[time-nuts] From GPS World - Lightsquared has been given the goahead

[Chris Albertson]

On Wed, Feb 2, 2011 at 1:01 PM, Charles P. Steinmetz
<charles_steinmetz at lavabit.com> wrote:
> Chris wrote:
>
>> A notch filter can also be constructed to notch out the jammer if it
>> is out of band.  A "twin T" design might be  effective and low cost
>
> Unfortunately, unless the interfering carrier is much too far away to be a
> problem in the first place, the phase shift of the notch filter (and
> particularly its changes with temperature) will appear essentially as a
> variable-length coax on your antenna -- not what you want for precision
> timing applications.

What would be the range of variability?    Are we talking about 10% of
the period of the 1.5GHz signal?  I could live with that or is the
effect much greater?  My simple understanding of the twin-t comes from
my use of it at audio frequencies.  Maybe there are better filter
designs.


-- 
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Chris Albertson
Redondo Beach, California