KR100693688B1 - Method for preventing interference with conditional access module in digital broadcasting system - Google Patents

Abstract

The present invention relates to a method for preventing interference between conditional access modules in a set-top box of a digital broadcasting system, wherein at least two conditional access modules for descrambled scrambled digital broadcast streams are provided. A method of controlling a set-top box of an embedded digital broadcasting system, the method comprising: resetting a state value of a conditional access module and determining whether the first conditional access module is inserted in hardware, and if the first conditional access module is inserted in hardware, Setting a state value of the box to the bypass state by software, determining whether the first conditional access module is forcibly removed by the user within a preset time, and removing the first conditional access module within the preset time. Set-top box software through Setting to a state, determining whether the second conditional access module is inserted in hardware while the first conditional access module is inserted, and if the second conditional access module is inserted in hardware, the second conditional access module Setting the bypass condition in software and determining whether the first conditional access module is removed, and setting the second conditional access module in software through state when the first conditional access module is removed. do. According to the present invention, interference between at least two cams in a set top box of a digital broadcasting system can be eliminated, and more stable system state transition can be realized.

Set Top Box, CAM, Descramble, Bypass, Through Pass

Description

How to prevent interference between conditional access modules in set-top boxes of digital broadcasting systems {METHOD FOR PREVENTING INTERFERENCE WITH CONDITIONAL ACCESS MODULE IN DIGITAL BROADCASTING SYSTEM}

1 is a schematic block diagram of an internal set-top box of a digital broadcasting system for implementing a method for preventing interference between conditional access modules according to the present invention;

2 is a flowchart of a process for preventing interference between conditional access modules in a set top box of a digital broadcasting system implemented according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: tuner 102: demodulator

104: CI control unit 106: CI module

108: Cam 110: Demux

112: MPEG decoder 114: CPU

116: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a set top box in a digital broadcasting system, and more particularly, to a digital broadcasting system suitable for preventing interference between a conditional access module (CAM) through bypass control. A method of preventing interference between cams in a set-top box.

Digital broadcasting is gradually being activated due to the commercial advantages of broadcasting a much wider range of channels than digital channels, and various functions such as high image quality, sound, interactive services, and internet access.

Accordingly, the digital set-top box industry is growing mainly in the United States and Europe, and is showing high growth in the Middle East and Asia due to the introduction of the digital broadcasting.

Digital broadcasting is mainly led by pay-TV operators, and the set-top box market is directly purchased by pay-TV businesses. In terms of technology, digital set-top boxes are designed to digitally code analog content at the broadcasting station so that the broadcast signal can be viewed on a regular TV through a satellite or cable ground. .

However, since the above process requires complicated processing, a technical problem may be raised in order for a broadcaster to supply various broadcast services. This is a matter of broadcasting standards, and the standards currently adopted by the world's largest broadcasters are the European standard DVB (Digital Video Broadcasting) or the US Direct Dict TV's own DSS (Digital Satellite Service). Various criteria are defined.

In addition, a conditional access system (hereinafter referred to as CAS) for conditionally accessing a transport stream, i.e., a digital satellite broadcast signal (Transport Stream), that restricts reception so that only subscribers can receive it in pay-TV. More than 10 companies compete, including Guard, NDS, and Viaccess.

Such CAS refers to a conditional access device for a digital satellite broadcasting set top box, and is responsible for a paid reception function of digital satellite broadcasting.

In this case, in order to transmit and receive only a specific satellite broadcast signal, that is, to protect the digital broadcast content, MPEG packets may be scrambled and transmitted for a specific satellite broadcast signal, and descrambled by the receiver so that the viewer can view the broadcast content. Will be.

This descrambling function is accomplished through a "cam" in the form of a card, and these cams are connected to a common interface (hereinafter referred to as CI) module and via which the first encrypted satellite broadcast signals are decrypted and then demultiplexer. The broadcast content finally transmitted through the MPEG decoder or the like is displayed to the user.

Here, the cam is a pay broadcasting module which is inserted (or connected) into the set-top box of the digital broadcasting system, and more specifically, the PCMCIA of the CI module. The cam is intercepted and decoded from the tuner to the chip. The module to execute. That is, as described above, the digital broadcasting system performs a scrambling operation to intentionally change the frequency so that the TV cannot be watched when a pay TV signal is transmitted. Descrambling is applied to the set-top box.

Cams are classified into various types according to the method of scrambling broadcast signals. For example, cams are designed according to viases, nagravision, conax, and cryptoworks. Each method is not compatible with each other. In order to eliminate such incompatibility, the set top box has a cam mounted on the outside, and the CI is defined between the cam and the set top box. Accordingly, the viewer only needs to connect the smart card provided by the broadcaster to the cam, and does not need to separately consider the scrambling method of the cam.

On the other hand, the general CI specification requires a setting process to allow the bypass stream to pass through the cam when the cam is inserted to some extent, which is specified to be performed unconditionally in the CI specification.

Even if two or more cams are inserted, the stream is set to pass through all the cams according to the CI specification. Conventionally, the stream has to be passed on the first cam among all cams that are allowed to pass or descramble. It is set to pass.

However, in actual operation, interference may occur between cams due to stream frequency modulation in a specific cam.

This means that no-zap CAMs on the market can adversely affect other cams receiving streams at their next location, and in the worst case, these effects may cause This causes the stream to disappear and not reach the main chip.

The present invention has been made to solve the above-mentioned problems of the prior art, by software control of the bypass in the initialization process of resetting the cam in the CI module that is used two or more cams only one of the two cams It is an object of the present invention to provide a method for preventing cam-to-cam interference in a set-top box of a digital broadcasting system, by setting the stream to pass therethrough.

Another object of the present invention is to set the set-top box to bypass in the initial stage when one cam is inserted, and then to thrupass when the cam is not removed for a certain time. By setting up, a method for preventing cam-to-cam interference in a set-top box of a digital broadcasting system implementing stable system state transition is provided.

According to an embodiment of the present invention for achieving this object, a set-top box control method of a digital broadcasting system in which at least two conditional access modules for descrambling a scrambled digital broadcast stream are inserted. Resetting and determining whether one conditional access module is inserted in hardware, and if the one conditional access module is inserted in hardware, setting the state value of the set top box to the bypass state in software; Determining whether the one conditional access module is forcibly removed by a user within a preset time, and if the one conditional access module is not removed within the preset time, setting the set-top box to the software through-pass state. And, the one above Determining whether the other conditional access module is inserted in hardware while the conditional access module is inserted; and if the other conditional access module is inserted in hardware, the other conditional access module is software-installed. Setting a bypass state to determine whether the conditional access module is removed, and if the conditional access module is removed, setting the other conditional access module to a software through state. Provides a method of preventing interference between conditional access modules in a set-top box of the present invention.

According to another embodiment of the present invention, a set-top box control method of a digital broadcasting system in which at least two conditional access modules for descrambling a scrambled digital broadcast stream are inserted, wherein a plurality of conditional access modules are inserted at the same time. Setting the second conditional access module to the reserved state while setting the first conditional access module to the bypass state by software; determining whether the first conditional access module is removed within a preset time; If the first conditional access module is not removed within the time period provides a method for preventing interference between conditional access modules in the set-top box of the digital broadcasting system comprising the step of setting the first conditional access module in the software through-pass state.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Prior to the description, the technical gist of the present invention allows a stream to pass through only one cam until the broadcast is descrambled if an illegal cam exists between two inserted cams, and decryption does not succeed even after a certain time. In the case of a forced cam removal, the bypass setting is changed so that the stream passes through only another cam, that is, the stream path switching operation is repeated alternately until the decoding succeeds. It will be easy to see what the purpose is.

1 is a schematic block diagram of a digital broadcasting system for performing a method according to the present invention, in which a tuner 100 for frequency tuning a received digital broadcast stream and a digital broadcast tuned by the tuner 100 are shown. A demodulator 102 is provided for demodulating the stream to detect the first broadcast stream signal. However, the received digital broadcast stream is scrambled in a predetermined manner, and the digital broadcast stream passed through the tuner 100 and the demodulator 102 is also scrambled.

As such, the digital broadcast stream passing through the tuner 100 and the demodulator 102 is descrambled through the CI control unit 104, the CI module 106, and the cam 108, followed by a demultiplexer (DEMUX) 110. Is synthesized into a single channel by the multiplexer of the first broadcasting station, and the digital broadcast stream separated by the demultiplexer 110 is decompressed by the MPEG decoder 112 and finally transmitted to the digital room. The song stream, that is, the broadcast content is displayed to the user.

At this time, the cam 108 serves to decrypt the encrypted digital broadcast stream, and this cam 108 is connected to the PCMCIA slot of the CI module 106, and the CI control unit 104 is connected to the CI module 106. It controls the operation.

The CI controller 104 executes each program corresponding to the type of the cam by the information stored in the memory 116 to decode the digital broadcast signal, and the CPU 114 uses the cam information table stored in the memory 116. It identifies the type of the cam and delivers it to the CI controller 104.

Here, only one cam 108 is shown for convenience of description, but a plurality of cams may be connected according to an applied product, and the following embodiments will be described as being limited to the case where two cams are connected.

Hereinafter, the above-described configuration will be described in detail with reference to a flowchart of FIG. 2 attached to an inter-cam interference prevention process in a set-top box of a digital broadcasting system according to an exemplary embodiment of the present invention.

First, in step S200, the CI control unit 104 resets the cam state value and proceeds to step S202. This cam state reset process is an initialization process to prevent the CI stack software from becoming unrecoverable when the bypass setting is forcibly changed during normal operation of the cam, that is, when the stream path is changed from the first cam to the second cam. By default, the cam is not inserted into the set top box.

In step S202, the CI control unit 104 determines whether the first cam is inserted in hardware. That is, it is determined whether one cam is inserted into the set top box by the user.

As a result of the determination in step S202, if the first cam is inserted in hardware, the CI control unit 104 proceeds to step S204 to set the state value of the set top box to the bypass state in software. In other words, the present step (S204) is not yet a state that the stream passes to the first cam.

At this time, the CI control unit 104 determines whether the first cam is forcibly removed by the user within a predetermined time, as in step S206, and if the first cam is not removed within the predetermined time, the CI control unit 104 performs the step. Proceeding to step S208 and step S210, the set-top box is set to the through-pass state by software and is switched to the insertion completion state.

That is, in this embodiment, even if one cam is inserted into the hardware, the stream does not go straight to the cam, but the stream passes only to the cam only if the cam is not removed within a certain time. To set. This allows for more reliable system state transitions.

Meanwhile, in step S212, the CI controller 104 determines whether a second cam, for example, an illegal cam, is inserted in hardware while the first cam is inserted. That is, it is determined whether another cam is additionally inserted while one cam is inserted into the set top box.

If the second cam is inserted in hardware, the CI control unit 104 proceeds to step S214 to set the second cam to the bypass state in software.

At this time, the CI control unit 104 determines whether the first cam is removed (S216), and if the first cam is removed, the CI control unit 104 proceeds to step S218 and step S220 to software the second cam. In general, the apparatus changes to the through-pass state and sets the second cam to be inserted. In other words, the stream is set to pass to the second cam.

On the other hand, one cam may be inserted into the set top box followed by another cam, but there may be cases where two cams are inserted into the set top box at substantially the same time with a slight time difference.

The process after step S222 takes this case into consideration. First, the CI control unit 104 determines whether the first and second cams are inserted at the same time as in step S222, and the first and second cams are simultaneously inserted. If it is inserted, the process proceeds to step S224.

In step S224, the control unit 104 sets the first cam to the bypass state by software. That is, as described above, the first cam is forced to not pass the stream yet.

At this time, the CI control unit 104 sets the second cam in the reserved state as in step S226. That is, even if two cams are inserted at the same time, the stream is not passed through the two cams, but only one cam is set to pass the stream so that interference between the cams does not occur.

Subsequently, the CI controller S104 determines whether the first cam is removed within a predetermined time in step S228, and if the first cam is removed within a predetermined time, the process proceeds to step S236, but the first cam is removed within the predetermined time. If not, the CI control unit S104 proceeds to step S230 and step S232.

In step S230 and step S232, the CI control unit 104 switches the first cam to the through-pass state by software and sets the first cam to be inserted.

Meanwhile, in step S234, the CI controller 104 determines whether the first cam is forcibly removed by the user, and if it is determined that the first cam has been removed, the CI controller 104 proceeds to step S236. 2 Set the cam to bypass by software. In this case as well, the removal of the first cam does not set the through-pass state so that the stream passes directly to the second cam, but is preceded by a bypass state in which the stream does not pass through the second cam.

In step S238, the CI control unit 104 determines whether the second cam is removed within a predetermined time, and if the second cam is not removed within a predetermined time, the CI control unit 104 proceeds to step S240 and the second cam is removed. Switch to the through-pass state by software to set the second cam as inserted.

However, if the second cam is removed within a predetermined time, the process returns to step S200 to reset the cam state value.

As described above, the present invention implements such that only one cam of the two cams passes through the stream by software control of the bypass in the initialization process of resetting the cam in the CI module using two or more cams. In the initial stage of insertion, the set-top box is set to bypass by software and is set to through-pass only when the cam is not removed for a certain time.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, it will be apparent to those skilled in the art that the number of the cams is not limited, and the present invention can be implemented by modifying the number of cams according to the product. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

According to the present invention, interference between at least two cams in a set top box of a digital broadcasting system can be eliminated, and more stable system state transition can be realized.

Claims (7)

A method of controlling a set-top box of a digital broadcasting system in which at least two conditional access modules for descrambling a scrambled digital broadcast stream are inserted. Resetting a state value of the conditional access module and determining whether one conditional access module is inserted in hardware; Setting the state value of the set-top box to the bypass state in software if the conditional access module is inserted in hardware; Determining whether the conditional access module is forcibly removed by a user within a preset time, and if the conditional access module is not removed within the preset time, setting the set-top box to the software through-pass state; Determining whether another conditional access module is inserted in hardware while the conditional access module is inserted; When the other conditional access module is inserted in hardware, setting the other conditional access module in a bypass state by software and determining whether the conditional access module is removed; When the conditional access module is removed, setting the other conditional access module to the software through-pass state. Method of preventing interference between conditional access modules in a set-top box of a digital broadcasting system comprising a. The method of claim 1, The method may further include resetting the state value if the first conditional access module is forcibly removed by the user within the preset time. . The method of claim 1, The bypass state is a state in which a stream passes to the conditional access module, the through-pass state is a state in which the stream does not pass to the conditional access module, the method of preventing interference between conditional access modules in a set-top box of a digital broadcasting system. . A method of controlling a set-top box of a digital broadcasting system in which at least two conditional access modules for descrambling a scrambled digital broadcast stream are inserted. When the plurality of conditional access modules are inserted at the same time, setting the second conditional access module to the reserved state while setting the first conditional access module to the bypass state by software; Determining whether the first conditional access module is removed within a preset time, and if the first conditional access module is not removed within the preset time, setting the first conditional access module to a software passthrough state; Method of preventing interference between conditional access modules in a set-top box of a digital broadcasting system comprising a. The method of claim 4, wherein The method, If the first conditional access module is forcibly removed by a user, setting the second conditional access module to the bypass state by software; If the second conditional access module is not removed within the preset time, setting the second conditional access module to the software through-pass state. Method for preventing interference between conditional access module in the set-top box of the digital broadcasting system further comprising a. The method of claim 4, wherein The method may further include resetting the state value if the second conditional access module is forcibly removed by the user within the preset time. . The method of claim 4, wherein The bypass state is a state in which a stream passes to the conditional access module, the through-pass state is a state in which the stream does not pass to the conditional access module, the method of preventing interference between conditional access modules in a set-top box of a digital broadcasting system. .

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