[aprssig] Poor GPS signal quality in Los Angeles County?

[Alex Carver]

Has anyone run into problems with GPS reception in and around Los Angeles County?  Until I moved out here, I never had a problem with reception unless I was driving through a thick tree canopy or into a parking garage.  But lately I've been having trouble even when I could see the whole sky (up near Pasadena).  I have an old Garmin 12XL with an external antenna.  My APRS performance has been spotty because the D700 will stop beaconing for a while (and I don't notice) until I observe that the GPS no longer has a lock.  In many cases, the GPS will even indicate it has no signals at all (RSSI bars on the constellation map screen are all zeros).  I never had this problem back east and it was all the same hardware, car, etc.