Eclipse - Fujitsu Ten CD5425E - Manual (Page 26)

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Operation
How to operate the tuner
In general, FM has much better tonal quality than AM. However, FM and FM stereo reception encounter
several characteristic problems not encountered with AM. FM is more difficult to receive than AM in a
moving vehicle. The following are explanatory notes on what to expect from FM reception and on how
to get satisfactory performance.
FM reception differs from AM
Fading out
In weak signal or "fringe" reception areas, FM stations may fade out completely, or fade in and out.
When driving in weak signal areas, such as near hills, through valleys or tunnels, among tall
buildings, etc., you may encounter unusual noise interference. THIS IS NOT A TUNER PROBLEM.
In this case, you can only wait until you are in a better reception area, tune to a stronger station, or
reduce the treble level.
FM reception characteristics
A characteristic of transmitted signals is that lower frequencies
travel further. FM frequencies are much higher than AM's (similar to
a ray of light): they won’t bend but they will reflect. Often, they will
be interrupted by tall buildings, mountains, etc., taking direct and
indirect paths to your vehicle’s antenna. The distance at which FM
stations can be received satisfactorily is usually not nearly as far as
that which AM stations can be received.
AM Radio Wave
Ionosphere
FM Radio Wave
Ionosphere