[time-nuts] GPS Filter

[Bob Camp]

Hi

Since you are after timing off of the sat's, having antennas that move, either physically or electrically seems like a problem. Any shift in the effective antenna location as you tracked the satellite would be "exciting" to compensate for. There was an early paper published based on doing this (early 80's). 

I did tear into a Thunderbolt. It certainly looks like there's a filter on the front end. It's roughly similar to the filters in the HP splitters. It might have the same sort of attenuation. 

Bob


On Mar 7, 2011, at 12:39 PM, Chris Albertson wrote:

> On Mon, Mar 7, 2011 at 5:01 AM, Bob Camp <lists at rtty.us> wrote:
>> Hi
>> 
>> In the case of a GPS, you really can't increase the aperture (gain = directivity) since you want to cover the entire sky.
> 
> 
> No, in theory it need not be an omnidirectional antenna. One could use
> a very high gain antenna if it were able to track each satellite.  If
> you had access to the GPS firmware one could build a phased array
> antenna that was electronically steered.  I think it could work but
> it's not practical because of the very high cost and large size.
> 
> Would it be possible to build a much simpler version that used a line
> array phased to null the nearby tower.
> 
> -- 
> =====
> Chris Albertson
> Redondo Beach, California
> 
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