CN2276694Y - Scrambling and descrambling device for wired TV. - Google Patents

Abstract

The utility model relates to a scrambling and descrambling device for wired television. The scrambling device controls a variable airway modulator by microcomputer by a frequency synthesizer, and realizes the jumping scrambling of the television signal carrier frequency. The descrambling parameter is mixed with a television sound signal through the frequency shift keying code device and sent to each user side. The descrambling device acquires the descrambling parameter from audio signal by an SCM utilizing a demodulator and the frequency shift keying decoder. According to the descrambling parameter, the SCM properly controls an airway converter to track the jumping airway of the scrambling program and converts the airway converter into a fixed airway emergent, and realizes the descrambling. The device has the advantages of secret, safety, low cost and positive quality.

Description

A kind of scrambling of cable TV and descrambler

The utility model belongs to the scrambling and the descrambler of cable TV signal, and is especially relevant with the frequency conversion scrambling.

The scrambling of known cable TV signal and descrambling technology, as " radio " magazine, o. 11th in 1994, the 3rd page, be entitled as: in " scrambling of cable TV and descrambling technology " introduction, present scrambling mode has analogue transmission mode and digital transmission mode; Wherein: the digital transmission mode signal scrambling technique only is applicable to digitized TV signal, and is impracticable in China at present; And the amplitude processing mode in the analogue transmission scrambling mode has confidentiality and poor stability, the shortcoming that the possibility of image restoration deterioration is big; Another kind of mode, that is: base treatment technology mode has decoder need adopt the large scale integrated circuit module time, and the cost of manufacture height is arranged, and is unsuitable for the shortcoming of Chinese mass consumption.Cause above-mentioned shortcoming reason to be: the signal of interfering TV is added in the TV signal and goes, and the residing channel of TV signal before and after scrambling and the descrambling all is constant, makes interference signal filtering difficulty, scrambling and descrambler complexity, specification requirement height, cost height; Or scrambling has the shortcoming of confidentiality, poor stability.

The purpose of this utility model provides a kind of TV signal by will desiring scrambling and realizes the scrambling apparatus of scrambling and a kind of descrambler that matches with it is provided in the mode of continuous its carrier frequency of change.

Order of the present utility model reaches like this: as disturb device and comprised microcomputer, variable channel modulator, sync separator circuit, frequency shift keying (FSK) encoder, frequency synthesizer; The vision signal of wired electric wire TV signal of scrambling be will desire during scrambling and sync separator circuit and variable channel modulator sent into respectively, microcomputer receives the synchronizing signal of desiring the scrambled television signal, and just in the TV flyback, send a channel hopping order through a pseudorandom time interval by certain algorithm is every, variable channel modulator is passed in this order, with the carrier frequency saltus step of TV signal of input is another channel, promptly changes its transmission channel; Simultaneously descramble signals such as this order and channel hopping parameter, customer management information or parameter are issued the frequency shift keying encoder, after the frequency shift keying encoder encodes, mix with the audio signal of cable TV, send into variable channel modulator, export the cable television program signal in saltus step channel mode at last, i.e. the cable television program signal of scrambling.

The transmission of channel hopping order and channel hopping parameter, customer management information also can be adopted alternate manner, sends as the appropriate location of adopting the digit pulse form to insert the flyback of TV signal.

Descrambler comprises set op converter and descrambling assembly, single-chip microcomputer, demodulator, frequency shift keying decoder.During descrambler work, cable TV signal inputting channel converter, frequency channel transformer are transformed to fixed channel output with the programme signal of desiring to watch under the control of single-chip microcomputer; When receiving scrambled program, isolate audio signal, behind the frequency shift keying decoder decode, obtain descramble signal or parameters such as channel hopping order, customer management information, give single-chip microcomputer again by demodulator; Single-chip microcomputer is according to the descramble signal or the parameter that receive, control frequency channel transformer in good time, follow the tracks of the channel hopping of scrambled program, make the scrambled program of the continuous saltus step of channel be transformed to fixed channel output, finish the descrambling process, and according to customer management information, decision goes out or ends the user rating of scrambled program is weighed.

The utility model has adopted the TV signal that will desire scrambling to be exported in saltus step channel mode by system controlled by computer, and a kind of new scrambling approach is provided; Because descrambling information adds TV signal by the synthetic back of audio signal, picture signal is not is not invaded and harassed, and the descrambling parameter only needs special element just can conveniently take out, need not large scale integrated circuit, just can realize addressable control and management, the conversion of channel is to carry out when the TV signal flyback, has guaranteed that also picture quality is unaffected; Whole scrambling, descrambling system have confidentiality and fail safe is good, reliable in quality, cheap advantage.

The utility model is described in further detail below in conjunction with drawings and Examples.

Fig. 1 is the circuit theory diagrams of the utility model scrambling apparatus;

Fig. 2 is the circuit theory diagrams of the utility model descrambler.

Referring to Fig. 1, scrambling apparatus of the present utility model is by sync separator circuit, variable channel modulator, and microcomputer and special-purpose scrambling system management software thereof, frequency synthesizer, frequency shift keying encoder are formed.Desire the cable television video signal of scrambling and send into sync separator circuit C respectively ₁(LM1682) and variable channel modulator, through IC ₁The synchronizing signal of taking out is sent into the parallel input interface J of microcomputer COMPAQ-486 ₁, microcomputer sends instructions such as channel hopping order, customer management information, saltus step parameter according to special-purpose scrambling system management software program.By the parallel output interface J of microcomputer ₂The Senior Two position be sent to the input of frequency shift keying (FSK) encoder, the FSK encoder of present embodiment is made up of elements such as CD4051, CD4046, TL004, the fsk signal behind the coding is through capacitor C ₉With send into the variable frequency modulator after the cable TV audio signal is mixed, the microcomputer output interface J that walks abreast ₂Low six control frequency synthesizers, frequency synthesizer is according to the binary code of control mouthful, the oscillator signal of output respective frequencies, and be sent to variable channel modulator, thereby the carrier frequency of scrambled program is desired in control, promptly microcomputer changes parallel output interface J ₂Low six outputs, just can realize saltus step to desire scrambled television signal carrier frequency.

Referring to Fig. 2, descrambler of the present utility model is to increase the descrambling assembly on the basis of common machine up converter (the ST-01 type set op converter of producing as Xiamen Ke Fa company), single-chip microcomputer PIC16C54, non-volatile RAM24LC02, demodulator, frequency shift keying (FSK) decoder CXA20106 form, during descrambler work, earlier isolate audio signal by demodulator, audio signal is through C ₁The FSK decoder is sent in coupling, and decoded serial digital pulse signal is sent into single-chip microcomputer input port RA through the 7th output pin of FSK decoding again ₃Make saltus step order, saltus step parameter and customer management information read in single-chip microcomputer, the RA of single-chip microcomputer ₁, RA ₂, the SCL as the I2C bus, SDA be connected with nonvolatile RAM, the address code of this descrambler, the parameter of each channel all exist among nonvolatile RAM, single-chip microcomputer is by I ²The C bus is read and write RAM, and single-chip microcomputer in time sends the saltus step that control signal is followed the tracks of channel, the RB of single-chip microcomputer according to above-mentioned information.And RB ₁Output two-way pulse-width-modulating signal (PWM), this pulse-width-modulating signal PWM is through V ₁, V ₂And R ₁To R ₁₀, C ₄, C ₅, C ₆, C ₇The composition smoothing circuit obtains one and stablizes accurate direct voltage, and this direct voltage is through single-chip microcomputer RB ₂, RB ₃The electronic switch V of foot control system ₃, V ₄Alternately be sent to the tuning voltage input of the frequency channel transformer of set op converter, TV programme signal that alternately will the scrambling of saltus step on different channel is converted to fixed channel output, and the RB of single-chip microcomputer ₄End is then in order to control V ₅, the tuning voltage when realizing descrambling and non-descrambling is switched.

During descrambling, single-chip microcomputer is earlier at RB ₄End is sent high level, turn-offs V ₅With original set op converter not the tuning voltage during descrambling cut off, change by the descrambling Single-chip Controlling RB of single-chip microcomputer ₀, RB ₁Send two kinds of pulse-width-modulating signals, simultaneously RB ₂Become low-voltage, RB ₃Be high level, V ₃Conducting, V ₄Turn-off, like this and RB ₀The tuning voltage of the pulse-width-modulating signal correspondence of end is sent into the tuning voltage input of the frequency channel transformer in the set op converter, the scrambled program that frequency channel transformer output desire is received.Single-chip microcomputer is according to RA ₃The information that end reads in is in good time with RB ₂And RB ₃Level counter-rotating, V like this ₃Turn-off V ₄Conducting is then with RB ₁The tuning voltage of the pulse-width-modulating signal correspondence of output is delivered to frequency changer, makes the channel hopping of acceptance, thereby traces into the channel hopping of scrambled program, and the descrambling of realization to scrambled program so goes round and begins again.

Claims (3)

1, a kind of scrambling of cable TV and descrambler, scrambling apparatus comprise microcomputer, frequency synthesizer, variable channel modulator, frequency shift keying (FSK) encoder; Descrambler comprises set op converter, descrambling assembly, single-chip microcomputer, demodulator, frequency shift keying (FSK) decoder, it is characterized in that:

Vision signal is sent into sync separator circuit IC respectively ₁And modulator; Through sync separator circuit IC ₁The synchronizing signal of taking out is sent into the parallel input interface J of microcomputer ₁The parallel output interface J of microcomputer ₂The Senior Two position be connected with the input of frequency shift keying FSK encoder, low six are connected with frequency synthesizer, the output of FSK encoder is through C ₉After connecting, electric capacity and cable TV sound accompaniment incoming line receive the sound accompaniment input of modulator;

TV signal is isolated audio signal by demodulator, and audio signal is through C ₁The FSK decoder is sent in coupling, and decoded serial digital pulse signal is sent into the input port RA of single-chip microcomputer again through the 7th pin output of FSK decoder ₃The RA of single-chip microcomputer ₁, RA ₂As I ²The SCL of C bus, SDA and nonvolatile RAM, V ₁₁Connect the RB of single-chip microcomputer ₀, RB ₁Output two-way pulse-width-modulating signal PWM sends into by V ₁, V ₂And R ₁To R ₁₀, C ₄, C ₅, C ₆, C ₇The smoothing circuit of forming passes through by RB respectively through the smoothing circuit output dc voltage again ₂, RB ₃The V of control ₃, V ₄Electronic switch is delivered to the tuning voltage input of the frequency channel transformer in the set op converter; RB ₄The V of control ₅Be used for the cutting machine up converter and receive the not tuning voltage of scrambled program.

2, according to the scrambling and the descrambler of the cable TV in the claim 1, it is characterized in that: data transmit to adopt sneaks into the sound accompaniment transmission behind the FSK coding.

3, according to the scrambling and the descrambler of the cable TV in the claim 1, it is characterized in that: data are inserted in the TV signal flyback sent.

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