JPH0362792A - Video descramble receiver - 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 Field of Industrial Application The present invention relates to a video descrambling receiving device for receiving a video signal broadcasted multiple times including a 4-in-1 system (line rotation system). Regarding.

171 ra v > 4-Ji (rlji A video signal scrambled by the intra-scanning line signal switching method is shown, for example, as shown in FIG. 3.

This figure takes the NTSC system as an example and shows how video signals on a certain horizontal line are also scrambled. 8 in the diagram
indicates the original signal, and b indicates the scrambled signal.

A scrambled signal is constructed by exchanging segments A and SEG/lB at the point P from the beginning of the effective transmission picture length Q of the original signal. Here, the descramble side id, ), the valid screen image of the video signal sent by 4 crumples, are written once to the 11th line memory; From the beginning, segment A and segment B are read in this order and descrambled. Here, since the position P from the beginning of the effective transmission screen range of the sword point is sent from the transmitting side simultaneously with the video signal, the scrambler side receives the start signal Q- when reading from the line memory. It is necessary to divide P for each line, but conventionally, this calculation has been performed using a circuit configuration such as the one in the 41st part. In the figure, 1 indicates the position of the cut point) P from the beginning of the effective screen range Q, and the digital data baru indicating P is calculated, and 2 calculates (effective screen range length Q - cut point) P) in the ROM. do. 3 is a data bus that outputs the calculation results of QP.

Problem to be Solved by the Invention The capacity of the ROM required in Fig. 4 is 5 bits input and 8 bits.
Taking the output as an example, it is approximately 2" bytes.The effective transmission screen length Q is not constant depending on the system, so
Considering that one descranzor can support multiple systems, this ROM has the effective transmission screen length Q of each system.
It is necessary to calculate Q-P for each time, which increases the circuit scale.

The present invention is based on these problems and aims to provide a circuit configuration that has a simple configuration and achieves the same effect without increasing the circuit scale.

A PAL that outputs multiple constants based on the method selection input to solve the problem,
It is characterized by calculating subtraction using an inverter and an adder.

Function: According to the video descrambling receiving device of the present invention, it is possible to support multiple systems with different effective screen transmission ranges without increasing the circuit scale, and it is possible to provide an inexpensive video descrambling receiving device. It is something to do.

′)! : Tired example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of main parts according to an embodiment of the present invention.

4), and parts common to those in FIG. 4 are designated by the same reference numerals.

In the figure, an inverter 4 inverts all bits of the input data bus 1. 6 is PAL, and selects the effective transmission screen range Q of the system in question plus "1" using the select line 8, and outputs it to the output bus line 7. An adder 6 adds the values of the inverter output 4 and the PAL output cuff to the bus line 3.

Next, P shows the operation in more detail from "○" to "254".
” and Q is “254” as an example. For example, in Figure 4, when the pig on data bus 1 is "l-115", when it is displayed in binary, it will be "01110011".
When all bits are inverted using an inverter, it becomes ``10001''.
100'', that is, ``139''. At this time, PAL6
outputs “Q+1” or “255”, so
Addition 3'): k takes the lower 8 bits of 115+255J, outputs 139, and calculates the result rQ-PJ.

In this way, by changing Q → -1 corresponding to the effective transmission screen range of each system using the select line 8 to PAL 6, it is possible to correspond to various systems, so rQ-PJ can be achieved without increasing the circuit scale. This eliminates the need for configuring a ROM for each system and increasing the circuit size, unlike the case where a ROM is used.

Next, the main parts of the NTSC video descrambler reception W'j:4, shown in FIG. 1 will be used for explanation. In Figure 2, 1 is the data bus that indicates the position of the cut point from the beginning of the right video screen, and 10 is the data bus that performs processing to make the 8-bit rPJ correspond to the effective transmission screen range "Q". .

13 is a block that performs subtraction according to the present invention, where r
Calculate Q-P J. 14 to 17 calculate the off-set address from the beginning of the effective transmission screen for each line in order to perform descransol, and use selector 2Q.
Switching to the "-" side and the "down" side is performed in the null crumple range and non-null crumple range within the scanning line, respectively. Reference numeral 21 denotes an address bus, which is connected to the RAM for read-modify-write operations.

22 is a switching signal, here the NTSC system.

Performs MUSE power type switching. NTSC system and MUS
In the E method, the value of Q is different, but by using the circuit of the present invention in the circuit 13 in the figure, the circuit size does not increase as in the case of using a ROM.

Effects of the Invention As described above, according to the present invention, an inexpensive video descrambling reception system that can accommodate multiple synutems with various right video screen ranges, regardless of whether it is a simple I11 with only an inverter, an adder, and an RAL, can be achieved. It is possible to provide a device with excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a video denucrambling receiver according to an embodiment of the present invention, and FIG. 2 shows how the present invention is actually used in an NTSC/MUSE video denucrambling receiver. Block fL FIG. 3 is a signal waveform diagram illustrating a video decimation system, and FIG. 4 is a block diagram of the main parts of a conventional video decimation receiving apparatus. 1... Data bus indicating the position of the point 1 from the beginning of the right video screen, 4... Inverter, 5
... Adder, 3 ... Q-P output data bus, 6 ... PAL for constant generation, 7 ...
・Constant output data fit, 8...Q selection line. Diagram

Claims (1)

[Claims] When a video signal scrambled using the intra-scanning line signal switching method is descrambled, all bits of data indicating the position of the cutting point during scrambling sent from the transmitting side are inverted by an inverter, and A video descrambling receiving device that calculates a reading start position in a line memory in which a receiving side video signal is written by adding "1" to data indicating the width of a signal switching range.