Broadcast Receiving System

Abstract

To provide a broadcast receiving system that converts 21 GHz band satellite broadcasting signals and standard compliant 12 GHz band satellite broadcasting signals into frequencies that can be mixed with digital terrestrial television broadcasting signals and transmits them to an in-home receiver using a coaxial cable.SOLUTION: A broadcast receiving system 1 of the present invention includes: functional units (12, 13R, 13L, 15R, 15L) that generate 21 GHz band right-handed / left-handed IF signals; functional units (18, 19) that generate 12 GHz band IF signals; a functional unit (20) that mixes the 12 GHz band IF signals and the 21 GHz band right-handed / left-handed IF signals to generate received signals that fall within a first intermediate frequency band; and functional units (23,24,27) that convert the 21 GHz band right-handed / left-handed IF signals into two types of new 21 GHz band first / second IF signals using hierarchical separation multiplexing, generate for-home IF signals that fall within a second intermediate frequency band, and transmit them to an in-home receiver 28 via a coaxial cable CC2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a broadcast receiving system for receiving terrestrial and satellite broadcasts. [Background technology]

[0002] Conventional satellite broadcast receiving systems include the following: (1) A satellite broadcast receiving system that converts 12 GHz band satellite broadcasts into 1.0 to 3.2 GHz bands and transmits them into the home via a coaxial cable (see, for example, Non-Patent Document 1). (2) A satellite broadcast receiving system that uses optical fiber to transmit signals with frequencies exceeding 3.2 GHz into homes (see, for example, Non-Patent Document 2).

[0003] In recent years, the following has been disclosed as a broadcast receiving system that uses LDM (Layered Division Multiplexing), a layer separation multiplexing method that multiplexes and transmits two layer signals with different power levels. (1) A broadcast receiving system that receives broadcasts multiplexed by LDM (see, for example, Patent Documents 1 and 2). (2) A broadcast receiving system that uses LDM to separate terrestrial broadcasts into 2K and 4K by frequency conversion and transmits them to the home (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-150521 [Patent Document 2] Patent Publication No. 2021-101584 [Patent Document 3] Patent Publication No. 2021-087115 [Non-patent literature]

[0005] [Non-Patent Document 1] ARIB STD-B63 Version 1.9, "Advanced Wideband Satellite Digital Broadcasting Receiver (Desired Specifications)", Revised December 5, 2019 [Non-patent document 2] Shinsuke Yokozawa et al., “A Study on In-Home Distribution of 21GHz-Band Satellite Broadcasting Using POF,” ITE, 2020 ITE 70th Anniversary Commemorative Conference, 12D-1, December 22, 2020. Summary of the Invention [Problem to be solved by the invention]

[0006] Current 12 GHz band satellite broadcasting uses the 11.7 to 12.75 GHz (12 GHz band). The frequency bandwidth of the signal output from a receiving antenna for 12 GHz band satellite broadcasting is 1050 MHz, and the polarization used is right-handed circular polarization (hereinafter simply referred to as "right-handed") and left-handed circular polarization (hereinafter simply referred to as "left-handed"). Different programs can be broadcast using each polarization.

[0007] To receive these satellite broadcasts, coaxial cables are generally used for distribution within homes. Because coaxial cables cannot transmit radio waves in the 12 GHz band, a block converter called an LNB (Low noise block converter) is used to convert the 12 GHz band satellite broadcast signal to an intermediate frequency (IF).

[0008] Therefore, in the ARIB standard STD-B63 (see Non-Patent Document 1), the left-hand circular polarization IF is specified to be a higher frequency than the right-hand circular polarization IF to enable simultaneous reception of right-hand and left-hand circular polarization IFs in the 12 GHz band. The IF band (BS / CS-IF) for 12 GHz band satellite broadcasting is 1032 to 3224 MHz in total for both right-hand and left-hand circular polarization.

[0009] On the other hand, terrestrial digital television broadcasting (terrestrial TV) uses a frequency range of 470 to 710 MHz. Therefore, in existing broadcast receiving systems, it is common for terrestrial TV broadcast waves and BS / CS-IF to be mixed together within the home and transmitted over a single coaxial cable. In addition, broadcast frequencies include FM broadcasting (76 to 95 MHz) and multimedia broadcasting (95 to 108 MHz). Figure 7 shows the frequency arrangement within an existing broadcast receiving system using conventional technology.

[0010] Incidentally, frequencies between 21.4 and 22.0 GHz (the 21 GHz band) are also allocated for satellite broadcasting. The frequency bandwidth of the signal output from a receiving antenna for 21 GHz band satellite broadcasting is 600 MHz, and the use of right-handed and left-handed polarizations is being considered. As with 12 GHz band satellite broadcasting, different programs can be broadcast using each polarization.

[0011] However, the "satellite broadcast receiving system that converts 12 GHz-band satellite broadcasts to 1.0 to 3.2 GHz and transmits them to the home via a coaxial cable" disclosed in Non-Patent Document 1 cannot secure the 1200 MHz frequency bandwidth required for right- and left-handed circular polarization of 21 GHz-band satellite broadcasts. Therefore, in order to transmit 21 GHz-band satellite broadcast signals to the home while utilizing this satellite broadcast receiving system using a coaxial cable, a frequency converter is required to convert the signals to a frequency that can be transmitted via the coaxial cable. However, if a 1200 MHz bandwidth is to be secured by combining right- and left-handed circular polarization, the upper frequency limit becomes approximately 4500 MHz, resulting in increased attenuation of the coaxial cable. As a result, multiple amplifiers (boosters) are required for level compensation. Simply constructing a satellite broadcast receiving system that receives both 12 GHz-band and 21 GHz-band satellite broadcasts poses the problem of increasing the complexity and cost of the receiving system.

[0012] Instead of using coaxial cable, there is a method of in-home distribution using optical fiber (see Non-Patent Document 2). That is, if a satellite broadcasting receiving system using an optical transmitter / receiver and optical fiber is constructed, good transmission with little attenuation is possible even at high frequencies. However, this requires the installation of new optical fiber, and existing satellite broadcasting receiving systems using coaxial cable cannot be utilized, which leads to an issue of increased costs.

[0013] Furthermore, the "broadcast receiving systems for receiving broadcasts multiplexed by LDM" disclosed in Patent Documents 1 and 2 are designed to receive terrestrial broadcasts and do not take into account the reception of satellite broadcasts, which require frequency conversion for transmission within the home.

[0014] Furthermore, in the "broadcast receiving system that separates terrestrial broadcasts using LDM into 2K and 4K by frequency conversion and transmits them into the home" as disclosed in Patent Document 3, frequency conversion is performed to avoid frequency overlap within the coaxial cable, and it is not possible to receive signals of different polarizations at the same frequency and transmit them into the home using a coaxial cable.

[0015] For this reason, it is desirable to build a broadcast receiving system that converts satellite broadcast signals in the 21 GHz band and the 12 GHz band that conforms to the standard into frequencies that can be mixed with terrestrial digital television broadcast signals, and transmits them to receivers in homes using existing or pre-existing coaxial cables.

[0016] Therefore, in view of the above-mentioned problems, the object of the present invention is to provide a broadcast receiving system that converts satellite broadcast signals in the 21 GHz band and the 12 GHz band conforming to the standard into frequencies that can be mixed with terrestrial digital television broadcast signals, and transmits them to a receiver in the home using a coaxial cable. [Means for solving the problem]

[0017] The broadcast receiving system of the present invention converts satellite broadcast signals in the 21 GHz band and 12 GHz band conforming to the standard into frequencies that can be mixed with terrestrial digital television broadcast signals, and transmits the converted signals to a receiver in a home using a coaxial cable. The system includes a first polarization separator that separates the 21 GHz band broadcast signals received by a satellite broadcast receiving antenna into right-handed and left-handed polarizations, and a bandpass filter that extracts 21 GHz band right-handed and left-handed signals that cover channels within the broadcast band from each of the polarization-separated signals obtained from the first polarization separator. a frequency conversion unit that converts the 21 GHz band right-hand circular polarization signal and the 21 GHz band left-hand circular polarization signal to a predetermined intermediate frequency (IF) that separates a predetermined band between polarizations for the 21 GHz band right-hand circular polarization signal and the 21 GHz band left-hand circular polarization signal, respectively, to generate a 21 GHz band right-hand circular polarization IF signal and a 21 GHz band left-hand circular polarization IF signal; a second polarization separator that separates the right-hand circular polarization signal and the left-hand circular polarization signal of a 12 GHz band broadcast signal received by a satellite broadcast receiving antenna; and a frequency conversion unit that converts the polarized separated signals obtained from the second polarization separator to a channel within the broadcast band. a block converter (LNB) that performs bandpass filtering to extract a 12 GHz band right-hand circularly rotated signal and a 12 GHz band left-hand circularly rotated signal that cover the 12 GHz band, and then performs frequency conversion to a predetermined intermediate frequency for the 12 GHz band right-hand circularly rotated and the 21 GHz band left-hand circularly rotated signal to generate a 12 GHz band IF signal; a first mixer that mixes the 12 GHz band IF signal with the 21 GHz band right-hand circularly rotated IF signal and the 21 GHz band left-hand circularly rotated IF signal without overlapping each other as frequency bands to generate a received satellite broadcast signal that falls within a first intermediate frequency band; and a first mixer that mixes the 12 GHz band IF signal with the 21 GHz band right-hand circularly rotated IF signal and the 21 GHz band left-hand circularly rotated IF signal that fall within the first intermediate frequency band obtained from the first mixer. a demultiplexer that demultiplexes a received satellite broadcast signal into a 12 GHz band IF signal, a 21 GHz band right-hand circular polarization IF signal, and a 21 GHz band left-hand circular polarization IF signal; and a 21 GHz band satellite broadcast remodulation unit that demodulates the 21 GHz band right-hand circular polarization IF signal and the 21 GHz band left-hand circular polarization IF signal obtained from the demultiplexer once for each right-hand polarization and left-hand polarization, and then remodulates the signals using hierarchical separation multiplexing to generate two new intermediate frequency band signals that are different from the 12 GHz band IF signal and the terrestrial digital television broadcast signal, thereby generating a 21 GHz band first IF signal and a 21 GHz band second IF signal.and a second mixer that mixes the 12 GHz band IF signal obtained from the branching filter, the 21 GHz band first IF signal and the 21 GHz band second IF signal obtained from the 21 GHz band satellite broadcast remodulation unit, and the terrestrial digital television broadcast signal without overlapping with each other as frequency bands, generates an IF signal for home use that falls within a second intermediate frequency band, and transmits it to a receiver in the home via a coaxial cable.

[0018] In addition, in the broadcast receiving system of the present invention, the received satellite broadcast signal falling within the first intermediate frequency band is characterized in that the 12 GHz band IF signal is placed between the 21 GHz band right-hand circularly polarized IF signal and the 21 GHz band left-hand circularly polarized IF signal.

[0019] Furthermore, in the broadcast receiving system of the present invention, the in-home IF signal falling within the second intermediate frequency band is characterized in that the 21 GHz band first IF signal and the 21 GHz band second IF signal are arranged in a lower intermediate frequency band than the 12 GHz band IF signal, and the 21 GHz band first IF signal is arranged in an empty space below the frequency band of terrestrial digital television broadcasting, and the 21 GHz band second IF signal is arranged in an empty space above the frequency band of terrestrial digital television broadcasting.

[0020] In addition, in the broadcast receiving system of the present invention, the 21 GHz band satellite broadcast remodulation unit generates the 21 GHz band first IF signal by layer separation multiplexing one of the two channels in the 21 GHz band right-hand circularly rotated IF signal and one of the two channels in the 21 GHz band left-hand circularly rotated IF signal, and generates the 21 GHz band second IF signal by layer separation multiplexing the other of the two channels in the 21 GHz band right-hand circularly rotated IF signal and the other of the two channels in the 21 GHz band left-hand circularly rotated IF signal. [Effects of the Invention]

[0021] According to the present invention, it is possible to configure a broadcast receiving system that converts 21 GHz band and 12 GHz band satellite broadcast signals conforming to the standard into frequencies that can be mixed with terrestrial digital television broadcast signals and transmits the signals to a receiver in a home using a coaxial cable. In particular, the broadcast receiving system according to the present invention can mix polarized received signals related to 21 GHz band satellite broadcast signals without affecting terrestrial broadcast signals and 12 GHz band satellite broadcast signals in a home using an existing or pre-existing coaxial cable, without affecting existing broadcast frequencies, and transmit the mixed signals to various receivers in a home related to terrestrial broadcast signals and satellite broadcast signals. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a block diagram illustrating a schematic configuration of a broadcast receiving system according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram illustrating an example of the frequency arrangement of received signals of satellite broadcasts when the reception frequencies of satellite broadcasts in the 12 GHz band and 21 GHz band are converted to the first intermediate frequency band by frequency conversion in a broadcast receiving system of one embodiment according to the present invention. [Figure 3] 1 is an explanatory diagram of layer separation multiplexing (LDM) related to a 21 GHz band satellite broadcast remodulation unit in a broadcast receiving system of one embodiment according to the present invention. [Figure 4] 1 is a block diagram illustrating a schematic configuration of a 21 GHz band satellite broadcast remodulation unit in a broadcast receiving system according to an embodiment of the present invention. [Figure 5] 1 is a diagram showing an example of a frequency arrangement of an IF signal for home use that is input to a receiver in a broadcast receiving system according to an embodiment of the present invention; [Figure 6] 1 is a block diagram illustrating the schematic configuration of a 21 GHz band right-hand circular polarization / left-hand circular polarization compatible (LDM compatible) receiver compatible with a broadcast receiving system according to an embodiment of the present invention. [Figure 7] FIG. 1 is a diagram showing a frequency arrangement in an existing broadcast receiving system in the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0023] A broadcast receiving system 1 according to an embodiment of the present invention will be described below with reference to the drawings.

[0024] (Broadcast receiving system) Fig. 1 is a block diagram illustrating the schematic configuration of a broadcast receiving system 1 according to an embodiment of the present invention. The broadcast receiving system 1 shown in Fig. 1 includes a first polarization separator 12 that separates right-handed and left-handed polarizations of a 21 GHz band broadcast signal received by a satellite broadcast receiving antenna 11, bandpass filters (BPFs) 13R and 13L for right-handed and left-handed circular polarizations of the 21 GHz band, first amplifiers (AMPs) 14R and 14L for right-handed and left-handed circular polarizations of the 21 GHz band, frequency converters 15R and 15L for right-handed and left-handed circular polarizations of the 21 GHz band, second amplifiers (AMPs) 16R and 16L for right-handed and left-handed circular polarizations of the 21 GHz band, and lowpass filters (LPFs) 17R and 17L for right-handed and left-handed circular polarizations of the 21 GHz band. The system is equipped with a second polarization separator 18 that separates the received 12 GHz band broadcast signal into right-hand and left-hand polarizations, a block converter (LNB) 19 that functions as a frequency converter for right-hand and left-hand circular polarizations in the 12 GHz band, a first mixer 20, first and second bias tees 21 and 22, a splitter 23, a demodulator 25 and a modulator 26 that constitute a 21 GHz band satellite broadcast re-modulation unit 24, and a second mixer 27 that transmits to a receiver 28 in a home an intermediate frequency signal that has been frequency-converted so that the 21 GHz band and 12 GHz band satellite broadcast signals that comply with the standard can be mixed with terrestrial digital television broadcast (terrestrial TV) signals.

[0025] The satellite broadcast receiving system 1 shown in Figure 1 has functional sections that are arranged in an outdoor section and an indoor section, and the functional sections of the outdoor section, including a first polarization separator 12, bandpass filters (BPF) 13R, 13L, first amplifiers (AMP) 14R, 14L, frequency conversion sections 15R, 15L, second amplifiers (AMP) 16R, 16L, lowpass filters (LPF) 17R, 17L, second polarization separator 18, block converter (LNB) 19, first mixer 20, and first bias tee 21, are arranged directly below the satellite broadcast receiving antenna 11 or are built into the satellite broadcast receiving antenna 11 itself.

[0026] Below, each functional unit of the satellite broadcast receiving system 1 will be described in more detail.

[0027] The first polarization separator 12 separates the 21 GHz band broadcast signal (21 GHz band BS broadcast signal) received by the satellite broadcast receiving antenna 11 into right-handed and left-handed polarizations and outputs the result to bandpass filters (BPF) 13R and 13L.

[0028] Bandpass filters (BPF) 13R, 13L perform bandpass filtering on each polarization-separated signal obtained from the first polarization separator 12 to extract a 21 GHz band right-hand circularly polarized signal and a 21 GHz band left-hand circularly polarized signal that cover channels within the broadcast band, and output the results to first amplifiers (AMP) 14R, 14L.

[0029] In this example, the 21 GHz band satellite broadcasting that is the target for viewing has a bandwidth of 300 MHz per channel, and two channels (Ch1 and Ch2) within the 600 MHz broadcast frequency band are assumed, with right-hand and left-hand circular polarization for a total of four channels.

[0030] The first amplifiers (AMPs) 14R and 14L amplify the 21 GHz band right-hand circularly polarized signal and the 21 GHz band left-hand circularly polarized signal obtained from the band-pass filters (BPFs) 13R and 13L after band-pass filtering to a predetermined signal level, and output the signals to the frequency conversion units 15R and 15L.

[0031] The frequency conversion units 15R, 15L perform frequency conversion on the amplified 21 GHz band right-hand circularly rotated signal and 21 GHz band left-hand circularly rotated signal obtained from the first amplifiers (AMPs) 14R, 14L to predetermined intermediate frequencies (IF) that separate a predetermined band portion between polarizations for the 21 GHz band right-hand circularly rotated and left-hand circularly rotated, respectively, to generate 21 GHz band right-hand circularly rotated intermediate frequency (IF) signals and 21 GHz band left-hand circularly rotated intermediate frequency (IF) signals, and output them to the second amplifiers (AMPs) 16R, 16L.

[0032] The frequency converters 15R and 15L can be realized by a mixer and a local oscillator (not shown). In this example, the difference between the reception frequency (RF) and the local oscillation frequency (LO) is used as an intermediate frequency (IF), which is converted into a frequency band that does not overlap with the 12 GHz band IF signal described later and can be transmitted over a relatively short coaxial cable CC1.

[0033] As a more specific example, frequency conversion unit 15R converts an input 21 GHz band right-handed circularly rotated signal (RF) into a 21 GHz band right-handed IF signal of 300 to 900 MHz using a right-handed local oscillation frequency (LO) of 21.1 GHz. Frequency conversion unit 15L converts an input 21 GHz band left-handed circularly rotated signal (RF) into a 21 GHz band left-handed IF signal of 3300 to 3900 MHz using a left-handed local oscillation frequency (LO) of 18.1 GHz. In this case, as will be described later with reference to FIG. 2, a 12 GHz band IF signal of 1032 to 3224 MHz is placed between the 21 GHz band right-handed IF signal of 300 to 900 MHz and the 21 GHz band left-handed IF signal of 3300 to 3900 MHz.

[0034] The second amplifiers (AMP) 16R and 16L amplify the 21 GHz band right-handed IF signal and the 21 GHz band left-handed IF signal obtained from the frequency conversion units 15R and 15L to a predetermined signal level, respectively, and output the signals to the low-pass filters (LPF) 17R and 17L.

[0035] The low-pass filters (LPFs) 17R and 17L perform low-pass filtering to remove unnecessary noise components from the amplified 21 GHz band right-hand circular IF signal and 21 GHz band left-hand circular IF signal obtained from the second amplifiers (AMPs) 16R and 16L, and output the signals to the first mixer 20. The first amplifiers (AMPs) 14R and 14L, the second amplifiers (AMPs) 16R and 16L, and the low-pass filters (LPFs) 17R and 17L are not essential but are provided as a preferred example. To obtain 21 GHz band IF signals that have been frequency converted to predetermined intermediate frequencies (IFs) for the 21 GHz band right-hand and left-hand circular IFs, the signals are amplified before and after the frequency conversion units 15R and 15L and then low-pass filtered, thereby accurately removing unnecessary noise components. Here, the low-pass filters (LPFs) 17R and 17L are used as an example of low-pass filtering, but band-pass filtering may also be used.

[0036] The second polarization separator 18 outputs to a block converter (LNB) 19 that separates right-handed and left-handed polarizations of the 12 GHz band broadcast signal (12 GHz band BS / CS broadcast signal) received by the satellite broadcast receiving antenna 11. In this example, the satellite broadcast receiving antenna 11 is assumed to be compatible with both the 12 GHz band and the 21 GHz band, but broadcasts may also be received from satellite broadcast receiving antennas dedicated to the 12 GHz band and the 21 GHz band.

[0037] The block converter (LNB) 19 functions as a signal extraction and frequency conversion unit for right-hand and left-hand circular polarization in the 12 GHz band. It performs bandpass filtering on each of the polarization-separated signals obtained from the second polarization separator 18 to extract 12 GHz band right-hand circular polarization signals and 12 GHz band left-hand circular polarization signals that cover channels within the broadcast band, and then performs frequency conversion to a predetermined intermediate frequency (IF) that conforms to the standard for 12 GHz band right-hand and left-hand circular polarization (see Non-Patent Document 1), generating a 12 GHz band intermediate frequency (IF) signal and outputting it to the first mixer 20.

[0038] That is, the block converter (LNB) 19 converts the 12 GHz band right-hand circularly rotated signal and the 12 GHz band left-hand circularly rotated signal related to the 12 GHz band satellite broadcasting (BS / CS) into a 12 GHz band IF signal of 1032 to 3224 MHz (BS right-hand circularly rotated signal / CS right-hand circularly rotated signal and BS left-hand circularly rotated signal / CS left-hand circularly rotated signal constitutes a line of channels as an intermediate frequency band.) Details of this are specified in the ARIB standard STD-B63 (Non-Patent Document 1).

[0039] Therefore, the received satellite broadcast signal generated by the first mixer 20 has a 12 GHz band IF signal of 1032 to 3224 MHz positioned between a 21 GHz band right-handed circularly rotated IF signal of 300 to 900 MHz and a 21 GHz band left-handed circularly rotated IF signal of 3300 to 3900 MHz.

[0040] The first mixer 20 mixes the 12 GHz band IF signal obtained from the block converter (LNB) 19 with the 21 GHz band right-hand circularly polarized IF signal and the 21 GHz band left-hand circularly polarized IF signal obtained from the low-pass filters (LPF) 17R and 17L without overlapping with each other as frequency bands, generates a received satellite broadcast signal that falls within the first intermediate frequency band (in this example, 300 to 3900 MHz), and outputs it to the branching filter 23 via the first bias tee 21 and the second bias tee 22.

[0041] Figure 2 shows an example of the frequency arrangement of received signals from satellite broadcasts when the receiving frequencies (RF) of satellite broadcasts in the 12 GHz band and 21 GHz band are converted to the first intermediate frequency band (in this example, 300 to 3900 MHz) by frequency conversion (frequency conversion units 15R, 15L and LNB 19) in the broadcast receiving system 1 of this embodiment.

[0042] Here, the connection between the first bias tee 21 and the second bias tee 22 uses an existing coaxial cable CC1, which allows the satellite broadcast receiving system 1 to be installed in two parts, outdoor and indoor, as shown in Fig. 1. The first bias tee 21 and the second bias tee 22 function as power supplies that supply power to each functional unit in the satellite broadcast receiving system 1, with a 15V DC power supply biased at the second bias tee 22 and a 15V DC power supply taken out at the first bias tee 21, to supply power to the functional units in the outdoor unit.

[0043] The existing coaxial cable CC1 connecting the outdoor and indoor sections can be made shorter in length, unlike the coaxial cable CC2 (described later) used for in-home transmission. Furthermore, because the outdoor and indoor sections are connected one-to-one, devices such as a booster or distributor are not required. Therefore, unlike the coaxial cable CC2 (described later) used for in-home transmission, the coaxial cable CC1 connecting the outdoor and indoor sections can transmit received satellite broadcast signals in the first intermediate frequency band (300 to 3900 MHz in this example), which includes frequencies higher than 3224 MHz. Therefore, the coaxial cable CC1 does not necessarily have to be used as the signal line connecting the outdoor and indoor sections; simple signal wiring may also be used. However, in this example, the existing coaxial cable CC1 is used in consideration of practical operation.

[0044] However, from the second bias tee 22 onwards, which constitutes the indoor portion of the broadcast receiving system 1, the received satellite broadcast signal in the first intermediate frequency band (300 to 3900 MHz in this example) is demultiplexed and further frequency converted to enable signal transmission to the in-home receiver 28 via the coaxial cable CC2 and to enable mixing without overlapping with the terrestrial TV signal. Specifically, the 21 GHz band right-hand circularly rotated IF and the 21 GHz band left-hand circularly rotated IF are positioned at frequencies below 3224 MHz, which can be transmitted even over the relatively long coaxial cable CC2, without overlapping with the terrestrial TV signal and the BS / CS-IF.

[0045] Hereinafter, the functional units arranged after the second bias tee 22 in the broadcast receiving system 1 will be described more specifically.

[0046] The branching filter 23 is a functional unit that branches out the received satellite broadcast signals falling within the above-mentioned first intermediate frequency band (300 to 3224 MHz in this example) obtained from the first mixer 20 via the first bias tee 21 and the second bias tee 22, sending the 12 GHz band IF signal to the second mixer 27 and the 21 GHz band right-hand circularly rotated IF signal and the 21 GHz band left-hand circularly rotated IF signal to the 21 GHz band satellite broadcast remodulation unit 24.

[0047] The 21 GHz band satellite broadcast remodulation unit 24 is composed of a demodulator 25 and a modulator 26. The 21 GHz band right-hand circularly polarized IF signal and the 21 GHz band left-hand circularly polarized IF signal obtained from the branching filter 23 are demodulated by the demodulator 25 into right-hand and left-hand polarized waves, respectively, and then remodulated by the modulator 26 using layer separation multiplexing (LDM) to generate two new intermediate frequency band signals separate from the 12 GHz band IF signal and the terrestrial digital television broadcast (terrestrial TV) signal, thereby generating a 21 GHz band first IF signal (IF1) and a 21 GHz band second IF signal (IF2). The 21 GHz band satellite broadcast remodulation unit 24 then outputs the remodulated 21 GHz band first IF signal (IF1) and 21 GHz band second IF signal (IF2) to a second mixer 27.

[0048] The second mixer 27 mixes the 12 GHz band IF signal obtained from the splitter 23, the 21 GHz band first IF signal (IF1) and the 21 GHz band second IF signal (IF2) obtained from the 21 GHz band satellite broadcast remodulation unit 24, and the terrestrial digital television broadcast (terrestrial TV) signal as frequency bands without overlapping with each other, generates an IF signal for home use that falls within the second intermediate frequency band (in this example, 160 to 3224 MHz), and transmits it to the home receiver 28 via the existing coaxial cable CC2.

[0049] Therefore, first, the BS / CS-IF signal is extracted by the splitter 23, and then the terrestrial TV signal is mixed by the second mixer 27. This makes it possible to generate a signal that mixes the existing terrestrial TV broadcast signal with the BS / CS-IF signal.

[0050] On the other hand, the 21 GHz band right-hand circular polarization IF signal and the 21 GHz band left-hand circular polarization IF signal transmitted from the outdoor part of the broadcast receiving system 1 via coaxial cable CC1 each have a frequency bandwidth of 600 MHz, and as such cannot be placed below 3224 MHz, which is the frequency band that can be transmitted via coaxial cable CC2, and would overlap with terrestrial TV signals.

[0051] Therefore, the 21GHz band satellite broadcast remodulation unit 24 applies layer demultiplexing (LDM) technology to demultiplex two channels (equivalent to a total of 600MHz) into a 300MHz frequency bandwidth for the 21GHz band right-hand circularly polarized IF signal (300-900MHz) and the 21GHz band left-hand circularly polarized IF signal (3300-3900MHz). LDM is a technology that multiplexes, transmits, and demultiplexes two modulated signals with different power levels. When demodulating the high-power layer (UL), the low-power layer (LL) can be considered noise. The LL signal component can be obtained by subtracting the demodulated UL signal from the original IF signal.

[0052] 3 is an explanatory diagram of layer demultiplexing multiplexing (LDM) in the 21 GHz band satellite broadcast remodulation unit 24 in the broadcast receiving system 1 of one embodiment according to the present invention. The 21 GHz band satellite broadcast remodulation unit 24 uses LDM to layer demultiplex and multiplex Ch1 in the 21 GHz band right-hand circularly polarized IF signal (shown as "21 GHz band right-hand circularly polarized Ch1-IF" in FIG. 3) and Ch1 in the 21 GHz band left-hand circularly polarized IF signal (shown as "21 GHz band left-hand circularly polarized Ch1-IF" in FIG. 3) to generate a 21 GHz band first IF signal (shown as "21 GHz band-IF1" in FIG. 3). Similarly, the 21 GHz band satellite broadcast remodulation unit 24 uses LDM to hierarchically separate and multiplex Ch2 in the 21 GHz band right-hand circularly polarized IF signal (shown as "21 GHz band right-hand circularly polarized Ch2-IF" in Figure 3) and Ch2 in the 21 GHz band left-hand circularly polarized IF signal (shown as "21 GHz band left-hand circularly polarized Ch2-IF" in Figure 3) to generate a 21 GHz band second IF signal (shown as "21 GHz band-IF2" in Figure 3).

[0053] 3 is an example, and the relationship between right-hand and left-hand circular polarization may be reversed, and furthermore, the relationship between the UL and LL channels may be reversed. In this example, in accordance with the current 12 GHz band satellite broadcasting, which first started service with right-hand circular polarization and then started service with left-hand circular polarization, here we show an example in which a 21 GHz band right-hand circular polarization channel is placed on UL, which is the main signal.

[0054] Therefore, the 21 GHz band satellite broadcast remodulation unit 24 is required to generate a 21 GHz band first IF signal (IF1) by layer separation multiplexing one of the two channels in the 21 GHz band right-hand circularly rotated IF signal and one of the two channels in the 21 GHz band left-hand circularly rotated IF signal, and to generate a 21 GHz band second IF signal (IF2) by layer separation multiplexing the other of the two channels in the 21 GHz band right-hand circularly rotated IF signal and the other of the two channels in the 21 GHz band left-hand circularly rotated IF signal.

[0055] FIG. 4 is a block diagram illustrating a schematic configuration of the 21 GHz band satellite broadcast remodulation unit 24 in the broadcast receiving system 1 of one embodiment according to the present invention.

[0056] The 21 GHz band satellite broadcast remodulation unit 24 shown in Figure 4 is composed of four systems of first to fourth high frequency units (251-1 to 251-4), demodulators (252-1 to 252-4), modulators (261-1 to 261-4), and attenuators (262-1 to 262-4) in which demodulator 25 and modulator 26 process a total of four channels of 21 GHz band satellite broadcast (right-handed circular polarization Ch1, right-handed circular polarization Ch2, left-handed circular polarization Ch1, and left-handed circular polarization Ch2) in parallel.

[0057] The high frequency unit (for example, the first high frequency unit 251-1) shown in FIG. 4 is a functional unit that selects an input signal (a 21 GHz band right-hand circularly polarized IF signal or a 21 GHz band left-hand circularly polarized IF signal) and converts it to an input frequency of the demodulation unit 25, and the frequency corresponding to this frequency conversion may be a predetermined fixed value.

[0058] The demodulation unit (for example, first demodulation unit 252-1) shown in FIG. 4 demodulates the signal tuned and frequency-converted by the high frequency unit, and outputs the signal to the subsequent modulation unit (for example, first modulation unit 261-1) for each signal system.

[0059] A modulation unit (e.g., first modulation unit 261-1) shown in Fig. 4 re-modulates a signal demodulated by a corresponding demodulation unit (e.g., first demodulation unit 252-1) so that it becomes a signal in a new intermediate frequency band of the corresponding channel illustrated in Fig. 3, and outputs the signal to a subsequent attenuator (e.g., first attenuator 262-1) for each signal system. Note that it is preferable for the modulation unit (e.g., first modulation unit 261-1) to perform error correction decoding and re-encoding and then re-modulation. The satellite broadcast signal received via coaxial cable CC1 is weak and therefore contains noise, but by performing error correction and re-modulation, the signal quality is improved.

[0060] The attenuator shown in Figure 4 (e.g., the first attenuator 262-1) attenuates the signal re-modulated by the corresponding modulation section (e.g., the first modulation section 261-1) so that it becomes the signal level of the new intermediate frequency band of the corresponding channel illustrated in Figure 3, and outputs it to the second mixer 27.

[0061] Here, each attenuator (262-1 to 262-4) operates to create a power difference between UL and LL as the signal components of the corresponding channel illustrated in FIG.

[0062] That is, in the 21 GHz band satellite broadcast remodulation unit 24 corresponding to the example shown in Figure 3, Ch1 in the input 21 GHz band right-hand circularly rotated IF signal passes through the first high frequency unit 251-1, the first demodulation unit 252-1, the first modulation unit 261-1, and the first attenuator 262-1, and is converted into a high power hierarchical (UL) signal in the 21 GHz band first IF signal (IF1).

[0063] In addition, in the 21 GHz band satellite broadcast remodulation unit 24 corresponding to the example shown in Figure 3, Ch1 in the input 21 GHz band left-hand circularly polarized IF signal passes through the second high frequency unit 251-2, the second demodulation unit 252-2, the second modulation unit 261-2, and the second attenuator 262-2, and is converted into a low power hierarchical (LL) signal in the 21 GHz band first IF signal (IF1).

[0064] In addition, in the 21 GHz band satellite broadcast remodulation unit 24 corresponding to the example shown in Figure 3, Ch2 in the input 21 GHz band right-hand circularly rotated IF signal passes through the third high frequency unit 251-3, the third demodulation unit 252-3, the third modulation unit 261-3, and the third attenuator 262-3, and is converted into a high power hierarchical (UL) signal in the 21 GHz band second IF signal (IF2).

[0065] In addition, in the 21 GHz band satellite broadcast remodulation unit 24 corresponding to the example shown in Figure 3, Ch2 in the input 21 GHz band left-hand circularly polarized IF signal passes through the fourth high-frequency unit 251-4, the fourth demodulation unit 252-4, the fourth modulation unit 261-4, and the fourth attenuator 262-4, and is converted into a low-power layer (LL) signal in the 21 GHz band second IF signal (IF2).

[0066] In this way, the 21 GHz band satellite broadcast remodulation unit 24 converts the 21 GHz band right-hand circularly polarized IF signal (300 to 900 MHz) and the 21 GHz band left-hand circularly polarized IF signal (3300 to 3900 MHz) into two types of intermediate frequency signals below 3224 MHz, namely, a 21 GHz band first IF signal (IF1) of 160 to 460 MHz and a 21 GHz band second IF signal (IF2) of 720 to 1020 MHz.

[0067] The second mixer 27 then mixes the 12 GHz band IF signal obtained from the splitter 23, the 21 GHz band first IF signal (IF1) and the 21 GHz band second IF signal (IF2) obtained from the 21 GHz band satellite broadcast remodulation unit 24, and the terrestrial digital television broadcast (terrestrial TV) signal as frequency bands without overlapping with each other, generates an IF signal for home use that falls within the second intermediate frequency band (160 to 3224 MHz), and transmits it to the home receiver 28 via the existing coaxial cable CC2.

[0068] Fig. 5 is a diagram showing an example of a frequency arrangement of the home IF signal to be input to receiver 28 in broadcast receiving system 1 of one embodiment according to the present invention. As shown in Fig. 5, the home IF signal generated by second mixer 27 and transmitted to home receiver 28 via existing coaxial cable CC2 is a 21 GHz band right-hand circularly polarized IF signal and a 21 GHz band left-hand circularly polarized IF signal, which are re-modulated using LDM to arrange IF signals corresponding to each channel of 21 GHz band satellite broadcasting without overlapping with terrestrial TV signals and BS / CS-IF, thereby making it possible to generate a signal of 3224 MHz or less that can be transmitted via existing coaxial cable CC2. More specifically, the in-home IF signal transmitted to the in-home receiver 28 is a signal in which the 21 GHz band first IF signal (IF1) and the 21 GHz band second IF signal (IF2) are placed in a frequency band lower than the 12 GHz band IF signal, and the 21 GHz band first IF signal (IF1) is placed in the empty space below the terrestrial TV frequency band, and the 21 GHz band second IF signal (IF2) is placed in the empty space above the terrestrial TV frequency band.

[0069] When transmitting the in-home IF signal to the in-home receiver 28, it can be done via an existing coaxial cable CC2. Generally, coaxial cables do not propagate through space, and a high C / N (signal to noise ratio) can be maintained.

[0070] The 21 GHz band satellite broadcast remodulation unit 24 (more precisely, modulator 26) can be configured to be connected to receive predetermined complementary information from a communication channel such as the Internet and transmit it to the home. 21 GHz band satellite broadcasts are significantly affected by rain, so rain attenuation can reduce the reception C / N ratio and potentially block the 21 GHz band satellite broadcasts. Even in such cases, the broadcaster can transmit complementary information from the communication channel to the 21 GHz band satellite broadcast remodulation unit 24 (more precisely, modulator 26) to transmit the 21 GHz band satellite broadcast program to the home, allowing the user to continue watching the program.

[0071] Therefore, the broadcast receiving system 1 of this embodiment can use existing coaxial cables CC1 and CC2 to transmit to a receiver 28 in the home an intermediate frequency signal (IF signal for home use) that has been frequency converted so that it can be mixed with terrestrial digital television broadcast (terrestrial TV) signals for 21 GHz band satellite broadcast signals and 12 GHz band satellite broadcast signals that comply with standards obtained from the satellite broadcast receiving antenna 11.

[0072] The receiver 28 can be configured as any of an existing terrestrial TV / BS (12 GHz band) / CS common receiver 28-1 that receives an IF signal for home use transmitted via coaxial cable CC2, with a booster, distributor, etc. inserted as necessary, a 21 GHz band right-hand circular polarization compatible receiver 28-2, and a 21 GHz band right-hand circular polarization / left-hand circular polarization compatible (LDM compatible) receiver 28-3 that is compatible with the broadcast receiving system of the present invention.

[0073] (21GHz band right-hand and left-hand circular polarization compatible (LDM compatible) receiver) 6 is a diagram illustrating the schematic configuration of a 21 GHz band right-handed / left-handed circular polarization (LDM compatible) receiver 28-3 compatible with the broadcast receiving system 1 according to the present invention. The 21 GHz band right-handed / left-handed circular polarization (LDM compatible) receiver 28-3 can be configured similarly to a conventionally known LDM compatible receiver, and will therefore only be briefly described here.

[0074] The 21 GHz band right-hand circular polarization / left-hand circular polarization (LDM compatible) receiver 28-3 shown in FIG. 6 includes a tuning unit 281, a high layer demodulation unit 282, a high layer decoder 283, an LDM processing unit 284, and a low layer decoder 285.

[0075] The tuning unit 281 inputs the IF signal for home use generated by the broadcast receiving system 1 via the coaxial cable CC2, and extracts the 21 GHz band first IF signal (IF1) or the 21 GHz band second IF signal (IF2) corresponding to the 21 GHz band satellite broadcast channel in accordance with the channel selection operation by the operator, and outputs it to the high-level demodulation unit 282 and the delay unit 2842.

[0076] When the 21 GHz band satellite broadcasting channel extracted by the tuning unit 281 is a right-hand circularly polarized broadcasting channel (Ch1 or Ch2) of the 21 GHz band satellite broadcasting in the example shown in Figure 3, the high layer demodulation unit 282 performs demodulation processing on the 21 GHz band first IF signal (IF1) or the 21 GHz band second IF signal (IF2) corresponding to the right-hand circularly polarized channel extracted by the tuning unit 281, and outputs it to the high layer decoder 283.

[0077] The high layer decoder 283 performs decoding processing including error correction decoding on the signal demodulated by the high layer demodulation unit 282, and outputs the result as the video / audio output 1 to a display or the like.

[0078] On the other hand, when the 21 GHz band satellite broadcast channel extracted by tuning unit 281 is a left-handed circularly polarized broadcast channel (Ch1 or Ch2) of 21 GHz band satellite broadcast in the example shown in Fig. 3, in addition to the operation of high layer demodulation unit 282, demodulation processing is performed by LDM processing unit 284. LDM processing unit 284 includes a modulation unit 2841, a delay unit 2842, a subtraction unit 2843, and a low layer demodulation unit 2844.

[0079] The modulation unit 2841 inputs the signal demodulated by the operation of the above-mentioned high layer demodulation unit 282, re-modulates it according to the original modulation method, and outputs it to the subtraction unit 2843. Note that the modulation unit 2841 may input data that has been subjected to error correction coding processing by the high layer decoder 283, re-encode it according to the original error correction coding processing, and re-modulate it according to the original modulation method to output it to the subtraction unit 2843.

[0080] The delay unit 2842 applies a delay process to the 21 GHz band first IF signal (IF1) or the 21 GHz band second IF signal (IF2) corresponding to the left-handed circular polarization channel extracted by the tuning unit 281, delaying the signal to a time corresponding to the operation time of the high-level demodulation unit 282 and the modulation unit 2841, and outputs the signal to the subtraction unit 2843.

[0081] The subtraction unit 2843 subtracts the power of the signal obtained from the modulation unit 2841 from the signal delayed by the delay unit 2842, and outputs the result to the low layer demodulation unit 2844 as a signal component corresponding to the left-handed circular polarization channel (Ch1 or Ch2) extracted by the tuning unit 281.

[0082] The low layer demodulation unit 2844 demodulates the signal components corresponding to the left-handed circular polarization channel (Ch1 or Ch2) extracted by the tuning unit 281, and outputs the demodulated signal to the low layer decoder 285.

[0083] The low layer decoder 285 performs decoding processing including error correction decoding on the signal demodulated by the low layer demodulation unit 2844, and outputs the result as video / audio output 2 to an external device such as a display.

[0084] In this way, in the 21 GHz band right-hand and left-hand circular polarization compatible (LDM compatible) receiver 28-3, the IF signal for home use generated by the broadcast receiving system 1 via the coaxial cable CC2, which serves as the input signal, has a sufficiently high reception C / N ratio, and the LL signal component can be obtained by re-modulating and subtracting the demodulated UL signal from the original IF1 or IF2 signal. By decoding the UL and LL respectively, it is possible to view all of the right-hand and left-hand circular polarization channels in the 21 GHz band (in this example, a total of four channels, Ch1 and Ch2, are illustrated). Note that the high layer decoder 283 and the low layer decoder 285 may be configured as a shared decoder, with a switch interposed between them to switch between processes.

[0085] As described above, according to the broadcast receiving system 1 of this embodiment, it is possible to transmit received signals of all frequency bands and polarizations of 21 GHz band satellite broadcasting to the in-home receiver 28 using existing coaxial cables CC1 and CC2. However, a receiver compatible with all 21 GHz band right-hand and left-hand circularly polarized channels (in this example, a total of four channels, Ch1 and Ch2, are exemplified) is assumed to perform processing compatible with the frequency arrangement determined in the broadcast receiving system 1 as exemplified in Fig. 3 and Fig. 5, such as the 21 GHz band right-hand circularly polarized left-hand circularly polarized (LDM compatible) receiver 28-3.

[0086] Furthermore, according to the broadcast receiving system 1 of this embodiment, since it does not affect existing broadcast frequencies, by connecting an existing receiver (terrestrial / BS / CS compatible receiver), you can watch current broadcasts as is.

[0087] Furthermore, according to the broadcast receiving system 1 of this embodiment, even a receiver 28 that does not have LDM processing functionality due to reasons such as cost reduction can watch broadcast programs on the main signal, UL (in the examples of Figures 3 and 5, Ch1 and Ch2 of the right-hand circular polarization in the 21 GHz band).

[0088] The above-described embodiments have been described as representative examples, but it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. For example, the above-described examples have been described assuming that signals from 21 GHz-band satellite broadcasts, 12 GHz-band satellite broadcasts conforming to standards, and terrestrial digital television broadcasts conforming to standards are to be received. However, in the future, the present invention will be applicable to 12 GHz-band or 21 GHz-band satellite broadcasts conforming to LDM systems, or terrestrial TV signals conforming to LDM systems, conforming to these standards. Furthermore, the 21 GHz-band satellite broadcasts to be viewed in this example have been described assuming two channels (Ch1 and Ch2) per polarization, with a total of four channels, including right- and left-handed circular polarization. However, the present invention will be applicable to viewing more channels. Therefore, the present invention is not limited to the above-described embodiments, but is limited only by the claims. [Industrial Applicability]

[0089] According to the present invention, it is possible to transmit IF signals capable of receiving satellite broadcasts in the 12 GHz band and 21 GHz band as well as terrestrial digital television broadcasts using existing or pre-existing coaxial cables, and therefore it is useful for receiving terrestrial broadcasts and satellite broadcasts. [Explanation of symbols]

[0090] 1 Broadcast receiving system 11 Satellite dish 12 First polarization separator 13R, 13L Bandpass Filter (BPF) 14R, 14L First amplifier (AMP) 15R, 15L frequency conversion section 16R, 16L Second amplifier (AMP) 17R, 17L Low-pass filter (LPF) 18 Second polarization separator 19 Block Converter (LNB) 20 First mixer 21 First bias tee 22 Second bias tee 23 Duplexer 24 21GHz band satellite broadcasting remodulation section 25 Demodulator 26 Modulator 27 Second Mixer 28 Receiver 28-1 Terrestrial TV / BS / CS common receiver 28-2 21GHz band right-hand circular polarization receiver 28-3 21GHz band right-hand and left-hand circular polarization compatible (LDM compatible) receiver 251-1 to 251-4 First to fourth high frequency sections 252-1 to 252-4 First to fourth demodulation units 261-1 to 261-4 First to fourth modulation units 262-1 to 262-4 First to fourth attenuators 281 Channel selection department 282 High-level demodulation section 283 High-level decoder 284 LDM Processing Section 285 Low-level decoder 2841 Modulation section 2842 Delay Device 2843 Subtraction section 2844 Low-level demodulation unit CC1, CC2 coaxial cable

Claims

1. A broadcast receiving system that converts 21 GHz band satellite broadcast signals and 12 GHz band satellite broadcast signals conforming to the standard into a frequency that can be mixed with terrestrial digital television broadcast signals, and transmits them to a receiver in a home using a coaxial cable, a first polarization separator that separates a 21 GHz band broadcast signal received by a satellite broadcast receiving antenna into right-handed and left-handed polarizations; a bandpass filter that performs bandpass filtering on each of the polarization-separated signals obtained from the first polarization separator to extract a 21 GHz band right-hand circularly polarized signal and a 21 GHz band left-hand circularly polarized signal that cover channels within a broadcast band; a frequency conversion unit that converts the 21 GHz band right-hand circularly rotated signal and the 21 GHz band left-hand circularly rotated signal to a predetermined intermediate frequency (IF) that separates a predetermined band between polarizations for the 21 GHz band right-hand circularly rotated signal and the 21 GHz band left-hand circularly rotated signal, respectively, to generate a 21 GHz band right-hand circularly rotated IF signal and a 21 GHz band left-hand circularly rotated IF signal; a second polarization separator for separating a 12 GHz band broadcast signal received by a satellite broadcast receiving antenna into right-handed and left-handed polarizations; a block converter (LNB) that performs bandpass filtering on each of the polarization-separated signals obtained from the second polarization separator to extract a 12 GHz band right-hand circularly polarized signal and a 12 GHz band left-hand circularly polarized signal that cover channels within a broadcast band, and then performs frequency conversion on the signals to predetermined intermediate frequencies for the 12 GHz band right-hand circularly polarized signal and the 12 GHz band left-hand circularly polarized signal, thereby generating a 12 GHz band IF signal; a first mixer that mixes the 12 GHz band IF signal with the 21 GHz band right-hand circularly polarized IF signal and the 21 GHz band left-hand circularly polarized IF signal without overlapping each other as frequency bands to generate a received satellite broadcast signal that falls within a first intermediate frequency band; a branching filter that branches a 12 GHz band IF signal, a 21 GHz band right-hand circular polarization IF signal, and a 21 GHz band left-hand circular polarization IF signal from the received satellite broadcast signal that falls within the first intermediate frequency band obtained from the first mixer; a 21 GHz band satellite broadcast remodulation unit that demodulates the 21 GHz band right-hand circular polarization IF signal and the 21 GHz band left-hand circular polarization IF signal obtained from the splitter, respectively, for each right-hand and left-hand polarization, and then remodulates the demodulated signals using hierarchical separation multiplexing to generate two new intermediate frequency band signals that are different from the 12 GHz band IF signal and the terrestrial digital television broadcast signal, thereby generating a 21 GHz band first IF signal and a 21 GHz band second IF signal; a second mixer that mixes the 12 GHz band IF signal obtained from the branching filter, the 21 GHz band first IF signal and the 21 GHz band second IF signal obtained from the 21 GHz band satellite broadcast remodulation unit, and the terrestrial digital television broadcast signal without overlapping with each other as frequency bands, generates an IF signal for home use that falls within a second intermediate frequency band, and transmits the IF signal to a home receiver via a coaxial cable; A broadcast receiving system comprising:

2. 2. The broadcast receiving system according to claim 1, wherein the received satellite broadcast signal falling within the first intermediate frequency band is a signal in which the 12 GHz band IF signal is positioned between the 21 GHz band right-hand circular polarization IF signal and the 21 GHz band left-hand circular polarization IF signal.

3. 3. The broadcast receiving system according to claim 1, wherein the in-home IF signal falling within the second intermediate frequency band is a signal in which the 21 GHz band first IF signal and the 21 GHz band second IF signal are placed in a lower intermediate frequency band than the 12 GHz band IF signal, and the 21 GHz band first IF signal is placed in a lower empty space in the frequency band of terrestrial digital television broadcasting, and the 21 GHz band second IF signal is placed in an upper empty space in the frequency band of terrestrial digital television broadcasting.

4. 4. The broadcast receiving system according to claim 1, wherein the 21 GHz band satellite broadcast remodulation unit generates the 21 GHz band first IF signal by layer-separating and multiplexing one of the two channels in the 21 GHz band right-hand circularly polarized IF signal and one of the two channels in the 21 GHz band left-hand circularly polarized IF signal, and generates the 21 GHz band second IF signal by layer-separating and multiplexing the other of the two channels in the 21 GHz band right-hand circularly polarized IF signal and the other of the two channels in the 21 GHz band left-hand circularly polarized IF signal.

Images