What are the three general categories used to produce modulation in radio frequency transmission today?

This is because there is much less interference with FM vs. other cost-effective modulation methods, like AM for example.

There are more than three amplifiers in a typical radio receiver. If, however, you are asking why there are three "stages" in the IF section, then the reason is that the IF section of a typical...

AM modulation produces separate frequencies because you are effectively mixing two signals together, the carrier and the signal. Recall that Fourier Analysis states that, if you mix two sinusoidal...

There are 40 CB channels defined in roughly the band between 27 and 28 MHz, and another few somewhere near 49 MHz. UK is 27MHz FM (not on US channel spot frequencies) and 934 MHz FM. AM CB is not...

Three different modulating techniques are emploed to provide digital television (i.e. satellite, cable, UHF ) and these are known as DQPSK, QAM and COFDM. Each technique is a variation of phase...