KR0158587B1 - Scramble apparatus having error correcting function - Google Patents

Abstract

The present invention provides a scrambler that scrambles a video signal to be viewed only by a subscriber having a converter that can not be watched by a non-subscriber in a Korean CATV system and that can decrypt the cipher data. A scrambler having a function of detecting and correcting an error caused by transmission path noise in data. By adding the above functions, there is an effect that can provide a better video service to the subscriber.

Description

Scrambler with Error Correction Function

1 is a block diagram showing the structure of a conventional scrambler.

2 is a block diagram showing the configuration of a scrambler according to the present invention.

Figure 3 shows an example of error correction.

* Explanation of symbols for main parts of the drawings

2: scrambler 21: invert / non-inverting

22: micom 23: encryption data generator

24: encoder 25: baseband modulator

26: synthesis unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scrambler provided in a Korean cable television system (CATV) system, and more particularly to a scrambler having a function of correcting an error occurring in data during transmission.

In general, in constructing a CATV system, an operator scrambles and sends a video signal to prevent subscribers from listening to the broadcast, and descrambles and receives the scrambled signal from a converter provided at the subscriber side.

FIG. 1 is a block diagram showing the structure of a conventional scramble device, and a conventional operation will be described with reference to the drawings. The horizontal signal of the video signal is separated and input to the scrambler 1. The image horizontal signal is input to the inverting / non-inverting unit 11, and the inverting / non-inverting unit 11 scrambles the image horizontal signal by inverting or non-inverting the phase of the input signal to the control signal of the microcomputer 12. The phase inversion is made in units of lines. For example, in the NTCS system, since there are 262.5 lines of horizontal signals, the phase of 262.5 lines is arbitrarily inverted and non-inverted. The microcomputer 12 sends a control signal to the inverting / non-inverting unit 11 and outputs the control signal to the encryption data generation unit 13. The encryption data generation unit 13 receiving the control signal generates encrypted data containing information about the phase inversion operation and outputs the encrypted data to the baseband modulation unit 14. The baseband modulator 14 modulates the input digital data into a baseband (eg, a Manchester code which is one of Non Return to Zero (NRZ) schemes) that is easily transmitted to the synthesizer 15. Output In addition, the image horizontal signal scrambled in units of lines in the inverting / non-inverting unit 11 is also input to the combining unit 15. The synthesizing unit 15 synthesizes the modulated cipher data input from the baseband modulator 14 at the H10 position of the horizontal image signal input from the inverting / non-inverting unit 11. H10 is a signal that does not carry image information and is used to carry control information only in the Korean CATV system. Since H10 does not contain image information, even if other signals are synthesized, there is no effect on the image. The scrambled horizontal video signal is high frequency modulated and transmitted to the converter of each subscriber. The converter on the subscriber side descrambles the scrambled signal and sends it to the TV. During transmission, the signal may change due to noise or other attenuation. Since the encryption data inserted in H10 is a digital signal, an error occurs due to noise. However, in the conventional system, since the function of detecting and correcting the error is not provided, the descrambler provided in the converter causes a problem in that the disc-blambled image is distorted by directly inputting the error data into the microcomputer.

An object of the present invention is to solve the above problems, an object of the present invention is to provide a scrambler having an error correction function by providing an encoding unit in the scrambler.

Another object of the present invention is to provide a subscriber with a better video service by correcting an error occurring during transmission.

As a technical means for achieving the above object, the present invention is an inverted / non-inverting unit for inverting or non-inverting the phase of the input horizontal image signal according to the control signal of the microcomputer, the inversion / non-inverting unit and the encryption data generation A microcomputer that sends a control signal to the data base, an encryption data generation unit for generating encrypted data according to the control signal of the microcomputer, an encoding unit for adding an error check bit to the generated encryption data, and an output signal of the encoding unit. And a baseband modulator for modulating the band, and a synthesizer for synthesizing the scrambled horizontal video signal and the baseband modulated data.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

2 is a block diagram showing the configuration of a scrambler according to the present invention, and the present invention provides an inverting / non-inverting portion 21 for scrambled by inverting or non-inverting a phase of an input horizontal video signal according to a control signal of a microcomputer. The microcomputer 22 controls the inversion / non-inverting unit 21 and the encryption data generator 23, and the encryption data generator 23 generates arbitrary encrypted data by the control signal of the microcomputer 22. And an encoder 24 for encoding the cipher data so that error correction is possible, a baseband modulator 25 for modulating the cipher data consisting of the error check bit and the information bit into a baseband in a transmission form, Composed of the scrambled horizontal video signal output from the inverting / non-inverting section 21, the synthesizer 26 for synthesizing the modulated cipher data output from the baseband modulator 25.

Hereinafter, the operation and effect according to the present invention will be described in detail.

The microcomputer 22 transmits a control signal to the inverted / non-inverted portion 21 so that the phase inversion is irregular, and at the same time, sends a control signal to the encryption data generator 23. The inverting / non-inverting unit 21 irregularly inverts the phase of the input horizontal video signal under the control of the microcomputer 22. The encryption data generator 23 outputs the information on the phase inversion as encrypted data that can be decrypted only by a decoder built in the converter, and inputs the output encrypted data to the encoder 24. The encoder 24 codes input data and outputs the data to which an error check bit is added. An example of an error correcting code is a horizontal / vertical parity check code, which forms a block of rectangular binary code (Fig. 3a), with one bit of check bits in both horizontal and vertical directions. It is a coding method to add one by one. FIG. 3B is an embodiment of a horizontal / vertical parity check code in which even parity check bits are added to each row and each column. The horizontal / vertical parity check code can be corrected only in the case of a single error. The error correcting code method determines an appropriate coding method according to an error rate on a transmission path.

The coded cipher data output from the encoder 24 is input to the baseband modulator 25. The baseband modulator 25 modulates input data consisting of 1,0 two bits into a baseband capable of transmission. For example, it modulates with Manchester code, which is one of NRZ (None Return to Zero) methods. The modulated data is input to the combining section 26, and the combining section 26 synthesizes the data at the H10 position of the scrambled horizontal video signal which is another input signal. As described above, this signal is used only in the Korean CATV system and does not affect the image. The signal output from the combiner 26 is modulated by the next high frequency modulator (not shown) and transmitted to the converter on the subscriber side.

As described above, the present invention has an effect of detecting and correcting an error occurring in encrypted data by providing an encoding unit for detecting and correcting an error occurring during transmission, thereby providing a better video service to a subscriber. There is an excellent effect that can be provided.

Claims (1)

In the Korean CATV scrambler for scrambling a horizontal video signal, an inverting / non-inverting portion 21 for inverting or non-inverting a phase of an input horizontal video signal according to a control signal of a microcomputer, and the inverting / non-inverting portion 21. And a microcomputer 22 which sends a control signal to the encryption data generator 23, an encryption data generator 23 which generates encrypted data according to the control signal of the microcomputer 22, and the generated encryption data. A coding unit 24 for coding an error check bit and a baseband modulator 25 for modulating the digital data output from the coding unit 24 into a baseband signal, and the inverting / non-inverting unit 21. And a synthesizer 26 for synthesizing the baseband signal outputted from the baseband modulator 25 to the 10th line frame H10 of the scrambled horizontal video signal outputted from the apparatus. Scrabble Rambling device.