>
> On Mon, May 16, 2011 at 12:27 PM, Nick Foster <
address@hidden> 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
> <
address@hidden>
> > 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
> > > <
address@hidden> 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.
> > >
> > >
> > >
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> > >
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> > >
>
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> > >
> >
> >
> >
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