[time-nuts] GPS Antenna -Receiver Mutual Interference...

Bill Hawkins bill at iaxs.net
Mon Jan 3 21:04:19 UTC 2011

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

-----Original Message-----
From: shalimr9 at gmail.com
Sent: Monday, January 03, 2011 1:50 PM

The additional advantage is to give you diversity and some immunity against
multipath (at least it reduces the probability that both receivers will be
affected at the same time due to weird constellation issues or local

But it now creates an issue which is how do you know who is right when both
receivers don't agree...

Didier KO4BB

-----Original Message-----
From: "Rob Kimberley" <rk at timing-consultants.com>
Sender: time-nuts-bounces at febo.com

Yes, I've seen this. On installations in the past, when we were putting up
dual GPS systems, we always put them at least 10 metres apart. What is
actually best practice, is to put one at one end of building and the other
one at the other end. 

Rob Kimberley

-----Original Message-----
From: Mark J. Blair
Sent: 03 January 2011 2:19 AM

On Dec 30, 2010, at 6:53 PM, Burt I. Weiner wrote:
> Has anyone run into a situation where two GPS Navigation type
Antenna/Receivers interfere with each other?

It's possible that LO leakage from one is jamming the other. When doing
mobile GPS receiver testing at work with a single antenna feeding multiple
receivers through a splitter, we sometimes had to insert attenuators in each
receiver's antenna feed to keep them from jamming each other.

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