CN201577142U - Electronic tuner for cable digital television - Google Patents

Abstract

An electronic tuner for cable digital television is characterized in that a digital RF (radio-frequency) signal input terminal, a digital RF signal output terminal, an analog IF (intermediate-frequency) signal output terminal and a digital IF signal output terminal are arranged outside a casing of the tuner, wherein the input terminal of a low-noise RF amplifying circuit arranged inside the casing is connected with the digital RF signal input terminal, the output terminal of the low-noise RF amplifying circuit is connected with both the digital RF signal output terminal and the input terminal of a tuning amplifying circuit, the output terminal of the tuning amplifying circuit is connected with the input terminal of a local oscillation mixer circuit, the output terminal of the local oscillation mixer circuit is connected with both the analog IF signal output terminal and the input terminal of a digital IF amplifying circuit, and the output terminal of the digital IF amplifying circuit is connected with the digital IF signal output terminal. The utility model has the advantages that a digital electronic tuner and the IF amplifying circuit are integrated in the casing to form an independent product, thereby elevating the electric properties, reliability and electromagnetic compatibility up to levels higher than national and industrial standards, and realizing the tuning filtering, mixing and IF amplifying of cable digital television signals. The electronic tuner is mainly applied to cable digital television set top boxes.

Description

The cable digital TV electronic tuning unit

Technical field

The utility model relates to a kind of cable digital TV electronic tuning unit.

Background technology

Along with progressively popularizing of Cable Network network, wired digital set-top box is as auxiliary products, the market demand increases, cabled digital electronic tuning unit demand increases thereupon, and all more in the past electronic tuning unit product is more strict at aspects such as energy-conserving and environment-protective, miniaturization, electric property, reliability, Electro Magnetic Compatibilities to require the cabled digital electronic tuning unit.Particularly in the dynamic control range of received signal, signal to noise ratio, aspects such as phase noise isolation are harsh more.Electronic tuning unit product of the prior art is difficult to satisfy these requirements.

Summary of the invention

The technical problem that the utility model solves: design a kind of cable digital TV electronic tuning unit, digital and electronic tuner and digital intermediate frequency amplifying circuit are integrated in the housing, form an independently product, electric property, reliability, Electro Magnetic Compatibility are higher than country, industry standard, reception, tuning filtering, Frequency mixing processing, the intermediate frequency that can realize digital catv signal amplify, and are mainly used in cable digital TV set-top box.

Technical solution of the present utility model: a kind of cable digital TV electronic tuning unit, its housing (1) is outside equipped with digital radio signal input port (2), digital radio signal output port (3), analog if signal output port (4), digital medium-frequency signal output port (5).Be provided with low noise radio frequency amplifying circuit, tuning amplification circuit, local oscillator mixting circuit and digital intermediate frequency amplifying circuit in the housing (1); The input termination digital radio signal input port (2) of low noise radio frequency amplifying circuit, output connects the input of digital radio signal output port (3) and tuning amplification circuit respectively, the input of the output termination local oscillator mixting circuit of tuning amplification circuit, the output of local oscillator mixting circuit connects the input of analog if signal output port (4) and digital intermediate frequency amplifying circuit respectively, the output termination digital medium-frequency signal output port (5) of digital intermediate frequency amplifying circuit.

Described tuning amplification circuit by VL import single-tunded circuit, VH input single-tunded circuit, UHF import single-tunded circuit, the VHF height is put back to the road, the UHF height is put back to the road, VL output double tuned circuit, VH output double tuned circuit, UHF output double tuned circuit composition; The output termination VHF height of VL input single-tunded circuit, VH input single-tunded circuit is put back to the input on road, and the output termination UHF height of UHF input single-tunded circuit is put back to the input on road; The VHF height is put back to the output termination VL output double tuned circuit on road, the input of VH output double tuned circuit; The UHF height is put back to the input of the output termination UHF output double tuned circuit on road; The local oscillator mixting circuit is made up of VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop, VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit, intermediate frequency output loop; The corresponding respectively input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of output of VL output double tuned circuit, VH output double tuned circuit and UHF output double tuned circuit; Corresponding respectively another input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of the output in VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop; The output of VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit all connects the input of intermediate frequency output loop, the output termination analog if signal output port (4) of intermediate frequency output loop; The digital intermediate frequency amplifying circuit is made up of digital filtering loop and digital intermediate frequency amplifying return circuit, the input in the output termination digital filtering loop of intermediate frequency output loop, the input of the output termination digital intermediate frequency amplifying return circuit in digital filtering loop, the output termination digital medium-frequency signal output port (5) of digital intermediate frequency amplifying return circuit.

Described VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit, intermediate frequency output loop are integrated into ICTUA6020, and the digital intermediate frequency amplifying return circuit is IC TDA6192-T.

The utility model compared with prior art is integrated in digital and electronic tuner, intermediate frequency amplifier circuit in the housing, form an independently product, electric property, reliability, Electro Magnetic Compatibility are higher than country, industry standard, can realize that the TV signal in surface wave digital television signal and two kinds of paths of closed circuit cable TV signal receives; Can realize simulating tuning filtering, Frequency mixing processing, the intermediate frequency demodulation of multiple systems colour TV signal handles.Be mainly used in cable digital TV set-top box.

Description of drawings

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

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

Fig. 3 is circuit theory diagrams of the present utility model.

Embodiment:

1,2,3 a kind of embodiment of the present utility model is described in conjunction with the accompanying drawings.

A kind of cable digital TV electronic tuning unit, its housing (1) is outside equipped with digital radio signal input port (2), digital radio signal output port (3), analog if signal output port (4), digital medium-frequency signal output port (5).Be provided with low noise radio frequency amplifying circuit, tuning amplification circuit, local oscillator mixting circuit and digital intermediate frequency amplifying circuit in the housing (1); The input termination digital radio signal input port (2) of low noise radio frequency amplifying circuit, output termination digital radio signal output port (3).

Tuning amplification circuit by VL import single-tunded circuit, VH input single-tunded circuit, UHF import single-tunded circuit, the VHF height is put back to the road, the UHF height is put back to the road, VL output double tuned circuit, VH output double tuned circuit, UHF output double tuned circuit composition; The output of the input termination low noise radio frequency amplifying circuit of VL input single-tunded circuit, VH input single-tunded circuit, the output termination VHF height of VL input single-tunded circuit, VH input single-tunded circuit is put back to the input on road, and the output termination UHF height of UHF input single-tunded circuit is put back to the input on road; The VHF height is put back to the output termination VL output double tuned circuit on road, the input of VH output double tuned circuit; The UHF height is put back to the input of the output termination UHF output double tuned circuit on road; The local oscillator mixting circuit is made up of VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop, VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit, intermediate frequency output loop; The corresponding respectively input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of output of VL output double tuned circuit, VH output double tuned circuit and UHF output double tuned circuit; Corresponding respectively another input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of the output in VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop; The output of VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit all connects the input of intermediate frequency output loop, the output termination analog if signal output port (4) of intermediate frequency output loop; The digital intermediate frequency amplifying circuit is made up of digital filtering loop and digital intermediate frequency amplifying circuit, the input in the output termination digital filtering loop of intermediate frequency output loop, the input of the output termination digital intermediate frequency amplifying circuit in digital filtering loop, the output termination digital medium-frequency signal output port (5) of digital intermediate frequency amplifying circuit.Wherein VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit, intermediate frequency output loop are integrated into IC TUA6020, and the digital intermediate frequency amplifying return circuit is IC TDA6192-T.

Operation principle: the digital RF input port (2) of receiving this electronic tuning unit from the digital radio signal input of closed circuit cable television system reception, requirement according to observer, by man-machine communication's control of receiver, the utility model is controlled by the selection control signal of receiver main control MCU output.The radiofrequency signal that receives is carried out after the low noise radio frequency amplifies, and the digital radio signal output port (3) of leading up to is used with radiofrequency signal output and miscellaneous equipment, and tv-if signal is exported through tuning, amplification, mixing in another road.One road tv-if signal is directly exported by analog if signal output port (4), another road tv-if signal carries out digital intermediate frequency filtering through SAW (Surface Acoustic Wave) filter again and export with the narrowband intermediate frequency signal of 36.125MHz digital intermediate frequency amplifying circuit control back, enter digital receiver processing television signals part, become audio-video signal output at last by DSP, decoding, DAC etc., excitation loudspeaker plays sound, the excitation display device display image.

Claims (2)

1. cable digital TV electronic tuning unit, comprise housing (1), it is characterized in that: housing (1) is outside equipped with digital radio signal input port (2), digital radio signal output port (3), analog if signal output port (4), digital medium-frequency signal output port (5) is provided with low noise radio frequency amplifying circuit, tuning amplification circuit, local oscillator mixting circuit and digital intermediate frequency amplifying circuit in the housing (1); The input termination digital radio signal input port (2) of low noise radio frequency amplifying circuit, output connects the input of digital radio signal output port (3) and tuning amplification circuit respectively, the input of the output termination local oscillator mixting circuit of tuning amplification circuit, the output of local oscillator mixting circuit connects the input of analog if signal output port (4) and digital intermediate frequency amplifying circuit respectively, the output termination digital medium-frequency signal output port (5) of digital intermediate frequency amplifying circuit.

2. cable digital TV electronic tuning unit according to claim 1, it is characterized in that: described tuning amplification circuit by VL import single-tunded circuit, VH input single-tunded circuit, UHF imports single-tunded circuit, the VHF height is put back to the road, the UHF height is put back to the road, and VL output double tuned circuit, VH output double tuned circuit, UHF output double tuned circuit are formed; The output termination VHF height of VL input single-tunded circuit, VH input single-tunded circuit is put back to the input on road, and the output termination UHF height of UHF input single-tunded circuit is put back to the input on road; The VHF height is put back to the output termination VL output double tuned circuit on road, the input of VH output double tuned circuit; The UHF height is put back to the input of the output termination UHF output double tuned circuit on road; The local oscillator mixting circuit is made up of VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop, VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit, intermediate frequency output loop; The corresponding respectively input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of output of VL output double tuned circuit, VH output double tuned circuit and UHF output double tuned circuit; Corresponding respectively another input that connects VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit of the output in VL local oscillator loop, VH local oscillator loop, UHF local oscillator loop; The output of VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit all connects the input of intermediate frequency output loop, the output termination analog if signal output port (4) of intermediate frequency output loop; The digital intermediate frequency amplifying circuit is made up of digital filtering loop and digital intermediate frequency amplifying return circuit, the input in the output termination digital filtering loop of intermediate frequency output loop, the input of the output termination digital intermediate frequency amplifying return circuit in digital filtering loop, the output termination digital medium-frequency signal output port (5) of digital intermediate frequency amplifying return circuit.

3, cable digital TV electronic tuning unit according to claim 2, it is characterized in that: described VL mixing return circuit, VH mixing return circuit, UHF mixing return circuit and intermediate frequency output loop are integrated into IC TUA6020, the digital intermediate frequency amplifying return circuit is IC TDA6192-T.

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