1999 Lexus SC 400 Owners Manual - Page 209

AIR CONDITIONING AND AUDIO D Fading and drifting: FM range is limited to about 40 km (25 miles), except for some high power stations. If a vehicle is moving away from the desired station's transmitter, the signal will tend to fade and/or drift. This phenomenon is more noticeable with FM than with AM, and is accompanied by distortion. Fading and drifting can be minimized to a certain degree by careful attention to fine tuning, or you should retune the radio to another stronger station. D Static and Fluttering: When the line-of-sight link between a transmitter and vehicle is blocked by large buildings or the like, the radio sound may be accompanied by static or fluttering because of the characteristic of FM. In a similar effect, a fluttering noise is sometimes heard when driving along a tree-lined road. This static and fluttering can be reduced by adjusting the tone control for greater bass response until the disturbance has passed. D Multipath: Because of the reflecting characteristics of FM, direct and reflected signals may reach the antenna at the same time (multipath) and cancel each other out. As a vehicle moves through these electronic dead spots, the listener may hear a momentary flutter or loss of reception. 191 D Station swapping: When two FM stations are close to each other, and an electronic dead spot, such as static or multipath area, interrupts the original signal, sometimes the stronger second signal will be selected automatically until the original one returns. This swapping can also occur as you drive away from the selected station and approach another station with a stronger signal.