XM™ Satellite Radio Service
XM Satellite Radio Service gives digital radio reception from coast to coast in the 48 contiguous United States, and in Canada. Just as with FM, tall buildings or hills can interfere with satellite radio signals, causing the sound to fade in and out. In addition, traveling or standing under heavy foliage, bridges, garages, or tunnels may cause loss of the XM signal for a period of time.
See also:
Global Positioning System (GPS)
○ Obstruction of the GPS can occur in a large city with tall buildings; in parking
garages; around airports; in tunnels, underpasses, or parking garages; or in an
area with very dense trees. ...
Control of a Vehicle
Braking, steering, and accelerating are important factors in helping to control a vehicle while driving. ...
Footnotes — Maintenance Schedule Additional Required Services — Normal
a) Or every two years, whichever comes first. More frequent replacement may be needed if the vehicle is driven in areas with heavy traffic, areas with poor air quality, or areas with high dust levels. ...