JP2019195147A - Broadcast system, control method of broadcast system, and customer premises device - Google Patents

Abstract

To view a satellite broadcast while reducing facility costs.SOLUTION: A center device 10 includes: down-converting means (downconverter) for down-converting at least part of a signal of an intermediate frequency included in a satellite broadcast signal supplied from a plurality of antennas into a different frequency; change means (NIT change unit) for changing information indicating a frequency of a signal of a transponder written in a NIT included in the down-converted satellite broadcast signal into a frequency different from an original frequency; modulation means (modulation unit) for modulating a TS or TLV in which the NIT is changed; and transmission means (mixing unit 18) for mixing a CATV broadcast signal and the satellite broadcast signal to transmit a resultant signal via a transmission path 20. A customer premises device 30 includes: reception means (distribution unit 31) for receiving a signal transmitted via the transmission path; and extraction means (distribution unit 31) for extracting the satellite broadcast signal from the signal received by the reception means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a broadcast system, a broadcast system control method, and a subscriber premises apparatus.

  In Patent Literature 1, for example, a conventional broadcast wave such as terrestrial digital broadcast and BS digital broadcast and CS digital broadcast are transmitted through different optical fiber transmission lines, so that BS digital broadcast and CS digital broadcast are transmitted by a pass-through method. Techniques to do this are disclosed.

Japanese Unexamined Patent Publication No. 2011-4008

  By the way, in the technique disclosed in Patent Document 1, since it is necessary to lay two optical fiber transmission lines between the head end and the extended ONU, there is a problem that the cost of the equipment increases.

  Accordingly, the present invention provides a broadcasting system, a broadcasting system control method, and a subscriber premises apparatus capable of viewing a stable satellite broadcast with improved transmission quality while reducing the cost of equipment. It is aimed.

In order to solve the above-described problems, the present invention provides a broadcasting system having a center device and a subscriber premises device, wherein the center device receives at least an intermediate frequency signal supplied from a plurality of antennas included in a satellite broadcast signal. Down-converting means for down-converting a part to a different frequency, and information indicating the frequency of the transponder signal described in the NIT (Network Information Table) included in the satellite broadcast signal down-converted by the down-converting means A changing means for changing to a frequency different from the original frequency, a modulating means for modulating TS (Transport Stream) or TLV (Type Length Value) whose NIT has been changed by the changing means, and CATV (Cable Television) broadcasting The signal and the satellite broadcast signal output from the modulation means are mixed and transmitted. The subscriber premises equipment receives the signal transmitted through the transmission path, and receives the satellite broadcast signal from the signal received by the receiving means. Extracting means for extracting.
According to such a configuration, it is possible to view a stable satellite broadcast with improved transmission quality while reducing the cost of equipment.

Further, the present invention is characterized in that the modulation means modulates the TS or TLV whose NIT has been changed by the changing means by the same modulation method as that of the satellite broadcast signal.
According to such a configuration, it is possible to view a stable satellite broadcast with improved transmission quality.

Further, according to the present invention, the down-conversion means down-converts at least a part of the plurality of intermediate frequency signals included in the satellite broadcast signal to an empty frequency band of the CATV broadcast signal, and the subscriber The in-home device has an up-conversion unit that up-converts the satellite broadcast signal extracted by the extraction unit.
According to such a configuration, the frequency band can be limited by down-converting the satellite broadcast signal to the frequency band of the CATV broadcast signal.

Further, in the present invention, the changing unit may directly perform at least a part of the plurality of intermediate frequency signals of the satellite broadcast signal down-converted by the down-converting unit by the up-converting unit. Thus, the frequency is changed to a frequency when shifted to the high frequency side on the frequency axis.
According to such a configuration, since the number of up-converters can be reduced, the manufacturing cost of the subscriber premises equipment can be reduced.

Further, according to the present invention, the changing unit arranges the plurality of intermediate frequency signals of the satellite broadcast signal down-converted by the down-converting unit when they are up-converted by the up-converting unit. Thus, the frequency is changed to the frequency when shifted to the high frequency side on the frequency axis.
According to such a configuration, since the number of up-converters can be reduced, the manufacturing cost of the subscriber premises equipment can be reduced.

In the present invention, the down-conversion means converts one or a plurality of intermediate frequency signals having a higher frequency out of the plurality of intermediate frequency signals of the satellite broadcast signal to a lower frequency. It is characterized by.
According to such a configuration, the bandwidth of the satellite broadcast signal can be compressed.

Further, the present invention is characterized in that the down-conversion means converts all of the plurality of intermediate frequency signals of the satellite broadcast signal to a lower frequency.
According to such a configuration, the bandwidth of the satellite broadcast signal can be compressed.

The present invention also provides a control method for a broadcast system having a center device and a subscriber premises device, wherein the center device receives at least a part of intermediate frequency signals supplied from a plurality of antennas included in a satellite broadcast signal. A down-conversion step for down-conversion to a different frequency, and information indicating the frequency of the transponder signal described in the NIT (Network Information Table) included in the satellite broadcast signal down-converted in the down-conversion step, A change step for changing to a frequency different from the frequency; a modulation step for modulating TS (Transport Stream) or TLV (Type Length Value) in which the NIT is changed by the change step; a CATV (Cable Television) broadcast signal; The satellite broadcast signal output from the modulation step; A transmission step of mixing and transmitting via a transmission path, wherein the subscriber premises apparatus receives a signal transmitted via the transmission path, and a signal received in the reception step. An extraction step for extracting the satellite broadcast signal.
According to such a method, it is possible to view a stable satellite broadcast with improved transmission quality while reducing the cost of equipment.

Further, the present invention provides the subscriber premises apparatus of a broadcasting system having a center apparatus and a subscriber premises apparatus, wherein at least one of the intermediate frequency signals supplied from the plurality of antennas included in the satellite broadcast signal in the center apparatus. A part of the signal is down-converted to a different frequency, and information indicating the frequency of the transponder signal described in the NIT (Network Information Table) included in the down-converted satellite broadcast signal is changed to a frequency different from the original frequency. The NIT changes the TS (Transport Stream) or TLV (Type Length Value), and the CATV (Cable Television) broadcast signal and the modulated satellite broadcast signal are mixed to change the transmission path. Receiving means for receiving the signal transmitted via the receiver, and the satellite broadcast from the signal received by the receiving means Having an extraction means for extracting, characterized in that.
According to such a configuration, it is possible to view a stable satellite broadcast with improved transmission quality while reducing the cost of equipment.

  According to the present invention, it is possible to provide a broadcasting system, a broadcasting system control method, and a subscriber premises apparatus capable of viewing a stable satellite broadcast with improved transmission quality while reducing the cost of equipment. it can.

It is a figure which shows the structural example of the broadcast system of 1st Embodiment of this invention. It is a figure which shows the structural example of the center apparatus shown in FIG. It is a figure which shows the structural example of the subscriber premises apparatus shown in FIG. It is a figure which shows the structural example of the conventional center apparatus. It is a figure which shows the structural example of the conventional subscriber premises apparatus. It is a figure for demonstrating operation | movement of the conventional broadcasting system. It is a figure for demonstrating operation | movement of the broadcasting system of 1st Embodiment of this invention. It is a figure which shows the structural example of the center apparatus of 2nd Embodiment of this invention. It is a figure which shows the structural example of the subscriber premises apparatus of 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the broadcasting system of 2nd Embodiment of this invention.

  Next, an embodiment of the present invention will be described.

(A) Description of Configuration of First Embodiment of the Present Invention FIG. 1 is a diagram illustrating an example of a configuration of a broadcasting system according to the first embodiment of the present invention. As shown in FIG. 1, the broadcasting system 1 according to the first embodiment of the present invention includes a center device 10, a transmission path 20, and subscriber premises devices 30-1 to 30-n (n> 1). .

  Here, the center apparatus 10 mixes satellite broadcast signals such as BS (Broadcasting Satellite) broadcast, advanced BS broadcast, CS (Communication Satellite) broadcast, and advanced wideband CS broadcast and CATV (Cable Television) broadcast signals. Then, the transmission signal is transmitted through the transmission line 20. The transmission path 20 transmits a transmission signal transmitted from the center apparatus 10 as, for example, an electric signal or an optical signal. The subscriber premises devices 30-1 to 30-n are installed in the subscriber's premises, receive transmission signals, separate CATV broadcast signals, supply them to television receivers, etc., and reproduce them, as well as satellite broadcast signals. Is up-converted and supplied to a television receiver or the like for reproduction.

  FIG. 2 is a diagram illustrating a configuration example of the center device 10 illustrated in FIG. 1. In the example of FIG. 2, the center apparatus 10 includes a distribution unit 11, demodulation units 12-1 to 12-4, NIT (Network Information Table) changing units 13-1 to 13-4, and modulation units 14-1 to 14-4. , Down converters 15-1 to 15-4, CATV device 16, satellite broadcast signal passage unit 17, and mixing unit 18.

  Here, the distribution unit 11 distributes and outputs an intermediate frequency satellite broadcast signal (for example, a BS-IF signal and a CS-IF signal) supplied from an antenna (not shown), for example. The demodulating units 12-1 to 12-4 demodulate each of a plurality of intermediate frequency signals included in the intermediate frequency satellite broadcast signals (hereinafter simply referred to as “satellite broadcast signals”) supplied from the distribution unit 11. TC8PSK demodulation, QPSK demodulation, or 16APSK demodulation) to generate and output TS (Transport Stream) or TLV (Type Length Value).

  The NIT changing units 13-1 to 13-4 extract the NIT included in the TS or the TLV-NIT included in the TLV, and change and output information indicating the center frequency of each transponder. The NIT is physical information relating to the transmission path, that is, information indicating the orbit of the satellite, the polarization, the frequency for each transponder, and the like in satellite broadcasting.

  Modulating sections 14-1 to 14-4 modulate TS or TLV output from NIT changing sections 13-1 to 13-4 into the original satellite broadcast signals, and output them.

  The down converters 15-1 to 15-4 down-convert the satellite broadcast signals output from the modulation units 14-1 to 14-4 to the CATV frequency band and output the satellite broadcast signals, as will be described later.

  The CATV device 16 generates and outputs a CATV broadcast signal. The satellite broadcast signal passing unit 17 is an intermediate frequency demodulated by the demodulation units 12-1 to 12-4 among satellite broadcast signals (for example, BS-IF signal and CS-IF signal) having an intermediate frequency supplied from an antenna (not shown). The signal except the satellite broadcast signal of the frequency is passed and output.

  The mixing unit 18 includes a CATV broadcast signal supplied from the CATV device 16, a satellite broadcast signal supplied from the satellite broadcast signal passing unit 17, and a down-converted satellite output from the down converters 15-1 to 15-4. Broadcast signals are mixed and output as transmission signals.

  FIG. 3 is a diagram illustrating a configuration example of the subscriber premises apparatuses 30-1 to 30-n illustrated in FIG. Note that the subscriber premises apparatuses 30-1 to 30-n have the same configuration, and therefore will be described as the subscriber premises apparatus 30 below.

  As shown in FIG. 3, the subscriber premises apparatus 30 includes a distribution unit 31, a BPF (Band Pass Filter) 32, an up-converter 33, a BPF 34, a satellite broadcast signal passage unit 35, and a mixing unit 36. Yes. Here, the distribution unit 31 distributes (separates) the received signal, supplies it to the BPF 32, and outputs it as a CATV broadcast signal.

  As will be described later, the BPF 32 passes the satellite broadcast signal accommodated in the frequency band of the CATV broadcast signal and attenuates and outputs the other band.

  The up-converter 33 up-converts and outputs the frequency of the satellite broadcast signal supplied from the BPF 32.

  The BPF 34 attenuates and outputs signal components other than the satellite broadcast signal included in the signal output from the up-converter 33.

  The satellite broadcast signal passing unit 35 passes and outputs a satellite broadcast signal that does not require up-conversion among the satellite broadcast signals supplied from the distribution unit 31.

  The mixing unit 36 mixes and outputs the satellite broadcast signal supplied from the BPF 34 and the satellite broadcast signal supplied from the satellite broadcast signal passing unit 35.

(B) Description of Operation of First Embodiment of the Invention Next, operation of the first embodiment of the present invention will be described. In the following, the configuration and operation of the prior art shown in FIGS. 4 and 5 will be described, and then the operation of the first embodiment of the present invention will be described.

  FIG. 4 is a diagram illustrating a configuration example of the conventional center apparatus 10. In FIG. 4, the same reference numerals are given to the portions corresponding to those in FIG. In the example illustrated in FIG. 4, the center device 10 includes a distribution unit 11, down converters 15-1 to 15-4, a CATV device 16, and a mixing unit 18. Compared with the first embodiment shown in FIG. 2, the conventional center device 10 shown in FIG. 4 has demodulating units 12-1 to 12-4, NIT changing units 13-1 to 13-4, and a modulating unit 14-. 1-14-4 are excluded.

  FIG. 5 is a diagram showing a configuration of a conventional subscriber premises apparatus 30. In FIG. 5, the same reference numerals are given to the portions corresponding to those in FIG. In the example shown in FIG. 5, the subscriber premises apparatus 30 includes BPFs 32-1 to 32-4, up-converters 33-1 to 33-4, BPFs 34-1 to 34-4, and 35. That is, in the conventional subscriber premises apparatus 30 shown in FIG. 5, the BPF 32-1 to 32-4, the up-converters 33-1 to 33-4, and the BPF 34-1 are compared with the first embodiment shown in FIG. 34-4 are increased according to the number of intermediate frequencies or the number of down-converted frequency arrays.

  The mixing unit 36 mixes and outputs the satellite broadcast signals output from the BPFs 34-1 to 34-4.

  FIG. 6 is a schematic diagram for explaining the operation of the conventional example shown in FIGS. In FIG. 4, the satellite broadcast signals (for example, BS-IF signal and CS-IF signal) input to the distribution unit 11 are f1 to f4 frequencies (for example, in the GHz band) as shown in FIG. Frequency). Further, the CATV broadcast signal output from the CATV device 16 is a signal having a frequency of 770 MHz or less as shown in FIG. FIG. 6 schematically shows the CATV broadcast signal and the satellite broadcast signal, and other modes may be used.

  In FIG. 4, the satellite broadcast signal output from the distribution unit 11 is supplied to the down converters 15-1 to 15-4. The down-converters 15-1 to 15-4 down-convert the signals related to the intermediate frequencies having the center frequencies f1 to f4 shown in FIG. 6A, respectively, and the center frequencies shown in FIG. It converts into the signal of f14. The mixing unit 18 mixes and outputs the down-converted satellite broadcast signal having the center frequency f11 to f14 output from the down converters 15-1 to 15-4 and the CATV broadcast signal output from the CATV device 16. . As a result, as shown in FIG. 6B, a CATV broadcast signal in which satellite broadcast signals having center frequencies f11 to f14 are arranged is output as a transmission signal with respect to an empty frequency band of the CATV broadcast signal. Is done.

  The transmission signal shown in FIG. 6B is transmitted via the transmission path 20 and supplied to the subscriber premises devices 30-1 to 30-n. In addition, since operation | movement of the subscriber premises apparatus 30-1 to 30-n is the same, below, these are demonstrated as the subscriber premises apparatus 30. FIG.

  The subscriber premises apparatus 30 shown in FIG. 5 receives the transmission signal shown in FIG. Distribution unit 31 distributes and outputs a CATV broadcast signal (a signal of 770 MHz or less in FIG. 6C) from the transmission signal. The distribution unit 31 distributes the CATV broadcast signal and supplies it to the BPFs 32-1 to 32-4.

  The BPFs 32-1 to 32-4 pass the signals having the center frequencies f11 to f14 included in the CATV broadcast signal shown in FIG. 6B, respectively, and attenuate the other bands to upconvert the converters 33-1 to 33. -4. For example, the BPF 32-1 passes the signal having the center frequency f11 shown in FIG. 6B and attenuates the other frequency components to supply to the up-converter 33-1. The BPFs 32-2 to 32-4 pass signals having center frequencies f12 to f14 shown in FIG. 6B, respectively, and attenuate other frequency components to the up-converters 33-2 to 33-4. Supply.

  Upconverters 33-1 to 33-4 up-convert signals having center frequencies f11 to f14 shown in FIG. 6B, and have the original frequencies f1 to f4 shown in FIG. 6C. Convert to signal. For example, the up-converter 33-1 up-converts the signal having the center frequency f11 shown in FIG. 6B and converts it to the original satellite broadcast signal having the center frequency f1 shown in FIG. 6C. Similarly, the up-converters 33-2 to 33-4 up-convert signals having the center frequency f12 to f14 shown in FIG. 6B, and the center frequencies shown in FIG. Convert to satellite broadcast signal and output.

  The BPFs 34-1 to 34-4 pass signals having center frequencies f1 to f4 shown in FIG. 6C, respectively, and attenuate and output the other frequency components. For example, the BPF 34-1 passes the signal having the center frequency f1 shown in FIG. 6C and attenuates and outputs the other frequency components. Similarly, the BPFs 34-2 to 34-4 pass signals having center frequencies f2 to f4 shown in FIG. 6C, respectively, and attenuate and output the other frequency components.

  The mixing unit 36 synthesizes the signals output from the BPFs 34-1 to 34-4 and outputs the signals as satellite broadcast signals to, for example, a television receiver (not shown).

  By the way, in the prior art shown above, the subscriber premises apparatus 30 requires a plurality of BPFs 32-1 to 32-4 and BPFs 34-1 to 34-4, and a plurality of upconverters 33-1 to 33-4. Need. The up-converters 33-1 to 33-4 are expensive because they require a stable local signal with high accuracy, for example. The BPFs 32-1 to 32-4 and the BPFs 34-1 to 34-4 are also expensive because it is necessary to use, for example, a SAW (Surface Acoustic Wave) filter having a steep cutoff characteristic. For this reason, there exists a problem that the subscriber premises apparatus 30 becomes expensive.

  On the other hand, in the first embodiment of the present invention, as shown in FIG. 3, the number of BPFs 32, BPFs 34, and up-converters 33 can be reduced as compared with the prior art, so the price of the subscriber premises equipment 30 is reduced. be able to. The operation of the first embodiment will be described below with reference to FIG.

  The distribution unit 11 receives satellite broadcast signals (for example, BS-IF signals and CS-IF signals), distributes them to the demodulation units 12-1 to 12-4, and outputs them. Demodulation sections 12-1 to 12-4 select and demodulate the respective signals having center frequencies f1 to f4 shown in FIG. For example, the demodulator 12-1 selects and demodulates the signal having the center frequency f1 shown in FIG. 7A and outputs it as TS or TLV. Similarly, the demodulation units 12-2 to 12-4 select and demodulate signals having center frequencies f2 to f4 shown in FIG. 7A, respectively, and output the signals as TS or TLV.

  The NIT changing units 13-1 to 13-4 change information on the NIT frequency included in the TS output from the demodulating units 12-1 to 12-4. More specifically, the NIT included in the TS or TLV output from the demodulator 12-1 has the center frequency of the transponder signal corresponding to the intermediate frequency indicated by (1) shown in FIG. F1, which is the center frequency of the transponder signal corresponding to the intermediate frequency indicated by (2) shown in FIG. 7 (A), and the intermediate frequency indicated by (3) shown in FIG. 7 (A) F3 which is the center frequency of the transponder signal and f4 which is the center frequency of the transponder signal corresponding to the intermediate frequency indicated by (4) in FIG. 7A are stored. The NIT changing unit 13-1 changes the information indicating the center frequencies f1 to f4 to f21 for the center frequency f1 shown in FIG. 7C, changes to f22 for f2, and changes to f23 for f3. And f4 is changed to f24.

  Also, all the information indicating the center frequencies f1 to f4 described above is stored in the NIT included in the TS or TLV output from the demodulator 12-2. Similar to the NIT changing unit 13-1, the NIT changing unit 13-2 changes the center frequency f1 to f21, f2 to f22, f3 to f23, and f4 to f24. Change to

  Also, all the information indicating the center frequencies f1 to f4 described above is stored in the NIT included in the TS or TLV output from the demodulator 12-3. Similarly to the NIT changing unit 13-1, the NIT changing unit 13-3 changes the center frequency f1 to f21, changes f2 to f22, changes f3 to f23, and changes f4 to f24. change.

  Also, all the information indicating the center frequencies f1 to f4 described above is stored in the NIT included in the TS or TLV output from the demodulator 12-4. Similarly to the NIT changing unit 13-1, the NIT changing unit 13-4 changes the center frequency f1 to f21, changes f2 to f22, changes f3 to f23, and changes f4 to f24. change.

  7A to 7C indicate satellite broadcast signals that pass through the satellite broadcast signal passage unit 17 and do not change the frequency. More specifically, in the case of changing the NIT of a satellite broadcast different from the broadcast that changes the NIT, for example, the advanced BS broadcast, it means other broadcast signals such as CS, advanced BS, and advanced broadband CS broadcast.

  Modulating units 14-1 to 14-4 modulate TS or TLV output from NIT changing units 13-1 to 13-4, and are the original satellite broadcast signals (for example, BS-IF signal and CS-IF signal). Is generated and output. For example, the modulation unit 14-1 modulates the TS or TLV output from the NIT changing unit 13-1, and generates and outputs the original satellite broadcast signal. Similarly, the modulation units 14-2 to 14-4 modulate the TS or TLV output from the NIT changing units 13-2 to 13-4, and generate and output the original satellite broadcast signal.

  The down converters 15-1 to 15-4 down-convert and output the signals supplied from the modulation units 14-1 to 14-4. For example, the down converter 15-1 down-converts the signal having the center frequency f1 shown in FIG. 7A supplied from the modulation unit 14-1 into the signal having the center frequency f11 shown in FIG. 7B. Output. Similarly, the down converters 15-2 to 15-4 show signals having the center frequencies f2 to f4 in FIG. 7A supplied from the modulation units 14-2 to 14-4 in FIG. 7B. Down-convert each signal into a center frequency f12 to f14 and output.

  The mixing unit 18 outputs the CATV broadcast signal output from the CATV device 16, the satellite broadcast signal output from the down converter 15-1 to 15-4, and the satellite broadcast signal output from the satellite broadcast signal passing unit 17. The signals are mixed, and a signal in which the down-converted satellite broadcast signal is inserted into the vacant frequency band of the CATV broadcast signal as shown in FIG. 7B is output as a transmission signal.

  The transmission signal output from the mixing unit 18 is transmitted through the transmission path 20 and is supplied to the subscriber premises devices 30-1 to 30-n. In addition, since operation | movement of the subscriber premises apparatus 30-1 to 30-n is the same, below, these are demonstrated as the subscriber premises apparatus 30. FIG.

  The distribution unit 31 of the subscriber premises apparatus 30 distributes the received transmission signal, supplies it to the television receiver as a CATV broadcast signal, and supplies it to the BPF 32.

  The BPF 32 passes all the signals having the center frequencies f11 to f14 shown in FIG. 7B from the signal supplied from the distribution unit 31, and attenuates and outputs the other frequency components. As a result, a signal having a center frequency of f11 to f14 is output from the BPF 32.

  The up-converter 33 up-converts the signal output from the BPF 32 into a signal having a center frequency f21 to f24 shown in FIG. Note that the signal having the center frequency f21 to f24 shown in FIG. 7C is obtained by shifting the signal having the center frequency f11 to f14 shown in FIG. 7B on the frequency axis. For this reason, the signals of the center frequencies f11 to f14 can be collectively up-converted by a local frequency signal of a single frequency.

  The signal output from the up-converter 33 is supplied to the BPF 34. The BPF 34 passes signals having center frequencies f21 to f24 out of the signals output from the up-converter 33, and attenuates and outputs the other frequency components. The signal output from the BPF 34 is supplied to a television receiver (not shown) as a satellite broadcast signal.

  Note that the satellite broadcast signal shown in FIG. 7C is different from the original satellite broadcast signal shown in FIG. 7A in the center frequency of each intermediate frequency. However, in the center apparatus 10, information (f1 to f4 in the example of FIG. 7) indicating the center frequency of each transponder stored in the NIT is transmitted to the f21 to f24 by the NIT changing units 13-1 to 13-4. Therefore, the television receiver can reproduce the satellite broadcast signal whose center frequency is changed without any trouble.

  As described above, according to the first embodiment of the present invention, the satellite broadcast signal is down-converted to the frequency band of the CATV broadcast signal and transmitted. Satellite broadcast signals can be transmitted using the band.

  Further, in the center apparatus 10, information f1 to f4 related to the center frequency stored in the NIT is changed to f21 to f24 that are center frequencies shifted from f1 to f4 on the frequency axis. As shown, the configuration of the subscriber premises apparatus 30 can be simplified. From the comparison of FIGS. 3 and 5, the number of BPFs and up-converters can be significantly reduced.

  In the conventional example shown in FIG. 5, it is necessary for the BPF 32-1 to 32-4 to extract each of the signal components having the center frequencies f11 to f14 shown in FIG. 6B. Since the width is as narrow as about 34.5 MHz and adjacent signal components are arranged close to each other, the frequency characteristics of the BPFs 32-1 to 32-4 need to be steep.

  Further, in the conventional example shown in FIG. 5, the signal components having the center frequencies f1 to f4 shown in FIG. 6C are passed through the BPFs 34-1 to 34-4 shown in FIG. Although it is necessary to attenuate unnecessary frequency components, these signal components have a narrow bandwidth of about 34.5 MHz as described above, and are also arranged close to adjacent signal components. The frequency characteristics of the BPFs 34-1 to 34-4 need to be steep.

  A BPF having such a steep characteristic is a SAW filter, but the SAW filter is expensive. For this reason, the subscriber premises apparatus 30 according to the prior art that needs to use a large number of SAW filters is very expensive.

  On the other hand, in the first embodiment of the present invention, the BPF 32 shown in FIG. 3 only needs to have a characteristic of collectively passing signals having the center frequency wave numbers f11 to f14 shown in FIG. Since the width is wide, the characteristics of the BPF 32 are not required to be as steep as the prior art.

  Further, in the first embodiment of the present invention, the BPF 34 shown in FIG. 3 only needs to have a characteristic of passing the signals having the center frequency wave numbers f21 to f24 shown in FIG. Since the width is wide, the characteristics of the BPF 34 are not required to be as steep as the prior art.

  As described above, according to the first embodiment of the present invention, the manufacturing cost of the subscriber premises device 30 can be significantly reduced.

(C) Description of Configuration of Second Embodiment of Present Invention Next, an operation of the second embodiment of the present invention will be described. FIG. 8 is a diagram illustrating a configuration example of the center apparatus 10 according to the second embodiment of the present invention. In FIG. 8, parts corresponding to those in FIG. In FIG. 8, compared to FIG. 2, the down converters 15-1 to 15-4 are replaced with frequency converters 19-1 to 19-4. The other configuration is the same as that of FIG.

  FIG. 9 is a diagram illustrating a configuration example of the subscriber premises apparatus 30 according to the second embodiment of the present invention. 9, parts corresponding to those in FIG. 3 are given the same reference numerals and explanation thereof is omitted. In FIG. 9, BPF 32, up-converter 33, and BPF 34 are excluded as compared with FIG. 3. Other configurations are the same as those in FIG.

(D) Description of Operation of Second Embodiment of the Present Invention Next, the operation of the second embodiment of the present invention will be described with reference to FIG. A CATV broadcast signal of 770 MHz or less shown in FIG. 10A is output from the CATV device 16 shown in FIG. 8 and supplied to the mixing unit 18.

  The distribution unit 11 inputs a satellite broadcast signal and supplies it to the demodulation units 12-1 to 12-4. The demodulating units 12-1 to 12-4 demodulate the intermediate frequency signals having the center frequencies f1 to f4 shown in FIG. 10 and supply them to the NIT changing units 13-1 to 13-4 as TS or TLV.

  The satellite broadcast signal passing unit 17 passes and outputs the signal having the center frequency f0 of the satellite broadcast signal shown in FIG.

  NIT changing units 13-1 to 13-4 change the information indicating the center frequencies f2 to f4 of the satellite broadcast signal shown in FIG. 10A to f32 to f34 shown in FIG. 10B, respectively. More specifically, the NIT changing units 13-1 to 13-4 change information indicating the frequency f2 included in the NIT to f32, change information indicating the frequency f3 to f33, and information indicating the frequency f4. Is changed to f34.

  Modulation sections 14-1 to 14-4 modulate TS or TLV output from NIT changing sections 13-1 to 13-4 with the same modulation method as the satellite broadcast signal, and output the result.

  The frequency conversion units 19-1 to 19-4 show signals (see FIG. 10A) whose center frequencies are f1 to f4 output from the modulation units 14-1 to 14-4, as shown in FIG. The frequency is converted into signals having center frequencies f1, f32 to f34, respectively, and output. More specifically, the frequency conversion unit 19-1 converts the signal having the center frequency f1 output from the modulation unit 14-1 into a signal having the center frequency f1 and outputs the signal. Further, the frequency converting unit 19-2 converts the signal having the center frequency f2 output from the modulating unit 14-2 into a signal having the center frequency f32 and outputs the signal. Further, the frequency conversion unit 19-3 converts the signal having the center frequency f3 output from the modulation unit 14-3 into a signal having the center frequency f33 and outputs the signal. Furthermore, the frequency conversion unit 19-4 converts the signal having the center frequency f4 output from the modulation unit 14-4 into a signal having the center frequency f34, and outputs the signal.

  Satellite broadcast signals having center frequencies f1 and f32 to f34 output from the frequency conversion units 19-1 to 19-4, satellite signal broadcasts output from the satellite broadcast signal passing unit 17, and output from the CATV device 16. The CATV broadcast signal is mixed by the mixing unit 18 and output as a transmission signal shown in FIG.

  The transmission signal output from the center apparatus 10 is supplied to the subscriber premises apparatuses 30-1 to 30-n via the transmission path 20. In addition, since operation | movement of the subscriber premises apparatus 30-1 to 30-n is the same, below, these are demonstrated as the subscriber premises apparatus 30. FIG.

  The subscriber premises apparatus 30 receives the transmission signal transmitted via the transmission path 20. The distribution unit 31 extracts the CATV broadcast signal from the transmission signal and supplies it to the television receiver. The distribution unit 31 extracts a satellite broadcast signal from the transmission signal and supplies the satellite broadcast signal to the television receiver.

  Note that the satellite broadcast signal shown in FIG. 10B is different from the original satellite broadcast signal shown in FIG. 10A in the center frequency except for f1. However, in the center apparatus 10, information indicating the frequency of each transponder stored in the NIT (f2 to f4 in the example of FIG. 10) is transmitted by the NIT changing units 13-1 to 13-4 to f1, f32 to Since it is changed to f34, the television receiver can reproduce the satellite broadcast signal whose frequency is changed without any trouble. The satellite broadcast signal having the frequency f1 can be viewed without any trouble because the frequency is not changed.

  As described above, according to the second embodiment of the present invention, since the frequency of the satellite broadcast signal existing in the high frequency band can be converted and transmitted, the frequency band can be limited.

  Further, in the second embodiment of the present invention, it is not necessary for the subscriber premises apparatus 30 to have a BPF and an upconverter, so that the manufacturing cost of the subscriber premises apparatus 30 can be reduced.

(E) Description of Modified Embodiment The above embodiment is an example, and it is needless to say that the present invention is not limited to the case as described above. For example, in the first embodiment, all the intermediate frequency signals of the satellite broadcast signal are down-converted, but at least a part of the intermediate frequency signals may be down-converted. In the second embodiment, the frequency conversion is performed for signals other than the signal having the frequency f1, but all the frequencies may be converted, or the signals of some frequencies may be converted. May be.

  In the first embodiment and the second embodiment, all intermediate frequency signals of the satellite broadcast signal are changed by NIT. However, some satellites are in units of BS, CS, advanced BS, advanced broadband CS, etc. The NIT of the broadcast signal may be changed.

  In the first embodiment, all the intermediate frequency signals of the down-converted satellite broadcast signal are up-converted. However, some signals may be up-converted.

  In the first embodiment and the second embodiment, the down converters 15-1 to 15-4 are arranged in the final stage. For example, the down converters 15-1 to 12-4 are arranged in front of the demodulating units 12-1 to 12-4. It may be.

  Further, the CATV broadcast signal and the satellite broadcast signal shown in FIGS. 7 and 10 are examples, and it goes without saying that the present invention is not limited to the cases shown in these drawings. For example, the number of transponders of the satellite broadcast signal may be different or the arrangement state may be different. Further, the number of transponders of the CATV broadcast signal may be different, or the arrangement state may be different.

  Further, in the first embodiment, the subscriber premises apparatus 30 has one upconverter 33, but may have two or more upconverters.

DESCRIPTION OF SYMBOLS 1 Broadcasting system 10 Center apparatus 11 Distribution part 12-1 to 12-4 Demodulation part 13-1 to 13-4 NIT change part 14-1 to 14-4 Modulation part 15-1 to 15-4 Down converter 16 CATV apparatus 17 Satellite broadcasting signal passing unit 18 Mixing unit 19-1 to 19-4 Frequency conversion unit 20 Transmission path 30 Subscriber premises equipment 30-1 to 30-n Subscriber premises equipment 31 Distribution unit 32, 32-1 to 32-4 BPF
33, 33-1 to 33-4 Upconverter 34, 34-1 to 34-4 BPF
35 Satellite Broadcasting Signal Passing Section 36 Mixing Section

Claims (9)

In a broadcasting system having a center device and a subscriber premises device,
The center device is
Down-converting means for down-converting at least a part of intermediate frequency signals supplied from a plurality of antennas included in the satellite broadcast signal to different frequencies;
Changing means for changing information indicating the frequency of the signal of the transponder described in the NIT (Network Information Table) included in the satellite broadcast signal down-converted by the down-convert means to a frequency different from the original frequency;
Modulation means for modulating TS (Transport Stream) or TLV (Type Length Value) in which the NIT is changed by the changing means;
A transmission means for mixing a CATV (Cable Television) broadcast signal and the satellite broadcast signal output from the modulation means and transmitting the mixed signal through a transmission path;
The subscriber premises equipment is:
Receiving means for receiving a signal transmitted through the transmission path;
Extracting means for extracting the satellite broadcast signal from the signal received by the receiving means,
A broadcasting system characterized by that.   The broadcasting system according to claim 1, wherein the modulation unit modulates the TS or TLV whose NIT has been changed by the changing unit, using the same modulation method as that of the satellite broadcast signal. The down-converting means down-converts at least a part of the plurality of intermediate frequency signals included in the satellite broadcast signal to a vacant frequency band of the CATV broadcast signal,
The subscriber premises apparatus has up-conversion means for up-converting the satellite broadcast signal extracted by the extraction means.
The broadcasting system according to claim 1 or 2, wherein   When the up-conversion means upconverts at least a part of the plurality of intermediate frequency signals of the satellite broadcast signal down-converted by the down-conversion means, the changing means is arranged on the frequency axis as it is. 4. The broadcasting system according to claim 3, wherein the frequency is changed to a frequency when shifted to a high frequency side.   When the up-conversion means up-converts all of the plurality of intermediate frequency signals of the satellite broadcast signal down-converted by the down-conversion means, the changing means is arranged as it is in the high frequency on the frequency axis. The broadcast system according to claim 3, wherein the frequency is changed to a frequency when shifted to the side.   The down-convert means converts one or more intermediate frequency signals having a higher frequency among the plurality of intermediate frequency signals of the satellite broadcast signal to a lower frequency. The broadcasting system according to 1 or 2.   The broadcast system according to claim 1 or 2, wherein the down-convert means converts all of the plurality of intermediate frequency signals of the satellite broadcast signal to a lower frequency. In a control method of a broadcasting system having a center device and a subscriber premises device,
The center device is
A down-conversion step of down-converting at least a part of intermediate frequency signals supplied from a plurality of antennas included in the satellite broadcast signal to different frequencies;
A change step of changing information indicating the frequency of the transponder signal described in the NIT (Network Information Table) included in the satellite broadcast signal down-converted in the down-conversion step to a frequency different from the original frequency;
A modulation step of modulating TS (Transport Stream) or TLV (Type Length Value) in which the NIT is changed by the changing step;
A transmission step of mixing a CATV (Cable Television) broadcast signal and the satellite broadcast signal output from the modulation step and transmitting the mixed signal through a transmission path;
The subscriber premises equipment is:
A receiving step of receiving a signal transmitted through the transmission path;
Extracting the satellite broadcast signal from the signal received in the receiving step,
A control method for a broadcast system. In the subscriber premises device of the broadcasting system having a center device and a subscriber premises device,
In the center device, at least some of the intermediate frequency signals supplied from the plurality of antennas included in the satellite broadcast signal are down-converted to different frequencies, and NIT (Network Information) included in the down-converted satellite broadcast signal. The information indicating the frequency of the transponder signal described in (Table) is changed to a frequency different from the original frequency, and the NIT is changed to modulate the changed TS (Transport Stream) or TLV (Type Length Value). Receiving means for receiving a signal transmitted through a transmission line by mixing a CATV (Cable Television) broadcast signal and the modulated satellite broadcast signal;
Extracting means for extracting the satellite broadcast signal from the signal received by the receiving means,
A subscriber premises device characterized by the above.

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