JP3022609B2 - Descramble device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to a scrambled M
The present invention relates to a stand-alone type descrambling device used for descrambling a USE signal.

[0002]

2. Description of the Related Art Conventionally, a stand-alone type descrambling device for restoring a scrambled MUSE signal and obtaining a normal MUSE signal, which is not built in an image receiving device, is configured as shown in FIG.

In FIG. 3, 1 is a scrambled M
This is a USE signal and is usually connected to an FM detection output signal from a BS tuner or the like. An A / D converter 2 converts an analog signal into a digital signal, and converts the scrambled MUSE signal into a digital signal. A data detection timing generation circuit 3 outputs a synchronization signal required for descrambling from a digital MUSE signal. An audio processing circuit 4 outputs a 1.35M-rate PCM digital audio signal, an audio frame signal, and an audio clock from the digital MUSE signal.

[0004] Reference numeral 5 denotes a descrambling unit, which restores a scrambled digital MUSE signal, outputs a regular digital MUSE signal, and further includes an audio mute switch 6 for performing an audio mute operation. Reference numeral 7 denotes a D / A converter for converting a digital signal into an analog signal, and converting the restored digital MUSE signal into an analog MUS signal.
Convert to E signal. Reference numeral 22 denotes a restored analog MUSE signal output, which is normally connected to a MUSE decoder or the like.

Reference numerals 8, 9, and 10 denote a frame pulse signal synchronized with the video frame of the MUSE signal, a horizontal pulse signal synchronized with the horizontal scanning line, and a reference clock for sampling the 16.2 MHz video signal. The reference clock 10 is supplied to the descrambling unit 5 and also to the A / D converter 2. Reference numerals 11, 12, and 13 denote a 1.35 MHz clock, PCM audio data, and audio frame pulse, which are the reference of the PCM audio data, and are supplied from the audio processing circuit 4 to the descrambling unit device 5, respectively.

Reference numeral 14 denotes a video unlock signal indicating that the video-related synchronization signal is not synchronized with the video signal. The video unlock signal 14 is supplied from the data detection timing generation circuit 3 to the descramble unit 5, and the input signal is non-MUSE. It becomes active when it is a signal or when C / N drops. Reference numeral 15 denotes an audio unlock signal indicating that the audio-related synchronization signal is not synchronized with the audio signal. The audio unlock signal is supplied from the audio processing circuit 4 to the descrambling unit 5, and the input signal is a non-MUSE audio unlock signal. When it is a signal or C / N
It becomes active when it drops. Reference numeral 16 denotes an audio mute logical OR device for calculating the logical sum of the video unlock signal 14 and the audio unlock signal 15;
The audio signal in the USE signal is muted by the output of the audio muting OR device 16.

Reference numeral 23 denotes a video scramble flag of the descrambling unit 5, which becomes active when the video of the input signal is scrambled. Numeral 24 denotes an audio scramble flag of the descrambling unit device 5, which becomes active when the audio of the input signal is scrambled. Reference numeral 25 denotes a display device for indicating a scrambling state of the video signal, and the presence or absence of the scrambling of the video signal is displayed by the output of the video scrambling flag 23. Reference numeral 26 denotes a display device for indicating the scrambling state of the audio signal, and displays the presence or absence of the scrambling of the audio signal by the output of the audio scrambling flag 24.

[0008] The operation of the conventional descrambling device thus configured will be described below. First, the scrambled MU input to the stand-alone descrambler
The A / D converter 2 converts the SE signal 1 into a digital MUSE signal. Next, the data detection timing generation circuit 3
In the next section, video-related synchronization detection from digital MUSE signal, 16.2
The reproduction of the MHz clock is performed, and the video-related reference signal is supplied to the descramble unit 5 and the A / D converter 2. The audio processing circuit 4 performs audio data detection, audio-related synchronization detection, and 1.35 MHz clock reproduction from the digital MUSE signal.
Provides audio related reference signals. The descrambling unit 5 restores the scrambled digital MUSE signal based on the video signal, the audio data, and the reference signal, and outputs the restored MUSE signal via the D / A converter 7. Further, in the descrambling unit 5, the video unlock signal 14 and the audio unlock signal 15 are connected to the audio mute switch 6 via the audio mute OR circuit 16, and the operation is further described in FIG.
This will be described with reference to FIG.

FIG. 4 is a diagram showing a video unlock signal 14, an audio unlock signal 15, and a signal showing a state of an audio mute operation when a non-MUSE signal is temporarily input such as channel switching in BS tuners of all stages of the scrambler. It is a waveform diagram. In FIG. 4, the time at which the channel of the BS tuner is switched is indicated by t1. As described above, when the channel is switched at time t1, the MUSE signal input to the descrambling device is temporarily invalid.
The video unlock signal 14 and the audio unlock signal 15 become active a little later than t1 to become the E signal as shown in FIG.
4 is output as shown in FIG. 4. By controlling the audio mute switch 6 with this signal, it is possible to minimize noise noise such as channel switching.

[0010]

However, the configuration as in the above-mentioned prior art has the following problems.

1) When a non-MUSE signal, for example, an NTSC signal is input to the descrambling device, the data detection timing generation circuit 3 and the like do not operate normally and a normal NTS
Since the C signal is not output from the descrambling device, the MUSE / NTS
Even if the C dual-use image receiving device is connected, it becomes impossible to normally receive the NTSC broadcast.

2) Unscrambled MU
Even when the SE signal is input to the descramble device, the input MUSE signal is A / D converted once, passes through the descramble unit device 5, is further D / A converted, and is output, so that image quality may be degraded.

The present invention solves the above-mentioned problem. In the present invention, a scrambled MUSE signal is descrambled to restore a normal MUSE signal, and a non-scrambled MUSE signal or a non-MUSE signal such as an NTSC signal is input. Can output the signal as it is,
It is an object of the present invention to provide a descrambling device that minimizes image quality deterioration and can normally receive NTSC broadcasting even at a stage subsequent to the descrambling device.

[0014]

In order to solve the above-mentioned problems, a descrambling device according to the present invention is characterized by adopting and combining the following technical means. Also successfully NT
It is designed to receive SC broadcasts.

(A) Scrambled digital MUS
(B) Data having a descrambling unit device to which an E signal is input and which obtains a restored digital MUSE signal output and a video scrambling flag output and a voice scrambling flag output indicating whether each of the video and audio of the input signal is scrambled. The video unlock signal output from the detection timing generation circuit indicating that the video-related synchronization signal is not synchronized with the video signal, and the audio-related synchronization signal output from the audio processing circuit is not synchronized with the audio signal. (C) A delay device for delaying a signal output from the first OR device for a certain period of time.

(D) An AND device for performing an AND operation of the first OR device output signal and the delayed first OR device output signal output from the delay device. (E) having a second logical sum device for calculating the logical sum of the output of the video scramble flag and the output of the audio scramble flag (F) the logic of the output of the second logical sum device and the output of the logical product device (G) The descramble unit device output signal is provided as a D /
An output signal switching device that switches and outputs one of the A-converted restored MUSE signal output and the input signal to the descrambling device by the output of the third OR device.

[0017]

With the above arrangement, when the signal input to the descrambling device is in the scramble MUSE signal format, both the video unlock signal and the audio unlock signal become inactive, and the video scramble flag and
The audio scramble flags are both active, and the descrambled MUSE signal output from the descramble unit is output after being descrambled and selected by the output signal switching device.

When the signal input to the descrambling device is in the non-scrambled MUSE signal format, the video unlock signal and the audio unlock signal are both inactive, but the video scramble flag and the audio scramble flag are both inactive. The input signal to the descrambling device is selected as it is by the output signal switching device and output through.

When the signal input to the descrambling device is in the non-MUSE signal format, both the video unlock signal and the audio unlock signal are active. When the non-MUSE signal format continues for a certain period of time, the video unlock signal is output. The output of the logical OR device for switching the output signal of the audio unlock signal and the logical product of the output of the logical OR device for switching the output signal and the signal passed through the delay circuit become active, so that the output to the descrambling device is increased. The input signal is directly selected by the output signal switching device and output as it is.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the descrambling device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a descrambling device according to one embodiment of the present invention. In FIG. 1, 1
Is a scrambled MUSE signal, which is usually connected to an FM detection output signal from a BS tuner or the like. 2
Is an A / D converter that converts an analog signal into a digital signal, and converts the scrambled MUSE signal into a digital signal. A data detection timing generation circuit 3 outputs a synchronization signal required for descrambling from a digital MUSE signal. Reference numeral 4 denotes an audio processing circuit, a digital MUS
From the E signal, a PCM digital audio signal, audio frame signal and audio clock at a 1.35M rate are output.

Reference numeral 5 denotes a descrambling unit for restoring the scrambled digital MUSE signal and outputting a regular digital MUSE signal. A D / A converter 7 converts a digital signal into an analog signal, and converts the restored digital MUSE signal into an analog MUSE signal. twenty one
Is an output signal switching device which selects one of an input signal to the descrambling device and an output of the D / A converter 7 and outputs it as a descrambling MUSE signal 22.

Reference numerals 8 and 9 denote a frame pulse signal synchronized with the video frame of the MUSE signal and a horizontal pulse signal synchronized with the horizontal scanning line, respectively, which are supplied from the data detection timing generation circuit 3 to the descramble unit device 5. Reference numeral 10 denotes a reference clock for sampling a video signal of 16.2 MHz, which is supplied from the data detection timing generation circuit 3 to the A / D converter 2 and the descramble unit. 11,
Reference numerals 12 and 13 denote a reference 1.35 MHz clock of PCM audio data, PCM audio data, and audio frame pulses, respectively, which are supplied from the audio processing circuit 4 to the descrambling unit device 5.

Reference numeral 14 denotes a video unlock signal indicating that the video-related synchronization signal is not synchronized with the video signal. The video unlock signal 14 is supplied from the data detection timing generation circuit 3 to the descramble unit 5, and the input signal is non-MUSE. It becomes active when it is a signal or when C / N drops. Reference numeral 15 denotes an audio unlock signal indicating that the audio-related synchronization signal is not synchronized with the audio signal. The audio unlock signal 15 is supplied from the audio processing circuit 4 to the descrambling unit device 5, and is used when the input signal is a non-MUSE signal. It is output when C / N drops. 16 is a video unlock signal 14 and an audio unlock signal 15
The audio mute switch 6 built in the descramble unit 5 mutes the audio signal in the MUSE signal by the output of the audio mute OR 16.

Reference numeral 18 denotes a first logical sum device which outputs a logical sum of the video unlock signal 14 and the audio unlock signal 15.
Reference numeral 19 denotes a delay unit which delays the output signal of the first OR unit 18 for a predetermined time. Reference numeral 20 denotes a logical AND device, which is a first logical OR device
It outputs the logical product of the output signal of 18 and the output signal of the delay device 19. Reference numeral 23 denotes a video scramble flag of the descrambling unit device 5, which becomes active when the video of the input signal is scrambled. Numeral 24 denotes an audio scramble flag of the descrambling unit device 5, which becomes active when the audio of the input signal is scrambled. Reference numeral 25 denotes a display device for indicating a scrambling state of the video signal, and the presence or absence of the scrambling of the video signal is displayed by the output of the video scrambling flag 23. 26
Is a display device for indicating the scrambling state of the audio signal, and displays the presence / absence of the scrambling of the audio signal by the output of the audio scrambling flag 24. Reference numeral 27 denotes a second logical sum device which outputs a logical sum of the video scramble flag 23 and the audio scramble flag 24. 28 is a third OR device, which is a logical AND device 20
And the output of the second OR device 27 is ORed to control the output signal switching device 21.

The operation of the conventional descrambler having the above configuration will be described below with reference to FIGS. FIG. 2 shows a video unlock signal 14 when a channel is switched from a scrambled MUSE broadcast channel to a non-scrambled MUSE broadcast in the BS tuner and when an NTSC signal is input to the descrambling device of this embodiment as an example of a non-MUSE signal. FIG. 4 is a timing chart showing timings of related signals from the audio unlock signal 15, the video scramble flag 23, the audio scramble flag 24 to the output of the output signal switching device 21.

In FIG. 2, the channel of the BS tuner is switched and the input signal to the descrambling device is changed from the scrambled MUSE broadcast channel A to the non-scrambled M
The time when the channel changed to USE broadcast channel B is indicated by t1. As described above, when the channel is switched at time t1, the MUSE signal input to the descrambling device temporarily becomes an irregular MUSE signal, so that the video unlock signal 14 and the audio unlock signal are slightly delayed from t1.
2 becomes active as shown in FIG. 2, and the output of the audio muting logical sum device 16 based on the logical sum of these signals becomes as shown in FIG. , Noise noise such as channel switching can be minimized.

The output of the AND device 20 is obtained by taking the logical product of the output of the output signal switching OR device 18 and the output of the delay device 19 as shown in the timing chart. It does not become active for a temporary non-MUSE signal input and does not unnecessarily switch the output signal switching device 21. On the other hand, in this example, the channel changes from scrambled broadcast to non-scrambled broadcast,
Video scramble flag 23, audio scramble flag 24
Becomes inactive as shown in the timing chart a little later than the time t1, and the second OR device 27, the third OR device
The output signal switching device 21 is switched to the input signal side to the descrambling device via 28, and the input signal is output through.

Next, at time t2, when the input signal to the descrambling device is switched from the MUSE signal to the NTSC signal, the timing operation up to the video unlock signal 14, the audio unlock signal 15, and the audio mute switch 6 is performed on the channel. Same as when switching, except that the delay device 19
The output of the AND device 20 which takes the logical product of the output of the logical AND device 18 and the output signal of the output signal switching OR device 18 becomes active after a certain time as shown in the timing chart. On the other hand, here, since the channel changes from MUSE broadcast to NTSC broadcast, the video scramble flag 23 and the audio scramble flag 24 become slightly indefinite as shown in the timing chart a little later than the time t2. The output of the third OR output device 28 is switched by the output of the AND device 20 to the output signal switching device 21 to the input signal side to the descrambling device after the delay device 19 outputs the output of the third OR operation device 28 for a fixed time. Output the input signal.

As described above, according to this embodiment, when a non-scrabble MUSE signal or a non-MUSE signal, for example, an NTSC signal is input to the descrambling device, the input signal can be directly output as it is. Can be minimized, and even after the descrambling device, not only the MUSE system but also the NTSC system can be viewed.

[0031]

As described above, according to the present invention, the first logical sum of the video unlock signal output from the data detection timing generation circuit and the audio unlock signal output from the audio processing circuit is obtained. A delay device for delaying a signal output from the first OR device for a predetermined time, a signal output from the first OR device, and a delayed first signal output from the delay device. A logical product circuit for obtaining a logical product of the logical sum device output signal, a second logical sum device for performing a logical sum of a video scramble flag signal indicating a video scramble state and an audio scramble flag signal indicating a voice scramble state, A third logical sum device that calculates the second logical sum of the logical product device and the third logical sum of the descramble unit output signal and the input signal to the descramble device; With the configuration including an output signal switching device for switching and outputting either one according to the path output, the signal can be normally restored for the scrambled MUSE signal input, and the video scramble flag can be restored for the non-scrambled MUSE signal. Both the signal and the audio scramble flag signal become inactive, and the output of the second OR device and the output of the third OR device are used to switch the output signal switching device to output the input signal through. Minimize image quality degradation and use non-MUSE
When the signal is input to the descrambling device, the video scramble flag signal and the audio scramble flag signal are undefined, but the output of the first OR device continues for a certain period of time. Loading device, third
By the output of the OR device, the output signal switching device switches so as to output the input signal through, so that not only the MUSE system but also the non-MUSE system can be viewed at the subsequent stage of the descrambling device, The practical effects are significant.

[Brief description of the drawings]

FIG. 1 is a block diagram of a descrambling device according to an embodiment of the present invention.

FIG. 2 is a timing chart of signals for explaining the operation of the descrambling device of FIG. 1;

FIG. 3 is a block diagram of a conventional descrambling device.

FIG. 4 is a timing chart of signals for explaining the operation of the conventional descrambling device.

[Explanation of symbols]

 3 Data detection timing generation circuit 4 Audio processing circuit 5 Descramble unit device 14 Video unlock signal 15 Audio unlock signal 18 First OR device 19 Delay device 20 AND device 21 Output signal switching device 23 Video scramble flag 24 Audio Scramble flag 27 Second OR device 28 Third OR device

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 7/10 H04N ^7/ 14-7/173 H04N ^7/ 20-7/22 H04N 5/44 H04N 7/015

Claims (1)

(57) [Claims] 1. A descramble unit which receives a scrambled digital MUSE signal and obtains a restored digital MUSE signal output, a video scramble flag output indicating a video and audio scramble state of an input signal, and an audio scramble flag output. Device, a first logical sum device for performing a logical sum of a video unlock signal output from the data detection timing generation circuit and an audio unlock signal output from the audio processing circuit, and an output from the first logical sum device A delay device for delaying a signal to be supplied for a predetermined time, and a logic for performing an AND operation on a signal output from the first OR device and a delayed first OR device output signal output from the delay device A second logical sum device for calculating the logical sum of the video scramble flag output and the audio scramble flag output A third logical sum device for calculating the logical sum of the second logical sum device and the logical product device, and a descrambling output signal of a MUSE signal and an input signal to the descrambling device. An output signal switching device for switching and outputting either one of the signals according to an output, wherein the input signal is a non-MUSE signal or a non-scrambled MUSE for a predetermined time.
A descrambling device configured to output an input signal through in the case of a signal.