JPS60171883A - Charged television equipment - Google Patents

Abstract

PURPOSE:To transmit a key code in a ciphering form depending on each terminal by encoding information which solves a terminal key code, storing it in a memory abd storing a decoding program in a ROM on a chip. CONSTITUTION:A transmission center 11 of satellite broadcast transmits a signal to a stationary satellite 13 via a parabolic antenna 12. A reception antenna 14 transmits a signal received from the broadcast satellite to a receiver 16 via a low noise converter 15. An IDU19 of the receiver 16 amplifies, detects the signal and outputs a signal of the base. A data processing circuit 20 extracts and processes a digital signal in the ouptut and applies it to a descrambler 21. The descrambler 21 switches inversion or non-inversion of an image and rearranges each bit of the sound digital signal and restores the result into the normal video image and sound.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pay television system that prevents regular video and audio from being provided to subscriber terminals that do not pay fees in an ATV system or the like.

Conventional configuration and its problems In the conventional 0ATV system, a key code is included to prevent eavesdropping, but the key code for breaking the encryption changes every month, but it is common to all terminals. It was something. Therefore, it was relatively easy to operate a paid terminal, read the key code from it, and use it to spy on other terminals.

First, the configuration of such a conventional example is shown in FIG.

In the figure, 1 is the center computer of the CATV station,
The CATV center 2 manages the subscriber's viewing fee payment status, the specification of broadcast programs according to the subscriber's wishes, and the creation of control codes. Send. 3B is the head end, and sends out multiple video signals from the CATV center 2 in parallel to the IHF midband. 3B is the back 1 circuit that receives upstream signals from each terminal, and the head end 3M and C) , the tuner/converter 4 on the terminal side of the TV and the buffer circuit aB are connected by the same cable or a separate cable.Also, a telephone line may be used instead of the cable from the tuner/converter 4 to the buffer circuit 3B. good.

4 is a tuner or converter on the terminal side that converts the mid-band signal to one channel of VHF (also two channels of Fi), and according to the command from the keypad 6, converts one channel of the mid-band (liATV signal) to VHF. Convert to 1 channel.In addition, 0AT
If the V signal is scrambled, convert it to a baseband signal, descramble it, and then convert it again to a baseband signal.
In some cases, the signal is converted into one signal and output as a one-channel VHF signal.

Reference numeral 6 denotes a television receiver that receives a normal VHF band.

A viewer applies for a desired program (charged) to the center computer 1 by operating the keypad 5 or via the telephone 7. At the center 1, charges are set for each terminal, and if the terminal is scrambled, the decoding key code is sent in the order of the center computer 1 → CATV center 2 → head end 3 → converter/tuner 4. There are many tuners/converters 4 to telephones a that descramble using this key code, play back the normal image NTSG video signal, convert it to VHF01 channel, and supply it to the television receiver e. A telephone office is interposed between the device T and the telephone interface 8. The telephone interface 8 generally allows a human to listen to requests from each terminal and convert them into input form for the center computer 1. This is an example.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a pay television device which eliminates the above-mentioned conventional disadvantages and whose key code is difficult to read, thereby effectively preventing surreptitious viewing.

Structure of the Invention In the pay television device of the present invention, billing information corresponding to the content of the program watched is received in the form of a digital signal at regular time intervals, and the terminal receives the billing information in the form of a digital signal at regular intervals. In a device that determines and stores the charge amount in a charging amount determination circuit in the receiving device, and reads out and displays charge data proportional to the amount as necessary, the unique address assigned to each terminal is In addition to encrypting it using the encryption method 1 and storing it in a memory such as FILM,
The information encrypted by the second encryption method and used to decode the terminal key code is encrypted by the first encryption method and stored in a memory such as a ROM, and the main program is to decode the first encryption method. Memo IJK such as ROM on the control microprocessor chip is stored.

This makes it possible to send a key code in a different encryption format to each terminal, effectively preventing unauthorized viewing of the key code.

DESCRIPTION OF EMBODIMENTS An embodiment in which the present invention is applied to a satellite broadcasting system will be described below with reference to the drawings.

First, FIG. 2 shows an example of a satellite broadcasting system.

In the figure, 11 is a satellite broadcasting transmission center, which is called a DSB center. 12 is a large parabolic antenna that sends signals to a geostationary satellite 13. 13 is a geostationary satellite, which is a broadcasting satellite that relays signals sent from the ground and retransmits them to the ground. 14 is a receiving antenna installed on the ground. 16 is a low noise converter, for example, the received 1
The 2GH2 band signal is converted to an IGHz band signal and transmitted to the receiver 16. 19 in the receiver 16 is called an IDU, and converts, for example, a 1 GHz input into a 400 MHz 21F signal, amplifies it, detects it, and outputs a baseband signal.

2o is a data processing circuit that extracts the output digital signal, processes it, and supplies it to the descrambler 21.

Assume now that the video signal is scrambled using a method of synchronized shifting and randomly inverting the video components, and the audio is scrambled using a method of randomly changing the bit arrangement using digital audio. The output of IDU19 is part one! When projected on the CRT of the color television receiver 17, the brightness of the screen is inverted and horizontal.

Since vertical synchronization cannot be achieved, the content flows and the content is unclear. Also, if you listen to the voice as it is from the speaker, it becomes noise. Therefore, the descrambler 21 switches between inverting and non-inverting the video based on the output of the data processing circuit 20.
Additionally, each bit of the audio digital signal is rearranged to restore (descramble) normal video and audio. In the human/V regeneration circuit 22, only the horizontal retrace period during the output of the IDU 19, that is, the portion from t1 to t2 in FIG.
By changing the C level, the output of the descrambler 21 (
It is synthesized with the part t2 to t11 of Fig. 3C), reproduces the original video signal (person in Fig. 3), and descrambler 21
Converts the output digital audio signal to an analog audio signal.

The output of this A/V reproducing circuit 22 is converted to Vl by an RF modulator 23.
(If you convert it to an appropriate F-band channel signal and supply the output to the antenna input of a normal color television receiver, you can watch the scrambled video and audio in their descrambled state.

If you want to watch such scrambled video and audio back to normal images and sounds, you often have to pay a fee. If there is a charge, the charge is indicated by a control digital signal superimposed on the vertical blanking period (VBL) of the video signal of the program, and the charge is recorded in the memory within the receiver. Generally, if you receive 2 to 10 minutes or more of a certain program, you are often required to pay for the entire program.

To pay the fee, for example, add a card reader to the data processing circuit 2o in Figure 2, insert the purchased card (such as a coupon ticket) into it, and check the amount paid. Data processing circuit 2 only for the time corresponding to
There is a method of sending a descrambling control signal from o to the descrambler 21. Alternatively, please contact the bank 18 in advance.
Pay the fee in advance to DB and save the prepaid fee as data.
A code representing the paid fee is sent from the S center 11 to each terminal (individually assigned an address) via the geostationary satellite 13, and the fee code is written in the memory of the terminal. Change the rate code in (
There is also a method in which the money is paid back to the bank 18 and the above procedure is repeated when it becomes OJ.

Now, here, the contents of the data processing circuit 2o in FIG. 2 are configured as shown in 31 to 60 in FIG. The fee corresponding to the viewing time is written in a nonvolatile memory according to the fee data, the viewing fee is paid to the bank every month, and the paid fee is polled from the DBS center 11 for each terminal (each address) and sent to the memory 47. In this method, the content of the memory 47 is reduced to make it impossible to watch pay programs from the next month unless the content of the memory 47 becomes FOJK. This is a binarization circuit for shaping the pulse signal into a pulse waveform as shown in the leftmost part of FIG. 5B. 32 is a clock detection circuit; Byte tv "1.1. Using the repeated chrono-cran signal OR (Cp, ock Run) of the "o" signal, synchronize with it and regenerate o, ri, the 8th of the framing code signal FC in the received signal B Frame synchronization is established by detecting the framing code at the th bit, and the sampling clock generated by the sampling clock generation circuit 33 is synchronized with the received signal B. 33 is a circuit that forms a sampling clock with an appropriate phase controlled in this way, and its output is divided by a main clock generation circuit 34 and then sent to a work RAM 37. It forms a main clock that drives the work ROM 3a, center processing unit (CPU) 39, etc.

FIG. 6B from the output of the sampling clock generation circuit 33
A clock synchronized with each bit of the received signal B is supplied to the sampling circuit 35, and each pit of the received signal B is sampled. It is difficult to operate the work RAM 37 to CPU 39 in FIG. 4 during this cycle of the received signal B.

Furthermore, when an 8-bit microprocessor is used as the CPU 39, it is more convenient to handle the received data as 8-bit parallel signals. Therefore, the sampling circuit 36
A serial input/parallel output type shift register such as 5N74LS164 is suitable. If the output is stored in the latch circuit 3e every 8 bits with the 8th bit of the framing code as a reference, the output will change in 8 bits in parallel at a cycle of 87-14 μB.

The period 1i is suitable for the operation of each circuit. Its output is connected to pass line 4o.

3rd is CtPU39's work RM M138 is ap■39
The work 1'tOM is υ, and the CPtT39 is an 8-bit microprocessor (for example, MBesoelC).

Now, in Fig. 5, the control code 'O+C1~C in the received signal B
To explain about 7, false and 01 are "1".

It is the clock run signal OR of the repetition of rOJ, and C2
is a framing code signal of "111oo1o1". C5 is 4 bits of information and mink check code 3
It consists of one bit and one parity bit.

The data after C4 also has the same structure for each byte. The contents of the information sections of C5 and C4 are summarized in Table 1. Here, only three types necessary for explanation are described. In reality, several types or more are possible.

Similarly, Table 2 shows the contents of the 4-bit information section of 05.

(Left below) Table 1 Table 2 In the case of satellite broadcasting, the 8 bits of C5 and C4 are “01oO
o00o” and C5 is “1oOoJ.

Either "0100" or "11oo" is used.

FIG. 5C shows a case where 28 bytes of data in the received signal as shown in FIG. 6M is program data. A number indicating the type of program is represented by a 4-byte, 4-digit BCD code as a tag code. Therefore, 9999 types can be specified.

The next keyword is a key code that changes every month. This key code is essential for descrambling the received signal on the terminal side, and this key code will not be sent from the DBS center to terminals that do not pay the fee. You can prevent reception by doing so. For example, assume that the fee payment deadline is the 20th of every month, and the key code is changed from the 1st of every month. Since the receiver 16 in FIG. 2 is always energized, it continues to operate unless the power cord is disconnected.

The next charge code is 4 bytes and contains 4 digits of BCD information. The charge code changes over time, and a charge proportional to the time the program was viewed (the time it was displayed on the CRT) is recorded. This content will be described in more detail later.

The next PN key represents the initial value of the PN code for descrambling the scrambled signal using 4 bytes (16 pits as information).

The first safety measure is to prevent eavesdropping using the PM key.

For the next month and day, the month is represented by two digits in BCD and the day is represented by two digits in B (3D), so 8004 digits, or 4 bits of information in 4 bytes x 4, are used. The digit BCD and minute are also expressed in 2-digit BCD.The above is the content for the program data packet (Os is "1").

Next, when C5 is "2"("oolo") indicating that scrambled data is being sent, how can all 28 bytes (of which 14 bytes are information data) be sent as data? 14 bytes of information therein are written to a predetermined location in the work RAM. This data has different contents for each program. There are various possible contents and uses for the scrambled data, but they will be omitted here.

Next, when C5 is "3"("0o11"), the address data packet is sent in 28 bytes as shown in C. This address data packet is 1 as shown in Figure 6C.
The packet contains addresses indicating two terminals. This C is shown enlarged in FIG. When the first 14 bytes are enlarged, they look like Figure 6. The information bits in the first half γ byte of D are 28 bits out of 7 bytes, which is 228, or about 2. C800 million terminal addresses can be distinguished.

The latter 8 bytes are divided as shown in Figure 6E. E indicates only information bits, that is, 32 bits out of 8 bytes. The 2 bytes at the front end of E (1 byte if only information) is used to send up to 2 instructions from the DBS center to each terminal.
This is for sending up to 66 types, for example, "1" as shown in Figure 6.
” indicates the total amount of pay TV that the terminal has watched so far. If the amount is in 26 cent increments, 210
C8-0, 12 bits (3
(1.6 bytes of information in a byte of data). Therefore, when clearing the charge, the amount (up to 1023
($76 cents) code is sent to each terminal, and the amount paid to the bank by each terminal owner is sent separately from the DBS center to each terminal to change the contents of the terminal's non-volatile memory 47.

The nonvolatile memory 47 will be briefly explained. The fee for the program currently being received is stored in the memory 41 at regular intervals, and is added up as the amount data. When the reception of the program is finished, the contents of the memory 41 and the contents of the memory 43 are added by the addition/subtraction register 46, and the result is stored in the memory 43. Then, the contents of the memory 43 are transferred to the memory 44 using a code sent from the sending side on a fixed day every month (or within a fixed period from that day) to the memory 44, and the contents of the memory 44 are transferred to the CI'tTs2. to be displayed. Since the output of the memory 44 represents the monetary amount in binary numbers, it is converted into a numerical pattern by the character generator 38B, and the numerical pattern is stored in the brightness memory 49. A write/read address for the brightness memory 49 is formed by an address circuit 5o. Reading of the brightness memory 49 is performed in synchronization with the scanning of the electron beam of 0RT62. The output of the luminance memory 49 and the output of the M/V reproducing circuit 22 are mixed (superimposed) or switched by the buffer 1 amplifier 61, and the payment amount is displayed on the CRT 62 either superimposed on the TV program screen or as a screen with only numbers.

When the terminal owner pays the displayed amount to the bank, DBL
The payment amount is sent from the computer 11 together with the address code in the form shown in FIG. 6E. The charge is clear for Metsu 7, and the charge is expressed by the 12 bits Co to Ca1 in co'' C23 in FIG. 7, which are obtained by decoding bo=b25 of E.

This data is written to the memory 41 in FIG.
If the two match, a match flag is formed in the flag register 46, and if the memory 41 is larger, a flag of ○ is formed in the flag register 46, and if the memory 41 is smaller, the Form a flag. ■When flagged, use the difference as a new memory 44
and display it on the insufficient charge fcRT62. When the flag is e, the value after the above subtraction is set as a negative number and added to the contents of the memory 43 using the addition/subtraction register 45. If the result is positive, the result is newly stored in the memory 43 and the flag register 46 indicates that the result is normal. Set a flag, and if the result is negative, set the overpayment flag to flag register 4.
6, and the resulting numerical value (absolute value) is newly written to the memory 43. From then on, the fee for the paid program is recorded in the memory 41, and when writing from the memory 41 to the memory 43,
The content of is set as a negative number, multiplied with the content of the memory 41, and an overflow flag whose result is positive is left.

Table 3 shows a list of flags created in the flag register 4e.

(Left below) Note that after the content of the memory 43 is transferred to the memory 44 using the charge display code, the memory 43 becomes zero once, and thereafter, each time a pay program is finished watching, the pay program from the memory 41 is transferred from the memory 43 to the memory 43 to receive the next period's pay program. It will be added to the total fee.

If memo 1747.53 is configured with non-volatile memory and the circuits 37 to 39 are supported by the battery for a short time when the power is turned off, the contents of memory 41 will be added to memory 43 when the power is turned off, and the power will be turned on again. If the previous information is not left in the memory 41, errors in charges for pay programs will not occur.

On the other hand, the memory 53 is also configured with a non-volatile memory, and the kill code and the date (time) of writing to the memory 47 are written therein. The memory 63 stores the date and time of data writing to the memory 47, and if the payment is mistakenly paid in two or more installments, the data will be correctly written to the memory 47 for the first, second, etc. It is used to manage such things.

Next, the key code will be explained. The key code is 12
PM system of (212-1) consisting of bits The generator polynomial that constitutes two sequences is shown. For example, [0110000100
If 01J and the key code are sent, the generator polynomial will be x''+x'+x2+x=f(x).

Instead of 12 bits, it may be a polynomial of 11 bits or less. Alternatively, the key code may be 16 bits and Go-C10 shown in FIG. 7 F2 may be used.

Next, we will discuss eavesdropping prevention in detail. The simplest method is to allocate 24 bits of calculation data to each terminal and write this into the ROM 38A along with a 28 bit address number according to a fixed rule. It is assumed that the work ROM 38A is different for each terminal. A program for correctly reading the addresses and calculation data in the work ROM 38A is stored in the program ROM in the CPU 39, and the CPU 39 reads the addresses and calculation data from the ROM 38A and stores them in a part of the work ROM 37. It is sufficient to have as many as 1,000 types of calculation data.

:As for the operation of the Chin transmitter, in order for a terminal to become valid, it is necessary to receive the address code of that terminal. It is assumed that the polling will be described later, and that the address of terminal X and the current month key as shown in FIG. 6 have been sent. Matching of the address codes is determined by the internal program of cptras, and as mentioned above, the address in the ROM 38A cannot be easily read without going through the CPU 39, so the second security against eavesdropping is performed at this stage. . Next, the exclusive OR of the current month key code in FIG. 6E and the calculation data is taken, and this is set as Co-C25 in FIG. 7 F2. The 12 bits of an""all are the aforementioned key code. The calculation is not limited to exclusive OR, but data may be shifted a predetermined number of times using boz b25 in FIG. 6E as a coefficient of the generator polynomial as an initial end. The third level of safety is achieved by performing calculations to obtain the key code. The video and audio are decoded using this key code and the keyword shown in FIG. 6C. The video is pseudo-randomly reversed field by field, and the audio is gauged)
If it is converted into a file, it is almost impossible to decipher it. Is the image reversed?
If non-inversion is determined by a key code, it changes from time to time and cannot be eavesdropped.

Furthermore, if the ROM 38A is made replaceable with a socket, it is easy to change the address of the terminal in the event of a failure.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) A pay TV system can also be configured in a one-way transmission system.

-(2) Fees are charged in proportion to the actual viewing time of paid programs.

(3) Eavesdropping is difficult.

(4) By changing the viewing time in the minimum unit of time without changing the minimum unit of charge, the unit price of one program can be determined in small increments.

(→ Good compatibility with the US teletext system, etc.

[Brief explanation of drawings]

Figure y'h1 is a block diagram of a conventional pay television system, Figure 2 is a block diagram of a pay television system in which the pay television broadcasting device of the present invention can be implemented, and Figure 3 is a waveform diagram of a video signal in the same system. , FIG. 4 is a block diagram of a pay television device according to an embodiment of the present invention, and FIG.
6 is a waveform diagram of a signal used in the receiver, and FIG. 7 is a waveform diagram of a code used in the receiver. 11...DBS center, 12...Large parabolic antenna, 13...Geostationary satellite, 14
...... Parabolic Annealer 7-S, 15... Converter, 16... Receiver, 17...
・Color television receiver, 18... Bank, 19.
...Intermediate frequency demodulation unit) (IDU), 20...
...Data processing circuit, 21...Descrambler 122...Music/V regeneration circuit, 23...
・RF modulation circuit, 31...Binarization circuit, 32...
... Clock detection circuit, 33 ... Sampling clock generation circuit, 34 ... Main clock generation circuit, 35 ... Sampling circuit, 36
...Latch circuit, 37...Work RAM
, 38...work ROM, 39...)...center processing unit) (CPU), 40...
...Pass line, 41.44.45...Memory, 4θ...Flag register, 47...
Amount memory, 49... Brightness memory, 50...
... Address circuit, 51 ... Buffer 1 amplifier,
62...cR'r, s3...Nonvolatile memory. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure! 3 Figure fit U2'rJtt 1:゛1F - 6) -) Figure! ? , 綜

Claims (2)

[Claims] (1) Billing information corresponding to the content of the program watched is received in the form of a digital signal at regular intervals, and based on this and the time spent watching the television program, the billing amount determination circuit in the receiving device of the terminal The amount is determined and stored, and charge data proportional to the amount is read out and displayed as necessary, and the unique address assigned to each terminal is encrypted using the first encryption method. information for decoding the terminal key code encrypted with the second encryption method sent from the sending side is encrypted with the first encryption method and stored in the memory; 1. A pay television device characterized in that a program for decoding the encryption method described in Item 1 is stored in a memory on a chip of a main control microprocessor. (2) The address and the information for decoding the terminal key code are stored in the same memory, and the memory is
2. The pay television device according to claim 1, wherein the pay television device is configured to be detachable by a button.