Hi Skipp -- there is a lot of info about interference mitigation in the u-blox integration manual for the ZED--F9T (available under the docs at https://www.u-blox.com/en/product/zed-f9t-module). It might give you some clues, and I think might also point to another u-blox app note on the topic.
Most of the antennas I've seen that have an LNA also include a SAW filter. I also once found on either Amazon or eBay so e new-product, relatively inexpensive, high pass filters with cutoff around 1 GHz. Those would help knock down broadcast, trunking, etc. stuff. (But of course nothing will help with on-frequency crud coming from outside the GPS system.) John On Jul 11, 2022, 8:49 AM, at 8:49 AM, skipp Isaham via time-nuts <time-nuts@lists.febo.com> 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 >_______________________________________________ >time-nuts mailing list -- time-nuts@lists.febo.com >To unsubscribe send an email to time-nuts-le...@lists.febo.com _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
