JPH04137838A - Unauthorized viewing prevention circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a system for viewing on an hourly basis within the range of fees paid in advance in a pay broadcasting system, and for each viewing hour. PPV that reduces prepaid fees and pays fees (
The present invention relates to an unauthorized viewing prevention circuit that prevents unauthorized viewing of programs (Pre-Paid View).

(Prior art) In paid broadcasting, in order to prevent viewing by non-subscribers, the broadcasting provider scrambles the video and audio signals of the program, making it impossible for general receivers to receive the program. .

Then, only subscribers can descramble the scrambled programs so that they can receive them normally.

In such a pay broadcasting system, a person who wishes to receive pay broadcasting makes a contract with a broadcasting provider for each predetermined contract period, and views the contracted programs in accordance with the contract. More specifically, it is determined whether or not a received program can be viewed based on the contract details, and descrambling control (control of whether viewing is possible) of the video signal and audio signal is performed. Information indicating contract details necessary to perform this descrambling control is supplied from the broadcasting provider to the pay broadcast receiving apparatus every predetermined contract period. In the pay broadcast receiving device, information indicating the contract contents is stored and used for descrambling control.In addition, the broadcast signal is a program information packet that transmits data indicating the contract and fee payment, scrambling key information, etc. in addition to the original program information. It is included.

In the PPV contract, this program information packet is stored for a predetermined time Ts.
It receives each message, decrypts it, and generates descrambled data. At this time, calculations of hourly prices for PPV programs, etc. are also performed at the same time. This time calculation is performed using a clock supplied to the system from the outside.

Therefore, the hourly price of a PPV contract is calculated by counting this externally supplied clock with a counter, but if this clock is changed to a lower frequency, the time will be longer than the original time, and it will take a longer time than usual. You will be able to watch it. This clock is generally generated by a crystal attached externally to the IC.

As shown in FIG. 3(a), in normal lock mode, program information packets are repeatedly transmitted, and the interval, that is, the period, is a waiting time of Ts. If the program information packet is decoded and descrambled data is transmitted within this Ts time, descrambling will be performed normally.

(Problem to be Solved by the Invention) In the above-mentioned paid broadcasting system, if the externally supplied taro clock is changed to a low frequency clock as shown in FIG. If the operation is successful and the decoding and descrambling data transmission is performed within the Ts time, descrambling will be performed normally, but in this case, since the clock is of low frequency, the unit There is a problem in that the time per price becomes longer and the counter that calculates the time differs from the original time, making it possible to illegally view the video for a long time. Conversely, if the clock is set to a high frequency,
There is a problem in that the time per unit price is shortened, putting the receiver at a disadvantage.

The present invention has been made in view of the above, and an object thereof is to provide an unauthorized viewing prevention circuit that prevents unauthorized viewing caused by illegally changing the clock frequency.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the unauthorized viewing prevention circuit of the present invention calculates the time based on a predetermined clock and prevents unauthorized viewing of paid broadcasts in which the fee is paid in units of the calculated time. An unauthorized viewing prevention circuit for preventing viewing, comprising a time extraction means for extracting time information included in transmitted program information, and a change for detecting a change over a predetermined time in the time information extracted by the time extraction means. a detection means, a time calculation means for calculating the time corresponding to the predetermined time by counting the clock, a comparison means for comparing the time calculated by the time calculation means and the predetermined time, and this comparison. The gist of the present invention is to have a determination means for determining unauthorized viewing based on the result.

(Function) The unauthorized viewing prevention circuit of the present invention detects a predetermined change in time information extracted from the transmitted program information, counts clocks, calculates the time corresponding to the predetermined time, and calculates the time corresponding to the predetermined time. Unauthorized viewing is prevented based on a comparison between the time and a predetermined time.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing the configuration of an unauthorized viewing prevention circuit according to an embodiment of the present invention. In the unauthorized viewing prevention circuit shown in the figure, a program information packet containing time information data of paid broadcasting is supplied to a time/minute extraction circuit 9 via a terminal 8, and the hour/minute extraction circuit 9 converts the program information packet into a program information packet. The included time information data is extracted. Further, the clock is supplied to the counter 12 via the terminal 11, and the counter counts the time based on the tarlock, and the counting result is sent to the latch circuit 1.
4.

The time information data extracted by the hour and minute extraction circuit 9 is supplied to a time and minute change detection circuit 10, where a change in hour and minute is detected and outputs this hour and minute change signal 13.
Hour and minute data b corresponding to a predetermined time period from the previous hour and minute change to the time and minute change that has just occurred is calculated. Specifically, 1
If the last time and minute change is, for example, 2:13 p.m., and this time and minute changes to 2:14 p.m., the hour and minute change signal 13 at this time of change is output from the hour and minute change detection circuit 10. This time change signal 13 is supplied to the counter 12 and the latch circuit 14, and the count result of the counter 12 is held in the latch circuit 4 by this time change signal 13, and the counter 12 is reset to zero. The next count starts from zero. That is,
The counter 12 counts the number of tarlocks during a predetermined period of time while the time-minute change signal 13 is supplied, calculates the clock time a, holds it in the latch circuit 14, and transfers it from the latch circuit 14 to the comparison circuit 15. supply.

Furthermore, in the above example, the hour/minute change detection circuit 10 detects the difference between 2:13 p.m., the time when the hour and minute changed the previous time, and 2:14 p.m., the time when the current hour and minute changed. Hour and minute data b, which is a predetermined time, is calculated, and this predetermined data b is supplied to a comparison circuit 15 and compared with the time a from the latch circuit 14.

That is, the time/minute change detection circuit 10 detects a predetermined period of time, for example, one minute, from the hour/minute data included in the number information packet, and the counter 12 counts the number of clocks in this predetermined time of one minute. Calculate the time a according to the clock, compare both times in the comparison circuit 15,
If the time a by the clock is much larger than the predetermined time (a) or b), it is determined that the clock has been changed illegally and the frequency is much different from the standard frequency, and the descramble disabling signal is output. The information is output from the terminal 16, thereby detecting and preventing unauthorized viewing.

FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention. The embodiment shown in FIG. 1 compares the time a by the clock with a predetermined time (a (b)) instead of the comparison circuit 15 in FIG. The difference is that a comparator circuit 17 is provided for detecting the difference, and if the time a by the clock is much smaller than the predetermined time a by this comparator circuit 17,
It is determined that the clock frequency has been changed to be lower than the standard frequency, and a system error signal is output from the terminal 18, thereby informing the receiver of the abnormality and preventing any disadvantage to the receiver.

〔Effect of the invention〕

As explained above, according to the present invention, a predetermined change in time information extracted from transmitted program information is detected, and the time corresponding to the predetermined time is calculated by counting clocks, and the time corresponding to the predetermined time is calculated. Since unauthorized viewing is prevented based on a comparison between the clock frequency and a predetermined time, unauthorized viewing due to a change in the clock frequency can be reliably detected, and disadvantages to the receiver can also be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an unauthorized viewing prevention circuit according to one embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of a program information packet processing circuit. FIG. 9... Hour and minute extraction circuit, 10... Hour and minute change detection circuit, 12... Counter, 15... Comparison circuit. Acting Patent Attorney Hidekazu Miyoshi Diagram

Claims (1)

[Claims] This is an unauthorized viewing prevention circuit that calculates time based on a predetermined clock and prevents unauthorized viewing of pay broadcasts in which fees are paid in units of calculated time, and extracts time information included in transmitted program information. a change detection means for detecting a change in the time information extracted by the time extraction means over a predetermined time; and a time calculation means for counting the clock and calculating a time corresponding to the predetermined time. An unauthorized viewing prevention circuit comprising: a comparing means for comparing the time calculated by the time calculating means with the predetermined time; and a determining means for determining unauthorized viewing based on the comparison result.