On Mon, 2011-05-16 at 12:32 -0500, John Andrews wrote: > I am using the 1st generation USRP with RFX2400 daughterboards each > connected to the TX/RX interface. > > In the sine source block I am using a frequency of 100kHz. As the > interpolation of USRP sink is 128 I am using a sampling frequency of > 1Msps.
And what center frequency are you running at? --n > > On Mon, May 16, 2011 at 12:27 PM, Nick Foster <[email protected]> wrote: > 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
