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

Bob kb8tq kb8tq at n1k.org
Fri Aug 31 13:15:11 EDT 2018


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 …..


> On Aug 31, 2018, at 12:04 PM, Mark Spencer <mark at alignedsolutions.com> wrote:
> Hi:
> I'm curious if anyone knows how typical GPSDO's are likely to respond to simple GPS jammers ?  Could the GPSDO be reasonably expected to go into hold over ?
> The use case I am thinking is along the lines of:
> -A commercial operation relies on a GPSDO for timing at a remote site.  
> -A vehicle with a simple GPS jammer (perhaps intended by the vehicle driver to defeat a GPS tracking system installed near the vehicle) parks near the GPS antenna.
> I'm thinking one likely outcome is the GPSDO goes into hold over and when the vehicle moves away it exits hold over ?   This is all just speculation on my part.
> Comments ?
> Thanks 
> Mark Spencer
> mark at alignedsolutions.com
> 604 762 4099
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