[time-nuts] Effects of Simple GPS jamming on GPSDO's ?

jimlux jimlux at earthlink.net
Fri Aug 31 13:39:05 EDT 2018


On 8/31/18 10:15 AM, Bob kb8tq wrote:
> Hi
> 
> Having spent a lot of my life designing GPSDO’s it’s a “that depends” sort of thing.
> For a simple noise jammer, yes, they pretty much all will go into holdover. When the
> jammer goes away, they come out of holdover. There are a few older units that may not
> do quite as well with various sorts of broadband jamming.  With a spoofing jammer that is flying
> around overhead and simulating an entire constellation … you could see any of them do odd
> things. An airborne jammer flying over this or that city likely gets you into a “act of war” sort of issue.
> It’s something you build if you are a nation state.
> 
> The performance with noise jammers is not a guess. It’s based on field experience and
> all those never ending meetings I keep referring to …..
> 


In effect, a broadband jammer (or, probably, a tone jammer that 
overwhelms the 1 bit ADC receiver) is the same as a "loss of signal" - 
the receiver probably doesn't know the difference - it just drops sync 
and tries to unsuccessfully reacquire.

So you can test your hold over behavior with aluminum foil (or your 
hand) over your antenna<grin>



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