The modulator is also called a radio frequency modulator, the TV modulator, and the full name of the modulator is an adjacent frequency modulator. The modulator is mainly used in the computer room of cable TV. There are many types of modulators, because some TVs have different formats, so the modulators can be divided into PAL modulators, SECAM modulators, and NTSC modulators. But in general it can be divided into digital modulators and analog modulators. Of course, there are many small categories in these two categories. Modulators are currently widely used in various satellite TV systems, residential closed systems, and cable television systems. So what effect does the modulator have on these systems? Next, Xiaobian will introduce to the friends!
If you take the TV in our life, the modulator is to modulate the video signal and audio signal from our digital TV set-top box or satellite digital TV receiver, and output the signal from the TV set-top box or receiver, that is, the input. The time is an audio video signal, and when it is output, it becomes a high frequency signal of a modulated specific frequency band. Different sources may use different modulators. If mismatched modulators and sources are used, character smearing may occur, so it is best to ask about the relevant modulator before installing the modulator. Personnel.
1. It can be used as a digital TV set-top box, satellite receiver set-top box, video recorder, DVD and other program sources.
2, using high IF modulation, primary frequency conversion and acoustic surface filter processing.
3. Use the mixer to connect up to 21 4-way modulators to form 84 channels.
4, microcomputer control, image sound double lock, standard view, audio input.
5, high-level output, with audio track deviation continuously adjustable, high reliability.
6. The RF modulator has an automatic RF output level calibration function.
7. Use frequency synthesis technology to ensure the frequency stability of the output TV channel.
8, convenient operation, volume, video hue saturation, RF output level can be adjusted on the front panel.
9. The image, sound high IF and RF local oscillator are all MCU phase-locked technology.
10, using IF sound table filtering, standard vestigial sideband feature technology.
11. Wide range linear power supply; using SMD technology, the whole machine has good stability.
12. The signal mixing system can mix the RF signals output by multiple modulators into one RF signal.
13. The signal transmission system consists of an amplifier and a branch distributor, which can amplify the signal and send it to each terminal television through a branch distributor.
14. The whole system is composed of equipment with high cost performance. It has a good input-output ratio, which can realize the smooth upgrade and expansion of the system scale and new business, and will not affect the normal operation of the original business. It is very convenient for the later transformation.
RF modulator circuit diagramRF modulators are an essential component of televisions, video recorders, satellite receivers, standard converters, home computers and gaming consoles. The circuit is simple and easy to manufacture, stable in performance, reliable in operation, and can be conveniently connected to various circuit boards and used in various electronic devices mentioned above. As shown in the figure, the specific circuit of the RF modulator, ICl is the modulator dedicated integrated circuit TA7673, its 10 feet and 11 feet generate image carrier frequency signals through the external crystal oscillator, 4 feet and 5 feet external LC oscillator circuit produces 6.5MHz second Sound signal. The audio signal is input from pin 6 of ICl, and the video signal is input from pin 16 of ICl. When the crystal oscillator of different working frequency is connected between pin 10 and pin 11 of IC1, this circuit can be in pin 2 and pin 15 of ICl. The image carrier frequency signals of channels 1 to 5 are output. There is no need to debug the circuit after it is installed, but the whole circuit should be shielded by a small metal box.
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