Question

In modulation process the
frequency of modulating
signal is always ..
equal to carrier frequency​

Answer 1

Answer:

Contravening Nyquist, and aliasing

When we apply a modulating frequency ( fm) that is slightly higher than half the sample rate ( fs) to an ADC, the frequency of the input signal is misinterpreted as a low frequency, and this phenomenon is known as aliasing. See Figure 4.26.

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Figure 4.26. Once fm > fs − fm, alias frequencies begin to crawl up from 0 Hz.

When audio or video leaves the analogue transducer and is converted to digits, the ADC is preceded by a low-pass anti-aliasing filter set to a maximum of slightly less than half the sampling frequency. In this way, aliasing is eliminated, but as we will see in a moment, digital oscilloscopes cannot incorporate an anti-aliasing filter, so they remain susceptible to this problem.