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

[Didier Juges]

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.

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

Can we go back to timing now? My 9V battery is running out...

Didier

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of J. Forster
> Sent: Sunday, November 15, 2009 6:51 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] The Demise of LORAN (was Re: 
> Reference oscillator accuracy)
> 
> See my earlier post. Briefly:
> 
> Antennas do not have an infinite front-to-back ratio. (<40 dB)
> 
> The path loss from a surface jammer to a plane (10 miles) is 
> many, many dB less than from plane to bird (15,000 miles).
> 
> -John
> 
> ============
>