[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] Cross band relais / bridge - DMR?

From: Nick Foster
Subject: Re: [Discuss-gnuradio] Cross band relais / bridge - DMR?
Date: Fri, 29 Apr 2011 12:51:14 -0700

On Fri, 2011-04-29 at 15:42 -0400, Feng Andrew Ge wrote:
> Nick,
> Could you confirm that switching TX frequency takes "a few ms"?  How did 
> you get this number?  Is it the same for switching TX frequency after 
> the code has been running for a while, that is, reconfiguring the TX 
> frequency dynamically?

We don't have a guaranteed spec for PLL settling time on the WBX, and we
encourage users to experimentally determine the settling time for their
particular setup and frequency. The figure I gave is based on what I've
seen in the lab, to the best of my recollection. =) It should be pretty
straightforward to determine the settling time for your setup and
frequency step by taking a data capture of a known source.

Any time you retune a PLL VCO, it will take some time to settle. If you
need to avoid that settling time, you can do CORDIC-only tuning with the
advanced tuning parameters to shift around within the bandwidth of your
ADC. This will provide a basically instantaneous tuning speed within a
range of 50MHz for USRP2/N2XX, or 32MHz for USRP1/E100.


> Andrew
> On 04/29/2011 12:00 PM, address@hidden wrote:
> > Every time you tune the TX you'll have to wait a few ms for it to become
> > stable. For voice transmission purposes, a few ms is effectively
> > instantaneous anyway. And if you aren't retuning, then it will come up
> > instantly, because the LO will still be running in between sample
> > bursts.
> >
> > --n
> >

reply via email to

[Prev in Thread] Current Thread [Next in Thread]