[USRP-users] tunnel.py doesn't receive packages when transmit and receive frequencies are different

Li Sun lisun.usrp at gmail.com
Fri Jun 29 18:32:37 EDT 2012


Thanks a lot!

Another question is we have 3 usrp nodes, all of which are installed
XCVR2450. We are using one usrp as relay node to do multihop communication.
If the relay node's TX and RX are set different. Can it receive & transmit
data at the same time? If not, do you have any other recommendation to do
it?

Li

On Fri, Jun 29, 2012 at 6:04 PM, Josh Blum <josh at ettus.com> wrote:

>
>
> On 06/29/2012 03:00 PM, Josh Blum wrote:
> >
> >
> > On 06/29/2012 02:58 PM, Li Sun wrote:
> >> But can we set one daughter board's RX and TX at different frequency,
> e.g.
> >> RX at 2.412GHz, TX at 2.432GHz ?
> >>
> >
> > Yes, it is possible to have two different center frequencies for
> > XCVR2450 RX and TX. The only requirement is that the RF frontend is
> > tuned to the same frequency for TX and RX. However, the DSPs can be used
> > to shift the signal digitally as long as you remain with the bandwidth
> > of the daughterboard.
> >
> > So, to so this: You can use the tune_request_t to ask for a desired
> > center frequency, but enforce a specific RF frequency.
> > 1) create a tune request with the desired center frequency
> > 2) set rf_freq to the desired LO frequency
> > 3) set rf_freq_policy to MANUAL.
> >
> > Note: tunnel.py does not have a command line option for this level of
> > control. So you will need to modify the gnuradio example to implement
> this.
> >
> > Some doxygen here for tune request:
> >
> http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html
> >
> > -Josh
> >
>
> And some additional links about XCVR2450 properties:
> http://files.ettus.com/uhd_docs/manual/html/dboards.html#xcvr-2450
>
> And some helpful explanation about the two stage tuning:
> http://files.ettus.com/uhd_docs/manual/html/general.html#tuning-notes
>
> Cheers!
> -josh
>
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