KR0146918B1 - Decoder of cable television - Google Patents

Abstract

The present invention relates to a decoder of a cable television, comprising: data detecting means for amplifying a tuned signal, filtering the frequency of a voice band, and outputting the filtered signal to a video and audio detecting means, and simultaneously detecting data related to decoding from the filtered signal; Decoding means for reading the detected data to decode the channel and the subscriber address to determine the decoding mode and the decoding permission, generating a timing pulse, and amplifying the tuned signal and filtering the signal to the frequency of the video band. By restoring means for decoding as a timing pulse and restoring the original video signal to output the video and audio detection means, it is possible to prevent the non-subscriber from watching the pay TV signal in an illegal manner. This is available for the decoding operation of cable television.

Description

Cable tv decoder

1 is a conventional cable broadcast signal processing block diagram

2 is a block diagram showing an embodiment of a decoder of a cable television according to the present invention.

3 is a waveform diagram for explaining the operation of the embodiment according to the present invention.

* Explanation of symbols for main parts of the drawings

10: tuner 22, 42: amplifier

24,44: Bandpass filter 60: Modulator

50: video and audio detection circuit 20: data detection circuit

26: buffer 28: data detector

30: decoding read circuit 32: logic section

34: microcomputer 36: data storage

40: restoration circuit 46: restoration section

70: receiver 80: display

The present invention relates to a decoder of a cable television, and more particularly, to a decoder of a cable television which decodes a pay-cast signal transmitted by being encrypted to prevent unauthorized eavesdropping into a viewable signal and restores the original signal.

In general, a cable television broadcasting system operates a pay channel system to transmit a broadcast signal. Accordingly, the signal transmitted through the pay channel should be operated so that only subscribers can watch.

The signal transmitted conventionally is signal-processed in each block of FIG. 1 and output to the terminal of each subscriber, ie, television. The general cable signal processing operation will be briefly described.

The signal transmitted through the cable is input to the tuner 2 and tuned for each channel. Here, the signal tuned and output for each channel is an intermediate frequency signal and is a signal generated for ease of modulation and detection. This signal is input to the amplifier 3, amplified to a predetermined level, and then input to the band pass filter 4.

The band pass filter 4 filters the output signal of the amplifier 3 input in the preset frequency band and outputs the same to detect the video and audio signals. Accordingly, the video and audio detection circuit 5 detects the signal filtered by the band pass filter 4 and outputs the video and audio signals separately. On the other hand, the video and audio detection circuit 5 has an automatic gain control (AGC) signal and an automatic frequency control (AFC) for automatic gain control (AGC) and automatic frequency control (AFC). The signal is fed back to the tuner (2). Accordingly, the tuner 2 adjusts the gain and frequency of the input signal. In addition, signals that are separately detected and output as video and audio signals are separately modulated for each signal and output to the television.

However, when a non-subscriber receives a conventional signal processed and output in such a manner, the reception of the pay channel signal is lowered as the signal distribution increases.

For this reason, the latest developments are encoding at the time of transmission of a pay broadcast signal and decoding at the time of reception. That is, if the transmitting side encodes and outputs the cable broadcasting signal when transmitting, the subscriber cannot prevent the encoded signal from being read, and the subscriber is provided with a decoder capable of reading the encoded signal. The transmitted signal can be received without error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a pre-encoded signal to be received only by subscribers subscribed to a pay channel, so that the subscriber can recover the signal on the subscriber's side. In providing a decoder.

A feature of the decoder of the cable television according to the present invention for achieving the above object is, by encoding to prevent the reception of the non-subscriber through the cable to the input signal to tune the channel by the tuner detected by the video and audio detector And a cable television decoder that feeds back a gain and frequency control signal to the tuner and modulates the signal to be output to the television. The amplified signal is filtered to a frequency of an audio band and then output to the video and audio detection means. And data detection means for detecting data related to decoding from the filtered signal, and decoding the channel and subscriber address by reading the detected data to determine a decoding mode and whether or not to permit decoding to generate timing pulses. Reading means and amplifying the tuned signal. There is a point after the filtering with the frequency band of the image by decoding a signal as said timing pulse are configured to restore the original video signal of a restoration means for outputting the video and audio detection means.

EMBODIMENT OF THE INVENTION Hereinafter, one preferred embodiment of the decoder of the cable television concerning this invention is described in detail with reference to an accompanying drawing.

2 is an embodiment according to the present invention, and FIG. 3 is a waveform diagram for explaining signal restoration according to the operation of the embodiment.

The data detection circuit 20 and the restoration circuit 40 are connected in parallel during the intermediate process of inputting the signal input through the cable to the tuner 10 and outputting the intermediate frequency signal to the video and audio detection circuit 50. Consists of. In addition, the decoding reading circuit 30 is configured such that a timing pulse for decoding is generated by the data detected by the data detecting circuit 20 and input to the restoring section 46 in the restoring circuit 40.

The signal detected and output by the video and audio detection circuit 50 is input to the modulator 60, modulated, and then output to the television. In this process, as shown in FIG. 1, a feedback operation for automatic gain control (AGC) and automatic frequency control (AFC) is performed. Detailed description thereof will be omitted.

In the data detection circuit 20, an amplifier 22, a band pass filter 24, a butter 26, and a data detector 28 are sequentially configured to process an audio signal, and the recovery circuit 40 includes an amplifier 42. And a band pass filter 44 and a reconstruction beam 46 are sequentially formed to process the image signal.

The decoding readout circuit 30 further includes a logic section 32, a microcomputer 34 connected thereto to enable a plurality of data exchanges, and a data storage section 36 connected to provide data and programs of the microcomputer 34. Consists of The logic unit 40 is connected to output the timing pulse to the recovery unit 46 in the recovery circuit 40 and is connected to input data from the data detection unit 28.

On the other hand, the microcomputer 34 is connected so that various data including data on a channel to be tuned by inputting the data of the receiving unit 70 to which a signal received from a remote controller (not shown) is inputted are connected, and the display unit 80 is input. It is connected to output data for displaying channel tuning status lights.

First, when the pay broadcast signal is input to the tuner 10 through a cable, an intermediate frequency signal tuned for each channel is output. This signal is input to the amplifier 22 of the data detection circuit 20 and the amplifier 42 of the recovery circuit 40 and amplified to a predetermined level. The signal amplified by the amplifier 22 is filtered into the voice frequency band by the band pass filter 24 and then input to the buffer 26. The buffer 24 is configured to reinforce the attenuation of the signal in the bandpass filter 24. The output of the butter 24 is input to the video and audio detection circuit 50 and to the data detector 28 at the same time.

The video signal of the pay broadcasting signal encoded and transmitted from the transmitting side is distorted by the encoding operation, and the audio signal contains data for restoring the distorted signal. Therefore, a voice signal is input to the data detector 28 to separate data necessary for reconstruction from the voice signal, and the reconstructed data is separated and then input to the logic unit 32.

The logic unit 32 logically combines the input data and outputs the channel recognition signal and the subscriber address to the microcomputer 34. In response, the microcomputer 34 outputs a control signal to the tuner 10 for accurate tuning, and determines a channel recognition signal and a subscriber address signal, and outputs a decoding permission signal and a decoding mode determination signal generated accordingly. Output to logic section 32.

When the decoding permission signal is input from the microcomputer 34, the logic unit 32 logically combines the decoding mode determination signal inputted simultaneously with the decoding permission signal, thereby generating a timing pulse for decoding, thereby restoring the 46. Will output

The reconstruction circuit 40 performs a reconstruction, that is, a decoding operation, of a signal encoded and transmitted using a timing pulse provided from the logic unit 32.

Referring to the operation of the restoration circuit 40 in detail, the intermediate frequency signal output from the tuner 10 is amplified by the amplifier 42, filtered by the band pass filter 44 into the image frequency band, and the restoration unit 46. Is entered. In this case, the video signal input to the reconstructor 46 needs to be decoded as a signal as it is encoded during transmission. As shown in FIG. 3A, the video signal area is not changed, but the synchronization signal portion is attenuated. Signal.

Of course, the transformation of the signal may be different according to the encoding method. In other words, the attenuation may be reduced as shown in FIG. 3A. Alternatively, the pulse width of the synchronization signal may be modified or the synchronization signal may be inverted. It is also possible to modify the video signal.

As described above, there may be various encoding methods, but the data necessary for the restoration is sufficiently loaded on the audio signal, the logic unit 32 is configured appropriately, and the microcomputer 34 can read the data for the restoration. You can configure it.

Meanwhile, the restoration unit 46 reinforces the registered signal portion attenuated in (a) of FIG. 3 using the timing pulse provided from the logic unit 32 to restore the original signal form as shown in (b) of FIG. Done.

By accurately reconstructing the synchronization signal as described above, the video signal can be detected by the video and audio detection circuit 50, modulated by the modulator 60, and then accurately investigated by a television as an accurate synchronization signal to a monitor not shown. The audio signal is also output to the television after the same detection and modulation process.

In addition, a channel signal input from a remote controller (not shown) is input to the microcomputer 34 to select a channel from the microcomputer 34, and the microcomputer 34 outputs data for the channel to the tuner 10. Meanwhile, as the information on the current channel tuning state is output to the display unit 80, the current channel tuning state is displayed on the display unit 80.

The configuration of the display unit 80 may be configured by a light emitting device in consideration of design ease and economical efficiency, or may be configured using a liquid crystal panel. Alternatively, the channel tuning status can be displayed using an on-screen display from a television using the microcomputer 34.

In this way, in order to prevent the non-subscriber from receiving a signal in an illegal manner, when the pay broadcasting signal transmitting side encodes the signal, the video signal is distorted, and the audio signal carries the data for encoding and transmits the audio signal to the subscriber side. By reconstructing, detecting and modulating a voice signal using the data for encoding of the subscriber, subscribers can watch the pay-TV and non-subscribers can generate.

As described above, according to the decoder of the cable television according to the present invention, the subscriber can view the encoded and transmitted signal, but the non-subscriber cannot recover the encoded and transmitted signal. There is.

If the microcomputer provides data on the channels to the light emitting or display means by connecting the light emitting means or the display means to the microcomputer, the user can easily recognize the information on the displayed channel. There is.

Claims (4)

The encoder encodes the signal to prevent the reception of non-subscribers through the cable and tunes the input signal by channel in the tuner, detects it in the video and audio detection circuit, feeds back the gain and frequency control signal to the tuner, modulates it, and outputs it to the TV. A decoder of a cable television, comprising: data detecting means for amplifying the tuned signal and filtering the frequency of an audio band and then outputting the video and audio detection circuits to detect data related to decoding from the filtered signal; Decoding reading means for reading the detected data to decode the channel and the subscriber address to determine a decoding mode and decoding permission, generating timing pulses, and amplifying the filtered signal to filter the frequency of an image band. Is decoded as the timing pulse to Decoder of a cable television, characterized by restoring a video signal composed of a restoration means for output to the video and audio detection circuit. 2. The apparatus of claim 1, wherein the data detecting means comprises: a first amplifier for amplifying the tuned signal to a predetermined level, a first bandpass filter for filtering an output signal of the first amplifier into an audio frequency band, And a data detector for detecting the decoded data carried in the output signal of the one-pass filter. The apparatus of claim 1, wherein the decoding reading means comprises: a logic unit configured to output a channel recognition and a subscriber address and generate timing pulses for decoding when data detected by the data detector is input, and to the channel recognition and subscriber address signal. And a microcomputer for outputting a decoding permission signal and a decoding mode determination signal to the logic unit to induce the output of the timing pulse, and a data storage unit for storing data and programs processed by the microcomputer. Decoder. The filter of claim 1, wherein the recovery unit comprises: a second amplifier for amplifying the tuned signal to a predetermined level; a second band pass filter for filtering an output signal of the second amplifier into an image frequency band; and the filtered signal. And a restoring unit for restoring an image signal by using the timing pulse.