Hi Eric, Thanks a ton for the reply. My main concern is not that the frequency offset is high enough but that it changes pretty often (every time I run a new run) which makes it difficult for repeatability.
So is there a way in software where I can make sure that the frequency offset is constant either by finely controlling the center frequency at the tranmitter every time I run or is there some other way around this problem? Thanks Shyam On Wed, 2008-01-09 at 11:15 -0800, Eric Blossom wrote: > On Wed, Jan 09, 2008 at 11:02:47AM -0800, Shyamnath wrote: > > > > Hi, > > I am trying to run a few experiments to transmit a data stream from a > > transmitter to receiver using a RFX 2400. However, I am observing that the > > frequency offset is extremely high at 40-80kHz. In addition, it also changes > > significantly, nearly 2-8kHz, every time I restart the usrps. I have used > > various ways of estimating the frequency offset and all of them converge on > > the above observations. > > > > So I have a couple of questions > > 1) Is this high a frequency offset in the specs? > > 2) Is this variation in the frequency offset in the specs of these radio? > > (I have been working on other costume made hardware and the frequency > > offset has been almost constant for the past couple of months) > > 3) Is there are way to prevent the frequency offset variation after every > > reboot? > > > > Thanks in advance for any replies > > Shyam > > I'm not sure of the tolerance of the oscillators Matt's currently > using on the 2400's, but 40k/2.4G is about 17 ppm. I wouldn't call > that "extremely high". In general any receiver has to be able to > track out any frequency offset and symbol timing variation. Expensive > test equipment has better specs (and costs more) because they use > things like ovenized crystal oscillators. > > All xtal oscillators move around with temperature. The question is > how much, and how much money is being spent on compensation and > environmental control. > > Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
