JP2006074268A - Receiving system for terrestrial digital tv broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiving system for terrestrial digital tv broadcast capable of reproducing TV broadcast signals with high reception quality among TV broadcast signals supplied by a wireless redistribution system and TV broadcast signals supplied by a direct reception system. <P>SOLUTION: The receiving system for terrestrial digital tv broadcast is provided with the wireless redistribution system for wirelessly retransmitting terrestrial digital tv broadcast signals received by an outdoor antenna to TV receivers; and the direct reception system for directly giving the terrestrial digital tv broadcast signals to the TV receivers via an indoor antenna, and each of the TV receivers includes: a selection means for selecting a TV broadcast signal with high reception quality among the TV broadcast signals supplied by the wireless redistribution system and the TV broadcast signals supplied by the direct reception system; 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 receiving 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, the 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 transmitter for redistribution collectively converts the frequency of the terrestrial digital TV broadcast signal input from the outdoor antenna to the frequency of the vacant channel in the VHF band of 322 MHz or less, and then amplifies and transmits the signal wirelessly. The receiver for redistribution receives and amplifies the signal transmitted from the transmitter, and then supplies it to the TV receiver. The TV receiver views a terrestrial digital TV broadcast by designating a VHF channel.

  However, in a general household in a relatively strong electric field region, depending on the installation location of the indoor TV receiver, the terrestrial digital TV broadcast signal is directly received by the indoor antenna without using such a retransmission system. As a result, a sufficient received signal level that can be reproduced by the TV receiver may be secured. In such a case, it is desirable to directly receive and reproduce the terrestrial digital TV broadcast signal with the indoor antenna.

  The present invention provides a TV broadcast signal supplied by a wireless redistribution system that wirelessly retransmits a terrestrial digital TV broadcast signal received by an outdoor antenna to a TV receiver, and a terrestrial digital TV broadcast signal directly via an indoor antenna. It is an object of the present invention to provide a terrestrial digital TV broadcast receiving system capable of reproducing a TV broadcast signal having a high reception quality among TV broadcast signals supplied by a direct receiving system inputted to a receiver.

  According to the first aspect of the present invention, there is provided a wireless redistribution system for wirelessly retransmitting a terrestrial digital TV broadcast signal received by an outdoor antenna to a TV receiver, and a direct TV receiver for transmitting a terrestrial digital TV broadcast signal via an indoor antenna. The TV receiver includes a TV broadcast signal supplied by the wireless redistribution system and a TV broadcast signal having high reception quality among the TV broadcast signals supplied by the direct reception system. And a reproducing means for reproducing the TV broadcast signal selected by the selecting means.

  According to a second aspect of the present invention, in the terrestrial digital TV broadcast reception system according to the first aspect, the selection means includes a reception signal level of the TV broadcast signal supplied by the wireless redistribution system, and the direct A TV broadcast signal with high reception quality is selected by comparing the reception signal level of the TV broadcast signal supplied by the reception system.

  According to a third aspect of the present invention, in the terrestrial digital TV broadcast reception system according to the first aspect, the selection means includes a reception signal error rate of a TV broadcast signal supplied by the wireless redistribution system, and A TV broadcast signal having a high reception quality is selected by comparing a reception signal error rate of the TV broadcast signal supplied by the direct reception system.

  According to a fourth aspect of the present invention, in the terrestrial digital TV broadcast receiving system according to any one of the first to third aspects, the wireless redistribution system converts a terrestrial digital TV broadcast signal received by an outdoor antenna into a vacant VHF band. A transmitter that performs frequency conversion to a channel frequency and then amplifies and transmits the signal; and a receiver that receives and amplifies a signal transmitted from the transmitter and then supplies the signal to the TV receiver. Features.

  According to a fifth aspect of the present invention, in the terrestrial digital TV broadcast receiving system according to the fourth aspect, the transmitter is a VHF band vacant channel for terrestrial digital TV broadcast signals received by an outdoor antenna. After frequency conversion to a frequency of 322 MHz or lower, the signal is amplified and transmitted wirelessly.

  According to the present invention, a TV broadcast signal supplied by a wireless redistribution system for wirelessly retransmitting a terrestrial digital TV broadcast signal received by an outdoor antenna to a TV receiver and a terrestrial digital TV broadcast signal via an indoor antenna. Of the TV broadcast signals supplied by the direct reception system directly inputted to the TV receiver, a TV broadcast signal with high reception quality can be reproduced.

  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, the data is down-converted to a low-frequency free channel (a channel that is not broadcast in the 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 the reception system for terrestrial digital TV broadcasting

  FIG. 2 shows an outline of a reception 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.

  A transmitter 4 for redistribution is connected to the TV terminal 3. The transmitter 4 converts the terrestrial digital TV broadcast signal obtained from the TV terminal 3 into an empty channel in the VHF band (in this example, the VHF_SHB band) and a channel of 322 MHz or less where the weak radio wave standard is loosely restricted. After all the broadcast reception channels (terrestrial digital TV broadcast reception channels) are frequency-converted so that they are multiplexed, the transmission antenna 44 is a weak radio wave having an allowable value (500 μV / m) or less of the weak radio wave standard. Retransmit wirelessly from.

  A redistribution receiver 5 is connected to a TV receiver 6 for terrestrial digital TV broadcasting. 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.

  The receiver 5 includes a receiving antenna 51 for receiving a retransmitted wave (VHF band retransmitted wave) from the transmitter 4 and a direct wave of a terrestrial digital TV broadcast (UHF band direct wave). The receiver 5 sends the retransmitted wave received by the receiving antenna 51 and the direct wave of the terrestrial digital TV broadcast to the TV receiver 6.

  The TV receiver 6 selects and reproduces the higher reception quality of the VHF band retransmitted wave and the UHF band direct wave.

  FIG. 3 shows the configuration of the transmitter 4.

  The transmitter 4 includes a UHF receiver 41, a frequency converter 42, a VHF transmitter 43, and a transmission antenna 44.

  The terrestrial digital TV broadcast signal received by the outdoor antenna 1 is amplified by the UHF receiver 41 and then sent to the frequency converter 42. In the frequency conversion unit 42, all the received terrestrial digital TV broadcast signals (reception signals) and the local signal from the oscillation unit 45 that transmits at a fixed frequency are mixed by the mixer 46. From the mixer 46, an addition signal and a subtraction signal of each received signal and the local signal are output. For example, assuming that the frequency of the received signal is fa and the frequency of the 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 46. The output of the mixer 46 is sent to the filter 47, and only the subtraction signal is extracted.

  The frequency fb of the local signal is 322 MHz where the frequency (fa−fb) of the subtraction signal output from the mixer 46 is an empty channel in the VHF band (in this example, VHF_SHB band), and the weak radio wave standard is loosely limited. The frequency is set to be as follows.

  In the Kinki wide area where the channel and the center frequency in which terrestrial digital TV broadcasting is performed are shown in Table 2, the frequency fb of the local signal is set to 224 MHz, for example. Table 7 shows the VHF transmission channel, the center frequency, the broadcasting station, and the corresponding channel after the frequency conversion when the frequency fb of the local signal is set in this way.

  That is, as shown in FIG. 4, assuming that all channels of the terrestrial digital TV broadcast signal received by the outdoor antenna 1 are A, all the channels A of the terrestrial digital TV broadcast signal are 322 MHz or less by the frequency converter 42. The frequency is converted to an empty channel B in the VHF_SHB band. Therefore, the TV receiver 6 can watch a terrestrial digital TV broadcast by selecting one of the vacant channels B in the VHF_SHB band.

  The terrestrial digital TV broadcast signal frequency-converted to the VHF_SHB band by the frequency converter 42 is amplified by the VHF transmitter 43 and wirelessly transmitted from the transmission antenna 44. Note that the VHF transmission unit 43 performs AGC so that the signal level transmitted wirelessly does not exceed the allowable value according to the weak radio wave standard.

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

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

  Receiving antenna 51 receives a retransmitted wave (VHF band retransmitted wave) from transmitter 4 and a terrestrial digital TV broadcast direct wave (UHF band direct wave). The VHF band retransmitted wave and the UHF band direct wave received by the receiving antenna 51 are amplified by the VHF / UHF receiving unit 52 and then sent to the TV receiver 6.

  The TV receiver 6 includes a VHF / UHF duplexer 60 and two reception systems. Each reception system includes RF / IF units 61 and 71 and OFDM demodulation units 62 and 72.

  On the TV receiver 6 side, the user designates a desired terrestrial digital TV broadcast channel (UHF channel) by the remote control transmitter 7. The UHF channel designated by the remote control transmitter 7 is input to the control unit 85 via the remote control receiving unit 86. The control unit 85 acquires a VHF channel corresponding to the input UHF channel based on a table indicating the relationship between the UHF channel and the corresponding VHF channel (VHF_SHB empty channel) as shown in Table 7 above.

  The control unit 85 controls the first RF / IF unit 61 to select the VHF channel corresponding to the designated UHF channel, and the second RF / IF unit 71 performs the designated UHF. Control to select a channel.

  The retransmitted wave in the VHF band and the direct wave in the UHF band input to the TV receiver 6 are sent to the VHF / UHF duplexer 60. The VHF / UHF duplexer 60 performs frequency separation so that the retransmitted wave in the VHF band and the direct wave in the UHF band do not interfere with each other. The retransmitted wave in the VHF band obtained by the VHF / UHF duplexer 60 is sent to the first RF / IF unit 61, and the direct wave in the UHF band obtained by the VHF / UHF duplexer 60 is sent to the second RF / IF. It is sent to the IF unit 71.

  The first RF / IF unit 61 down-converts the TV broadcast signal (retransmission wave signal) of the VHF channel corresponding to the designated UHF channel into a baseband signal. The signal obtained by the first RF / IF unit 61 is digitally demodulated by the first OFDM demodulator 62 and then sent to the first input terminal of the changeover switch 81 and also sent to the VHF channel level detector 63. . The VHF channel level detection unit 63 detects the level of the reception signal of the predetermined VHF channel obtained by the first OFDM demodulation unit 62 and supplies it to the control unit 85.

  The second RF / IF unit 71 down-converts the specified UHF channel TV broadcast signal (direct wave signal) into a baseband signal. The signal obtained by the second RF / IF unit 71 is digitally demodulated by the second OFDM demodulator 72 and then sent to the second input terminal of the changeover switch 81 and also sent to the UHF channel level detector 73. . The UHF channel level detection unit 73 detects the level of the received signal of the predetermined UHF channel obtained by the second OFDM demodulation unit 72 and supplies the detected level to the control unit 85.

  The control unit 85 compares the reception signal level of the VHF channel given from the VHF channel level detection unit 63 with the reception signal level of the UHF channel given from the UHF channel level detection unit 73, and based on the comparison result. The changeover switch 81 is controlled. That is, when the received signal level of the VHF channel is higher than the received signal level of the UHF channel, the changeover switch 81 is controlled so that the received signal of the VHF channel is selected, and conversely, the received signal level of the UHF channel is VHF. When the received signal level is higher than the channel, the selector switch 81 is controlled so that the received signal of the UHF 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.

  If the two RF / IF units 61 and 71 are V-compatible (with a VHF filter) and U-compatible (with a UHF filter), respectively, the TV broadcast signal input to the TV receiver 6 (VHF band re-transmission) The transmission wave and the UHF band direct wave) may be simply distributed to the two RF / IF units 61 and 71.

  FIG. 6 shows a modification of the TV receiver.

  In FIG. 6, the same components as those in FIG.

  In the TV receiver of FIG. 5, the changeover switch 81 is controlled by comparing the received signal level of the VHF channel corresponding to the designated UHF channel with the received signal level of the designated UHF channel.

  On the other hand, in the TV receiver 6A of FIG. 6, the switching is performed by comparing the error rate of the reception signal of the VHF channel corresponding to the designated UHF channel with the error rate of the reception signal of the designated UHF channel. The switch 81 is controlled.

  The error rate of the first OFDM demodulator 62 is detected by the VHF channel error rate detector 64. The error rate of the second OFDM demodulator 72 is detected by the UHF channel error rate detector 74. The error rates detected by both error rate detection units 64 and 74 are given to the control unit 85.

  The control unit 85 compares the error rate of the reception signal of the VHF channel given from the VHF channel error rate detection unit 64 with the error rate of the reception signal of the UHF channel given from the UHF channel error rate detection unit 74, Based on the comparison result, the changeover switch 81 is controlled. That is, when the error rate of the received signal of the VHF channel is lower than the error rate of the received signal of the UHF channel, the changeover switch 81 is controlled so that the received signal of the VHF channel is selected. When the error rate of the signal is lower than the error rate of the reception signal of the VHF channel, the selector switch 81 is controlled so that the reception signal of the UHF channel is selected.

  FIG. 7 shows a modification of the TV receiver.

  In FIG. 7, the same components as those in FIG.

  This TV receiver has only one receiving system. The reception system includes an RF / IF unit 61 and an OFDM demodulation unit 62. The VHF band retransmitted wave and the UHF band direct wave input to the TV receiver 6 are sent to the RF / IF unit 61.

  On the TV receiver 6 side, the user designates a desired terrestrial digital TV broadcast channel (UHF channel) by the remote control transmitter 7. The UHF channel designated by the remote control transmitter 7 is input to the control unit 85 via the remote control receiving unit 86. The control unit 85 acquires a VHF channel corresponding to the input UHF channel based on a table indicating the relationship between the UHF channel and the corresponding VHF channel (VHF_SHB empty channel) as shown in Table 7 above.

  The control unit 85 first controls the RF / IF unit 61 to select a VHF channel corresponding to the designated UHF channel at the time of initial setting (for example, when the power is turned on). Therefore, the RF / IF unit 61 down-converts the TV broadcast signal (retransmission wave signal) of the VHF channel corresponding to the designated UHF channel into a baseband signal. The signal obtained by the RF / IF unit 61 is digitally demodulated by the OFDM demodulator 62 and then sent to the AV decoder 82 and also to the VHF / UHF channel level detector 63A. The VHF / UHF channel level detection unit 63A detects the level of the reception signal of the VHF channel obtained by the OFDM demodulation unit 62, and provides it to the control unit 85. The control unit 85 stores the received signal level of the VHF channel.

  Thereafter, the control unit 85 controls the RF / IF unit 61 so as to select the designated UHF channel. Therefore, the RF / IF unit 61 down-converts the specified UHF channel TV broadcast signal (direct wave signal) into a baseband signal. The signal obtained by the RF / IF unit 61 is digitally demodulated by the OFDM demodulator 62 and then sent to the AV decoder 82 and also to the VHF / UHF channel level detector 63A. The VHF / UHF channel level detector 63A detects the level of the received signal of the UHF channel obtained by the OFDM demodulator 62 and supplies it to the controller 85. The controller 85 compares the level of the received signal of the UHF channel with the level of the received signal of the VHF channel stored before that. Then, the RF / IF unit 61 is controlled so as to select the channel (VHF channel or UHF channel) with the higher signal level.

  In this way, the reception wave to be reproduced is selected and set from the VHF band retransmitted wave and the UHF band direct wave input to the TV receiver 6 at the initial setting. After the reception wave selection setting, the setting is maintained until reception is disabled or the power is turned off.

  FIG. 8 shows a modification of the TV receiver.

  8, the same components as those in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted.

  The TV receiver of FIG. 8 differs only in that a VHF / UHF channel error rate detector 63B is used instead of the VHF / UHF channel level detector 63A of the TV receiver of FIG.

  The control unit 85 first controls the RF / IF unit 61 to select a VHF channel corresponding to the designated UHF channel at the time of initial setting (for example, when the power is turned on). Therefore, the RF / IF unit 61 down-converts the TV broadcast signal (retransmission wave signal) of the VHF channel corresponding to the designated UHF channel into a baseband signal. The signal obtained by the RF / IF unit 61 is digitally demodulated by the OFDM demodulator 62 and then sent to the AV decoder 82 and also to the VHF / UHF channel error rate detector 63B. The VHF / UHF channel error rate detector 63B detects the error rate of the received signal of the VHF channel obtained by the OFDM demodulator 62 and supplies it to the controller 85. The control unit 85 stores the error rate of the received signal of this VHF channel.

  Thereafter, the control unit 85 controls the RF / IF unit 61 so as to select the designated UHF channel. Therefore, the RF / IF unit 61 down-converts the specified UHF channel TV broadcast signal (direct wave signal) into a baseband signal. The signal obtained by the RF / IF unit 61 is digitally demodulated by the OFDM demodulator 62 and then sent to the AV decoder 82 and also to the VHF / UHF channel error rate detector 63B. The VHF / UHF channel error rate detection unit 63B detects the error rate of the received signal of the UHF channel obtained by the OFDM demodulation unit 62, and provides it to the control unit 85. The control unit 85 compares the error rate of the received signal of the UHF channel with the error rate of the received signal of the VHF channel stored before that. Then, the RF / IF unit 61 is controlled so that the channel with the lower error rate (VHF channel or UHF channel) is selected.

  In this way, the reception wave to be reproduced is selected and set from the VHF band retransmitted wave and the UHF band direct wave input to the TV receiver 6 at the initial setting. After the reception wave selection setting, the setting is maintained until reception is disabled or the power is turned off.

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 schematic diagram for demonstrating the frequency conversion of the frequency conversion part 42 of FIG. 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. It is a block diagram which shows the further another example of TV receiver. It is a block diagram which shows the further another 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 Frequency conversion part 43 VHF transmitting part 44 Transmitting antenna 51 Receiving antenna 52 VHF / UHF receiving part 60 VHF / UHF duplexer 61, 71 RF / IF Unit 62, 72 OFDM demodulation unit 63, 73 Level detection unit 64, 74 Error rate detection unit 85 Control unit 63A VHF / UHF channel level detection unit 63B VHF / UHF channel error rate detection unit

Claims (5)

A wireless redistribution system that wirelessly retransmits a terrestrial digital TV broadcast signal received by an outdoor antenna to a TV receiver, and a direct reception system that inputs a terrestrial digital TV broadcast signal directly to the TV receiver via an indoor antenna;
The TV receiver includes: a selecting unit that selects a TV broadcast signal having high reception quality among a TV broadcast signal supplied by the wireless redistribution system and a TV broadcast signal supplied by the direct reception system; and the selection A receiving system for terrestrial digital TV broadcasting, comprising: reproducing means for reproducing the TV broadcast signal selected by the means. The selection means compares the reception signal level of the TV broadcast signal supplied by the wireless redistribution system with the reception signal level of the TV broadcast signal supplied by the direct reception system, so that a TV with high reception quality is obtained. The terrestrial digital TV broadcast receiving system according to claim 1, wherein the broadcast signal is selected. The selection means compares the reception signal error rate of the TV broadcast signal supplied by the wireless redistribution system with the reception signal error rate of the TV broadcast signal supplied by the direct reception system, thereby improving the reception quality. The terrestrial digital TV broadcast receiving system according to claim 1, wherein a high TV broadcast signal is selected. The wireless redistribution system includes a transmitter that performs frequency conversion of a terrestrial digital TV broadcast signal received by an outdoor antenna to a frequency of an empty channel in the VHF band, and then amplifies and transmits the signal, and a signal transmitted from the transmitter Receiver that receives and amplifies the signal and supplies it to the TV receiver,
The terrestrial digital TV broadcast receiving system according to any one of claims 1, 2, and 3. The transmitter is a vacant channel in the VHF band of a terrestrial digital TV broadcast signal received by an outdoor antenna, frequency-converted to a frequency of 322 MHz or lower, and then amplified and wirelessly transmitted. The terrestrial digital TV broadcast receiving system according to claim 4.

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