Advantages of FM over AM - Dis-advantages of FM over AM

FM signal is better than AM signal because

Options:

a) less immune to noise
b) less adjacent channel interference
c) amplitude limiters are used to avoid amplitude variations
d) all of the above

Correct Answer: d) all of the above

Explanation:

FM signal is better than AM signal because FM signals are less immune to noise. Guard bands are provided for less adjacent channel interference so it is easy to be recovered. Amplitude limiters are used to avoid amplitude variations that are caused while transmission due to noise.

FM is disadvantageous over AM signal because

Options:

a) much wider channel bandwidth is required
b) FM systems are more complex and costlier
c) Adjacent channel interference is more
d) Both a) and b)

Correct Answer: d) Both a) and b)

Explanation:

The guard bands are provided to prevent the interference between adjacent channels in FM signals. Guard bands of 25 KHz are allowed on the either sides so the channel width becomes 2(75+ 25) = 200KHz where 75KHz is the maximum permissible frequency deviation allowed for commercial FM broadcast. So a much wider channel width is required for FM transmission. FM systems are more complex and therefore costlier than AM transmitters and receivers.