JPH0226485A - Charged television system - Google Patents

Abstract

PURPOSE:To transmit a charged satellite signal with an existent CATV system by continuing the output of a desk rumbler only when an address involved in the demodulating signal of a television signal formed with the modulator of a head end is coincident with an address assigned to a CATV tuner. CONSTITUTION:The output signal of a tuner circuit 27 is demodulated in an AM demodulating circuit 30 and added to a desk rumbler D. At the desk rumbler D, it is made back to the signal receivable with a monitor television, it is discriminated whether an address fetched from an input signal is the one of the address of a self machine or not, and since it in contracted, a switching control signal is outputted with coinciding with it. The switching control signal is added to switching circuits 39 and 40, and a contact is switched so that the desk rumbler D may be connected to the monitor television. Consequently, since an image and a voice signal receivable with the television from the desk rumbler D are added to the monitoring television, it can be viewed well in the same way as the case of the television signal of ground broadcasting. Thus, a satellite signal from a still satellite can be transmitted with the existent CATV.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pay television system using a glossy satellite and CATV.

(Prior Art) A geostationary satellite is planned to be launched, and a scrambled satellite signal is scheduled to be sent from the geostationary satellite. On the other hand, CATv is being developed into a pay-TV system on its own, and we are now in an era where it is strongly desired to connect geostationary satellites to the existing CATV system to make it more flexible.

(Problems to be Solved by the Invention) An object of the present invention is to provide a pay TV system that allows pay satellite signals from geostationary satellites to be transmitted using an existing CATV system.

(Means for Solving the Problems) In order to solve the above problems, the measures described in the claims above have been taken, and their effects are as follows.

(Operation) A scrambled satellite signal is sent from a geostationary satellite. The signal also includes the address of a subscriber device that has a viewing contract in a subscriber device that is downstream of the CATV system. This satellite signal is received by a receiving antenna, frequency converted by a down converter, and sent to the headend. At the head end, a receiver selects and demodulates one wave of the frequency-converted satellite signal, and then a modulator converts it into a television signal of a channel not used in terrestrial broadcasting. On the other hand, at Hesodoend, terrestrial broadcast waves are also signal-processed, and the terrestrial broadcast television signal and the television signal from the modulator are mixed by a mixer and sent to the subsequent stage of the CATV system. These television signals reach each of a number of tap-offs.

Each subscriber device connected to the tap-off can select and receive terrestrial broadcast television signals using a CATV tuner. For subscriber equipment that has already contracted to receive satellite signals, even if the TV signal from the headend modulator is selected in the tuner circuit of the CATV tuner, the output signal of the tuner circuit that can be received by the monitor TV is 0, that is, the output signal of the tuner circuit is AM. It is demodulated in the demodulation circuit and transferred to the descrambler. The descrambler returns the signal to a signal that can be received by the monitor TV, and also determines whether the address extracted from the input signal is the address of the machine itself, and since the contract is already in place, it matches and outputs a switching control signal. .

The switching control signal is applied to a switching circuit that switches the contacts to connect the descrampler to the television monitor. Since the video and audio signals that can be received by the TV from the descrambler mentioned above are added to the monitor TV, it can be viewed as well as in the case of terrestrial broadcast TV signals.

On the other hand, in the CATV tuner of a subscriber device without a contract, the address of the device cannot be found in the address signal extracted from the input signal of the descrampler, so no switching control signal is output to the switching circuit. . Then, the switching circuit brings the contacts on the side of the AM and FM demodulation circuit into conduction with the monitor television, so that the undescrambled signal is applied to the monitor television. Cannot receive on monitor TV.

(Example) The drawings showing the embodiments of the present application will be described below.

FIG. 1 shows a pay television system using satellites. 1 indicates a geostationary satellite such as a communication satellite. 2 is a transmitter that transmits a signal that is the basis of a 12 GHz band satellite signal sent to the ground via geostationary satellite 1. 03 is a geostationary satellite l
This is a transmitting antenna that sends the signal from the transmitter 2 toward the. Reference numeral 4 indicates a receiving antenna for receiving satellite signals from the geostationary satellite 1. 5 is a down converter that selects either horizontally polarized or vertically polarized satellite signals from the 12 GHz band satellite signals, and then
It is used for frequency conversion to intermediate frequency signals. Reference numeral 6 indicates an antenna for receiving terrestrial broadcast waves, and reference numeral 7 indicates a head end, which will be described in detail later. 8 indicates a CATV main line, and a coaxial cable is used. Reference numeral 9 indicates a trunk branch amplifier interposed in the trunk 8. 10 is a distribution line, and 11 is a lead-in line, each of which uses a coaxial Keple. Reference numeral 12 indicates a tap-off, and 13 indicates a subscriber device connected to the tap-off 12.

14 is a CATV channel (AM-IRD) which will be explained in detail later.
(Also referred to as an AM receiver with a descrambling function), and 15 indicates a monitor television connected to the CATV tuner 14.

The CATV system starting from the receiving antenna 4 and the antenna 6 and ending at the subscriber unit 13 is provided with a plurality of facilities as shown in the figure.

Next, 16 indicates an operation center. A host computer 17 is connected to a telephone line (not shown) and is located within the operation center 16. Reference numeral 18 indicates a communication line connecting the transmitter 2 and the host computer 17 described above.

Next, FIG. 2 is a block diagram showing details of the head end 7. As shown in FIG. In the figure, 20 is a divider, which is a well-known divider that equally divides the input first intermediate frequency signal to a plurality of terminals and outputs it.

21a, 21b, e...indicate satellite receivers (receivers 21a, 2lb, --), respectively.
As is well known, the fist has a channel selection function and a demodulation function. These receivers 21 a, 2 l b, -
0 22a, 22b are designed to select and demodulate first intermediate frequency signals of mutually different channels.

...are respectively desk clampers, 23 a t 23
b +... is a synchronous signal generator, 24 a, 24
b+...indicates a modulator, respectively. 25 is a receiving station amplifier, and 26 is a mixer.

Next, FIG. 3 is a block diagram showing details of the CATV tuner 14. 27 is a tuner circuit, and the tuning control section 2
Based on the channel selection control signal from 8, a desired channel is selected and sent out from a large number of channel signals sent by CATV.

An intermediate frequency amplification circuit 29 amplifies the television intermediate frequency signal from the tuner circuit 27. 30 is an FM modulation circuit;
Reference numeral 31 indicates an audio multiplexing demodulation circuit.

32 is an AM demodulation circuit, and 33 is a video amplifier circuit.

Next, the descrampler D will be explained. 34 is a data demodulation circuit, 35 is a synchronization signal generation circuit, and 36 is a synchronization signal regeneration circuit. Further, 37 is a PCM demodulation circuit, 38 is an address data discrimination circuit, and 039 and 40 are switching circuits, respectively. The switching circuits 39 and 40 have a similar configuration and include control terminals 39a and 40a, respectively. These switching circuits 39 and 40 are connected to the control terminal 39, respectively.
a, 40 It is switched to the contact B side only when a switching control signal is applied to a, and in other cases it is connected to the contact A side.

Next, the operation and signal flow of the pay TV system having the above configuration will be explained.

Paid TV viewing contracts are made on a monthly or weekly basis, and each subscriber device 13 of a plurality of CATV systems is connected to the operation center 1 using a telephone line, etc. not shown.
6 is sent to the host computer 17. Each subscriber device 13 is provided with a specific address, and the host computer 17 sends the address of the subscriber device with which the pay TV viewing contract has been concluded to the transmitter 2 via the communication line 18.
sent to. The transmitter 2 adds the address of the contracted subscriber device to the baseband video signal of the pay channel as a data signal and transmits the signal. Figure 4 is a schematic diagram showing the baseband video signal before it is modulated by the transmitter and sent out, where X is the color burst signal part, and Y is the address of the subscriber equipment mentioned above and the PCM audio signal. 2 indicates the data signal portion, and 2 indicates the image signal portion.

The viewing fee is billed using the host computer 16.

Next, the flow of signals in the pay television system having the above configuration will be explained.

The carrier wave in the 14 GHz band is transmitted from transmitting antenna 3 to pay TV.
A signal FM-modulated with the signal is sent toward the geostationary satellite 1. The geostationary satellite 1 relays this signal, converts it into a 12 GHz band satellite signal, and sends it to the ground. For example, this satellite signal has vertical polarization in odd channels such as C81 channel and C3-3 channel, and horizontal polarization in C8-2 channel, etc.
It is an even number channel such as C8-4 channel,
Each channel has a frequency band of 27MHz,
Each channel is scrambled, and there are 32 channels in total. These signals are received by a receiving antenna 4 in each CATV system, and a down converter 5 selects either a vertically polarized or horizontally polarized channel group and converts the frequency to become a first intermediate frequency signal in the IGHz band. It is sent to the head end 7.

At the head end 7, the output is divided into a plurality of parts by a divider 20, and outputted to receivers 21a and 2lb, respectively.

can be added to... In each receiver 21, signals of different channels are selected, and each becomes a baseband signal of 4.2 MHz band. For example, C8 in receiver 21a
-2 channel signals become baseband signals. For example, when the signal of the C3-2 channel becomes a baseband signal in the receiver 21a, the signal is sent to the modulator 24a and also applied to the descrambler 22a. The signal descrambled by the descrambler 22a is applied to a synchronization signal generator 23a, and a television synchronization signal synchronized with the input signal of the modulator 24a is sent from the synchronization signal generator 23a. The modulator 24a uses this synchronization signal to clamp the scrambled video signal to keep the modulation degree of AM modulation constant, and then modulates it into a TV signal of a channel that does not interfere with the reception of terrestrial broadcasting. Ru. Similar processing is performed for the other modulators 24a. On the other hand, terrestrial broadcast waves are received by an antenna 6, and after being subjected to well-known level setting and channel conversion by a receiving amplifier 25, a mixer 2
6. In the mixer 26, modulators 24a, 24
b, . . . or the respective television signals from the receiving amplifier 25 are mixed and sent to the subsequent stage as a signal in the 75 to 450 MHz band.

Each television signal from the head end 7 is connected to a main line 8. Main branch amplifier 99 distribution line 10. Tap off 12. It is sent to each subscriber device 13 through the drop-in line 11 and the like.

Next, the flow of signals in the CATV team 14 of the subscriber device 13 will be explained. First, the channel selection control section 28 is operated so that the channel selection control signal of the desired channel is output. Then, the tuner 27 receives the signal, selects the television signal of the desired channel from among a large number of channels, and converts it into a television intermediate frequency signal in the 50 MHz band. This signal is amplified by an intermediate frequency amplification circuit 29 and sent to an FM demodulation circuit 30 and an AM demodulation circuit 32.

(b) When the reception channel is a terrestrial broadcast wave such as channel 1 or 3, the switching circuits 39 and 40 are connected to the contact A side, respectively, so the audio signal obtained by the FM demodulation circuit 30 is After being further demodulated by the audio multiplex demodulation circuit 31,
The signal is output to the monitor television 15 through the switching circuit 39. Further, the video signal obtained by the AM demodulation circuit 32 is outputted to the monitor television 15 through the switching circuit 40.

(b) If the received channel is pay television from a satellite, the signal applied to the AM demodulation circuit 32 is demodulated and amplified by the video amplification circuit 33. This signal is applied to the synchronization signal reproducing circuit 36 and also to the data demodulation circuit 34 where it is demodulated. This demodulated signal is applied to the address discrimination circuit 38, and if it is determined that the address of the own aircraft is not included in the demodulated signal, no switching control signal is output from the address discrimination circuit 38, so the switching circuit 39 and 40 remain on the contact A side, and the AM demodulation circuit 3
Only the undescrambled video signal from 2 is sent to the monitor television 15.

On the other hand, when the address determination circuit 38 determines that the address of the device is present in the demodulated signal, a switching control signal is sent. Therefore, the switching circuits 39 and 40 are switched to the contact B side, so that pay TV channels can be viewed as shown below. The signal from the pig demodulation circuit described above is applied to the synchronization signal generation circuit, and the synchronization signal generated here is sent to the synchronization signal regeneration circuit 36 to the video amplifier circuit 33.
is superimposed on the signal from This completes the descrambling, and the video signal is sent to the monitor television 15 through the switching circuit 39. Further, the signal obtained by the data demodulation circuit is demodulated by the PCM demodulation circuit 37, and the audio signal obtained as a result of this demodulation is sent to the monitor television 15 through the switching circuit 40.

Although the pay TV system described above is a large-scale system that uses geostationary satellites, it is possible to charge multiple CATVs at once at the operation center 16, so even small-scale CATVs can be operated economically. Needless to say, it can be done.

Furthermore, since there is no need for there to be anyone at the head end of each CATV system to perform the scrambling process or the billing process, this also contributes to the efficient operation of the pay television system. In the case of an existing CATV system, there is little deterioration in distortion, and even if a large number of channels are added, a decrease in the operational level can be kept to a minimum.

(Effects of the Invention) As described above, in the present application, a satellite signal from a geostationary satellite can be transmitted by an existing CATV, so that an extremely economical pay television system can be provided.

[Brief explanation of the drawing]

The drawings relate to the embodiment of the present application, and Fig. 1 is a system diagram of a pay TV system using geostationary satellites, Fig. 2 is a block diagram of a head end, Fig. 3 is a block diagram of a CATV tuner, and Fig. 4 is a block diagram of a CATV tuner. Schematic diagram of a scrambled baseband signal waveform. DESCRIPTION OF SYMBOLS 1...Geostationary satellite, 4...Receiving antenna, 5...Down converter, 7...Head end, 8...Main line, 12...Tap off, 13.Fist/subscriber equipment, 14
...CATV tuner 15---Monitor TV, 2
1a, 21bII...Receiver 24 a, 24
b: Modulator, 26: Mixer, 27: Tuner circuit, 30: FM demodulation circuit, 32: AM demodulation circuit, 39.40: Switching circuit, D... Desk clamper. Patent Applicant Maspro Electric Works Co., Ltd. Representative Takashi Hata Figure 4 Time Procedure Amendment (Method) % Formula % 1. Indication of the case 1988 Patent Application No. 177734 2. Name of the invention Pay TV System 3. Amendment 4. Date of amendment order: September 27, 1985. 5. Full text of the specification to be amended.

Claims (1)

[Claims] Terrestrial broadcast waves are signal-processed at the head end and sent to the main line, and at the subscriber equipment side, the signal from the tap-off is converted to C.
In a pay TV system in which channels are selected using an ATV tuner and received on a monitor TV, the head end receives a scrambled signal sent from a geostationary satellite, converts the frequency using a down converter, and converts the signal into a baseband signal. a receiver that demodulates the signal into a signal of The CATV tuner is equipped with a tuner circuit for selecting one station from among a large number of television signals sent from the tap-off, and an AM and FM demodulator for demodulating the output from the tuner circuit. This AM/FM demodulation circuit is also provided with a descrambler in series with the AM/FM demodulation circuit, which tunes the television signal produced by the modulator of the head end and also tunes the television signal. The output of the descrampler is made conductive only when the address included in the demodulated signal matches the address assigned to its own CATV tuner, and the output of the AM and FM demodulator is made conductive at other times. A pay TV system characterized by having a circuit provided on the rear side.