JP3041240B2 - Terminal device for transmission of television signal voice confidential. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmitting / receiving system, for example, a television system in which only a subscriber can listen to a secret speech in a CATV system and a non-subscriber cannot listen to a secret speech. The present invention relates to a terminal device used in a signal private transmission system.

[0002]

2. Description of the Related Art Conventionally, in a CATV system, video scrambling has been performed for non-subscribers, but audio scrambling has not been performed. Therefore, although the non-subscriber cannot see the video, there is a problem that the voice can be heard by an unspecified person because the voice can be clearly heard. There are several ways to solve this problem. For example, a method of inverting a low frequency and a high frequency in a spectrum of an audio signal, or a method of scrambling some sounds, such as exchanging or shifting the audio spectrum, and exchanging the amplitude of the audio signal, can be considered.

[0003]

However, of the above methods, the method of inverting the spectrum of the audio signal is as follows.
There is a problem that the inversion method is complicated and the method of demodulating the sound after inversion again becomes complicated. If the key is displaced, demodulation cannot be performed accurately, resulting in a muffled sound. In addition, a method of exchanging or shifting the audio spectrum, a method of exchanging the amplitude of the audio signal, and the like require digital processing, and thus are more expensive than a method of inverting the spectrum.

Accordingly, an object of the present invention is to provide a television signal transmitting and receiving system, for example, a CAT.
An object of the present invention is to provide a simple and inexpensive voice in a V system with a confidential function to prevent a non-subscriber from hearing a confidential voice.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the structure described in claim 1 can be adopted.
According to the system in which this terminal device is used , the audio signal of the television signal to be confidential is converted into an audio sub signal without transmitting a multiplex control signal of a predetermined frequency indicating that the television broadcast is transmitted in the two-audio system. Output to the channel, and output no signal or insignificant sound to the main audio channel. Then , the terminal device receives the received television signal.
Generates multiplex control signal when demodulation permission is given.
Input to the terminal device by superimposing on the audio signal
Confidential speech can be resolved even with a receiver that can demodulate two-voice
Can be removed. Thus, the received television signal
Audio signal is demodulated by the two-sound system, and
An audio signal can be output. Therefore, even if the multiplex control signal is not superimposed by this system, only the contract terminal that can demodulate in the two-sound system can release the confidential speech, and the non-subscriber does not include the multiplex control signal in the television signal. Can not be canceled.

[0006] The terminal device generates a multiplex control signal to generate a voice.
Since it is only superimposed on the signal,
Output the left and right audio signals easily.
It becomes possible.

[0007]

According to the third aspect, when the demodulation permission command means receives the demodulation permission data transmitted from the transmitting station and determines that the demodulation permission has been given to its own terminal device. Then, a demodulation permission signal is output. This allows the transmitting station to instruct the demodulation of the received television signal.

According to a fourth aspect of the present invention, the multiplex control detecting means detects a multiplex control signal included in the received television signal, and the audio subcarrier detecting means detects the audio subcarrier included in the television signal. Is detected. The output means outputs the demodulation permission signal only when the multiplex control signal is not detected and the audio subcarrier is detected. Thereby, the confidential talk can be released only when the terminal device is provided.

[0010]

[0011]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment The present invention will be described below based on specific embodiments. FIG. 1 is a block diagram showing a configuration of a head end 101 (corresponding to a transmission device) and a control device 100 of a CATV system in a first embodiment according to the present invention. Usually, in the head end 101, in the case of two audio signals, a main audio signal composed of Japanese is input to the main channel amplifier 5,
A sub audio signal composed of a foreign language is input to sub channel amplifier 11. When the audio signal is a stereo signal,
When the left signal and the right signal pass through the matrix circuit 10, (left signal + right signal) is input to the main channel amplifier 5, and (left signal−right signal) is input to the sub-channel amplifier 11. Then, a multiplex control signal is superimposed on the audio signal for discrimination between the two audio signals and the stereo signal. In the present embodiment, the transmission is performed as described above in the case of a normal voice signal other than voice confidential, but in the case of transmitting voice confidential, the multiplex control signal is not superimposed on the voice signal and the main signal is not transmitted. It is characterized in that a non-signal or an unintentional sound is transmitted as a channel signal, and an audio signal is transmitted as a sub-channel signal.

After being amplified by a video amplifier 1 by a video signal from a VTR or a broadcast wave, a video amplitude modulator 2
Performs amplitude modulation on the video carrier. The amplitude of the horizontal-modulated signal is compressed by the synchronous compression circuit 3 and output to the mixer 6b. The modulation circuit 9 outputs a KEY signal for detecting a synchronization signal based on the output signal of the synchronization compression circuit 3, and outputs the KEY signal to the mixer 6b. The audio signal input to the main channel amplifier 5 is amplified and output to the mixer 6a. The audio signal input to the sub-channel amplifier 11 is amplified, and the sub-carrier FM modulator 1
2f _H in 2 (f _H is the horizontal scanning frequency) is used to FM modulate the subcarriers. F at subcarrier FM modulator 12
The M-modulated subcarrier passes through a band-pass filter (BPF) 13 having a pass band of 16 to 47 kHz and is output to the mixer 6a. The audio signal on the main channel side and the audio signal on the sub-channel side are mixed by a mixer 6a, and an audio FM modulator 7 performs FM modulation of the main carrier using the output of the mixer 6a.
The FM-modulated main carrier is output to mixer 6b.
If the voice signal is not a voice confidential speech, the multiplex control signal is mixed by the mixer 6a.

If the voice signal is a voice secret story, the CPU
Under the control of 14, the switch 4b is switched to the insignificant sound generator 4a side, and an insignificant sound such as a dummy sound generated from the insignificant sound generator 4a is input to the main channel amplifier 5 as a main channel signal. The process of generating the unintended sound corresponds to the first voice control means. In the case of voice confidential speech, a voice signal is output as a sub-channel signal. This processing corresponds to the second voice control means. The video signal from the synchronous compression circuit 3 and the audio signal from the audio FM modulator 7 are mixed together with other signals by the mixer 6b, and then the frequency converter 8 outputs a signal of a predetermined band in the lower channel of the transmission path. Is converted to Then, the signal is mixed with an output signal from another frequency converter by the mixer 6c, and transmitted to each home terminal via a coaxial cable.

The control device 100 includes a ROM 17, a RAM 1
Based on the data stored in 8, output of control data (corresponding to demodulation permission data) and control of generation of a multiplex control signal are performed. The control data is command data for controlling permission of demodulation of the received signal, and an example of the format is shown in FIG. As shown in FIG. 4A, the control data includes an address of a target home terminal, a code of a target channel, and demodulation instruction data for instructing permission or non-permission of demodulation of a received signal. Have been. The data table in which the contract channels are arranged corresponding to each home terminal has a configuration as shown in FIG. 4B and is stored in the RAM 18.

The control data from the CPU 14 is transmitted to the modulator 2
After FSK (Frequency Shift Keying) modulation by 0, the signal is mixed with audio and video signals by the mixer 6c and transmitted to each home terminal. The multiplex control signal is output to the multiplex control signal generator 19 when the voice signal is not a voice narration.
And output to the mixer 6a. The control device 100 is provided with a keyboard 16, a monitor 15, and the like, and performs data input, communication control, system monitoring, and the like.

Here, using the flowchart of FIG.
The control data transmission process in the PU 14 will be described. Note that the program in FIG. 5 is repeatedly executed at predetermined time intervals. First, the data table is searched (step 502), and control data of one address is selected (step 504). The selected control data is transmitted (step 506), and it is determined whether the data table has completed one round (step 508). If the data table has not yet completed one cycle, the process proceeds to the next control data (step 512), and if the control data has completed one cycle, the process returns to the control data of the first address (step 510). Thus, the control data is continuously transmitted. Note that the processing shown in FIG. 5 corresponds to demodulation permission data transmission means.

FIG. 2 is a block diagram showing the configuration of a home terminal 200 (corresponding to a terminal device) of the CATV system, and includes a video receiving circuit 200a and an audio receiving circuit 200.
b. The signal received via the coaxial cable is selected by the tuner 21. The video signal among the selected signals is IF-amplified by the video intermediate frequency amplifier 22. K based on the output signal of amplifier 22
The EY signal detector 37 detects a KEY signal. The descrambling circuit 38 inputs a KEY signal and outputs a signal for canceling video scrambling. Using the output of the descramble circuit 38, the video detector 23
, The video signal is detected, amplified by the video amplifier 24, and output to the picture tube 34. In this way, the video signal is extracted from the home terminal 200. If demodulation at home terminal 200 is not permitted,
Since the television receiver cannot detect the synchronization signal, the video is scrambled. Note that the KEY signal detector 37, the descramble circuit 38, the tuner 21, the video intermediate frequency amplifier 22, and the video detector 23 constitute a video reception circuit 200a.

The audio signal among the signals selected by the tuner 21 is converted into an IF signal by an audio intermediate frequency detector 25.
When the signal is detected, the signal is IF-amplified by the audio intermediate frequency amplifier 26. The amplified signal is subjected to FM detection by the audio FM detector 27. The control data of the predetermined data channel of the received signal is demodulated by the FSK data demodulator 29. The CPU 30 decodes the output signal from the FSK data demodulator 29 and controls the output of the multiplex control signal from the multiplex control signal generator 31 (corresponding to multiplex control signal generating means). This processing will be described with reference to the flowchart of FIG. The program shown in FIG. 6 is repeatedly executed at predetermined time intervals.

First, the demodulated control data is received from the FSK data demodulator 29 (step 602), and it is determined whether the home terminal address specified by the control data is its own address (step 604). If the home terminal address specified by the control data is its own address, it decodes the control data and stores the channel from which the voice confidential release is to be performed. Delete the number (step
606), it is determined whether or not the selected channel is a cancellation target channel (step 608). If the selected channel is a channel to be released, a generation command is given to the multiplex control signal generator 31 to generate a multiplex control signal and the KEY
A command for detecting the KEY signal from the audio signal is given to the signal detector 37 to enable the demodulation of the compressed synchronizing signal in the descramble circuit 38 (step 610). If the selected channel is not the channel to be released, multiplex control is performed. Signal generator 3
1 to stop the output of the multiplexed control signal by giving a stop command to the KEY signal detector 37, and to give a command to the KEY signal detector 37 to prohibit the detection of the KEY signal from the audio signal. Demodulation is prohibited (step 612). If the home terminal address specified in step 604 is different from its own address, the process is terminated. The multiplex control signal is superimposed on the audio signal at the home terminal 200 for which demodulation is permitted in this way. The flow from step 604 to step 612 corresponds to demodulation permission command means.

FIG. 9 shows the relationship between the frequency spectrum and the frequency shift in the audio signal. In case of two audio signals, 3.5 F _H in sinusoidal 922.5Hz the audio signal
A multiplexed control signal obtained by modulating a control signal subcarrier (about 55.125 kHz) is superimposed. In the case of a stereo signal is superimposed multiple control signal modulated control signal subcarrier 3.5 F _H sine wave 982.5Hz the audio signal.
Usually, by decoding the multiplex control signal included in the received signal at the home terminal, the two audio signal and the stereo signal are switched, but in the present embodiment, the multiplex control signal is generated at the home terminal 200, The received signal is demodulated using the signal.

In the configuration shown in FIG.
In step 2, the received audio signal is demodulated into two audio signals using the multiplex control signal output from the multiplex control signal generator 31. The demodulated signal is supplied to low frequency amplifiers 28 and 33
, And output as audio from the speakers 35 and 36. In this way, the audio signal is extracted at home terminal 200. The portion surrounded by the dotted line in FIG. 2 constitutes the audio receiving circuit 200b.

As described above, when the audio signal output from the head end 101 is a voice confidential speech, since the multiplex control signal is not included, only the main channel signal is demodulated on the home terminal side where demodulation is not permitted. It will be demodulated. Since this main channel signal consists of silence,
Even if the main channel signal is demodulated, it cannot be heard as meaningful voice. As described above, in the present embodiment, it is possible to prevent the home terminal from which the demodulation is not permitted from hearing the voice. On the other hand, in the home terminal 200 for which demodulation is permitted, the multiplex control signal is generated from the multiplex control signal generator 31 of the home terminal 200 by decoding the control data included in the received signal. Thus, the voice can be demodulated from the sub-channel, so that the confidential voice can be heard.

Next, a specific example of the home terminal according to the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the home terminal 201. The received signal is input from the input terminal 41 into the home terminal 201, and is selected by the CATV tuner. The audio signal and the video signal included in the selected signal are SAW
(Surface Acoustic Wave: surface acoustic wave filter) 46,
47 separates the video signal and the audio signal from each other.
It is input to the video / audio demodulation circuit 48. The video signal among the signals demodulated by the video / audio demodulation circuit 48 is
Output from VIDEOOUT and visualized. The KEY signal detecting circuit 55 detects a KEY signal for descrambling the video from the audio signal output from the tuner 42, and synchronizes the KEY signal with the signal to decompress the synchronizing signal by the descramble control circuit 56.
4 to reduce the amount of attenuation to restore the compressed synchronization signal.

On the other hand, the audio signal is demodulated using the multiplex control signal generated from the multiplex control signal generation circuit 57.
That is, when the control data is demodulated by the FSK data demodulation circuit 51, the control data is decoded by the CPU 53, and when the demodulation command is confirmed, a signal is output from the terminal AUDIO-SCR of the CPU 53 to the switch 58, and the switch 58 is turned on.
When the switch 58 is turned on, the multiplex control signal output from the multiplex control signal generation circuit 57 is superimposed on the audio signal output from the video / audio demodulation circuit 48. Using the multiplex control signal, the audio multiplex demodulation circuit 49 demodulates the audio signal demodulated by the video / audio demodulation circuit 48 into two audio outputs. Then, a demodulated sound is output from a speaker (not shown). The home terminal to which the demodulation is not permitted from the head end 101 cannot demodulate the audio of the sub-channel, and can demodulate only the random sound of the main channel because the multiplex control signal is not superimposed on the audio signal. In this way, when the received signal is the secret speech, demodulation of the secret speech on the contractor side is permitted, and demodulation of the secret speech on the non-contractor side is not permitted. Further, since the device configuration is simple, cost reduction can be realized.

In the present embodiment, an insignificant sound such as a dummy sound is generated from the insignificant sound generator 4a as a main channel signal at the time of voice confidential talk, but may be a non-signal. In the above embodiment, the control data is output from the transmission side, the signal is decoded on the reception side, and the received audio signal is demodulated based on the decoding result. A configuration may be adopted in which data specifying a permitted channel is stored, and an audio signal is demodulated based on the stored data.

(Second Embodiment) In the first embodiment, the multiplex control signal is output based on the control data output from the head end 101. The present embodiment is characterized in that it detects that there is no multiplex control signal in the signal output from the head end 101, outputs a multiplex control signal on the home terminal side, and listens to a secret voice. This will be described below with reference to FIGS. FIG. 7 shows the home terminal 202.
FIG. 2 is a block diagram showing the configuration of FIG. The difference from the configuration of FIG. 3 is that BPFs 61 and 62 and a smoothing circuit 63,
64 are provided in series, and output signals from the smoothing circuits 63 and 64 are input to the CPU 53. The other device configuration is the same as that of FIG. Here, the BPF 61 is
Have a bandwidth of only passing audio subcarrier 2f _H (approximately 31.5 kHz), BPF 62 has a bandwidth of only passing subcarrier 3.5 F _H (about 55.126KHz) of the multiplex control signal . The output of the multiplex control signal generation circuit 57 is
A video / audio demodulation circuit 48 is provided inside the audio multiplex demodulation circuit 49.
Is superimposed on the audio signal output by

Next, the procedure of controlling the generation of the multiplex control signal in the CPU 53 will be described with reference to the flowchart shown in FIG. First, the respective outputs of the smoothing circuits 63 and 64 are input from the terminals C ₁ and C ₂ (step 802), and 55.1
It is determined whether there is a signal of 26 kHz (step 804).
). If there is a signal of this frequency, the multiplex control signal is included in the received signal, and the received voice signal is not a confidential voice, that is, the multiplex control signal is regarded as a two-voice or stereo signal. A command for stopping the generation of the multiplex control signal from the generation circuit 57 is output, and the switch 58 is output.
Is turned off (step 810). Thus, the received signal is demodulated as usual, and output as two voices or stereo.
The processing in step 804 corresponds to the multiplex control signal detecting means.

[0029] If there is no multiplex control signal subcarrier 3.5 F _H at step 804, no contains multiplexed control signal to the reception signal, regarded audio signal received is a privacy speech, or monaural signal, Proceed to the next step. Steps
In 806, it is judged whether there is audio subcarrier 2f _H,
If there is no carrier of this frequency, it is determined that there is no sub-channel signal and the received signal is a non-secret mono signal, and the flow advances to step 810 to output a multiplex control signal generation stop command and turn off the switch 58. . At step 806, if there is a sound subcarrier 2f _H determines that the sub-channel signal is present, because it is polarized manner, in order to perform a two audio output, for generating a multiplex control signal of the two-voice protocol A command is output and the switch 58 is turned on (step 80
8). The processing in step 806 corresponds to the voice sub-carrier detection means, and the processing in step 808 corresponds to the output means.

As described above, when the received signal does not include the multiplex control signal and the sub-channel signal is present, the multiplex control signal is output from the multiplex control signal generating circuit 57 to cancel the secret. Then, the user can select the sub-channel from the two voices and listen to the secret voice. At the time of this confidential voice, a configuration may be employed in which audio is output only from the sub-channel, or a configuration in which the voice is selected by remote control operation and output from the sub-channel. On the other hand, the non-subscriber cannot listen to the sound of the sub-channel in the picture tube, but listens to the silent sound of the main channel, because the received signal does not include the multiplex control signal and is regarded as monaural. Can not.

As indicated above, according to the present invention,
In the case of voice confidentiality, by outputting the main channel signal as an insignificant sound or a no-signal, the sub-channel signal as an audio signal, and a signal containing no multiplex control signal from the head end, the audio at the home terminal for which demodulation is not permitted. Can be prevented from being heard. In the home terminal where demodulation is permitted, the control data included in the received signal is detected, or the multiplex control signal is generated by detecting that the multiplex control signal is not included. By demodulating the audio signal, the secret voice can be demodulated. Furthermore, since the apparatus configuration is simple, the cost of the system can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a center in a first embodiment according to the present invention.

FIG. 2 is a block diagram showing a configuration of a home terminal in the first embodiment according to the present invention.

FIG. 3 is a block diagram showing a specific configuration of a home terminal in the first embodiment according to the present invention.

FIG. 4 is a schematic diagram showing a configuration of a format of control data in the first embodiment according to the present invention.

FIG. 5 is a flowchart showing the processing contents of a center in the first embodiment according to the present invention.

FIG. 6 is a flowchart showing processing contents of a home terminal in the first embodiment according to the present invention.

FIG. 7 is a block diagram showing a specific configuration of a home terminal in a second embodiment according to the present invention.

FIG. 8 is a flowchart showing the processing contents of a home terminal in a second embodiment according to the present invention.

FIG. 9 is a schematic diagram showing a relationship between a frequency spectrum of an audio signal and a frequency shift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Video amplifier 2 Video amplitude modulator 3 Synchronous compression circuit 4a Silent sound generator 6a-6c Mixer 5 Main channel amplifier 7 Audio FM modulator 8 Frequency modulator 10 Matrix circuit 11 Subchannel amplifier 12 Subcarrier FM modulator 13 Band Pass filter 14, 30 CPU 19, 31 Multiplexed control signal generator 21 Tuner 29 FSK data demodulator 32 Multiplexed demodulator 100 Control device 101 Headend 200, 201 Home terminal 200a Video receiving circuit 200b Audio receiving circuit

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 7/10 H04N ^7/ 14-7/173 H04N ^7/ 20-7/22

Claims (4)

(57) [Claims] 1. A transmitting station scrambles and transmits a video signal of a television signal including a video signal and an audio signal .
Rutotomoni without te revision broadcast sends a multiplex control signal of a predetermined frequency indicating that it is transmitted in two audio system outputs the audio signal of the polarized target of the television signal to an audio sub-channel, audio main channel Output a no-signal or a silent sound to the receiver
Used in transmission systems that enable demodulation of television signals.
Terminal that outputs the received signal to the television receiver
A device for permitting demodulation of the received television signal.
And demodulating permit command means for outputting a tone permission signal, and inputs the demodulated permission signal from said demodulating permission instruction means
If the television broadcast is transmitted in a two-audio format
To generate a multiplex control signal of a predetermined frequency indicating that
Multiplex control signal generating means for superimposing on a received audio signal band
Voice secret of the television signal, characterized in that it comprises bets
Terminal device in talk transmission system. 2. The sound on which the multiplex control signal is superimposed.
Input a signal in the signal band to convert the left audio signal and right audio signal.
Characterized by having an audio multiplex demodulation circuit for outputting
The terminal device according to claim 1. 3. The apparatus according to claim 2, wherein the demodulation permission instruction means is configured to be connected to the transmitting station.
Receiving the demodulation permission data transmitted from the
If it is determined that demodulation permission has been granted to the
Means for outputting the demodulation permission signal .
3. The sound of a television signal according to claim 1 or 2.
A terminal device in a voice confidential transmission system. 4. The demodulation permission command means includes: a multiplex control signal detecting means for detecting a multiplex control signal included in a received television signal; and an audio subcarrier detecting an audio subcarrier included in the received television signal. Detection means, and output means for outputting the demodulation permission signal only when the multiplex control signal is not detected by the multiplex control signal detection means and an audio subcarrier is detected by the audio subcarrier detection means. Claims 1 to 3 characterized by the above-mentioned.
A terminal device in a television confidential sound transmission system for a television signal according to claim 3 .