CN201294585Y - Combined electronic tuner - Google Patents

Abstract

The utility model relates to a composite electronic tuning unit. A printed circuit board is arranged in a case body (1) which is provided with a radiofrequency signal input port (2), a composite video signal VIDEO output port (3) and an audio signal AUDIO output port (4) outside, an input end of a frequency synthesis electronic tuning circuit is connected with the radiofrequency signal input port (2), an output end of the frequency synthesis electronic tuning circuit is connected with an input end of an intermediate frequency demodulation processing circuit, and two output ends of the intermediate frequency demodulation processing circuit are respectively connected with the composite video signal VIDEO output port (3) and the audio signal AUDIO output port (4). The composite electronic tuning unit integrates the electronic tuning circuit and the intermediate frequency demodulation processing circuit in the case body to form an independent product which is characterized in that electric property, reliability and electromagnetic compatibility are better than national and industry standards. The composite electronic tuning unit is mainly used for large-screen, multi-functional, multi-standard and high-definition television receivers such as LCD and PDP television receivers.

Description

Combined electronic tuner

technical field

The utility model relates to a combined electronic tuner.

Background technique

The electronic tuner in the prior art has no built-in intermediate frequency demodulation processing circuit, and can only output intermediate frequency signals. The intermediate frequency signal demodulation processing circuit is generally installed on the motherboard, and the electrical performance, reliability, and electromagnetic compatibility are low, which is difficult to meet Supporting needs of medium and high-end TV sets for TV complete set factories.

Contents of the invention

The technical problem solved by the utility model is to design a combined electronic tuner, which integrates the electronic tuner and the intermediate frequency demodulation processing circuit into one housing to form an independent product with high electrical performance, reliability and electromagnetic compatibility In accordance with national and industry standards, it can realize tuning filtering, frequency mixing processing, and intermediate frequency demodulation processing of color TV signals of various systems. Mainly used in large-screen, multi-function, multi-standard, high-definition TV receivers, including LCD, PDP TV receivers, etc.

The technical solution of the utility model: a combined electronic tuner, including a housing (1), a printed circuit board is arranged inside the housing (1), and a radio frequency signal input port (2) is arranged outside the housing (1) ), a composite video signal VIDEO output port (3) and an audio signal AUDIO signal output port (4), the printed circuit board is provided with a frequency synthesis type electronic tuning circuit and an intermediate frequency demodulation processing circuit, and the input of the frequency synthesis type electronic tuning circuit The terminal is connected to the radio frequency signal input port (2), the output terminal is connected to the input end of the intermediate frequency demodulation processing circuit, and the two output ends of the intermediate frequency demodulation processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output port ( 4).

The frequency synthesis type electronic tuning circuit is composed of VL input circuit, VH input circuit, UHF input circuit, VHF high-amplification circuit, UHF high-amplification circuit, VL tuning circuit, VH tuning circuit, UHF tuning circuit, mixing circuit, VL local oscillator circuit, VH local oscillator circuit, UHF local oscillator circuit, and intermediate frequency output circuit; the input terminals of VL input circuit, VH input circuit and UHF input circuit are connected to the RF signal input port (2), and the output terminals of VL input circuit and VH input circuit Connect to the input end of the VHF high-amplification circuit, the output end of the UHF input circuit is connected to the input end of the UHF high-amplification circuit, the output end of the VHF high-amplification circuit is connected to the input end of the VL tuning circuit and the VH tuning circuit, and the output end of the UHF high-amplification circuit Connect to the input terminal of UHF tuning circuit; the output terminals of VL tuning circuit, VH tuning circuit and UHF tuning circuit are connected to the input terminal of mixing circuit, and the output terminals of VL local oscillator circuit, VH local oscillator circuit and UHF local oscillator circuit are connected to frequency mixing The input end of the circuit, the output end of the mixing circuit are connected to the input end of the intermediate frequency output loop, and the output end of the intermediate frequency output loop is connected to the input end of the intermediate frequency demodulation processing circuit.

The intermediate frequency demodulation processing circuit is made up of filter circuit, intermediate frequency notch circuit and signal processing circuit, the input terminal of filter circuit is connected with the output end of intermediate frequency notch circuit, and the input terminal of intermediate frequency notch circuit is connected with frequency synthesis type electronic tuning circuit The output terminal, the output terminal of the filter circuit is connected to the input terminal of the signal processing circuit, and the two output terminals of the signal processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output port (4).

The frequency mixing circuit is IC TDA6509AHN.

The signal processing circuit is IC TDA9881HN.

Compared with the prior art, the utility model integrates the electronic tuning circuit and the intermediate frequency demodulation processing circuit in one shell to form an independent product, the electrical performance, reliability and electromagnetic compatibility are higher than the national and industry standards, and can realize Tuning filtering, frequency mixing processing, and intermediate frequency demodulation processing of multi-system color TV signals. Mainly used in large-screen, multi-function, multi-standard, high-definition TV receivers, including LCD, PDP TV receivers, etc.

Description of drawings

Fig. 1 is the structural representation of the utility model,

Fig. 2 is the circuit block diagram of the present utility model,

Fig. 3 is the schematic circuit diagram of the utility model.

Detailed ways:

A kind of embodiment of the utility model is described in conjunction with accompanying drawing 1,2,3.

A combined electronic tuner, comprising a casing (1), a printed circuit board is arranged inside the casing (1), a radio frequency signal input port (2) is arranged outside the casing (1), and a composite video signal VIDEO output port (3) and the audio signal AUDIO signal output port (4), the printed circuit board is provided with a frequency synthesis type electronic tuning circuit and an intermediate frequency demodulation processing circuit, the input terminal of the frequency synthesis type electronic tuning circuit is connected to the radio frequency signal input port (2 ), the output end is connected to the input end of the intermediate frequency demodulation processing circuit, and the two output ends of the intermediate frequency demodulation processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output port (4).

Frequency synthesis electronic tuning circuit consists of VL input circuit, VH input circuit, UHF input circuit, VHF high-amplification circuit, UHF high-amplification circuit, VL tuning circuit, VH tuning circuit, UHF tuning circuit, mixing circuit, VL local oscillator circuit, VH local oscillator circuit, UHF local oscillator circuit, and intermediate frequency output circuit; the input terminals of VL input circuit, VH input circuit and UHF input circuit are connected to the RF signal input port (2), and the output terminals of VL input circuit and VH input circuit are connected to VHF The input end of the high-amplification circuit, the output end of the UHF input circuit is connected to the input end of the UHF high-amplification circuit, the output end of the VHF high-amplification circuit is connected to the input end of the VL tuning circuit and the VH tuning circuit, and the output end of the UHF high-amplification circuit is connected to the UHF The input terminal of the tuning circuit; the output terminals of the VL tuning circuit, VH tuning circuit and UHF tuning circuit are connected to the input terminal of the mixing circuit, and the output terminals of the VL local oscillator circuit, VH local oscillator circuit and UHF local oscillator circuit are connected to the mixing circuit The input terminal and the output terminal of the frequency mixing circuit are connected to the input terminal of the intermediate frequency output loop, and the output terminal of the intermediate frequency output loop is connected to the input terminal of the intermediate frequency demodulation processing circuit.

The intermediate frequency demodulation processing circuit is made up of filter circuit, intermediate frequency notch circuit and signal processing circuit, the input terminal of filter circuit is connected with the output end of intermediate frequency notch circuit, and the input terminal of intermediate frequency notch circuit is connected with frequency synthesis type electronic tuning circuit The output terminal, the output terminal of the filter circuit is connected to the input terminal of the signal processing circuit, and the two output terminals of the signal processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output port (4).

The frequency mixing circuit is IC TDA6509AHN, and the signal processing circuit is IC TDA9881HN.

Working principle: The color TV radio frequency signal input by the radio frequency signal input port, the input circuit performs input impedance matching and channel frequency selection, tuning and filtering, and enters three radio frequency channels respectively for high frequency amplification and dual tuning useful signal selection. After IC TDA6509AHN mixing, IF frequency selection and amplification processing, output IF TV signal. The intermediate frequency TV signal passes through the corresponding intermediate frequency surface acoustic filter to separate the signal from the image and sound, and then enters the intermediate frequency processing chip IC TDA9881AHN, which separates the signal for detection, phase detection, demodulation, AGC control, and finally outputs the baseband signal of video VIDEO and audio AUDIO and the second audio IF signal.

Claims (5)

1. A combined electronic tuner, comprising a casing (1), a printed circuit board is arranged inside the casing (1), a radio frequency signal input port (2) is arranged outside the casing (1), and a composite video signal VIDEO The output port (3) and the audio signal AUDIO signal output port (4) are characterized in that: the printed circuit board is provided with a frequency synthesis type electronic tuning circuit and an intermediate frequency demodulation processing circuit, and the input terminal of the frequency synthesis type electronic tuning circuit The radio frequency signal input port (2), the output end is connected to the input end of the intermediate frequency demodulation processing circuit, and the two output ends of the intermediate frequency demodulation processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output port (4) . 2. The combined electronic tuner according to claim 1, characterized in that: the frequency synthesis electronic tuning circuit is composed of VL input circuit, VH input circuit, UHF input circuit, VHF high-amplification circuit, UHF high-amplification circuit, VL tuning circuit, VH tuning circuit, UHF tuning circuit, mixing circuit, VL local oscillator circuit, VH local oscillator circuit, UHF local oscillator circuit, intermediate frequency output circuit; the input terminals of VL input circuit, VH input circuit and UHF input circuit are connected to RF Signal input port (2), the output terminals of VL input circuit and VH input circuit are connected to the input terminal of VHF high-amplification circuit, the output terminal of UHF input circuit is connected to the input terminal of UHF high-amplification circuit, and the output terminal of VHF high-amplification circuit is connected to VL The tuning circuit, the input terminal of the VH tuning circuit, the output terminal of the UHF high-amplification circuit are connected to the input terminal of the UHF tuning circuit; the output terminals of the VL tuning circuit, VH tuning circuit and UHF tuning circuit are connected to the input terminal of the mixing circuit, and the VL local oscillator The output terminals of the circuit, the VH local oscillator circuit, and the UHF local oscillator circuit are connected to the input terminal of the mixing circuit, the output terminal of the frequency mixing circuit is connected to the input terminal of the intermediate frequency output circuit, and the output terminal of the intermediate frequency output circuit is connected to the input of the intermediate frequency demodulation processing circuit end. 3. The combined electronic tuner according to claim 1, characterized in that: the intermediate frequency signal processing circuit is composed of a filter circuit, an intermediate frequency notch circuit and a signal processing circuit, and the input terminal of the filter circuit is connected to the terminal of the intermediate frequency notch circuit. Output terminal, the input terminal of the intermediate frequency notch circuit is connected to the output terminal of the frequency synthesis electronic tuning circuit, the output terminal of the filter circuit is connected to the input terminal of the signal processing circuit, and the two output terminals of the signal processing circuit are respectively connected to the composite video signal VIDEO output port (3) and the audio signal AUDIO output terminal (4). 4. The combined electronic tuner according to claim 2, characterized in that: said mixing circuit is IC TDA6509AHN. 5. The combined electronic tuner according to claim 3, characterized in that: said signal processing circuit is IC TDA9881HN.

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