KR19980023270A - Device for Scrambling and Descrambling of Color Burst Section of Broadcast Signal - Google Patents

Abstract

According to the present invention, a scrambling and descrambling apparatus for a color burst section of a broadcast signal, which enables a user who is not permitted to watch, to illegally watch a broadcast program, in a pay channel broadcasting system. It is about.

In the present invention, a scrambling pulse signal is generated in a color burst section of a video signal by generating a reference clock having a frequency corresponding to an integer multiple of the horizontal sync signal based on the horizontal sync signal of the composite video signal, and counting it using a counter. Will be synthesized. Then, this pulse signal and the inverted pulse signal are added to descramble.

Therefore, in a television receiver or the like which is not equipped with a device capable of descrambling the scrambling pulses, the synchronization screen is caused by the scrambling pulses inserted at the transmitting side, so that the video screen cannot be viewed.

Description

Device for Scrambling and Descrambling of Color Burst Section of Broadcast Signal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pay channel broadcasting system. In particular, scrambling and descrambling of a color burst section of a broadcast signal to prevent an unauthorized user from watching a broadcast program illegally. Relates to a device.

At present, as the society is advanced, professional channel broadcasting, which provides only a certain kind of programs such as movies and sports, is being implemented in the broadcasting system, and in such a broadcasting system, only specific customers or members have their own broadcasting. The broadcast signal is scrambled and transmitted so that the program can be viewed.

In such a method or apparatus for scrambling a broadcast signal, in most cases, the broadcast signal is digitally converted and then the broadcast signal is sequentially reversed using various interleaving techniques, or a specific portion of the video signal of the broadcast signal is changed. For example, many methods of mixing separate code data such as PN (Pseudo Noise) codes or pseudo noise signals are employed.

However, in the above scrambling method, the configuration of an apparatus for performing scrambling becomes complicated, and the configuration of a descrambling apparatus for restoring the scrambled broadcast signal back to the original broadcast signal is complicated. There is a problem that the burden of the viewer according to the installation becomes very large.

Accordingly, the present invention has been made in view of the above-described circumstances, and in a relatively simple configuration, a color burst section of a broadcast signal, which can be scrambled and broadcast on a color burst signal region of a video signal, and descrambled on the television receiver side. It is an object of the present invention to provide a scrambling and descrambling apparatus.

1 is a waveform diagram showing a video signal of one horizontal scanning period for explaining the basic concept of the present invention.

2 is a block diagram illustrating a scrambling apparatus for a color burst section of a broadcast signal according to an embodiment of the present invention.

3 is a circuit diagram showing the configuration of a vertical blanking signal generation unit in FIG.

4 is a signal waveform diagram for explaining the operation of the apparatus shown in FIG.

FIG. 5 is a circuit diagram showing the configuration of a reference clock generator and a scrambling pulse generator in FIG. 2; FIG.

6 is a signal waveform diagram for explaining the operation of the configuration shown in FIG.

7 is a block diagram showing the configuration of a descrambling apparatus for a color burst section of a broadcast signal according to an embodiment of the present invention;

* Explanation of symbols for main parts of the drawings

21: Sync separation unit 22: Vertical blanking signal generation unit

23: horizontal synchronous separator 24: reference clock generator

25: scrambling pulse generator 26: the first clamp circuit

27: delay circuit 28: second clamp circuit

29: adder 30: modulator

31: integrating circuit 32: comparison circuit

33: monostable multivibrator 71: synchronous separation section

72: vertical blanking signal generator 73: horizontal synchronous separation unit

74: reference clock generator 75: descrambling pulse generator

76: third clamp circuit 77: delay circuit

78: fourth clamp circuit 79: adder

242: voltage controlled oscillator

A scrambling apparatus for a color burst section of a broadcast signal different from the first aspect of the present invention for realizing the above object comprises horizontal synchronous separation means for separating horizontal synchronous signals from a composite video signal, and a predetermined basis based on the horizontal synchronous signals. A reference clock generating means for generating a reference clock having a frequency; section pulse generating means for generating a section pulse signal corresponding to a color burst section of an image signal by counting the reference clock on the basis of the horizontal synchronization signal, and the section pulse signal And scrambling pulse generating means for generating a scrambling pulse signal based on a reference clock, signal synthesizing means for synthesizing the scrambling pulse signal in a color burst region of a North video signal, and modulating and outputting a signal output from the signal synthesizing means. Characterized in that it comprises a modulation means.

The section pulse generating means further includes a first counter for outputting a first detection signal indicating a start point of a pulse section, a second counter for outputting a second detection signal indicating an end point of a pulse section, and the first and second counters. And logical AND means for ANDing the output of the second counter.

In addition, the descrambling apparatus for a color burst section of a broadcast signal according to the second aspect of the present invention is a broadcast system in which a scrambling pulse is inserted into a color burst signal of a broadcast signal and transmitted. Horizontal synchronous separating means for separating, reference clock generating means for generating a reference clock having a predetermined frequency based on the horizontal synchronous signal, and scrambling added to the broadcast signal by counting the reference clock based on the horizontal synchronous signal And descrambling pulse generating means for generating descrambling pulses in a section corresponding to the pulse, and signal synthesizing means for synthesizing the descrambling pulses into the composite video signal.

The descrambling pulse generating means further includes a first counter for outputting a first detection signal indicating a start point of a pulse section, a second counter for outputting a second detection signal indicating an end point of a pulse section, and the first counter. And logical AND means for ANDing the output of the second counter.

According to the present invention having the above-described configuration, a reference clock having a frequency corresponding to an integer multiple of the horizontal synchronous signal is generated based on the horizontal synchronous signal of the composite video signal, and counted using a counter to colorburst the video signal. The scrambling pulse signal is generated in the interval. The decoded color burst signal to which the scrambling pulse is added is descrambled by adding a pulse in phase opposite to the scrambling pulse signal.

Therefore, in a television receiver or the like which is not equipped with a device capable of descrambling the scrambling pulses, synchronous decay is caused by the scrambling pulses inserted at the transmitting side, and the pedestal level of the video signal is changed, so that the video screen can be viewed. It becomes impossible.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

First, the basic concept of the present invention will be described with reference to FIG.

Fig. 1 is a waveform diagram showing an image signal of one horizontal scanning period 1H, which is composed of a horizontal synchronous pulse, a color burst signal, and an image signal. The front portion of the horizontal synchronous pulse, that is, the rear portion of the video signal, is called a front porch, and the rear portion of the horizontal synchronous pulse, that is, the front portion of the video signal, is called a back porch. And the back porch section are combined to form a horizontal blanking period.

In addition, the horizontal synchronous pulse has a length of 5㎲, the front porch is 1.3㎲, the back porch is 4.5㎲.

A color burst signal is carried on the back porch portion, and the color burst signal section and the video signal section are generally used as a reference level of the video signal as a pedestal level.

The present invention is to scramble a desired color burst signal by, for example, combining a scrambling pulse having a different frequency into the color burst signal region.

That is, when the scrambling pulse signal is inserted into the color burst region of the video signal as described above, the video screen that is not recognized by the viewer due to the horizontal synchronization of the video signal scanned on the CRT (Cathode-ray Tube) on the receiving side is collapsed. This output makes it impossible to watch a broadcast screen without providing a separate descrambling device.

FIG. 2 is a block diagram illustrating a scrambling apparatus for a color burst section of a broadcast signal according to an embodiment of the present invention, which realizes the basic concept of the present invention. FIG. 4 is an operation waveform diagram of the apparatus shown in FIG. to be.

In FIG. 2, reference numeral 21 denotes a synchronization separator which separates a synchronization signal from the composite video signal of FIG. 4A, which has a predetermined slice level for the composite video signal as indicated by a dotted line in FIG. By performing the synchronization signal detection, the synchronization signal as shown in Fig. 4B is separated and output.

In the drawing, reference numeral 22 denotes a vertical blanking signal generator for generating and outputting a vertical blanking signal from the synchronous signal [FIG. 4 (B)] output from the synchronous separator 21, as shown in FIG. The integrating circuit 31 for integrating the synchronizing signal output from the synchronizing separator 21 and the signal level output from the integrating circuit 31 are compared with predetermined reference voltages set by the resistors R2 and R3. And a monostable multivibrator that generates and outputs a vertical blanking signal based on the vertical synchronous detection signal output from the comparison circuit 32, and outputs a vertical synchronous detection signal corresponding to the vertical synchronous pulse section. It is comprised including 33.

That is, as can be seen from Fig. 4B, the vertical synchronization pulse is generally set to have a lower duty ratio than the pulses of other signal sections. Therefore, when the output signal of the synchronous separator 21 is integrated into the integrating circuit 31 of FIG. 3, the integrated value in the vertical synchronous pulse section is lower than that of the other sections as shown in FIG. When the reference voltages of the resistors R2 and R3 are input to the comparator 321 having the level indicated by a dotted line in Fig. 4C, the pulse width corresponding to the vertical synchronous pulse interval is shown in Fig. 4D. The signal will be output.

On the other hand, when the pulse signal applied to the input terminal A1 rises to the high level, the monostable multivibrator 33 raises its output Q to the high level, and then to the capacitor C2 and the resistor R4. If a high level signal is not inputted through the input terminal A1 for a predetermined time by the time constant set by the output, the output is lowered to a low level.

Therefore, when the time constant value of the monostable multivibrator 33 is set to T in Fig. 4F, the output ( ) Is a signal corresponding to the vertical blanking section as shown in FIG.

In addition, reference numeral 23 in FIG. 2 denotes a horizontal synchronous separator that separates the horizontal synchronous as shown in FIG. 4 (F) from the signal of FIG. 4 (B) output from the synchronous separator 21. It consists of a Malt Vibrator.

Further, reference numeral 24 denotes a reference clock generator which generates and outputs 910f _H , which is, for example, a 910 divided signal of the horizontal synchronization frequency f _H , from the horizontal synchronization signal output from the horizontal synchronization separator 23. Based on the reference clock output from the reference clock generator 24, the vertical blanking signal output from the vertical blanking signal generator 22, and the horizontal synchronization signal output from the horizontal synchronization separator 23, And a scrambling pulse generator for generating a signal for adding a scrambling pulse.

FIG. 5 is a block diagram showing the configuration of the reference clock generator 24 and the scrambling pulse generator 25, which will be described with reference to the operation timing diagram shown in FIG.

In FIG. 5, the reference clock generator 24 compares the phase difference between the horizontal synchronization signal and the frequency signal applied from the divider 244 described later, and outputs a voltage signal corresponding to the phase difference. (Phase Locked Loop) circuit 241, a voltage controlled oscillator 242 for outputting a predetermined frequency signal in accordance with the voltage signal output from the PLL circuit 241, and a frequency signal output from the voltage controlled oscillator 242 And a divider 244 for dividing the frequency signal outputted from the clock buffer 243 by (1/910).

That is, in the above configuration, a voltage signal corresponding to the phase difference between the output signal of the (1/910) frequency divider 244 and the horizontal synchronization signal is applied to the voltage controlled oscillator 242 so that the output frequency of the voltage controlled oscillator 242 is increased. The output frequency signal of the voltage controlled oscillator 242 is divided through the divider 244 and inputted to the PLL circuit 241 again.

Therefore, the horizontal synchronizing signal and the output signal of the divider 244 are adjusted so that their frequencies are the same, and when the frequency of the horizontal synchronizing signal is 15.734 KHz, the signal frequency output from the voltage controlled oscillator 242 is 14.318. M ㎐ (910 x 15.734 K ㎐), and this frequency signal is output as a reference clock.

On the other hand, the scrambling pulse generator 25 outputs the first and second counters 251 and 252 for down counting predetermined count values based on the reference clock G output from the reference clock generator 24. And AND gate AND2 outputting the AND of the signal.

Here, the first counter 251 executes down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the section T1 of FIG. The level detection signal is output. In addition, the second counter 252 executes down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the section T2 of FIG. The level detection signal is output.

The first and second counters 251 and 252 are cleared at the falling edge of the horizontal synchronization signal F to perform the counting operation again. The output of the first counter 251 is shown in FIG. 6 (H) and the output of the second counter 252 is shown in FIG. 6 (I).

Subsequently, the output of the first counter 251 and the inverted output of the second counter 252 are logically multiplied by the AND gate AND2 to add a scrambling pulse as shown in FIG. 6 (J) in the AND gate AND2. The pulse signal that can be specified is output.

In addition, a vertical blanking signal E is input as one input of the AND gate AND2, which is normally applied to a vertical blanking section to which text multi-broadcast data is added, in particular, 10H to 21H section (see FIG. 4). This is to prevent the scrambling pulses from being added.

In FIG. 2, reference numeral 26 denotes a first clamp circuit for converting a reference level of an input video signal, and the clamp circuit 26 is provided for stability of the video signal. It is a delay circuit having a predetermined delay element.

On the other hand, the AND gate AND1 performs an AND operation on the signals input from the scrambling pulse generator 25 and the reference clock generator 24 to output a signal as shown in FIG.

Next, reference numeral 28 denotes a second clamp circuit for converting the reference level for stability of the image signal, and reference numeral 29 denotes an image signal input through the delay circuit 27 and the second clamp circuit 28. An adder for synthesizing the input scrambling pulse signal, 30 is a modulator for modulating the composite video signal output from the adder 29.

That is, in the scrambling apparatus of the broadcast signal having the above-described configuration, the horizontal synchronous signal is separated from the composite video signal, and then a reference clock having a frequency corresponding to N times (910 times in the above example) of the horizontal synchronous signal is based on this. Will generate a signal.

The scrambling pulse signal is synthesized in the color burst section of the composite video signal by a method of counting the reference clock based on the horizontal synchronization pulse.

On the other hand, Figure 7 is a block diagram showing a descrambling apparatus for descrambling the broadcast signal scrambled and transmitted according to the above method.

In FIG. 7, reference numeral 71 denotes a synchronization separator for separating the synchronization signal as shown in FIG. 4 (B) from the detected composite video signal, and 72 denotes a synchronization signal B output from this synchronization separator 71. The vertical blanking signal generator for generating and outputting a vertical blanking signal E corresponding to the horizontal synchronous pulse period of the vertical blanking section, 73 is a horizontal synchronous signal (B) from the synchronous signal B output from the synchronous separator 71; A horizontal synchronous separation section for separating and outputting F), 74 is an integer multiple of the horizontal synchronous signal F based on the horizontal synchronous signal F output from the horizontal synchronous separation section 73 (910 times in this example). The reference clock generator generates and outputs a frequency signal corresponding to the reference clock.

Further, reference numerals 76 and 78 denote third clamp circuits provided for the stability of the video signal, 77 denotes a delay circuit, 79 denotes an adder, and reference numeral AND3 denotes an AND gate.

On the other hand, the circuit portion is substantially the same as the configuration and operation of the circuit shown in Figure 2 described above.

Reference numeral 75 denotes a de-scrambling pulse that generates an inverted descrambling pulse with respect to the scrambling pulse added to the color burst section of the composite video signal based on the vertical blanking signal E, the horizontal synchronization signal F, and the reference clock. Scrambling pulse generator.

That is, as described above, in the transmitting side, the scrambling pulse is added to the color burst section of the video signal and is transmitted. In this case, when the receiving side detects the video signal with the scrambling pulse added, the synchronization signal collapses. As a result, the video screen is disturbed, so that the video screen output to the CRT becomes unviewable.

Accordingly, the scrambling pulse generator 75 removes the scrambling pulse by generating and synthesizing a pulse signal inverse to the scrambling pulse.

That is, in the above configuration, after the synchronization signal is separated from the composite video signal, a reference clock signal having a frequency corresponding to N times (910 times in the above example) of the horizontal synchronization signal is generated.

The scrambling pulses are synthesized and broadcast in the color burst section of the composite video signal by a method of counting the reference clock based on the horizontal synchronization pulses, and the receiving side generates and synthesizes an inverse descrambling pulse. It removes the scrambling pulse added to.

Therefore, according to the above embodiment, effective scrambling and descrambling can be executed with a simple configuration.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention.

As described above, according to the present invention, a scrambling and descrambling apparatus for a color burst section of a broadcast signal capable of performing scrambling and broadcasting on a color burst signal region of a video signal with a relatively simple configuration and descrambling on the television receiver side. Can be realized.

Claims (4)

Horizontal synchronous separation means for separating a horizontal synchronous signal from the composite video signal; Reference clock generating means for generating a reference clock having a predetermined frequency based on the horizontal synchronization signal; Section pulse generation means for counting the reference clock on the basis of the horizontal synchronization signal to generate a section pulse signal corresponding to a color burst section of an image signal; Scrambling pulse generation means for generating a scrambling pulse signal based on the interval pulse signal and a reference clock; Signal synthesizing means for synthesizing the scrambling pulse signal to a color burst region of a North composite video signal; And a modulation means for modulating and outputting a signal output from the signal synthesizing means. The method of claim 1, The interval pulse generating means includes a first counter for outputting a first detection signal indicating a start point of a pulse section, a second counter for outputting a second detection signal indicating an end point of a pulse section, and the first and second counters. And a logical multiplication means for logically multiplying the output of the counter. In a broadcasting system in which a scrambling pulse is inserted into a color burst signal of a broadcasting signal and transmitted, Horizontal synchronous separation means for separating a horizontal synchronous signal from the composite video signal; Reference clock generating means for generating a reference clock having a predetermined frequency based on the horizontal synchronization signal; Descrambling pulse generation means for counting the reference clock on the basis of the horizontal synchronization signal and generating descrambling pulses corresponding to the scrambling pulses added to the broadcast signal; And a signal synthesizing means for synthesizing the descrambling pulses with the composite video signal. The method of claim 3, wherein The descrambling pulse generating means includes a first counter for outputting a first detection signal indicating a start point of a pulse section, a second counter for outputting a second detection signal indicating an end point of a pulse section, and the first and second counters. And a logical multiplication means for logically multiplying the outputs of the two counters.