Caliber MCD795 - To receive GPS signals successfully; When the positioning by GPS is impossible

If signals cannot be received from more than two GPS satellites,
GPS positioning does not take place.
In some driving conditions, signals from GPS satellites may not
reach your vehicle. In this case, it is impossible for the system to
use GPS positioning. The following are some examples:
In tunnels or
enclosed parking garages
Under elevated
roads or similar structures
Navigation Operation
To receive GPS signals successfully
You have a clear sight of sky
The weather is good enough. GPS signal is weaker in bad
weather conditions
The time needed for establishing a GPS connection ranges
from seconds to minutes.
You are outdoor.
The GPS antenna is not covered
When the positioning by GPS is impossible
When driving
among high buildings
When driving through
a dense forest or tall trees