2011 GMC Acadia Owner's Manual - Page 213

Infotainment System AM The range for most AM stations is greater than for FM, especially at night. The longer range can cause station frequencies to interfere with each other. For better radio reception, most AM radio stations boost the power levels during the day, and then reduce these levels during the night. Static can also occur when things like storms and power lines interfere with radio reception. When this happens, try reducing the treble on the radio. 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. 7-13 Multi-Band Antenna The multi-band antenna is located on the roof of the vehicle. This type of antenna is used with the AM/FM radio, as well as OnStar® and the XM™ Satellite Radio Service System, if the vehicle has these features. Keep this antenna clear of snow and ice build up for clear radio reception. If the vehicle has a sunroof, the performance of the radio system may be affected if the sunroof is open. Loading items onto the roof of the vehicle can interfere with the performance of the radio system and, if the vehicle has this feature, OnStar®. Make sure the multi-band antenna is not obstructed. Cellular Phone Usage Cellular phone usage may cause interference with the vehicle's radio. This interference may occur when making or receiving phone calls, charging the phone's battery, or simply having the phone on. This interference can cause an increased level of static while listening to the radio. If static is received while listening to the radio, unplug the cellular phone and turn it off. 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.