CN1154628A

CN1154628A - Disturbing and de-disturbing device for closed-circuit TV system

Info

Publication number: CN1154628A
Application number: CN 96102909
Authority: CN
Inventors: 熊宪; 龚华珠
Original assignee: Xiamen Branch Trade Ltd Co; KEHUALI DEVELOPMENT Co Ltd XIAMEN CITY
Current assignee: Xiamen Branch Trade Ltd Co; KEHUALI DEVELOPMENT Co Ltd XIAMEN CITY
Priority date: 1995-03-03
Filing date: 1996-03-02
Publication date: 1997-07-16

Abstract

The present invention relates to a jamming and jam-eliminating device for cable TV. Said invented jamming mode is characterized by that under the control of microcomputer the TV signal to be jammed is passed through a variable channel modulator, and is delivered inc arrier frequency continuously-jumping mode so as to implement jamming. Its jam-eliminating parameters are mixed with sound, and transfered together with sound, then taken out from jam-eliminating device, processed by one-chip computer, and the jammed signal is passed through channel control converter, then is delivered from fixed frequency channel so as to implement elimination of jam. It possesses the advantages of good secrecy and safety and low cost, etc..

Description

A kind of scrambling of cable TV and descrambler

The invention belongs to the scrambling and the descrambler of cable TV signal, 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 the reason of above-mentioned shortcoming to be: the signal of interfering TV is added in the TV signal and goes, 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, the specification requirement height, the cost height; Or scrambling has the shortcoming of confidentiality, poor stability.

The purpose of this invention is to provide a kind of TV signal by will desiring scrambling 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.

Total design of the present invention is: the TV signal that will desire scrambling is by a variable channel modulator, mode with continuous frequency hopping is exported, the phenomenon that occurs the multiple video of constantly saltus step of image, shake when making no descrambler watch this program, as the saltus step in three channels of two program scramblings is transmitted, then video is multiple saltus step.Descrambler then utilize the frequency parameter that transmits in the TV signal will be in different channel the same program of saltus step transmission transform in the fixed channel and export because above-mentioned saltus step is in the TV flyback, make the switching saltus step of channel not influence image quality.

The objective of the invention is to reach like this: it is FSK and signal synthesis circuit that scrambling apparatus is provided with variable channel modulator, microcomputer, switching signal generator, frequency shift keying encoder; Wherein, microcomputer accept to be desired the synchronizing signal of scrambled television signal, whenever just sends a channel hopping order through a pseudorandom time interval in the TV flyback, and 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; It also sends channel hopping parameter and user management instruction to FSK, switching signal, channel hopping parameter and user management instruction are mixed by signal synthesis circuit with TV signal together through FSK coding back formation descramble signal or parameter, send into variable channel modulator, export in saltus step channel mode at last.

Signal synthesis circuit in the scrambling apparatus can be synthetic sound accompaniment circuit, and it is synthetic to be about to descramble signal and audio signal, and this moment, picture signal was directly inputted in the variable channel modulator, and it is retrace interval in picture signal that channel switches.

Descrambler is provided with channel converter, single-chip microcomputer, band pass filter and FSK decoder.Its operation principle is as follows: cable TV signal inputting channel transducer goes out.When receiving scrambled program, the signal that contains the descrambling parameter is selected communication signal through band pass filter, obtains skip signal and other communication datas then behind the FSK decoder decode, gives single-chip microcomputer again.Single-chip microcomputer sends the order of following the tracks of channel change according to the scrambling parameter and the skip signal that send in good time, makes the scrambled program of the continuous saltus step of channel be converted to fixed channel output, finishes the descrambling process.The communication channel of setting up in TV signal also transmits other information, and the addressable control command is wherein arranged, and it can make arbitrary appointment descrambler obtain or end the rating power of scrambled program.

The switching of above-mentioned scrambled program, frequency conversion all are in the flyback of TV signal.

When the TV signal of desiring scrambling when being a plurality of, these signals should carry out Synchronous Processing earlier.

The present invention has adopted the TV signal that will desire scrambling to export in saltus step channel mode, and a kind of new scrambling approach is provided; Because descrambling information adds TV signal by the synthetic back of sound accompaniment, picture signal is not is not invaded and harassed, and the descrambling parameter is taken out easily, need not large scale integrated circuit, just can realize addressable control and management, because the switching of channel can be carried out when the TV signal flyback, picture quality is also unaffected; Take a broad view of whole system, it has confidentiality and fail safe is good, advantages of being cheap, and be mature technology respectively forming among the present invention, have the advantage that steady quality is easy to realize.

The invention will be further described below in conjunction with drawings and Examples.

Fig. 1 is a scrambling apparatus of the present invention when the circuit block diagram of signal synthesis circuit during for synthetic sound accompaniment circuit.

Fig. 2 is " microcomputer " partial circuit figure among Fig. 1;

Fig. 3 is " synthetic sound accompaniment circuit " partial circuit figure among Fig. 1;

Fig. 4 is " TV synchronousing signal, FSK encoder and switching signal generator " partial circuit figure among Fig. 1;

Fig. 5 is the circuit block diagram of descrambler of the present invention;

Fig. 6 is " channel converter " partial circuit figure among Fig. 5;

Fig. 7 is " band pass filter, FSK decoder, single-chip microcomputer " partial circuit figure among Fig. 5.

Referring to Fig. 1-4, scrambling apparatus of the present invention is FSK by variable channel modulator, microcomputer, switching signal generator, frequency shift keying encoder, and synthetic sound accompaniment circuit is formed.Microcomputer receives the synchronizing signal of desiring the scrambled television signal, whenever, send the channel hopping order after the time interval through a pseudorandom, controlling variable channel modulator will desire the scrambled television signal and export in saltus step channel mode, realize scrambling, microcomputer also sends switching command to switching signal generator respectively in addition, send switching signal by it, send channel hopping parameter and customer management information to FSK, they are exported in saltus step channel mode by variable channel modulator with picture signal after audio signal is synthetic through synthetic sound accompaniment circuit, realize scrambling.

Referring to Fig. 5-6, descrambler of the present invention partly is made up of channel converter and descrambling, and descrambling partly comprises band pass filter, memory U ₁₁, FSK decoder U ₁₃, single-chip microcomputer U ₁₂Form; The audio signal that contains descrambling information that channel converter receives is through band pass filter, FSK decoder U ₁₃Solve, after single-chip microcomputer is handled, the control channel converter, the scrambled program that makes the continuous saltus step of channel by fixed channel output, realizes descrambling after conversion.Wherein, channel converter possesses all functions of common machine up converter, and its course of work is: IC ₃There are the data of whole CATV channels single-chip microcomputer inside.The TV signal of CATV is sent into the CATV high-frequency tuner through the RF input, single-chip microcomputer IC ₃According to the channel of wanting rating, send instructions to phase-locked loop circuit IC ₄, produce tuning voltage and deliver to tuner.Intermediate-freuqncy signal IF exports demodulation to--modulation module PFMD4/5, produce sound, vision signal output, and the RF of fixed channel output.IC ₃Single-chip microcomputer also can receive remote control command.The single-chip microcomputer U of descrambling part ₁₂Logical IC ₂Bus and IC ₃Communication.When receiving common frequency channel, U ₁₂Oxide-semiconductor control transistors V ₅Conducting, tuning voltage is passed through V ₅The tremendously high frequency head, channel is by IC ₃Control.When receiving descramble signal, U ₁₂According to the fsk data in the audio signal, determine saltus step on which channel, control V ₁And V ₂Export correct tuning voltage, then, control V again ₃And V ₄Conducting and close, thereby follow the tracks of the signal of saltus step, stably received television program is realized descrambling.In addition, customer management information can also authorize single-chip microcomputer to make whether descrambling determines, realizes user management.

For example, be A, B if establish the TV programme of desiring scrambling, synchronously, a, b, c are three different channels earlier for they, microcomputer can be at t ₁Constantly send A in the output of a channel, B is t in the instruction of b channel output after the time interval in a pseudorandom ₂In time, sends A and jumps to b channel output, and B jumps to the instruction of a channel output, and then A, B have realized channel hopping, in like manner at t ₃The time, sending A at the c channel, B at this moment, as does not have descrambler in the instruction of b channel, and then television set has been realized scrambling at a channel unclear image of only beating, and descrambler then obtains the descrambling parameter from the sound accompaniment of A program, next at t in the control of single-chip microcomputer ₁A channel program with input is modulated on a ' channel constantly, at t ₂Program with the b channel is modulated on a ' channel constantly, at t ₃In time, should be modulated to the program of c channel on a ' program, and the A program then with fixed channel a ' output, has been realized descrambling, and in like manner the B program also can be modulated to fixed channel a ' with it and go up output by adjusting on descrambler; Promptly a descrambler synchronization only sends a cover scrambled program, can prevent to buy a descrambler and broadcast the different scrambling program simultaneously for a plurality of users, promptly prevents to usurp the scrambled television signal.

Claims

1, a kind of scrambling apparatus of cable TV, comprise microcomputer and signal synthesis circuit, it is characterized in that: it also is provided with variable channel modulator, switching signal generator, frequency shift keying encoder, wherein microcomputer receives the TV synchronousing signal of desiring scrambling, every through a pseudorandom after the time interval, in the TV flyback, send frequency change control signal, input TV signal is wherein exported in the mode of the continuous saltus step of carrier frequency to variable channel modulator; Microcomputer sends switching command to switching signal generator, is produced switching signal and is passed to the frequency shift keying encoder by it; It also sends channel hopping parameter and customer management information to the frequency shift keying encoder, forms the descrambling parameter jointly with switching signal, and after this they and TV signal are synthetic through signal synthesis circuit, by variable channel modulator output.

2, cable TV scrambling apparatus according to claim 1 is characterized in that: its signal synthesis circuit is synthetic sound accompaniment circuit, and synthetic by television audio signals and descrambling parameter, picture signal is then directly imported variable channel modulator.

3, a kind of descrambler of cable TV comprises a single-chip microcomputer, it is characterized in that: it also establishes conversion modulator, band pass filter, FSK decoder; Wherein conversion modulator converts the same TV signal of channel hopping to fixed channel output under the control of single-chip microcomputer, and output contains the TV signal of descrambling parameter, translate the descrambling parameter and pass to the single-chip microcomputer processing by band pass filter and FSK decoder, when the descrambling parameter is with audio signal when synthetic, then this TV signal is synthetic audio signal.