughterboards; otherwise, users of your daughterboards will face the same problem in the future. Bruhtesfa -- Posted via http://www.ruby-forum.com/. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
