CN2192996Y

CN2192996Y - Adding frequence channel inverter for wire-TV

Info

Publication number: CN2192996Y
Application number: CN 94205093
Authority: CN
Inventors: 王志恒; 孟雅娟; 王艳敏; 徐红兵
Original assignee: 王志恒
Priority date: 1994-03-23
Filing date: 1994-03-23
Publication date: 1995-03-22
Anticipated expiration: 2004-03-23

Abstract

The utility model relates to an adding frequency channel inverter for a wire-TV, belonging to signal conversion equipment of the wire-TV. The utility model is composed of a low-pass filter circuit, high-pass filter circuits I and II, a high frequency amplification circuit, a local oscillation circuit and an up-conversion circuit. Wire-TV signals go into the high frequency amplification circuit through the low-pass filter circuit and the high-pass filter circuits to be amplified, the high frequency amplification signals together with local oscillation signals go into the up-conversion circuit to be converted, and the VHF wave band and the adding frequency channel TV signals are converted into the TV signals of the UHF wave band. The utility model is suitable for the mounting of wire-TV user terminals to watch the whole TV programs including the adding frequency channels, and is also suitable for being used on the wire-TV terminals and the front end of the signal amplifiers as the channel conversion.

Description

Adding frequence channel inverter for wire-TV

The utility model relates to a kind of cable TV additional channel converter, belongs to the cable TV signal converting means.

At present, all cable TV is being installed in the many cities of China, it has advantages such as signal stabilization, channel are many.General cable TV all is to use the L section of VHF and H section (1-12 channel) and additional channel (augmenting the 1-35 channel) to transmit TV signal.And for the UHF wave band since its be subject to disturb and transmission loss big, seldom be used for cable TV.Our employed multichannel television set can only be received the 1-12 channel of VHF wave band and the 13-68 channel of UHF wave band, and can not watch additional channel.In order to make the TV function watch all cable television programs, then need on television set, to install additional a device.This device all is to utilize the method that increases a tuner at present.This method complex structure, cost height, and need television set is transformed.

The purpose of this utility model is exactly to provide a kind of at the problems referred to above need not reequip television set and additional channel is moved to the cable TV additional channel converter of UHF wave band.

The utility model comprises the low-pass filter circuit that is made of inductance L 1, L2, capacitor C 1, the high-pass filtering circuit 1 that constitutes by capacitor C 2, C3, C4 and inductance L 3--L6, the high-frequency amplifier circuit that constitutes by MOS dual gate FET DG and resistance R 1--R8, capacitor C 6, the oscillating circuit that constitutes by transistor BG1, capacitor C 9--C12, resistance R 9--R12, inductance L 9, the up-converter circuit that constitutes by transistor BG2, resistance R 13--R16, the high-pass filtering circuit II that constitutes by capacitor C 17--C19, inductance L 11--L14.Cable TV signal enters low-pass filter circuit, the frequency signal that filtering 480MHz is above, C2 in the output of low-pass filter circuit and the high-pass filtering circuit, an end of L3 parallel connection are connected, the frequency signal that filtering 40MHz is following, one end of C4, L6 parallel connection links to each other with an end of capacitor C 5 as output, and grid G 1 end of the field effect transistor DG in the other end of capacitor C 5 and the high-frequency amplifier circuit links to each other.The frequency signal of the 40-480MHz that is left in the cable TV signal enters high-frequency amplifier circuit by capacitance C5 and amplifies, wherein R1, R2, R3, R4 constitute the working point of fet gate G1, G2, R5, R7 constitute the working point of source S, C6 is the filter capacitor of source S, C7, L7 are the filter capacitor and the inductance of power supply, and the input of the drain D of DG by capacitor C 14 and up-converter circuit is that the base stage of BG2 is connected.C9, L9 form frequency of oscillation in the oscillating circuit, and L8, C8 are power filtering capacitor and inductance, and the input of the output of oscillating circuit by C13 and up-converter circuit is that the base stage of BG2 is connected.High-frequency signal and oscillator signal inject by the base stage of transistor BG2, L10, C15 are the filter capacitor and the inductance of power supply, R13--R16 constitutes the working point of BG2, and the input of the collector electrode C of BG2 by capacitor C 16 and high-pass filtering circuit is that the parallel connected end of C17 and L11 is connected in the up-converter circuit.Signal after the frequency conversion enters high-pass filtering circuit through capacitor C 16, and the high-frequency signal that filtering 450MHz is following is exported to the signal input part of television set by the parallel connected end of C19 and L14.

Operation principle of the present utility model is: the television frequency signal (1-12 channel, 1-35 additional channel) of cable TV signal only remaining 40-480MHz after low-pass filter circuit, high-pass filtering circuit I.This signal is amplified by high-frequency amplifier circuit, through the base stage that enters up-converter circuit with the local oscillation frequency signal behind the capacitance, after frequency conversion, generate the UHF wave band high-frequency signal (13-68 channel) of 470-940MHz, the high-frequency signal of this signal below filtering 450MHz after the high-pass filtering, export then, promptly input to the signal input part of television set.

The utility model compares with existing other converter, has the principle novelty, and circuit structure is simple, and cost is low, need not reequip advantages such as television set.

Accompanying drawing is the utility model circuit theory diagrams.

The utility model has only tv signal input, TV signal output end and three sockets of power input.It uses single positive 12V DC power supply, is applicable to cable TV subscriber's terminal, is applicable to that also CATV terminal signal amplifier front end is as channel switch.When being used for cable TV subscriber's terminal, only need cable TV signal transmission line (home terminal) is imported input of the present utility model, output is connected to the television signal input by the camera cable line gets final product.When being used for cable TV signal terminal amplifier front end, cable TV signal is imported signal input part of the present utility model earlier, lead to amplifier in from signal output part and get final product.

Claims

1, a kind of cable TV additional channel converter, it is characterized in that comprising a low-pass filter circuit that constitutes by inductance L 1, L2, capacitor C 1, the high-pass filtering circuit I that constitutes by capacitor C 2, C3, C4 and inductance L 3--L6, the high-frequency amplifier circuit that constitutes by MOS dual gate FET DG and resistance R 1-R8, capacitor C 6, the oscillating circuit that constitutes by transistor BG1, capacitor C 9--C12, resistance R 9--R12, inductance L 9, the up-converter circuit that constitutes by transistor BG2, resistance R 13--R16, the high-pass filtering circuit II that constitutes by capacitor C 17--C19, inductance L 11--L14.Cable TV signal enters low-pass filter circuit, the frequency signal that filtering 480MHz is above, C2 in the output of low-pass filter circuit and the high-pass filtering circuit, an end of L3 parallel connection are connected, the frequency signal that filtering 40MHz is following, one end of C4, L6 parallel connection links to each other with an end of capacitor C 5 as output, and grid G 1 end of the field effect transistor DG in the other end of capacitor C 5 and the high-frequency amplifier circuit links to each other.The frequency signal of the 40-480MHz that is left in the cable TV signal enters high-frequency amplifier circuit by capacitance C5 and amplifies, wherein R1, R2, R3, R4 constitute the working point of fet gate G1, G2, R5, R7 constitute the working point of source S, C6 is the filter capacitor of source S, C7, L7 are the filter capacitor and the inductance of power supply, and the input of the drain D of DG by capacitor C 14 and up-converter circuit is that the base stage of BG2 is connected.C9, L9 form frequency of oscillation in the oscillating circuit, and L8, C8 are power filtering capacitor and inductance, and the input of the output of oscillating circuit by C13 and up-converter circuit is that the base stage of BG2 is connected.High-frequency signal and oscillator signal inject by the base stage of transistor BG2, L10, C15 are the filter capacitor and the inductance of power supply, R13--R16 constitutes the working point of BG2, and the input of the collector electrode C of BG2 by capacitor C 16 and high-pass filtering circuit is that the parallel connected end of C17 and L11 is connected in the up-converter circuit.Signal after the frequency conversion enters high-pass filtering circuit through capacitor C 16, and the high-frequency signal that filtering 450MHz is following is exported to the signal input part of television set by the parallel connected end of C19 and L14.