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

J. Forster jfor at quik.com
Mon Nov 16 01:21:26 UTC 2009


> GPS receivers have considerable coding gain, which makes it possible for
> them to detect such low signals in the first place. The jamming signal
> will
> not benefit from the coding gain because it does not have the right coding
> and will be uncorrelated to the actual spread-spectrum signals the
> receiver
> is tracking.
>
> This is probably 30 dB or more.
>
> Also, you assume that your jammer has a similar antenna gain and radiation
> efficiency as the GPS transmitter on the satellite, that is unlikely.

I don't assume ANY gain in the jammer. 0 dB.

> Bottom line, it is unlikely that a jammer running off a 9V battery, even
> on a balloon will jam the entire US for weeks.

I never implied that. Nothing close. But a few hundred to tens of
thousands, operating intermittantly, is another story.

-John

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