My experience with a number of GPS devices in a number of cars is that the little buggers, while extremely sensitive (they are getting signals from satellites after all) are also extremely prone to interference and signal degradation from a variety of environmental conditions. For instance, just a garage roof likely diminishes the strength of the signals going to the sensor by huge factors. Clouds will also, as will tree leaves, rain and humidity. Then there is the potential for electrical interference around the GPS sensor from the car itself, other cars, computers and stuff inside homes that may have over-limit spurious emissions that could either interfere with or overload the front end of the GPS receiver.
This is why the current FCC proceeding involving GPS is so tense and multi-faceted as the FCC is on its way to plopping one more potential interference source right next to GPS frequencies (see i..e. EXCLUSIVE GPS Fight Erupts As Trimble Accuses Ligado Of ‘Inaccurate’ Claims In FCC Ruling and U.S. agencies ask FCC to rescind Ligado spectrum decision among many other articles). The frequencies Ligado would like to use for terrestrial 5G are frequencies that were originally authorized by the FCC, and bought at an FCC auction years ago then strictly reserved for satellite to earth transmissions which were not likely to interfere with the GPS band. Then in an effort to make the licenses more valuable, several successive licensees of these frequencies have tried to re-purpose them for terrestrial communications with immensely higher powers and much greater potential for interference to the GPS bands.
Some car navigation radios have a feature on them that will show the various GPS satellites being received and with what signal strength. There are times when there are more than a dozen satellites received while other times where it is only two or three satellites if that. This a long way around of saying that intermittent failures of the Roadster to receive adequate GPS signals in a garage or anywhere else are probably to be expected, and like many things, not noticed until one is sensitized to it and is looking for it.
This is why the current FCC proceeding involving GPS is so tense and multi-faceted as the FCC is on its way to plopping one more potential interference source right next to GPS frequencies (see i..e. EXCLUSIVE GPS Fight Erupts As Trimble Accuses Ligado Of ‘Inaccurate’ Claims In FCC Ruling and U.S. agencies ask FCC to rescind Ligado spectrum decision among many other articles). The frequencies Ligado would like to use for terrestrial 5G are frequencies that were originally authorized by the FCC, and bought at an FCC auction years ago then strictly reserved for satellite to earth transmissions which were not likely to interfere with the GPS band. Then in an effort to make the licenses more valuable, several successive licensees of these frequencies have tried to re-purpose them for terrestrial communications with immensely higher powers and much greater potential for interference to the GPS bands.
Some car navigation radios have a feature on them that will show the various GPS satellites being received and with what signal strength. There are times when there are more than a dozen satellites received while other times where it is only two or three satellites if that. This a long way around of saying that intermittent failures of the Roadster to receive adequate GPS signals in a garage or anywhere else are probably to be expected, and like many things, not noticed until one is sensitized to it and is looking for it.
