[time-nuts] PN sequence generation using GPS

[Bob Camp]

Hi

Obviously I'd have to be in the neighborhood (as in well under a KM away). To be bothered by a fast system, I'd also have to be there already. With a poor system, I'd be bothered further out and could track it further out. 

I would put a good RF filter in front of the detector to get rid of a lot of the clutter. Switchers aren't going to put out 10 watts of RF at 144 MHz. The biggest thing would be cable TV leakage that's "in band". If I had to put something together this weekend, I'd chop the front end out of a donor radio and keep it's RF stage intact. That would take care of a lot of the little loss issues that the filtering would bring to the party. 

My real concern is more interference to GPS from some of these odd systems various commercial outfits come up with. I'd like to be able to keep running timing via GPS for a while. The same things that apply to tracking down a strange ham system apply equally to other spread spectrum systems. Simply figuring out who / what / where is going to get harder as time goes on. 

Bob


On Feb 25, 2011, at 1:55 PM, Chuck Harris wrote:

> Of course.  A simple field strength meter comes to mind.  But how
> are you going to know that you want to stand at my mailbox and look?
> 
> And with a direct sequence system, the power is going to be smeared so
> thin over a wide band that you really won't have anything to see, other
> than a bulk reading of power in my vicinity.  I'm already doing that with
> the switching supplies, compact fluorescent lamps, ordinary fluorescent
> lamps, cell phones, wireless routers, microwave ovens, ...  It's a literal
> RF sewer over here!
> 
> -Chuck Harris
> 
> Bob Camp wrote:
>> Hi
>> 
>> If you are putting out>  20 watts and I'm close enough to see your mailbox, I'll detect you with some pretty simple
>> stuff.
>> 
>> Bob
> 
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