[time-nuts] Re: GPS failed

[Matthias Welwarsky]

Hi,

if you're worried about in-band interference, the 23cm HAM radio band is 
reasonably close to the L1 GPS frequency. When I was still active in packet 
radio back in the days, our digipeater DB0DAR lost an interlink due to 
interference with a precision GPS receiver in use by another university 
institute. We had to shut it down. I think they operated a DGPS site at the 
time and our link traffic caused errors in the correction data. Or something.

BR,
Matthias

On Montag, 11. Juli 2022 01:19:18 CEST skipp Isaham via time-nuts wrote:
> Hello to the Group,
> 
> I'd like to get some opinions and war stories regarding GPS reliability at
> high RF level and elevation locations.
> 
> Background:  Three different hill-top GPS receivers, all different types,
> using different antennas mounted on an outside fixiture, plain view of the
> open sky, all stopped working.
> 
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
> 
> From what I understand, the original antennas are what I would call straight
> preamp with no pre-selection / filtering.
> 
> The ordered and now inbound replacements are said to contain a SAW filter
> system. It is the intent of the client to just place these "improved
> antennas" in to service and get on with life.
> 
> I would suspect a GPS antenna (and receiver) could be subject to RF overload
> or blocking, however, we're assuming nothing major has changed at the site,
> nor any nearby location.  One might think there are more GPS receivers
> being pushed out of reliable operation by the world around them, I'm just
> not hearing those stories from a lot of people using them (GPS receivers).
> 
> Any new install GPS receiver antenna ordered will/should contain some
> pre-selection to potentially avoid a problem, even some years down the
> road? Seems like that's where things are going... no more off the shelf,
> wide band, (hot) preamplified GPS antennas in busy locations?
> 
> Thank you in advance for any related comments and/or opions ...
> 
> cheers,
> 
> skipp
> 
> skipp025 at jah who dot calm
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