for what it's worth ... the UK gov. is nice enough to warn about GPS jamming exercises https://www.ofcom.org.uk/spectrum/information/gps-jamming-exercises not sure about the US of A announcements on such activities. At least in France I have never seen such warnings.
Best, JM -- JM Friedt, FEMTO-ST Time & Frequency, 26 rue de l'Epitaphe, 25000 Besancon, France July 11, 2022 7:42 PM, "Bob kb8tq via time-nuts" <time-nuts@lists.febo.com> wrote: > Hi > > Are all the receivers the same type / model? If so what are they? Various > receivers made over the last 20 years have some “issues” that can pop up. > > Is the antenna gain properly matched to the needs of the receiver? Some > are designed for a “target gain” of 20 db, others 30, some 50. Match a > 20 db receiver with a 50 db antenna …. you have issues. > > Are all the hilltops in common view of each other? Somebody jamming their > ankle bracelet could be the simple answer if they are …. > > Just what overloads this or that receiver often is a bit obscure. Most are > pretty > good at taking out CW tones. It often takes something a bit more complex > to drive them insane. This makes testing a bit exciting. > > Lots of strange and weird possibilities. > > Bob > >> On Jul 10, 2022, at 3:19 PM, 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 _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com