The ratio of frequency deviation to modulating signal frequency✓پاسخ درست
The ratio of modulating signal amplitude to frequency deviation
The modulating signal frequency divided by the bandwidth of the transmitted signal
The bandwidth of the transmitted signal divided by the modulating signal frequency
توضیح
Modulation index is defined as the peak frequency deviation of the carrier divided by the frequency of the modulating signal that produced it. Because the modulating frequency sits in the denominator, the same deviation yields a large index on low audio frequencies and a small one on high audio frequencies.