[time-nuts] time-nuts Digest, Vol 78, Issue 7

Burt I. Weiner biwa at att.net
Mon Jan 3 22:33:51 UTC 2011


The system in question is being used for navigation, but a little 
more than your typical find a restaurant type of navigation 
system.  The symptoms are that they will lock on birds erratically, 
maybe for a few seconds at a time As I may have mentioned in an 
earlier post, for my frequency standards at home I have two separate 
DATUM 9130 systems running all the time with their antennas only 
about 1-2 feet apart on my roof and have absolutely no issues.  It's 
just this one repeatable situation in the car that's a curious 
issue.  Whenever my associate and I run radial measurements in his 
car, our two GPS systems refuse to behave nicely.  One at a time, 
they're each fine.  I often run a Magellan 4250 and my Delorme system 
in my car with the two antenna/receivers less than a foot apart 
without problems.  I'm beginning to wonder if it's something unique 
to the Garmin's GPS128 and its antenna that's affecting both 
systems.  I'll have to do some more playing.


Burt, K6OQK

At 01:04 PM 1/3/2011, time-nuts-request at febo.com wrote

>Well, I have two HP conical antennas 4 feet apart and just
>below the roof level, with an elevation cutoff of 30 degrees
>for the large and growing oak trees on 3 sides. Fifty feet
>of RG-8 each connects to two Z3801A receivers.
>I've had no trouble in a dozen years, here in Minneapolis.
>T1 to GPS runs at about +4E-008 for both from GPSCon.
>My son runs a 50' deep sea fishing boat out of Ocean City, MD.
>It has two GPS navigation antennas less than 4 feet apart up
>on the signal mast. It also has portable GPS receivers used
>by fishermen who want to learn his fishing spots, but these
>are about 10' away. He has had no trouble with navigation.
>What would be the symptoms of interference? A disturbance in
>PPS signals at the 10E-12 level?
>Bill Hawkins

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net

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