Threshold effect at the receivers

Threshold effect is:

Options:

a) Reduction in output signal to noise ratio
b) Large noise as compared to input signal to envelope detector
c) Detection of message signal is difficult
d) All of the above

Correct Answer: All of the above

Explanation:

It is defined as the value of input signal to noise ratio below which the output signal to noise ratio decreases much rapidly than the input signal to noise ratio. It is the property of envelope detectors used for the demodulation of modulated signals. It occurs due to presence of large noise and therefore causes loss in the message signal. When the noise is very large as compared to the input at envelope detector, the message signal at the output is mixed with noise.