An RF modulator is an electronic device used to convert signals from devices such as media players, VCRs and game consoles to a format that can be handled by a device designed to receive a modulated RF input, such as a radio or television receiver. Its input is a baseband signal, which is used to modulate a radio frequency source.
ASTEC UM 1286 UHF modulator, top cover taken off
The motherboard of an early microcomputer, the Microtan 65, showing the silver-cased ASTEC 1111EM36 UHF TV modulator at top left
RF modulator inside the Commodore 64 manufactured in 1984, PAL system
Modulation is defined as the process by which some characteristics like amplitude, frequency, and phase of a carrier signal are varied in accordance with a modulating wave.
Waterfall plot of a 146.52 MHz radio carrier, with amplitude modulation by a 1,000 Hz sinusoid. Two strong sidebands at + and - 1 kHz from the carrier frequency are shown.
A carrier, frequency modulated by a 1,000 Hz sinusoid. The modulation index has been adjusted to around 2.4, so the carrier frequency has small amplitude. Several strong sidebands are apparent; in principle an infinite number are produced in FM but the higher-order sidebands are of negligible magnitude.
