[USRP-users] using tune_request_t

Sanat Gulvadi sanatgulvadi at gmail.com
Wed Jun 27 08:52:14 EDT 2012


Hi Josh,

I'm sorry for asking again. But could you please tell me if the following
line will help push out the dc component outside my band.
usrp->set_rx_freq(uhd::tune_request_t(2.44e9,100e6/32));
Here I am trying to tune to 2.44 GHz and my sampling rate is 100e6/64.
Should this work ?

Regards,
Sanat

On Tue, Jun 26, 2012 at 7:37 PM, Josh Blum <josh at ettus.com> wrote:

>
>
> On 06/26/2012 12:39 AM, Sanat Gulvadi wrote:
> > Hi Josh,
> > I actually read through those pages before I emailed the list. Just want
> to
> > know if lo_offset is the variable that represents the frequency offset by
> > which I have to push the dc or if it's the frequency to which I want to
> set
> > the dc to.
>
> The constructor with the lo_offset will do exactly this.
>
> > Also is it necessary to set the policy to manual first ?
>
> No, the constructor with lo_offset sets this automatically.
>
> -josh
>
> > Regards, Sanat
> > On Jun 26, 2012 8:30 AM, "Josh Blum" <josh at ettus.com> wrote:
> >
> >>
> >>
> >> On 06/25/2012 11:17 PM, Sanat Gulvadi wrote:
> >>> Greetings,
> >>>
> >>> I have a question about using the tune_request_t in my application. I
> >> have
> >>> read from previous posts that there is an inherent DC component at the
> >>> receiver which cannot be eliminated but can be pushed so that it occurs
> >>> outside the band of interest.
> >>> When I use
> usrp->set_rx_freq(uhd::tune_request_t(target_freq,lo_offset))
> >> I
> >>> am not sure what lo_offset is. I assume target_freq is the center freq
> to
> >>> which I want the RF to tune to. Is lo_offset the offset by which I want
> >> to *
> >>> push* the DC component so it ends up outside my band of interest ?
> >>
> >>
> >> You might find helpful notes here:
> >> http://files.ettus.com/uhd_docs/manual/html/general.html#tuning-notes
> >>
> >>
> >>
> http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html
> >>
> >>> So in this case, if I made lo_offset say, once or twice my sampling
> rate,
> >>> should this be enough to accomplish this? Do I have to additionally set
> >> the
> >>> tuning policy to POLICY_MANUAL ?
> >>>
> >>
> >> That constructor w/ the LO offset is simply a shortcut for doing this.
> >>
> >> -josh
> >>
> >> _______________________________________________
> >> USRP-users mailing list
> >> USRP-users at lists.ettus.com
> >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> >>
> >
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20120627/05ff1b27/attachment-0002.html>


More information about the USRP-users mailing list