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

Rob Kimberley rk at timing-consultants.com
Mon Nov 16 09:39:18 UTC 2009


GPS antennae are mounted top and bottom on tactical aircraft.

Rob Kimberley
 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Francesco Ledda
Sent: 16 November 2009 00:37
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The Demise of LORAN (was Re: Reference oscillator
accuracy)


Considering that the GPS antenna in aircrafts is mounted on top of fuselage,
and that its radiation pattern is upward, it seems that a ground jammer will
have an uphill battle.


-----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 6:28 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The Demise of LORAN (was Re: Reference
oscillator accuracy)


Or even into MP3 players, iPods, laptops, or cell phones. Then they'd
wander all over the place too. With the latter two hosts, they could even
be controlled remotely and even be fairly powerful. Would you notice
having to recharge your battery a bit more often?

-John

===========


> Magnus Danielson wrote:
>> Chuck,
>>
>> Chuck Harris wrote:
>>> What makes you think it needs to be CW, and cannot be pulsed and
>>> chirped?
>>
>> May I roll in a noise jammer into the debate?
>
> Absolutely!  They can be extremely power efficient.  Raise the noise
> floor in the vicinity of the receiver, and it is all done.
>
> Probably the easiest solution would be to take a PN source and use it
> to drive a pulser that pulses a chirp oscillator.  If you are feeling
> really polite, you could put a bandpass filter on the thing to protect
> other services.
>
>>> All it has to do is confuse the receiver enough so that you can't
>>> trust its readings.
>>
>> Depends on the goal. For some strategies, blackout is the goal, for some
>> getting the readings go haywire every once in a while suffice.
>
> Agreed!
>
> My 9V battery suggestion was for a localized blackout device.  You only
> have to make the receiver question each satellite's signal often enough
> for it to rule it out.  No way is CW necessary, or even desirable.
>
> As John suggested, someone (say the Chinese) could put these things in
> battery operated stuffed animals, and set them up to jam a little bit
> now and then.  After Xmas, the GPS landscape would be littered with these
> little stealth jammers, and willing supplicants to replace their
> batteries.
>
> -Chuck
>
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