Twice this year, my car's GPS receiver got totally lost. It seemed the cause of this was heavy cloud, (because I can't think of any other reason), and the GPS stayed in "Recalculating" mode, until the clouds cleared.
I do know that some long distance van drivers carry GPS jammers, in order to elude their employer's tracking systems for short periods of time, but there were no vans or trucks on the motorway at the time, just very heavy cloud above me.
I wonder is there a physics based reason, (signal interference or to save satellite power, for example), why more power is not put into the transmission signal?
I ask this as a physics based question, I am not looking for a directly engineering or electronics based answer