2008 Chevrolet HHR Owner's Manual - Page 212

FM Stereo FM stereo gives the best sound, but FM signals only reach about 10 to 40 miles (16 to 65 km). Tall buildings or hills can interfere with FM signals, causing the sound to fade in and out. Check occasionally to make sure the mast is still tightened to the roof. If tightening is required, tighten by hand. If you are putting a protective cover over the vehicle, remove the mast by hand. 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 through tunnels could cause loss of the XM signal for a period of time. The radio may display NO XM SIGNAL to indicate interference. XM™ Satellite Radio Antenna System The XM™ Satellite Radio antenna is located at the rear of the vehicle. Keep this antenna clear of snow and ice build up for clear radio reception. If your vehicle has a sunroof, the performance of the XM™ system may be affected if the sunroof is open. If your vehicle has a roof rack, loading items onto the roof of your vehicle can interfere with the performance of the XM™ system. Make sure the XM™ Satellite Radio antenna is not obstructed. Fixed Mast Antenna This type of antenna is called a fixed mast antenna. It is mounted at the center of the roof, just behind the windshield. The mast antenna can withstand most car washes without being damaged. If the mast should ever become slightly bent, straighten it out by hand. If the mast is badly bent, replace it. 3-80