JP2016005037A - Reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reception system for receiving a signal transmitted by using a plurality of signal waves within a predetermined band allocated for digital broadcasting.SOLUTION: A reception system 1 includes an outdoor unit 11 and an indoor unit 12. The outdoor unit 11 defines a part of the predetermined band (e.g., a UHF band) as a first band (e.g., an upper part of the UHF band), performs frequency conversion on a reception signal of any other signal wave than a first signal wave between the plurality of signal waves within the first band (e.g., two signal waves of a vertically polarized wave and a horizontally polarized wave in a polarization MIMO transmission system) to a fixed band within a second band (e.g., an SHB band) and combines the reception signal with a reception signal of the first signal wave by multiplexing frequencies to generate a multiplex signal. The indoor unit 12 is connected with the outdoor unit 11 by one cable 13, demultiplexes the multiplex signal, and performs inverse frequency conversion on the reception signal of the frequency converted signal wave, thereby restoring a plurality of kinds of polarized reception signals.

Description

  The present invention relates to a technique for receiving a signal transmitted using a plurality of signal waves within a predetermined band, and in particular, a polarization MIMO (Multiple Input Multiple Output) transmission method using a plurality of types of polarization as a plurality of signal waves. The present invention relates to a receiving system that transmits a received wave of a MIMO transmission system, such as a spatial MIMO transmission system that uses a plurality of signal waves with the same polarization.

  ISDB-T (Integrated Services Digital Broadcasting Terrestrial), a Japanese terrestrial digital television broadcasting system, realizes high-definition broadcasting (or standard image broadcasting of multiple channels) for fixed reception. The next generation digital terrestrial television broadcasting system is required to provide services with more information such as 3D high-definition broadcasting instead of conventional high-definition and super high-definition with 16 times the resolution of this high-definition. ing. For this reason, in order to double the transmission capacity per channel, signal transmission of a polarization MIMO transmission system using both horizontal and vertical polarized waves has been studied (for example, see Non-Patent Document 1).

  When receiving a signal of the MIMO transmission system, two or more cables are generally required for wiring from an outdoor unit having a receiving antenna to an indoor unit (receiver).

  On the other hand, although it is different from the MIMO transmission system, a terrestrial digital television broadcast signal in the UHF band is received by a plurality of receiving antennas (for example, two receiving antennas), and one of the received signals is sent to the SHB (super high band) band. Diversity receiving system configured to frequency-convert to an unused band such as an unused channel, frequency multiplex the other received signal and the frequency-converted received signal, and transmit this multiplexed signal to the receiver with a single cable. Is disclosed (for example, see Patent Document 1).

Japanese Patent No. 4719229

Japan Broadcasting Corporation, “Success in Super Hi-Vision Transmission Experiment on Terrestrial!”, Press Release, [online], May 15, 2012, ARIB, [Search June 6, 2014], Internet <URL: http://www3.nhk.or.jp/pr/marukaji/pdf_ver/327.pdf>

  As described above, in general, when configuring a receiving system for receiving a MIMO transmission system signal, two or more cables are required for wiring from an outdoor unit having a receiving antenna to an indoor unit (receiver). To do. However, normally, there is only one wiring for the existing digital terrestrial television broadcasting system, and it is not preferable to add a cable.

  Therefore, by applying the MIMO transmission method to the technique of Patent Document 1, it is assumed that transmission using a single cable, which is an existing wiring for digital broadcasting, is realized. That is, for example, as a 2 × 2 MIMO transmission system reception system with two transmission antennas and two reception antennas, one of the two reception signals (for example, a vertically polarized reception signal) is unused. It is assumed that frequency conversion is performed (for example, SHB band), and the frequency-converted reception signal and the other reception signal (for example, horizontal polarization reception signal) are frequency-multiplexed.

  However, according to the technique of Patent Document 1, when the SHB band is used as an unused band, almost all of this SHB band (current band allocation: 222 to 468 MHz) is used to transmit a digital terrestrial television broadcast signal. It is necessary to configure all UHF bands including all channels (470 to 710 MHz as current band allocation) so that block conversion (frequency conversion) is possible, and it is not possible to substantially leave a vacant space in the SHB band. . This hinders other uses of the SHB band and is not preferable.

  In the next-generation digital terrestrial television broadcasting system, the use of the MIMO transmission system is also considered in view of the high possibility that the use band is concentrated on the upper part of the UHF band (566 to 710 MHz) which is relatively free at present. Therefore, block conversion (frequency conversion) with high accuracy and high frequency utilization efficiency is required.

  Further, block conversion (frequency conversion) requires a local signal indicating the conversion amount for each channel. In order to avoid interference with other signals, the frequency of this local signal is also within an unused band. It is desirable to devise as follows.

  In order to connect an outdoor unit having a receiving antenna and an indoor unit with a single cable, a block conversion (frequency conversion) function is provided in both the outdoor unit and the indoor unit. It is necessary to supply both the indoor unit and the indoor unit, and it is desirable to configure the functional unit that generates the local signal in a manner that improves the downsizing and maintainability of the outdoor unit.

  In view of the above-described problems, an object of the present invention is to provide a plurality of signal waves within a predetermined band assigned for digital broadcasting (for example, in the case of a polarization MIMO transmission system, two polarizations, vertical polarization and horizontal polarization). It is an object of the present invention to provide a receiving system for receiving a signal transmitted using two signal waves.

  The reception system according to the present invention has a plurality of signal waves (for example, two types of vertical polarization and horizontal polarization in the case of a polarization MIMO transmission system) within a predetermined band (for example, UHF band) allocated for digital broadcasting. The signal is transmitted using two signal waves).

  In particular, the receiving system according to the present invention uses a part of the predetermined band (for example, UHF band) as a first band (for example, the upper part of the UHF band), and uses the first band as a second band (for example, The outdoor unit having a receiving antenna (for example, a polarization sharing antenna) and an indoor unit connected to the outdoor unit are provided as target bands to be frequency-converted into a fixed band in the SHB band. As a result, when the SHB band is used as an unused band used for frequency conversion, it is possible to leave an empty space in the SHB band, and an unused band in the SHB band can be secured.

  The outdoor unit receives a received signal of a signal wave (for example, vertical polarization) other than the first signal wave (for example, horizontal polarization) among the plurality of signal waves in the first band (for example, the upper part of the UHF band). Is converted to a fixed band within the second band, and frequency-multiplexed with the received signal of the first signal wave to generate a multiplexed signal, which is transmitted to the indoor unit via a single cable. Output. The indoor unit separates the multiplexed signal, performs inverse frequency conversion on the received signal of the frequency-converted signal wave (for example, vertical polarization), and restores the received signals of the plurality of signal waves. As a result, transmission can be performed with one cable, and for example, existing wiring for digital broadcasting can be used as it is. Note that the number of signal waves other than the first signal wave is not limited to one, such as a 4 × 2 MIMO transmission scheme in which the number of transmission antennas is four and the number of reception antennas is two.

  Preferably, the first band (for example, the upper part of the UHF band) that is a target band of the frequency conversion is divided into a plurality of predetermined types, and divided bands (for example, bands described later in the description of the embodiment). A frequency conversion is selectively performed for each of A, B, and C), and a band after frequency conversion of each of the bands A, B, and C is a part of the fixed band in the second band (for example, the SHB band). It is comprised so that it may become. Thereby, for example, when using a polarization MIMO transmission method using both horizontal and vertical polarizations, the frequency utilization efficiency is higher with high accuracy.

  In addition, each frequency of the local signal corresponding to this divided band is determined to be in the second band (for example, SHB band), and is preferably determined to be a ratio represented by an integer ratio. As a result, when the functional unit for generating a local signal is configured by, for example, a PLL (phase synchronization circuit), it can be inexpensive and highly accurate.

  The local signal supplied to both the outdoor unit and the indoor unit is configured to be generated on the indoor unit side. Thereby, downsizing of the outdoor unit and high maintainability of the receiving system can be realized.

  That is, a receiving system according to the present invention is a receiving system for receiving a signal transmitted using a plurality of signal waves within a predetermined band allocated for digital broadcasting, and a part of the predetermined band is a first band. The received signal of the signal wave other than the first signal wave among the plurality of signal waves in the first band is converted into a fixed band in the second band, and the first band is converted into the first band. An outdoor unit that generates a multiplexed signal by frequency-multiplexing with the received signal of the signal wave, and the outdoor unit that is connected to the outdoor unit with one cable, separates the multiplexed signal, and the frequency-converted signal wave And an indoor unit that performs inverse frequency conversion on the received signals, restores the received signals of the plurality of signal waves, and performs signal processing.

  Further, in the reception system according to the present invention, the outdoor unit includes a first frequency conversion unit that performs frequency conversion from a divided band that is divided in advance with respect to the first band to a fixed band in the second band. The indoor unit includes a second frequency conversion unit that performs inverse conversion of the frequency conversion.

  In the receiving system according to the present invention, the frequency of the local signal corresponding to the divided band is determined to be within the second band.

  In the receiving system according to the present invention, each frequency of the local signal corresponding to the divided band is determined to be a ratio represented by an integer ratio.

  In the reception system according to the present invention, the indoor unit includes a local signal generation unit that generates a local signal corresponding to the divided band, and the local signal generation unit converts the local signal into the second frequency conversion unit. And is supplied to the first frequency conversion unit via the one cable.

  In the receiving system according to the present invention, the predetermined band may be a UHF band, the first band may be a part of the UHF band, and the second band may be a SHB band. And

  In the receiving system according to the present invention, the plurality of signal waves are signal waves based on a MIMO transmission system.

  According to the present invention, transmission can be performed with one cable, and for example, existing digital broadcast wiring can be used as it is. Then, it becomes possible to leave an empty space in the second band (for example, the SHB band) after the frequency conversion of the first band (for example, the upper part of the UHF band), and in the second band (for example, the SHB band) The bandwidth used can be secured.

  Further, for example, when using a polarization MIMO transmission system using both vertical and horizontal polarized waves, the frequency utilization efficiency is high with high accuracy.

  In addition, as a function unit that generates a local signal, for example, the configuration of a PLL (phase synchronization circuit) can be made inexpensive and highly accurate. And if it comprises so that a local signal may be produced | generated by the indoor unit side, size reduction of an outdoor unit and the high maintainability of a receiving system are realizable. Since the hardware load of the entire receiving system is reduced, it is possible to reduce the size and price.

It is the schematic which shows the whole transmission / reception system structure provided with the receiving system of one Embodiment by this invention. It is a block diagram which shows the outline of the transmitter which transmits a signal to the receiving system of one Embodiment by this invention. It is a block diagram which shows the outline of the outdoor unit in the receiving system of one Embodiment by this invention. It is a block diagram which shows the outline of the reception control part in an indoor unit in the receiving system of one Embodiment by this invention. It is a block diagram which shows the outline of the reception process part in an indoor unit in the receiving system of one Embodiment by this invention. It is a flowchart which shows operation | movement of the receiving system of one Embodiment by this invention. It is a figure showing an example of frequency arrangement concerning a receiving system of one embodiment by the present invention. It is a figure which shows the frequency of the division band and local signal which concern on the receiving system of one Embodiment by this invention.

  Hereinafter, a receiving system 1 according to an embodiment of the present invention will be described with reference to the drawings. The receiving system 1 according to an embodiment described below can be applied to a polarization MIMO transmission system that uses a plurality of types of polarization as a plurality of signal waves, and a spatial MIMO transmission system that uses a plurality of signal waves with the same polarization. A typical example is a polarization MIMO transmission system.

[Transmission / reception system]
First, a transmission / reception system including the reception system 1 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an overall configuration of a transmission / reception system including a reception system 1 according to an embodiment of the present invention. This transmission / reception system is configured to realize a polarization MIMO transmission system using both vertical and horizontal polarizations, and includes the reception system 1 and the transmission device 2 of the present embodiment. The receiving system 1 includes an outdoor unit 11 and an indoor unit 12, and the outdoor unit 11 and the indoor unit 12 are connected by a single cable 13 (for example, existing wiring for digital broadcasting). The indoor unit 12 includes a reception control unit 120 and a reception processing unit 130. In the following description, the transmission device 2 transmits, for example, two types of polarized waves of vertical polarization and horizontal polarization in the UHF band from the transmission units Tx1 and Tx2 of the transmission antenna, respectively, and the reception system 1 performs vertical modulation in the UHF band In the following description, it is assumed that two types of polarization, that is, polarization and horizontal polarization, are received via the reception units Rx1 and Rx2 of the reception antenna. As such a transmission antenna and a reception antenna, any antenna that can be used as a polarization MIMO transmission system can be used, for example, a polarization sharing antenna as shown in Non-Patent Document 1.

(Transmitter)
FIG. 2 is a block diagram showing an outline of a transmission apparatus 2 that transmits a signal to the reception system 1 according to an embodiment of the present invention. The transmission apparatus 2 includes an error correction encoding unit 21 and a MIMO-OFDM (Orthogonal Frequency-Division Multiplexing) modulation unit 22. In FIG. 2, only functional units related to the present invention are shown, and functional units not related to the present invention are omitted.

  The error correction encoding unit 21 inputs data to be transmitted and performs error correction encoding using a predetermined code.

  The MIMO-OFDM modulation unit 22 receives the data corrected by the error correction encoding unit 21 and performs MIMO-OFDM modulation such as carrier modulation using a predetermined carrier modulation method, and divides the modulated signal. Then, a vertically polarized OFDM signal and a horizontally polarized OFDM signal are generated and transmitted from the transmitters Tx1 and Tx2, respectively.

  The transmitter 2 adds a control signal (for example, a TMCC (Transmission and Multiplexing Configuration and Control) signal) including station information and a polarization identification flag to each of the vertically polarized wave and the horizontally polarized wave OFDM signal. Send. Here, the station information is information for identifying a broadcasting station indicating the transmission source of data to be transmitted, and the polarization identification flag is information for identifying the type of polarization. With this control signal, the reception system 1 can identify vertically polarized waves and horizontally polarized signals.

(Configuration of receiving system)
As described above, the reception system 1 includes the outdoor unit 11 and the indoor unit 12, and the outdoor unit 11 and the indoor unit 12 are connected by a single cable 13 (for example, existing wiring for digital broadcasting). ing. FIG. 3 is a block diagram showing an outline of the outdoor unit 11 in the receiving system 1 according to the embodiment of the present invention. The outdoor unit 11 is provided immediately below a receiving antenna 11a such as a polarization sharing antenna, and includes a power supply unit 111, amplifiers 112 and 116, a block converter 113 that functions as a frequency conversion unit, and a bandpass filter (BPF) 114. , And a synthesis unit 115 and a band pass filter (BPF) 117.

  The power supply unit 111 receives power supply with an AC signal from the indoor unit 12 via the cable 13, converts it into a DC source, and supplies power to the amplifiers 112, 116 and the like.

  The amplifier 112 receives a UHF band vertically polarized signal received by the receiving antenna 11a via the receiving unit Rx1, amplifies the signal with a predetermined gain value, and outputs the amplified signal to the block converter 113. The amplifier 116 receives a UHF band horizontally polarized signal received by the receiving antenna 11a via the receiving unit Rx2, amplifies the signal with a predetermined gain value, and outputs the amplified signal to the combining unit 115.

  Based on the local signal obtained through the bandpass filter (BPF) 117, the block converter 113 converts the UHF band vertically polarized signal into a SHB band signal and outputs it to the bandpass filter (BPF) 114. To do. As will be described in detail later, the destination of the frequency conversion is a part of the fixed band in the SHB band, and the local signal is a signal indicating the conversion amount of the frequency conversion supplied from the indoor unit 11, It corresponds to the band of the channel specified by the user.

  The band-pass filter (BPF) 114 extracts a vertically polarized signal, which has been frequency-converted into an SHB band signal, by band-pass filtering using a SAW (Surface Acoustic Wave) filter or the like, and outputs the extracted signal to the synthesizing unit 115. In addition, since the transfer destination of the frequency conversion is a part of the fixed band in the SHB band, the band pass filter (BPF) 114 can be set as a fixed filter process, and the accuracy can be improved as compared with the variable type. It is easy and can be downsized.

  The synthesizing unit 115 generates a multiplexed signal by frequency-multiplexing the horizontally polarized signal obtained from the amplifier 116 and the frequency-converted vertically polarized signal obtained from the bandpass filter (BPF) 114. And output to the indoor unit 12 via the cable 13.

  The band-pass filter (BPF) 117 extracts a local signal from the indoor unit 12 obtained via the cable 13 by band-pass filter processing and outputs it to the block converter 113.

  FIG. 4 is a block diagram illustrating an outline of the reception control unit 120 in the indoor unit 11 in the reception system 1 according to the embodiment of the present invention. The indoor unit 11 is provided indoors, and the reception control unit 120 includes a power supply superimposing unit 121, a block converter 122 that functions as a frequency converting unit, BPFs 123 and 126 for UHF bands, amplifiers 124 and 127, A signal generation unit 125.

  The power supply superimposing unit 121 supplies power to the power supply unit 111 of the outdoor unit 11 with an AC signal via the cable 13.

  The block converter 122 inputs the multiplexed signal generated by the synthesizing unit 115 of the outdoor unit 11 through the cable 13 and also inputs the local signal from the local signal generating unit 125, and based on the local signal, the multiplexed signal Then, the vertically polarized signal frequency-converted into the SHB band signal is separated, the SHB band vertically polarized signal is frequency-converted into the UHF band signal, and output to the UHF band BPF 123.

  The UPF band BPF 123 extracts a vertically polarized signal, which has been frequency-converted into a UHF band signal, by band-pass filter processing, and outputs the extracted signal to the amplifier 124. The UHF band BPF 126 receives a multiplexed signal generated by the combining unit 115 of the outdoor unit 11 via the cable 13 and separates a UHF band horizontally polarized signal from the multiplexed signal by bandpass filter processing. Are extracted and output to the amplifier 127.

  The amplifier 124 amplifies the vertically polarized signal obtained through the UHF band BPF 123 with a predetermined gain value, and outputs the amplified signal to the reception processing unit 130 as a reception signal of the reception unit Rx1. The amplifier 127 amplifies a horizontally polarized signal obtained via the UHF band BPF 126 with a predetermined gain value, and outputs the amplified signal to the reception processing unit 130 as a reception signal of the reception unit Rx2.

  The local signal generation unit 125 receives a band (channel) selection signal from the reception processing unit 130 and corresponds to a band (divided bands A, B, and C to be described later) selectively designated by the band (channel) selection signal. A local signal to be generated is output to the block converter 122 and output to the outdoor unit 11 via the cable 13. As described above, since the local signal is generated on the indoor unit 12 side, the downsizing of the outdoor unit 11 and the high maintainability of the receiving system 1 can be realized.

  FIG. 5 is a block diagram illustrating an outline of the reception processing unit 130 in the indoor unit 11 in the reception system 1 according to the embodiment of the present invention. In FIG. 5, only functional units related to the present invention are shown, and functional units not related to the present invention are omitted. The reception processing unit 130 is a functional unit that processes reception signals of both vertical and horizontal polarizations of the reception units Rx1 and Rx2 obtained through the reception control unit 120, and includes a channel selection signal generation unit 131, a MIMO-OFDM A demodulation unit 132 and an error correction decoding unit 133 are provided.

  The channel selection signal generation unit 131 receives information on a channel selectively designated by a user from a display device (not shown), and indicates one of divided bands A, B, and C (details will be described later) corresponding to this channel. A band (channel) selection signal is generated and output to the reception control unit 120. A channel scanning unit (not shown) is provided in the indoor unit 11 (for example, the reception processing unit 130), and the channel scanning unit accepts an instruction for identifying the bands of the divided bands A, B, and C from the display device, A configuration may be adopted in which channel scanning of the divided bands A, B, and C is executed, and the band of the divided bands A, B, and C after the channel scanning is set in the channel selection signal generation unit 131.

  The MIMO-OFDM demodulator 132 receives reception signals of both vertical and horizontal polarizations of the reception units Rx1 and Rx2 obtained through the reception control unit 120, and receives the control signal (in the above example, the specified channel). The station information and the polarization identification flag are read out from the TMCC signal), the vertically polarized wave and the horizontally polarized signal are identified, and the MIMO-OFDM demodulation process which is the reverse process of the MIMO-OFDM modulation unit 22 of the transmitter 2 is performed. Are combined and output to the error correction decoding unit 133.

  The error correction decoding unit 133 inputs a reception signal combined by performing MIMO-OFDM demodulation processing, performs decoding processing that is reverse processing of the error correction coding unit 21 of the transmission device 2, and restores data, and displays the display device Output to. Even if an error occurs when frequency conversion is performed on a unipolar signal, the error correction decoding unit 133 performs decoding that is a reverse process of the error correction encoding unit 21 of the transmission apparatus 2 for the combined received signal. Since the process is performed, the error can be suppressed to a negligible level.

  The reception system 1 configured as described above receives a plurality of types of polarization signals from an outdoor unit 11 installed directly below a polarization sharing antenna or the like by an indoor unit 12 connected by a single cable 13. Can be processed.

(Reception system operation)
Next, the operation of the receiving system 1 will be described in detail with reference to FIG. First, the reception processing unit 130 receives channel information selectively designated by the user from the display device by the channel selection signal generation unit 131 (step S1), and the division bands A, B, and C corresponding to this channel are received. A band (channel) selection signal indicating either one is generated and output to the reception control unit 120 (step S2).

  FIG. 7 is a diagram illustrating a frequency arrangement example according to the reception system 1 of the embodiment of the present invention. Moreover, FIG. 8 is a figure which shows the frequency of the division band and local signal which concern on the receiving system 1 of one Embodiment by this invention. The target band for block conversion (frequency conversion) is a part of the UHF band (the upper part of the UHF band), and preferably, the target band is divided into a plurality of divided bands A, B, and C, which are further divided. To do. Furthermore, the transition destination after frequency conversion of each of the divided bands A, B, and C is a part of the fixed band in the SHB band. By changing the local signal according to the band, a fixed bandpass filter is used in the SHB band. It can be used, and the device cost can be reduced and the frequency utilization efficiency can be increased. Therefore, the hardware of the receiving system 1 as a whole is lightened, so that downsizing and cost reduction can be realized. Note that some fixed bands in the SHB band, which is the destination of the transition after frequency conversion, are assumed to be unused frequency regions that are not used in cable television etc. in the home to be used. Assuming that there is a possibility, a plurality of candidates can be selected and set from the outside, or a free area in the SHB band can be detected and set by channel scanning.

  Then, by determining that each of the local signal and the frequency-converted unipolar signal is within the SHB band, it is possible to improve the frequency utilization efficiency and leave a free space in the SHB band after the frequency conversion. An unused band in the band can be secured. Since the SHB band is not used as a broadcast wave, it has a small influence even if it is leaked to the outside, so it is suitable as a frequency conversion destination band.

  Further, regarding the frequencies of the local signals in the divided bands A, B, and C, for example, as shown in FIGS. 7 and 8, the center frequencies fc of the bands A, B, and C, which are the target bands for frequency conversion in the UHF band. Is converted into a band having a fixed center frequency fc ′ of the use band in the SHB band, and the frequencies (fc−fc ′) of the local signals in the bands A, B, and C are comparison frequencies indicating the greatest common divisor. At 18 MHz, the ratio is expressed as 15/13 or 17/13.

  In other words, the frequency fa * 13 of the local signal in the band A is equal to the frequency fb * 15 of the local signal in the band B, and the frequency fa * 13 of the local signal in the band A is equal to the frequency fc * 17 of the local signal in the band C. It is configured. In the frequency of the local signal represented by such an integer ratio, the comparison frequency indicating the greatest common divisor is also larger (18 MHz in this example), and the relative error of the frequency of each local signal can be further reduced. . In addition, the generation of a local signal represented by a frequency of an integer ratio can simplify the PLL configuration, can be made inexpensive and highly accurate, and can be downsized by reducing the number of components and the reliability of its operation. Can increase the sex.

  Next, referring to FIG. 6, the reception control unit 120 receives a band (channel) selection signal from the reception processing unit 130 by the local signal generation unit 125 and selectively designates the band (channel) selection signal. A local signal corresponding to the band (divided bands A, B, and C described later) is generated and output to the block converter 122 and also output to the outdoor unit 11 via the cable 13 (step S3).

  The outdoor unit 11 uses the block converter 113 based on the local signal obtained through the band-pass filter (BPF) 117 and obtained from the amplifier 112 to specify any of the designated division bands (bands A, B, and C) of the UHF band. The frequency of the vertically polarized signal is converted into an SHB band signal (step S4).

  Subsequently, the outdoor unit 11 frequency-multiplexes the vertically polarized signal after frequency conversion obtained through the band pass filter (BPF) 114 and the horizontally polarized signal obtained from the amplifier 116 by the synthesis unit 115. To generate a multiplexed signal and output the signal to the indoor unit 12 side via the cable 13 (step S5).

  The reception control unit 120 receives the multiplexed signal generated by the synthesizing unit 115 of the outdoor unit 11 by the block converter 122, and separates the vertically polarized signal frequency-converted from this multiplexed signal into a SHB band signal. (Step S6) Based on the local signal, the inversely frequency-converted signal of the vertically polarized signal in the SHB band is converted into a signal in the UHF band (Step S7).

  Subsequently, the reception control unit 120 receives the vertically polarized signal and the horizontally polarized signal after inverse frequency conversion via the BPF 123 and 126 for the UHF band and the amplifiers 124 and 127, respectively. (Step S8).

  Subsequently, the reception processing unit 130 performs demodulation / decoding processing corresponding to the modulation / coding processing on the transmission device 2 side on the vertically polarized signal and the horizontally polarized signal, and outputs the result to the display device (Step S9).

  As described above, the outdoor unit 11 is installed directly below a polarization-sharing antenna or the like, receives each polarization received signal, and performs block conversion (frequency conversion) only on one polarization side. At this time, frequency conversion is performed based on the local signal sent from the indoor unit 12. Thereafter, the two polarized signals are combined and sent to the indoor unit 12 as a multiplexed signal via one cable 13. In the indoor unit 12, the multiplexed two polarization signals are separated for each band, and the frequency-converted signal is re-block-converted to the original band with a local signal common to the horizontal and vertical polarizations. The Therefore, compared to the technique of frequency converting the entire UHF band, the frequency conversion efficiency is increased because the three types of bands A, B, and C are selectively converted.

  The present invention should not be construed as limited by the above-described embodiments, but only by the claims. For example, although an example has been described in which vertical polarization is a target of frequency conversion, horizontal polarization can be a target of frequency conversion. In addition to a mode using horizontal polarization or vertical polarization, a mode using 45 ° right-polarization and 45 ° left-polarization, or right-handed polarization and left-handed polarization are used. It can also be set as an aspect. Furthermore, the same can be applied to MIMO transmission configured by spatial separation instead of polarization. That is, the present invention can be applied to an NxM MIMO transmission scheme in which a plurality of signal waves transmitted from N transmission antennas are received by M reception antennas. A spatial MIMO transmission system and a polarization MIMO transmission system are included. Moreover, it is applicable also to the use aiming at diversity synthesis as described in Patent Document 1.

  In the above description of the embodiment, an example in which two signal waves with two types of polarizations are received and controlled as two received signals has been described. However, three or more signal waves may be used. It can also be applied and configured to control as a received signal. In this case, however, each received signal is frequency-converted into a separable band.

  In addition, the example in which the frequency conversion target area is the upper part of the UHF band and the three divided bands A, B, and C are defined has been described. It may be a region, and the divided band may be one or more bands.

  According to the present invention, an outdoor unit that receives a signal transmitted using a plurality of types of polarized waves and an indoor unit that controls the outdoor unit are connected only by a single cable, and in particular, frequency use Since the efficiency can be increased, it is useful for receiving a signal transmitted using a plurality of signal waves within a predetermined band assigned for digital broadcasting.

DESCRIPTION OF SYMBOLS 1 Reception system 2 Transmitter 11 Outdoor unit 12 Indoor unit 13 One cable 21 Error correction encoding part 22 MIMO-OFDM modulation part 111 Power supply part 112 Amplifier 113 Block converter (frequency conversion part)
114 Band pass filter (BPF)
115 Synthesizer 116 Amplifier 117 Band Pass Filter (BPF)
120 Reception Control Unit 121 Power Supply Superimposition Unit 122 Block Converter (Frequency Conversion Unit)
123 UHF band-pass filter (BPF)
124 Amplifier 125 Local Signal Generator 126 UHF Band Pass Filter (BPF)
127 Amplifier 130 Reception Processing Unit 131 Channel Selection Signal Generation Unit 132 MIMO-OFDM Demodulation Unit 133 Error Correction Decoding Unit

Claims (7)

A receiving system for receiving a signal transmitted using a plurality of signal waves within a predetermined band allocated for digital broadcasting,
A part of the predetermined band is set as a first band, and a reception signal of a signal wave other than the first signal wave among the plurality of signal waves in the first band is transferred to a fixed band in the second band. And an outdoor unit that performs frequency conversion with the received signal of the first signal wave and frequency multiplexes to generate a multiplexed signal;
Connected to the outdoor unit with a single cable, separates the multiplexed signal, performs inverse frequency conversion on the received signal of the frequency-converted signal wave, restores the received signal of the plurality of signal waves, and performs signal processing Indoor unit,
A receiving system comprising: The outdoor unit includes a first frequency conversion unit that performs frequency conversion from a divided band that is divided in advance with respect to the first band to a fixed band in the second band,
The reception system according to claim 1, wherein the indoor unit includes a second frequency conversion unit that performs inverse conversion of the frequency conversion.   The receiving system according to claim 2, wherein a frequency of a local signal corresponding to the divided band is determined to be within the second band.   4. The receiving system according to claim 2, wherein each frequency of the local signal corresponding to the divided band is determined to be a ratio represented by an integer ratio. 5.   The indoor unit includes a local signal generation unit that generates a local signal corresponding to the divided band, and the local signal generation unit supplies the local signal to the second frequency conversion unit, and The receiving system according to any one of claims 2 to 4, wherein the receiving system is configured to be supplied to the first frequency converter via a cable.   6. The predetermined band is a UHF band, the first band is a part of the UHF band, and the second band is an SHB band. The receiving system according to any one of the above.   The reception system according to any one of claims 1 to 6, wherein the plurality of signal waves are signal waves based on a MIMO transmission scheme.