On Mon, 2011-05-16 at 12:23 -0500, John Andrews wrote: > I am using GRC. I used a signal source block generating a complex sine > at 100kHz. The USRP interpolation is 128 and the sampling rate of the > sine generator is 1MHz. The USRP connected to another computer has > USRP source configured at 64 decimation and is connected to an FFT > block. I don't see any peak at the expected frequency or anywhere in > the plot. Its just a flat plot. I checked the USRP settings on both > and they are configured right. I even have transmit gain and receive > gain as 10dB on both sides. > > What can be wrong here?
What daughterboards are you using? What frequency are you using on the source/sink blocks? The BasicRX/TX should be used with >1MHz signals (configure the USRP source/sink center freq to 1MHz or above), since the transformers won't pass lower frequencies than this. --n > > Thanks > > On Mon, May 16, 2011 at 12:09 PM, Marcus D. Leech <[email protected]> > wrote: > On 16/05/2011 1:03 PM, John Andrews wrote: > > Shouldn't I use some kind of modulation scheme to do this, > > like FM or AM, to transmit a tone? > No, you can just transmit a narrow, single-frequency tone, and > use the receivers FFT to determine how far off it is from > where you expect it. > > use a signal-source producing a SIN wave at, let's say, 1KHz, > feed that into a UHD/USRPx sink tuned to whatever your > frequency is. > The tone will appear at TUNED-FREQUENCY+1KHz. > > > > > > > > On Mon, May 16, 2011 at 10:02 AM, Marcus D. Leech > > <[email protected]> wrote: > > On 16/05/2011 10:26 AM, Alexander Chemeris wrote: > > You may also look into this code: > > http://thre.at/kalibrate/ > > It estimates offset of an USRP with regards > > to a GSM base station, but > > it can be easily modified to measure offset > > from any clean tone, e.g. > > transmitted by a second USRP. > > > > Keep in mind that the offset measured must > > necessarily be the total offset--that is, both Rx > > and Tx can be "off" in frequency. > > > > The practical consequence should be NIL, because > > frequency correction should normally only be done on > > the Rx-side, and it should > > simply adapt to whatever it sees, regardless of the > > Tx and Rx components of the offset. > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > [email protected] > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
