[time-nuts] Re: GPS failed

[Björn]

Hi Matthias,

There has been interference reported and resolved between 23cm and Galileo, which have signals in the 23cm band. 

/Björn 

Sent from my Phone

> On 12 Jul 2022, at 09:20, Matthias Welwarsky via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 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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> 
> 
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