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Re: [Discuss-gnuradio] How can we measure the frequency offsets between
From: |
Nick Foster |
Subject: |
Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs? |
Date: |
Mon, 16 May 2011 10:27:35 -0700 |
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.
> >
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
>
>
>
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- [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/15
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Brian Padalino, 2011/05/15
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Alexander Chemeris, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Marcus D. Leech, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Marcus D. Leech, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?,
Nick Foster <=
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Nick Foster, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Nick Foster, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Marcus D. Leech, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, Marcus D. Leech, 2011/05/16
- Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?, John Andrews, 2011/05/16