CN2198724Y

CN2198724Y - FM/TV changer

Info

Publication number: CN2198724Y
Application number: CN 94201485
Authority: CN
Inventors: 李铁铮
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-01-17
Filing date: 1994-01-17
Publication date: 1995-05-24
Anticipated expiration: 2004-01-17

Abstract

The utility model belongs to a broadcast television system, which provides an FM/TV conversion device which converts wireless fm broadcast signals into broadcast signals which can be received by a television. A circuit comprises a frequency-modulated signal and frequency conversion stage, a second oscillating stage and a mixing output stage, wherein, the frequency-modulated signal and frequency conversion stage converts the wireless fm broadcast signals into local empty frequency through frequency conversion, and then the second oscillating stage (an oscillator or a TV radio frequency modulator) generates TV radio frequency signals below 5MHz; simultaneously, the TV radio frequency signals are output by the mixing output stage for a television to receive video signals, such as wireless fm broadcast, color bar, caption, etc.

Description

FM/TV changer

The utility model belongs to radio data system, propose a kind of frequency modulation (FM) broadcast singal is transformed into to power look the FM/TV converting means of the broadcast singal that (TV) receiver receives.

At present, the audience rating in wireless frequency modulation broadcasting station is not high, checking station especially at county level listen to amount and the total amount ratio in the whole county, audience rating is too low, is bordering on sky and broadcasts.Because development of television has influenced the development of FM receiver.It is impossible that checking station at county level requires each household to increase a FM receiver, and television set has spread to the family, if utilize the fm broadcast signal of television audio circuit reception checking station, county, just can improve audience rating.

At present, the cable tv system project development is very fast, and as fm broadcast signal is input to cable television system after conversion, each family television receiver is just can receive fm broadcast signal.But present cable TV all is a simple function.

The utility model purpose utilizes the FM/TV converting means to provide receivable fm broadcast signal for television set exactly, the TV RF signals of captions, colour bar (image) is provided in cable TV simultaneously, thereby reaches the purpose of the audience rating that improves the wireless frequency modulation platform.

The utility model is achieved in that sound accompaniment FM signal in the signal of television system is than the high 6.5MHZ of picture intelligence; Sound intermediate frequency is than the low 6.5MHZ of visual intermediate frequency.Image utilizes the nonlinear difference of the vision signal detector of television set to go out 6.5MHZ sound accompaniment second intermediate frequency with the intermediate-freuqncy signal of sound accompaniment, after putting in sound accompaniment, again through frequency discriminator frequency discrimination output audio signal, again behind audio amplifier circuit, by the loud speaker sounding again.This FM/TV translation circuit comprises fm signal frequency level, second oscillator stage, mixes output stage and power stage.

Wireless frequency modulation broadcast singal and TV sound FM signal, just frequency difference.If is the local empty channel frequency of TV through the converter stage frequency conversion earlier with FM signal, just can be equally sound accompaniment circuit by television receiver.But importantly need to add for fm broadcast signal the carrier wave of a low 6.5MHZ, this carrier wave is produced by second oscillator stage, through mixing output stage output.Like this, just be lower than sound carrier frequency 6.5MHZ as the TV image carrier frequency, second intermediate frequency that just can utilize the nonlinear difference of television vision signal detector to go out the FM signal of 6.5MHZ comes, in the sound accompaniment of television set, put again, behind the frequency-discriminating circuit to loud speaker, the brightness of TV is closed, exempt the image point of making an uproar.

When the utility model was used for cable television system, what the second oscillator stage circuit adopted was the TV RF modulator.The wireless frequency modulation broadcast singal is local empty channel frequency through the frequency conversion of fm signal frequency level, and notes hiding frequently, again with the TV RF signals of TV RF modulator output through mixing output stage, mix output, and keep Voice ﹠ Video level 1:10.Through camera cable input Headend circuit, receive for television set through cable television system more again.Second oscillator stage is the low 6.5MHZ of FM signal (local empty channel) of the TV RF frequency ratio frequency modulation converter stage output of TV RF modulator output.

In addition, the Voice ﹠ Video signal can directly be imported the TV RF modulator, and vision signal refers to: the output signal of vision signal holder, enlarger, electronic typewriter circuit, color bar signal device.TV RF modulator output can directly be connected with the input of cable television system front end, has saved the fm signal frequency level and has mixed output stage, and the utility model circuit has only adopted the TV RF modulator circuit herein.

Devices such as the transistor in this circuit, integrated package can replace with the device of close function, but FM/TV converting means feature structure is constant.As state: circuit comprises fm signal frequency level, second oscillator stage, power stage, it is characterized in that: fm signal frequency level output is connected with two inputs that mix output stage respectively with the output of second oscillator stage, and the output that mixes output stage is connected with camera cable.

When being used for cable television system, fm signal frequency level output is connected with two inputs that mix output stage respectively with TV RF modulator (second oscillator stage) output.The output that mixes output stage is connected with camera cable.

In addition, also the Voice ﹠ Video signal directly can be imported the TV RF modulator, TV RF modulator output is connected through the input of camera cable with the cable television system front end.Owing to adopted above-mentioned measure, can utilize television set to receive the wireless frequency modulation broadcast singal, and receive colour bar vision signals such as (captions, images) simultaneously.

Below in conjunction with description of drawings embodiment of the present utility model:

Accompanying drawing 1:FM/TV converting means block diagram;

Accompanying drawing 2: the FM/TV converting means block diagram that is used for cable TV;

Accompanying drawing 3:FM/TV converting means example electrical schematic diagram;

Accompanying drawing 4: the example electrical schematic diagram that is used for the FM/TV converting means of cable TV.

As accompanying drawing 1, shown in the FM/TV converting means block diagram:

It is the empty channel frequency of local TV that the wireless frequency modulation signal enters 1 frequency conversion of fm signal frequency level, and input mixes output stage 3; The frequency of oscillation of second oscillator stage 2 is than the low 6.5MHZ of fm signal frequency level 1 output frequency, and also input mixing output stage 3 mixing output stages 3 outputs link to each other with the television set input through camera cable.Power stage is common power circuit or battery.

As accompanying drawing 2, be used for shown in the FM/TV converting means block diagram of cable TV: the wireless frequency modulation broadcast singal enters fm signal frequency level 1, frequency conversion is the empty channel frequency of local TV, input mixes output stage 3, the second oscillator stage 2(is the TV RF modulator), the circuit of incoming video signal has: memory of video signal S, color bar signal device C, electronic typewriter D, enlarger F.The signal frequency of TV RF modulator output is than the low 6.5MHZ of signal frequency of fm signal frequency level 1 output, and also input mixes output stage 3.Mixing output stage 3 outputs is connected with cable television system front end input through camera cable.

In addition, audio frequency, vision signal also can directly be imported the TV RF modulator, and TV RF modulator output directly is connected with the input of cable television system front end.

As accompanying drawing 3, shown in the FM/TV converting means example electrical schematic diagram: fm signal frequency level 1, by BG1, C1, L1, C2, L2, compositions such as BG2, C3, L3, C4, L4.BG1 is a high-frequency amplifier, and C1, L1 are FM signal input resonant tanks, and C2, L2 are the output resonant tanks of high-frequency amplifier BG1.BG2 is the local oscillator frequency mixer of holding concurrently, and C3, L3 are oscillation circuits, and C4, L4 are frequency mixer output resonant tanks.Output signal frequency is the empty channel frequency of local TV.Second oscillator stage 2 is made up of BG3, BG4, C5, L5, C6 etc.The low 6.5MHZ of BG3 oscillator, the frequency of oscillation frequency after than fm signal frequency, BG4 is a buffer amplifier, 2 outputs of second oscillator mix output stage through the C6 input.Mix output stage 3, form, mix output stage 3 output impedance 75 by L6, L7, half variable capacitance C7, resistance R.Be connected with the television set input through camera cable.So just, can utilize television set to listen to wireless frequency modulation and broadcast,, can close brightness for the release image point of making an uproar.

Shown in the FM/TV converting means example electrical schematic diagram that accompanying drawing 4 is used for cable TV: each circuit is all identical with accompanying drawing 3 circuit, and just second oscillator stage 2 has adopted the TV RF modulator.The TV RF modulator is by IC(such as MC1374), L5, L6, C6, C8, C etc. form.TV color bar signal generator C output, memory of video signal S output, electronic typewriter D output, enlarger F output, all the input with TV RF modulator IC is connected, and also audio signal directly can be imported the audio input end of IC.TV RF frequency modulating signal through TV RF modulator IC output is connected with two inputs that mix output stage 3 respectively than the low 6.5MHZ of signal frequency of fm signal frequency level 1 output and the output of fm signal frequency level 1 output TV RF modulator (second oscillator stage 2).Keep audio signal level and be 1:10 with the video level ratio.Mix output stage 3 and be connected with cable television system front end input, so just can utilize cable TV to receive wireless frequency modulation broadcasting and video image colour bar or caption signal through camera cable.

In addition, with wireless frequency modulation platform signal demodulate behind the audio frequency with video (figure, word) signal with through TV RF modulator input cable television system front end, realize with cable television system transmission wireless frequency modulation broadcast singal.

The used letter character of components and parts all is a circuit common letter character commonly used in the accompanying drawing, as transistor (BG), electric capacity (C), inductance (L), integrated circuit (IC), resistance (R).

Claims

1, the utility model, belong to radio data system, propose a kind of wireless frequency modulation (FM) broadcast singal to be transformed into the FM/TV converting means that the broadcast singal that (TV) receiver receives is looked in power supply, circuit comprises the fm signal frequency level, second oscillator stage (oscillator or TV RF modulator), mix output stage, power stage, it is characterized in that: fm signal frequency level output is connected with mixing output stage input, frequency is that local TV is frequently empty, second oscillator stage (oscillator or TV RF modulator) output is connected with mixing output stage input, frequency of oscillation is mixed the output stage output and is connected with television set input (or cable television system front end input) through camera cable than the empty frequently low 6.5MHZ of TV.