GPS no signal or it take GPS time to find a signal, these are two major problems when we use GPS device. Many factors will affect GPS receivers to receive satellite signals. some barriers or parking deck will interrupt GPS to start receiving a signal. like:
Method (code) to identify each satellite.
The location of the satellite or some information on how to determine it.
Information regarding the amount of time elapsed since the signal left the satellite.
Details on the satellite clock status, etc.
Most GPS receivers allow you to set up a margin …

Can a car gps antenna receive dab signal?
Yes, but you will need a receiver to get the programmes.Though both GPS and DAB are in L-band, GPS antenna manufacturers build the antennas specifically for GPS signals. Unless the antenna is designed specifically for both, it likely won’t be able to do DAB. gps uses microwaves, or certainly UHF, whereas DAB I think uses VHF