CN1620139A

CN1620139A - Method of implementing interference addition or substraction to wired television signal

Info

Publication number: CN1620139A
Application number: CN 200410009550
Authority: CN
Inventors: 王晋豫
Original assignee: 王晋豫
Current assignee: Beijing Orient View Technology Co., Ltd.
Priority date: 2004-09-13
Filing date: 2004-09-13
Publication date: 2005-05-25
Anticipated expiration: 2024-09-13
Also published as: CN100385943C

Abstract

A method for scrambling/descrambling cable TV signal contains following steps A, scrambling, a, every channel video signal connected with a time base corrector, b, erasing synchronous signal and compressing black level within image level, c, making video signal slotting, front and post equalization, color synchronous erasing and random phase shifting process, d, sending video signal and original audio signal to modulator, e, completing scrambling through mixing, amplifying, distributing, sending in cable network, B, descrambling, a, descrambler selecting frequency to RF signal, b, amplifying, filtering and redemodulating selected pilot signal, c, filtering, shaping and synchronous separating, d, sending said signal to descrambler, e, obtaining data and generating control pulse and synchronization through deciphering operation, f, restoring destroyed black level and obtaining right synchronous position, g, output stable line frequency descrambling pulse and restoring video image to complete descrambling.

Description

A kind of method of cable TV signal being carried out the scrambling descrambling

Technical field

The invention belongs to the cable TV signal transmission field, particularly a kind of cable TV signal is added the mode of descrambling, belong to cable TV signal transmission and reception technique field.

Background technology

Development along with wired tv industry, the application that adds the descrambling charging administration system more and more is subjected to cable television operator's attention, because development of technology, addressable in recent years terminal shutoff type product is because fail safe and reliability are all undesirable, the market of having faded out gradually.The terminal descrambling of front end scrambling becomes mainstream technology adding on the descrambling market, classifies from the signal processing mode to cable TV, roughly can reduce analog form and digital form two big classes:

1. analog form

1) synchronous shift.Image is torn as zigzag after the scrambling, still can find out image content difficultly, only can see a long way off ability is distinguishable to go out visual general contents; Image injury behind the descrambling is bigger.

2) synchronous head suppressor mode also is a scrambling mode the most commonly used at present

The principle of this system is: the synchronous head of the multi-channel video signal method with time base correction is corrected into synchronously and homophase, again multi-channel video signal synchronous and homophase is modulated into and different cable television channels corresponding radio frequency signals, again their mixing is become No. one cable TV radiofrequency signal.This radiofrequency signal is divided into two-way, the radiofrequency signal of the arbitrary channel in a tunnel wherein is demodulated to vision signal and it is gone to separate obtain the row field sync signal, with line synchronizing signal delay time and width adjustment after, make it to become the scrambling control signal, decay with another road cable TV radiofrequency signal of this signal controlling, make that picture signal is undamped to be passed through, and synchronous head signal obtains decay, thereby realize scrambling cable TV; Line synchronizing signal delay time and width adjustment after add descrambling information and just become descramble signal, after this signal was modulated into the radiofrequency signal of specific channel, the cable TV radiofrequency signal that is mixed into scrambling with cable TV radiofrequency signal through overdamping entered cable TV network again.The process of descrambling in contrast, the cable TV radiofrequency signal that is about to scrambling is divided into two-way, the radiofrequency signal of one tunnel specific channel wherein is demodulated to vision signal, it is the descrambling control signal, if when wherein containing the data-signal that shows the descrambling of having the right, then the data bit in the descrambling control signal is masked and become correct descrambling control signal, in order to the wherein decay of the cable TV radiofrequency signal of another road scrambling of control, make the picture signal quilt than high attenuation, pass through and synchronous head signal is undamped, realize the descrambling of cable TV.(drawing from " a kind of method of cable TV scrambling and descrambling " application number 00109497.1 publication number CN1275031A)

Adopt image warping after this mode scrambling, still can find out image content difficultly, it is bigger that the scrambling degree of depth is influenced by image; Image behind the descrambling is not discovered damage substantially.

The advantage of synchronous head suppressor mode is: 1. implement simply to need not existing facility and network are transformed, help promoting; 2. the image restoring degree is good; 3. the cost performance height is easy to be accepted by the user; 4. easy to use, descrambling is reliable, and need not special operational once mandate can complete descrambling.

Its shortcoming is: can occur dangerous leaks such as residual sideband when still having compression synchronously, illegal code breaker can recover synchronous head according to it, in case the descrambler of the rear clone that is cracked can be applicable to the whole network.This threat for cable television operators is undoubtedly huge.

3) video paraphase (polarity inversion).Mainly be before front end signal enters modulator, with vision signal polarity inversion, the television image light and shade put upside down, shown color is the complementary color of primary colors, and just the image that receives of television set is a negative-appearing image.

Visual black white reverse is colored chaotic after adopting this technology scrambling, still can find out image content difficultly; Image behind the descrambling is not discovered damage substantially.

4) inhibition and video paraphase synchronously and usefulness.Image warping after the scrambling, black white reverse is colored chaotic; Image behind the descrambling is not discovered damage substantially.

2. digital form

This mode is that analog video signal is at first changed through A/D, carries out the D/A conversion again after handling through scrambling, and by sending into network after modulation, the mixing, after the user received, the process of descrambling was the contrary processing procedure of scrambling mode, makes image restoring then.

Adopt the digital processing mode to mainly contain two kinds at present:

1) row cutting rotation mode.This is after the A/D conversion signal of each row to be chosen cut point one or two at signal, then, the signal location after the segmentation is replaced, or be called rotation, the signal of each scan line is misplaced like this, and whole two field picture also just can't have been watched, reaches the purpose of scrambling.

2) the row order confuses mode, claims the row branch mode again.31,33,35,37 it is to keep under the complete situation of each row, and its row order is upset, and as the order of first field scan is: ... and just become 37,35,31,33 through confusing order after the processing ... Deng.In one, the combination of original image has just been upset, and reaches the purpose of scrambling, and in order to strengthen the scrambling effect, what have has also adopted the line displacement technology simultaneously.

In order to guarantee the reduction effect of image, row cutting rotation and row order confuse two kinds of digital processing scrambling modes all needs clock circuit accurately, therefore, generally all need to install a time base corrector, these two kinds of scrambling modes are compared, and the former handles each row signal, and the latter is the processing that scanning sequency is arranged, signal of each row is complete, so the former compares the latter clock is had higher requirement.

Adopt the digital processing mode to add descrambling, its advantage makes safe, and reduction effect is preferably arranged, and its shortcoming is that technical sophistication and cost are higher.

All to add the most commonly used at present in the descrambling mode be the synchronous head suppressor mode above, but all there is safety issue in all scrambling modes.In recent years, with the breakthrough of microelectric technique, computer technology, digital technology, the fail safe of these interference blanking systems is impacted, and the decoding accident takes place, and makes the cable television operator suffer the tremendous economic loss

Summary of the invention

The technical issues that need to address of the present invention are at existing the unsafe leak of residual sideband with analog form in the existing method that cable TV signal is added descrambling; Use digital form, to there be technical sophistication cost height, in order to overcome these weak points, and a kind of new de-scrambling method that adds proposed again, the object of the present invention is to provide a kind of method of cable TV signal being carried out the scrambling descrambling, it is the synchronizing regeneration mode, the present invention seeks to realize by the following technical solutions, a kind of method of cable TV signal being carried out the scrambling descrambling, it is characterized in that, carry out scrambling descrambling, A as follows, the scrambling of cable TV signal: a, each road vision signal is connected a time base corrector, and this time base corrector is undertaken phase-locked synchronous by same a reference source; B, synchronous laggard every trade synchronizing signal are wiped, and further destroy black level, and black level is compressed in the picture level; C, vision signal fluting, forward and backward equilibrium and colour burst are done erased and random phase moves processing simultaneously; D, each road vision signal of wanting scrambling is passed through above-mentioned processing respectively, again processed video signal and former audio signal are sent into modulator respectively; E, after being modulated into the radiofrequency signal that can transmit, again through mixing, amplification, the every processing of distribution, and then enter wired network, finish scrambling to signal; The descrambling of B, cable TV signal, a, descrambler carry out frequency-selecting to the radiofrequency signal of input, select pilot signal; B, pilot signal is amplified, carry out filtering again, carry out demodulation then; C, demodulate the vision signal that contains data and control command, after handling through filtering, shaping, carry out separated in synchronization again; D, synchronizing signal separation is sent into the descrambler control section; E, by decrypt operation, obtain data and control command, generate control impuls, produce synchronously; F, recover the synchronizing information wipe, reduce ruined black level, learn correct capable sync bit through deciphering repeatedly; G, utilize the stable line frequency descrambling pulse of digital phase-locked loop technology export, finally restore video image, finish descrambling.

The synchronizing regeneration technology has kept the advantage that synchronous inhibition scrambling mode is not destroyed picture signal, can guarantee the preferable image reproducibility.Remedied the problem that dangerous leaks such as residual sideband can appear in synchronous suppressor mode simultaneously.

The invention has the beneficial effects as follows that this method has greatly improved the level security of system in the advantage that the existing synchronous inhibition scrambling de-scrambling method of reservation is had.

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

Description of drawings

Fig. 1 is a theory diagram of the present invention.

Fig. 2 is the scrambling circuit schematic diagram of a kind of embodiment of the present invention.

Fig. 3 is the descrambling circuit schematic diagram of a kind of embodiment of the present invention.

Embodiment

With reference to Fig. 1, represent theory diagram of the present invention.Among the figure, 1 represents the scrambling machine, total n group, be respectively the synchronous scrambling machine of signal source a, signal source b, signal source n, 2 organize corresponding modulator for each, and 3 is the toll administration computer, and it is connecting addressing main frame 4, the limit is to data modulator 5 again, together linking

blender

6,7 with modulator is cable TV network, is connected to user's descrambler 8 after the network, the descrambler that comprises user a, user b, user n respectively, 9 is corresponding each user's television set.In descrambler 8,8.1 is the radio frequency input module, and 8.2 and 8.3 is amplification module, and 8.3,8.4 for amplifying output module, and 8.5 are the frequency-selecting amplification module, and 8.6 is demodulation module, the 8.7th, and single-chip microcomputer, the 8.8th, synchronous head regeneration module.

With reference to Fig. 2, represent the scrambling circuit schematic diagram of a kind of embodiment of the present invention, it links to each other with each road signal source and each road modulator respectively corresponding to the position relation of mark square 1 among Fig. 1.

With reference to Fig. 3, the descrambling circuit schematic diagram of representing a kind of embodiment of the present invention, it is corresponding to the position relation of mark square 8 among Fig. 1, include radio frequency input module 8.1 respectively in this figure inside, amplification module 8.2,8.3 amplifies output module 8.4, frequency-selecting amplification module 8.5, demodulation module 8.6, single-chip microcomputer 8.7 and synchronous head 8.8.

Claims

1, a kind of method of cable TV signal being carried out the scrambling descrambling, it is characterized in that, carry out the scrambling descrambling as follows, the scrambling of A, cable TV signal: a, each road vision signal connected a time base corrector, this time base corrector by same a reference source carry out phase-locked synchronously; B, synchronous laggard every trade synchronizing signal are wiped, and further destroy black level, and black level is compressed in the picture level; C, vision signal fluting, forward and backward equilibrium and colour burst are done erased and random phase moves processing simultaneously; D, each road vision signal of wanting scrambling is passed through above-mentioned processing respectively, again processed video signal and former audio signal are sent into modulator respectively; E, after being modulated into the radiofrequency signal that can transmit, again through mixing, amplification, the every processing of distribution, and then enter wired network, finish scrambling to signal; The descrambling of B, cable TV signal, a, descrambler carry out frequency-selecting to the radiofrequency signal of input, select pilot signal; B, pilot signal is amplified, carry out filtering again, carry out demodulation then; C, demodulate the vision signal that contains data and control command, after handling through filtering, shaping, carry out separated in synchronization again; D, synchronizing signal separation is sent into the descrambler control section; E, by decrypt operation, obtain data and control command, generate control impuls, produce synchronously; F, recover the synchronizing information wipe, reduce ruined black level, learn correct capable sync bit through deciphering repeatedly; G, utilize the stable line frequency descrambling pulse of digital phase-locked loop technology export, finally restore video image, finish descrambling.