[time-nuts] The Demise of LORAN (was Re: Reference oscillator accuracy)

[Chuck Harris]

Mike,

A defective TV antenna preamp (oscillating in an uncontrolled manner),
on board a boat in California wiped out GPS for several kilometers!
Because it only wiped it out when the owner was watching TV, the
interferrence went on for months.  This is well documented.  Do a
google search and you will find the report from the guys that found
the jammer.

When a modern high sensitivity GPS receiver cannot get a fix through
the shingled roof of a house, you have to understand that the signals
are really weak.

The folks selling commercial GPS jammers are being rather brutish with their
methods.  They are using sledge hammers where a little tack hammer would
do nicely.

-Chuck

Mike Monett wrote:
> Chuck Harris <cfharris at erols.com> wrote:
>> What makes you think it needs to be CW, and cannot be pulsed and
>> chirped?
>>
>> All it has to do is confuse the receiver enough so that you can't
>> trust its readings.
>>
>> -Chuck
> 
> I said nothing about the type of modulation. The equipment I listed is
> designed specifically to disrupt GPS. Presumably they use whatever
> modulation method that gives the best results.
> 
> However, GPS is spread-spectrum, so it  inherently rejects noise that is
> not correlated with the satellite signal. This means effective jamming
> requires a lot more power than is available from a 9V transistor radio
> battery, and even then, the range is only a few meters.