JP2006074269A - Wireless redistribution system for terrestrial digital tv broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless redistribution system for terrestrial digital tv broadcasting capable of enhancing the reception quality and the reception probability. <P>SOLUTION: A transmitter includes: a first means that frequency-converts a terrestrial digital tv broadcast signal of a view desirable channel received by a view desirable channel input means among received terrestrial digital tv broadcast signals into signals of a plurality of free channels with a preset VHF band; and a second means that amplifies the terrestrial digital tv broadcast signals of the view desirable channel frequency-converted into a plurality of the free channels of the VHF band by the first means and wirelessly transmits the amplified signals, and a TV receiver is provided with: a selection means for selecting a TV broadcast signal of a channel with high reception quality among TV broadcast signals of a plurality of channels supplied from the transmitter via a receiver; and a reproducing means for reproducing the TV broadcast signal selected by the selection means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless redistribution system for terrestrial digital TV broadcasting.

  Japan's terrestrial digital TV broadcasting has started on December 1, 2003 in the three major metropolitan areas of Kanto, Chukyo, and Kinki. Terrestrial digital TV broadcasting uses OFDM (Orthogonal Frequency Division Multiplexing), which is resistant to multipath interference, and there is almost no multiplex image (ghost disturbance) generated in analog TV broadcasting, etc., and stable high image quality. Can receive. Terrestrial digital TV broadcasting is broadcast in the UHF band (470 to 770 MHz).

  As a form of receiving a terrestrial digital TV broadcast by a terrestrial digital TV receiver, there are generally the following forms.

(1) A terrestrial digital TV broadcast signal is received by an outdoor antenna. A terrestrial digital TV broadcast signal received by an outdoor antenna is distributed to each room by an antenna cable and guided to a TV terminal provided on the wall surface of each room. Then, the antenna terminal of the terrestrial digital TV receiver is connected to the TV terminal provided on the wall surface of each room via an antenna cable.
In such a receiving mode, it is necessary to connect the antenna terminal of the terrestrial digital TV receiver to the TV terminal provided on the wall surface by using an antenna cable, which is detrimental to the appearance and troublesome wiring. There is. Further, since the layout of the TV receiver is limited, there is a problem that the degree of freedom of the installation position of the TV receiver is hindered.

(2) Without installing an antenna on the rooftop (on the roof), install a UHF antenna (for example, UDMF62: made by Japan Antenna) on the eaves or veranda, and then pull the antenna cable indoors to receive digital terrestrial TV Connect directly to the antenna terminal of the machine.
Even in such a receiving mode, it is necessary to draw the antenna cable into the room and connect it to the terrestrial digital TV receiver, which causes a problem that the aesthetics are impaired and the wiring is troublesome. Further, since the layout of the TV receiver is limited, there is a problem that the degree of freedom of the installation position of the TV receiver is hindered.

(3) The terrestrial digital TV broadcast signal is received by the indoor antenna connected to the terrestrial digital TV receiver.
In such a receiving mode, there is no restriction on the layout of the TV receiver due to the wiring of the antenna cable, but there is a problem that a radio wave blocking loss occurs in the room. In particular, the UHF band used for terrestrial digital TV broadcast signals has a larger attenuation loss when passing through buildings than the VHF band used for terrestrial analog TV broadcasts. There is a problem that the installation position is limited.

  Therefore, an indoor retransmission system has been developed in which a terrestrial digital TV broadcast signal input indoors is amplified by a wireless transmitter and retransmitted wirelessly to a TV receiver (Japanese Patent Laid-Open No. 2004-128719, JP, 2004-12720, A). In this indoor retransmission system, UHF band terrestrial digital TV broadcast signals input indoors are amplified and retransmitted as they are without frequency conversion.

  In the frequency band of the UHF band, as will be described later, since the transmission output level of the wireless transmitter is limited to a very low level, there is a problem that the transmission distance is almost short distance transmission only.

  In addition, when both the direct broadcast radio wave transmitted from the broadcasting station and the retransmitted radio wave transmitted from the wireless transmitter are received and input from the indoor receiving antenna, the signal of the same frequency channel is input to the TV receiver. As a result, there is a case where interference cannot be received due to the interference of the same channel.

In order to prevent this, there is a problem that a device for preventing the deterioration of the terrestrial digital TV broadcast signal due to the interference with the same channel is separately required for the antenna and the circuit.
JP 2004-128719 A Japanese Patent Laid-Open No. 2004-12720

  Therefore, the present applicant can prevent the occurrence of interference interference on the same channel of the terrestrial digital TV broadcast signal by performing the frequency conversion on the transmitter side, and does not require the frequency conversion on the receiver side. A wireless redistribution system for TV broadcasting (not known at the time of this application) has been developed.

  Hereinafter, a wireless redistribution system for terrestrial digital TV broadcasting developed by the present applicant will be described.

  This wireless redistribution system is made using the following actual situations (1) and (2).

(1) As will be described later, in addition to the UHF band, a stationary TV receiver for terrestrial digital TV broadcasting includes a VHF_Low / High band (VHF1ch to VHF12ch), a VHF_MID band (C13ch to C22ch), and a VHF_SHB band (C23ch). ~ C63ch) are often designed to be received.

(2) Further, as described later, in the weak radio wave standard, the restriction on the electric field strength for the frequency band of 322 MHz or less and 150 GHz or more is looser than the restriction of the electric field strength for the frequency band of 322 MHz to 150 GHz.

  The wireless redistribution system for terrestrial digital TV broadcasting developed by the present applicant is capable of receiving VHF band TV broadcast signals in addition to UHF band TV broadcast signals, which are the frequency bands of terrestrial digital TV broadcast signals. A TV receiver, a redistribution transmitter, and a redistribution receiver are provided.

  The redistribution transmitter has a terrestrial digital TV broadcast signal of a desired viewing channel designated by a predetermined input means among terrestrial digital TV broadcast signals input from an outdoor antenna, and has a frequency of 322 MHz or less. In addition, the input digital terrestrial TV broadcast signal is frequency-converted in a batch so that the frequency is converted into the frequency of one specific empty channel in the VHF band, and the VHF band is specified among the obtained TV broadcast signals. Only the TV broadcast signal in the frequency band of one vacant channel is extracted, and the extracted TV broadcast signal is amplified and wirelessly transmitted.

  The receiver for redistribution receives and amplifies the signal transmitted from the transmitter, and then supplies it to the TV receiver. In the TV receiver, a specific vacant channel in the VHF band is selected, so that the terrestrial digital TV broadcast signal of the desired viewing channel designated by the user is broadcast.

  However, in the wireless redistribution system developed by the present applicant, the terrestrial digital TV broadcast signal of the desired viewing channel designated by the predetermined input means is transmitted at a frequency of 322 MHz or less and a specific one in the VHF band. Although the frequency is converted to an empty channel frequency, if other weak radio wave equipment is used at this one frequency or a frequency in the vicinity of it, interference or interference may occur, resulting in poor reception or reception. It may become defective.

  The present invention can prevent the occurrence of interference interference on the same channel of a terrestrial digital TV broadcast signal, eliminates the need for frequency conversion on the receiver side, and improves the reception quality and the reception probability. The purpose is to provide a redistribution system.

  According to the first aspect of the present invention, in addition to the TV broadcast signal in the UHF band, which is the frequency band of the terrestrial digital TV broadcast signal, the TV receiver capable of receiving the TV broadcast signal in the VHF band, and the ground received by the outdoor antenna. A receiver that receives a digital terrestrial TV broadcast signal, converts the frequency of the input terrestrial digital TV broadcast signal and then wirelessly transmits it, and inputs a desired viewing channel for causing the transmitter to input a desired terrestrial digital TV broadcast viewing channel. And a receiver that receives and amplifies a signal transmitted from the transmitter and then supplies the signal to the TV receiver. The transmitter includes the receiver among the input terrestrial digital TV broadcast signals. The terrestrial digital TV broadcast signal of the desired viewing channel input by the desired viewing channel input means is converted into a plurality of empty channels in a preset VHF band. And a second means for amplifying and wirelessly transmitting the terrestrial digital TV broadcast signal of the desired viewing channel frequency-converted to a plurality of free channels in the VHF band by the first means. The TV receiver includes: a selecting unit that selects a TV broadcast signal of a channel with high reception quality from a plurality of TV broadcast signals supplied from the transmitter via the receiver; It is characterized by comprising reproducing means for reproducing the selected TV broadcast signal.

  According to a second aspect of the present invention, in the radio terrestrial digital TV broadcast wireless redistribution system according to the first aspect, the frequency of each preset empty channel in the VHF band is 322 MHz or less. It is a frequency.

  According to a third aspect of the present invention, in the terrestrial digital TV broadcast wireless redistribution system according to the first or second aspect, the selection means includes a plurality of channels supplied from the transmitter via the receiver. By comparing the reception signal level of the TV broadcast signal, a TV broadcast signal of a channel with high reception quality is selected.

  According to a fourth aspect of the present invention, in the terrestrial digital TV broadcast wireless redistribution system according to the first or second aspect, the selection means includes a plurality of channels supplied from the transmitter via the receiver. By comparing the reception error rates of TV broadcast signals, a TV broadcast signal of a channel with high reception quality is selected.

  According to the present invention, it is possible to prevent the occurrence of interference interference on the same channel of a terrestrial digital TV broadcast signal, eliminate the need for frequency conversion on the receiver side, and improve reception quality and reception probability.

  Embodiments of the present invention will be described below with reference to the drawings.

[1] Description of a terrestrial digital broadcast TV receiver to which the present invention is applied

  Table 1 shows each reception channel and center frequency of terrestrial digital TV broadcasting.

  The reception channels of terrestrial digital TV broadcasting are UHF13ch to UHF62ch. The center frequency is 473 + 1/7 MHz for 13 ch, 479 + 1/7 MHz for 14 ch, and 767 + 1/7 MHz for 62 ch.

  Since the frequency band in which terrestrial digital TV broadcasting is introduced is in the range of UHF13 channel to 62 channels, it is necessary that the frequency can be received as the reception frequency range of the terrestrial digital broadcast TV receiver.

  Currently, broadcasting has started in December 2003 in the three major metropolitan areas (Kanto wide area, Chukyo wide area, and Kinki wide area). For example, broadcasting in the Kinki area is as shown in Table 2. ing.

  On the other hand, in the reception form of the current terrestrial analog TV broadcasting, including collective housing joint listening, joint reception accounts for almost half of all households. Most of the transmission bands in these hearing facilities are not widened to the UHF band, and UHF TV broadcasts are VHF_Low / High (VHF low / high band), VHF_MID (VHF midband), and VHF_SHB (VHF super band). In many cases, it is down-converted to a low-frequency vacant channel (a channel that is not broadcast in that area) such as a high band.

  For this reason, joint reception is also assumed especially for a stationary TV receiver for terrestrial digital TV broadcasting. Therefore, the reception channel range of the receiver for terrestrial digital broadcasting is VHF_Low / High in addition to the UHF band. It is specified in the ARIB standard ARIB STD-B21 that it is desirable to support the band (VHF1ch to VHF12ch), the VHF_MID band (C13ch to C22ch) and the VHF_SHB band (C23ch to C63ch).

  Therefore, the stationary TV receiver for terrestrial digital TV broadcasting also receives the VHF_Low / High band (VHF1ch to VHF12ch), VHF_MID band (C13ch to C22ch) and VHF_SHB band (C23ch to C63ch) in addition to the UHF band. It is thought that it is often designed to be possible.

  Table 3 shows each reception channel and center frequency in the VHF_Low / High band (VHF1ch to VHF12ch).

  Table 4 shows each reception channel and center frequency of the VHF_MID band (C13ch to C22ch).

  Table 5 shows each reception channel and center frequency of the VHF__SHB band (C23ch to C63ch).

  In the present invention, in addition to the original UHF band 13ch to 62ch (470 MHz to 770 MHz), VHF_Low / High band (VHF1ch to VHF12ch), VHF_MID band (C13ch to C22ch) and VHF_SHB band (C23ch to C63ch) can also be received ( TV receivers for terrestrial digital TV broadcasting that can be selected and viewed) are targeted for application.

[2] Explanation of weak radio wave standards

  The weak radio wave standard will be described. The standard for weak radio waves is defined by the Ordinance of the Ministry of Internal Affairs and Communications as radio equipment that emits extremely weak radio waves, and is defined by the electric field strength at a point of 3 meters.

  FIG. 1 and Table 6 show the electric field strength (allowable value) for the frequency band defined by the weak radio wave standard.

  As shown in Table 6, the allowable value is limited to 500 μV / m for frequency bands of 322 MHz or less and 150 GHz or more. In addition, for the frequency band from 322 MHz to 10 GHz, the allowable value is limited to 35 μV / m in consideration of interference protection for land mobile service, UHF TV broadcasting, fixed service, and space service (earth station). For the frequency band from 10 GHz to 150 GHz, the allowable value is limited to 3.5 fμV / m (f is the used frequency band (GHz)) in consideration of the system noise temperature, the reception bandwidth, and the like.

  As long as the radio system according to the weak radio wave standard satisfies the electric field strengths shown in Table 6, there are no restrictions on the frequency, modulation method, and communication method, so a relatively free system design is possible.

[3] Explanation of wireless redistribution system for terrestrial digital TV broadcasting

  FIG. 2 shows an outline of a wireless redistribution system for terrestrial digital TV broadcasting.

  A terrestrial digital TV broadcast signal is received by the outdoor antenna 1 provided on the rooftop. The terrestrial digital TV broadcast signal received by the outdoor antenna 1 is guided to the TV terminal 3 provided on the wall surface of the room by the antenna cable 2.

  The terrestrial digital TV broadcast wireless redistribution system includes a redistribution transmitter 4 connected to a TV terminal 3, a remote control transmitter 10 for transmitter, and a redistribution unit connected to a TV receiver 6 for terrestrial digital TV broadcast. A distribution receiver 5 is provided.

  The remote controller transmitter 10 for transmitter is used for allowing the user to input a desired channel of terrestrial digital TV broadcasting to the transmitter 4 by infrared rays or wirelessly. In addition to the original UHF band 13ch to 62ch (470 MHz to 770 MHz), the TV receiver 6 for terrestrial digital TV broadcasting includes a VHF_Low / High band (VHF1ch to VHF12ch), a VHF_MID band (C13ch to C22ch), and a VHF_SHB band ( (C23ch to C63ch) can also be received (selection viewing is possible), and a TV tuner (terrestrial digital broadcasting TV tuner compatible with VHF reception) is provided.

  FIG. 3 shows the configuration of the transmitter 4.

  The transmitter 4 includes a UHF receiver 41, a first frequency converter 42, a second frequency converter 43, a VHF transmitter 44, a transmission antenna 45, a remote control receiver 46, a controller 47, and a frequency synthesizer 48. Yes.

  The terrestrial digital TV broadcast signal received by the outdoor antenna 1 is amplified by the UHF receiver 41 and then sent to the first frequency converter 42 and the second frequency converter 43.

  Based on the desired channel input by the transmitter remote control transmitter 10, the first frequency conversion unit 42 sets the frequency of the terrestrial digital TV broadcast signal of the desired channel in the first VHF band determined in advance. The terrestrial digital TV broadcast signals obtained from the TV terminal 3 are collectively converted so as to be converted into the frequency of a specific vacant channel, and the first terrestrial digital TV broadcast signal is converted from the frequency-converted terrestrial digital TV broadcast signal. Only a TV broadcast signal having a frequency of a specific empty channel is extracted.

  Based on the desired channel input by the transmitter remote control transmitter 10, the second frequency conversion unit 43 sets the frequency of the terrestrial digital TV broadcast signal of the desired channel to the second in the predetermined VHF band. The terrestrial digital TV broadcast signals obtained from the TV terminal 3 are collectively converted so as to be converted to the frequency of a specific vacant channel, and the second terrestrial digital TV broadcast signal is converted from the terrestrial digital TV broadcast signal after the frequency conversion. Only a TV broadcast signal having a frequency of a specific empty channel is extracted.

  As the first specific vacant channel and the second specific vacant channel, a channel of 322 MHz or less that is a vacant channel in the VHF band and loosely limited by the weak radio wave standard is used. In this example, the C36 channel (center frequency: 303 + 1/7 MHz) of the VHF_SHB band is used as the first specific empty channel, and the C38 channel (center frequency: 315 + 1/1/2) of the VHF_SHB band is used as the second specific empty channel. 7 MHz) is used. In this case, the allowable value of the weak radio wave standard is 500 μV / m.

  More specifically, in the first frequency converter 42, all of the received terrestrial digital TV broadcast signals (received signals) and the first local signal output from the frequency synthesizer 48 are mixed into the mixer 101. Mixed by. From the mixer 101, an addition signal and a subtraction signal of each received signal and the first local signal are output. For example, assuming that the frequency of the received signal is fa and the frequency of the first local signal is fb, an addition signal having a frequency of fa + fb and a subtraction signal having a frequency of fa−fb are output from the mixer 101. The output of the mixer 101 is sent to the first bandpass filter (BPF1) 102, and a first specific empty channel in the VHF band set in advance (in this example, the C36 channel in the VHF_SHB band (center frequency: 303 + 1 / Only the 7 MHz)) signal is extracted.

  The frequency fb of the first local signal output from the frequency synthesizer 48 is controlled by the control unit 47. The control unit 47 determines the relationship between the desired channel of the terrestrial digital TV broadcast designated from the remote control transmitter for transmitter 10 via the remote control receiving unit 46, the preset desired channel, and the first local frequency. The frequency fb of the first local signal output from the frequency synthesizer 48 is controlled based on the table shown.

  That is, the control unit 47 converts the frequency of the desired channel of the terrestrial digital TV broadcast into a first specific empty channel in the VHF band that is set in advance (in this example, the C36 channel in the VHF_SHB band). The frequency fb of the first local signal is controlled. Specifically, the frequency (fa−fb) of the subtracted signal between the terrestrial digital TV broadcast signal of the desired channel and the first local signal is the first specific empty channel in this predetermined VHF band (this example Then, the frequency fb of the local signal is controlled so as to be the frequency of the VHF_SHB band (C36 channel).

  In the second frequency conversion unit 43, all the received terrestrial digital TV broadcast signals (reception signals) and the second local signal output from the frequency synthesizer 48 are mixed by the mixer 111. From the mixer 111, an addition signal and a subtraction signal of each received signal and the second local signal are output. For example, assuming that the frequency of the received signal is fa and the frequency of the first local signal is fc, an addition signal having the frequency fa + fc and a subtraction signal having the frequency fa−fc are output from the mixer 111. The output of the mixer 111 is sent to the second bandpass filter (BPF2) 112, and a second specific empty channel in the VHF band (in this example, the C38 channel in the VHF_SHB band (center frequency: 315 + 1 / Only the 7 MHz)) signal is extracted.

  The frequency fc of the second local signal output from the frequency synthesizer 48 is controlled by the control unit 47. The control unit 47 determines the relationship between the desired channel of the terrestrial digital TV broadcast designated from the remote control transmitter for transmitter 10 via the remote control receiving unit 46, the preset desired channel, and the second local frequency. The frequency fc of the second local signal output from the frequency synthesizer 48 is controlled based on the table shown.

  That is, the control unit 47 converts the frequency of the desired channel of the terrestrial digital TV broadcast into a second specific empty channel in the VHF band (in this example, the C38 channel in the VHF_SHB band). The frequency fc of the second local signal is controlled. Specifically, the frequency (fa-fc) of the subtraction signal between the terrestrial digital TV broadcast signal of the desired channel and the second local signal is the second specific empty channel in the predetermined VHF band (this example Then, the frequency fc of the second local signal is controlled so as to be the frequency of the VHF_SHB band (C38 channel).

  Table 7 shows a specific free channel (redistribution transmission center frequency) in a predetermined VHF band in the Kinki wide area where the channel on which terrestrial digital TV broadcasting is performed and the center frequency are shown in Table 2. ) Is set to the C36 channel (center frequency: 303 + 1/7 MHz) of the VHF_SHB band, the relationship between the desired channel of the terrestrial digital TV broadcast and the frequency of the first local signal (first redistribution local frequency) Show.

  Table 8 shows a specific free channel (redistribution transmission center frequency) in a predetermined VHF band in the Kinki wide area where the channel and center frequency in which terrestrial digital TV broadcasting is performed are shown in Table 2. ) Is set to the C38 channel (center frequency: 315 + 1/7 MHz) of the VHF_SHB band, the relationship between the desired channel of the terrestrial digital TV broadcast and the frequency of the second local signal (second redistribution local frequency) Show.

  For example, when the desired channel is UHF13ch (center frequency: 473 + 1/7 MHz), the frequency fc of the second local signal is set to 158 MHz. Since the frequency fa of the UHF 13ch TV broadcast signal is 473 + 1/7 MHz, the frequency of the subtraction signal between the UHF 13ch TV broadcast signal and the second local signal is 315 + 1/7 (= 473 + 1 / 7-158) MHz, This is the frequency of the C38 channel in the VHF_SHB band.

  The terrestrial digital TV broadcast signal frequency-converted by the first frequency conversion unit 42 to the first specific empty channel of the VHF band (C36 channel of the VHF_SHB band in this example), and the second frequency conversion unit 43 The terrestrial digital TV broadcast signal frequency-converted to the second specific empty channel in the VHF band (in this example, the C38 channel in the VHF_SHB band) is amplified by the VHF transmission unit 44 and wirelessly transmitted from the transmission antenna 45. The The VHF transmission unit 44 performs AGC so that the signal level transmitted wirelessly does not exceed the allowable value according to the weak radio wave standard.

  FIG. 4 shows the configuration of the receiver 5 and the TV receiver 6.

  The receiver 5 includes a receiving antenna 51 and a VHF receiving unit 52.

  TV broadcast signal wirelessly transmitted from the transmitter 4 (the terrestrial digital TV broadcast signal and the VHF band after being frequency-converted to the first specific empty channel in the VHF band (in this example, the C36 channel in the VHF_SHB band)) The second specific vacant channel (in this example, the terrestrial digital TV broadcast signal after frequency conversion into the VHF_SHB band C38 channel) is received by the receiving antenna 51. The TV broadcast signal received by the receiving antenna 51 is amplified by the VHF receiver 52 and then sent to the TV receiver 6 for terrestrial digital TV broadcast.

  The TV broadcast signal input to the TV receiver 6 is sent to the first RF / IF unit 61 and also sent to the second RF / IF unit 71. The first RF / IF unit 61 is controlled by the control unit 86 so as to select the first specific empty channel (C36 channel), and the second RF / IF unit 71 is controlled by the control unit 86. It is controlled to select a specific empty channel (C38 channel).

  The first RF / IF unit 61 down-converts the C36 channel TV broadcast signal into a baseband signal. The signal obtained by the first RF / IF unit 61 is digitally demodulated by the first OFDM demodulator 62, then sent to the first input terminal of the changeover switch 81 and sent to the first level detector 63. It is done. The first level detector 63 detects the level of the received signal of the C36 channel obtained by the first OFDM demodulator 62 and supplies it to the controller 86.

  The second RF / IF unit 71 downconverts the C38 channel TV broadcast signal into a baseband signal. The signal obtained by the second RF / IF unit 71 is digitally demodulated by the second OFDM demodulator 72, then sent to the second input terminal of the changeover switch 81 and sent to the second level detector 73. It is done. The second level detector 73 detects the level of the C38 channel received signal obtained by the second OFDM demodulator 72 and supplies it to the controller 86.

  The control unit 86 compares the C36 channel reception signal level given from the first level detection unit 63 with the C38 channel reception signal level given from the second level detection unit 73, and determines the comparison result. Based on this, the changeover switch 81 is controlled. That is, when the received signal level of the C36 channel is higher than the received signal level of the C38 channel, the changeover switch 81 is controlled so that the received signal of the C36 channel is selected, and conversely, the received signal level of the C38 channel is C36. When the received signal level is higher than the channel, the changeover switch 81 is controlled so that the received signal of the C38 channel is selected.

  The received signal selected by the changeover switch 81 is sent to the AV decoding unit 82. In the AV decoding unit 82, the received signal is decoded and a video signal and an audio signal are reproduced. The reproduced video signal is sent to the display unit (monitor) 83, and the reproduced audio signal is sent to the speaker 84.

  The remote control receiving unit 85 receives a remote control signal from the TV remote control transmitter 200 and gives it to the control unit 86. The first specific empty channel (C36) and the second specific empty channel (C38) are set by operating the TV remote control transmitter 200.

  FIG. 5 shows a modification of the TV receiver.

  5, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

  In the TV receiver of FIG. 4, the received signal level of the first specific empty channel (C36 channel) in the VHF band is compared with the received signal level of the second specific empty channel (C38 channel) in the VHF band. Thus, the changeover switch 81 is controlled.

  On the other hand, in the TV receiver 6A of FIG. 5, the error rate of the received signal in the first specific empty channel (C36 channel) in the VHF band and the second specific empty channel (C38 channel) in the VHF band. The changeover switch 81 is controlled by comparing the error rates of the received signals.

  The error rate of the first OFDM demodulator 62 is detected by the first error rate detector 64. The error rate of the second OFDM demodulator 72 is detected by the second error rate detector 74. The error rates detected by both error rate detection units 64 and 74 are given to the control unit 86.

  The controller 86 compares the error rate of the C36 channel received signal given from the first error rate detector 64 with the error rate of the C38 channel received signal given from the second error rate detector 74. Then, the changeover switch 81 is controlled based on the comparison result. That is, when the error rate of the C36 channel reception signal is lower than the error rate of the C38 channel reception signal, the changeover switch 81 is controlled so that the C36 channel reception signal is selected. When the signal error rate is lower than the error rate of the C36 channel received signal, the selector switch 81 is controlled so that the C38 channel received signal is selected.

  In the above-described embodiments (embodiments 1 and 2), the transmission channels to be rearranged are two channels (C36 and C38). However, the transmission channels to be rearranged may be three or more channels.

  According to the above-described embodiments (embodiments 1 and 2), the terrestrial digital TV broadcast signal of the desired channel is rearranged in a plurality of transmission channels, and the TV receiver among the rearranged TV broadcast signals of the plurality of channels. Since high quality reception quality is selected and reproduced, reception quality and reception probability can be improved.

It is a graph which shows the electric field strength (allowable value) with respect to the frequency band defined by the weak radio wave standard. It is a schematic diagram which shows the outline | summary of the radio | wireless redistribution system of terrestrial digital TV broadcasting. It is a block diagram which shows the structure of a transmitter. It is a block diagram which shows the structure of a receiver and TV receiver. It is a block diagram which shows the other example of TV receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outdoor antenna 4 Transmitter 5 Receiver 6,6A TV receiver 41 UHF receiving part 42,43 Frequency conversion part 44 VHF transmission part 46 Remote control receiving part 47 Control part 48 Frequency synthesizer 61,71 RF / IF part 62,72 OFDM Demodulator 63, 73 Level detector 64, 74 Error rate detector 81 Changeover switch 86 Controller

Claims (4)

In addition to the TV broadcast signal in the UHF band, which is the frequency band of the terrestrial digital TV broadcast signal, a TV receiver capable of receiving a TV broadcast signal in the VHF band and a terrestrial digital TV broadcast signal received by an outdoor antenna are input. Transmitter for wireless transmission after frequency conversion of input terrestrial digital TV broadcast signal, desired viewing channel input means for inputting desired viewing channel of terrestrial digital TV broadcast to transmitter, and transmitted from said transmitter A receiver that receives and amplifies the signal and supplies it to the TV receiver,
The transmitter transmits the terrestrial digital TV broadcast signal of the desired viewing channel input by the desired viewing channel input means among the input terrestrial digital TV broadcast signals to a plurality of vacant channels in a preset VHF band. First means for frequency conversion, and second means for amplifying and wirelessly transmitting the terrestrial digital TV broadcast signal of the desired viewing channel frequency-converted to a plurality of empty channels in the VHF band by the first means,
The TV receiver is selected by a selection unit that selects a TV broadcast signal of a channel with high reception quality from among a plurality of TV broadcast signals supplied from the transmitter via the receiver, and is selected by the selection unit. A terrestrial digital TV broadcast wireless redistribution system comprising a playback means for playing back a TV broadcast signal. 2. The radio redistribution system for terrestrial digital TV broadcasting according to claim 1, wherein the frequency of each empty channel in the VHF band set in advance is a frequency of an empty channel in the VHF band of 322 MHz or less. The selection means selects a TV broadcast signal of a channel with high reception quality by comparing received signal levels of TV broadcast signals of a plurality of channels supplied from the transmitter via the receiver. The wireless redistribution system for terrestrial digital TV broadcasting according to claim 1 or 2. The selection means selects a TV broadcast signal of a channel having a high reception quality by comparing reception signal error rates of TV broadcast signals of a plurality of channels supplied from the transmitter via the receiver. The terrestrial digital TV broadcast wireless redistribution system according to any one of claims 1 and 2.

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