The adjacent frequency modulator (also referred to as a radio frequency modulator, frequency modulation modulator or television modulator) is one of the main equipments in the front-end cable television room. Its function is to provide the video signal (VIDEO) and audio signal (AUDIO) modulation provided by the signal source (can be a digital TV set-top box, satellite digital television receiver, DVD player, computer, video camera, TV demodulator, etc. AV signal source). A stable high-frequency RF oscillation signal. The video is AM modulation, and the audio is FM modulation. According to the different color television systems in the world, the adjacent frequency modulators also have PAL system modulators, NTSC modulators, and SECAM modulators. In China, the PAL-D system is used.