[time-nuts] The Demise of LORAN (was Re: Referenceoscillatoraccuracy)

jmfranke jmfranke at cox.net
Mon Nov 16 03:19:44 UTC 2009


For the marina story, see:
http://www.gpsworld.com/gps/system-challenge/the-hunt-rfi-776

The L1 signal was unintentionally jammed.

John  WA4WDL

--------------------------------------------------
From: "Didier Juges" <didier at cox.net>
Sent: Sunday, November 15, 2009 9:55 PM
To: "'Discussion of precise time and frequency measurement'" 
<time-nuts at febo.com>
Subject: Re: [time-nuts] The Demise of LORAN (was Re: 
Referenceoscillatoraccuracy)

> I was shooting from the hip, I thought the DGPS signals were sent at UHF,
> but maybe not, but that's not the point. The point is that you can
> significantly affect DGPS operation without having to jam the GPS signal
> itself.
>
> I found a reference saying the Monterey Bay jammer was jamming the DGPS
> station, rather than the DGPS signal. I have not found the original 
> article
> I was looking for about it, but I think I remember that the boaters and
> Coast Guards were the most affected, as you should expect because they 
> rely
> on and need the additional accuracy of the DGPS system.
>
> Didier
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of David I. Emery
>> Sent: Sunday, November 15, 2009 8:30 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] The Demise of LORAN (was Re:
>> Reference oscillatoraccuracy)
>>
>>
>> That is the first I've heard of a UHF DGPS correction
>> transmission
>> can you provide a frequency and modulation mode ?    Most I
>> know of are
>> re purposed LF NDBs or similar transmitters in the 200 to 400
>> KHz or so range that transmit a PSK'd carrier with the DGPS
>> data at fairly low speed on it.
>>
>> I have heard of cases of wide area GPS outages noted by
>> many folks with NON DGPS receivers (DGPS receivers  mostly
>> will just indicate no DGPS available and still show a pretty
>> good position) that were caused by UHF signals on the L2
>> frequency... though I am sure there are incidents of
>> accidental interference to LF or other distribution of DGPS.
>>
>
>
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