JP2005012583A - Transmission device and receiving device of terrestrial digital television broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a plurality of indoor receivers or portable terminals to effectively receive a terrestrial DTV broadcast on the radio. <P>SOLUTION: A transmission device 4 relays and re-transmits indoors the signal of UHF band received with a reception antenna (1) for terrestrial digital television broadcast waves to television receivers (9-11, 12, and 16). There are provided a frequency conversion circuit (5) which converts the frequency of UHF band at 470 MHz or higher into the frequency of VHF band at 90-222 MHz, middle band, or super high band at 322 MHz or lower, an amplifier circuit (6) for amplifying the signal having been converted at the frequency conversion circuit (5), and an antenna (7) which receives the output of the amplifier circuit (6) and emits the radio wave (8) of a specified field intensity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a terrestrial digital television (hereinafter abbreviated as terrestrial DTV) broadcast transmission apparatus and reception apparatus, and more particularly to a case where a plurality of receivers are used indoors, such as at home, or a reception function for terrestrial DTV. The present invention relates to a wireless transmission apparatus and a receiving apparatus that are suitable for use when using a portable terminal or the like.
[0002]
[Prior art]
When receiving the current analog television broadcast, as shown in a typical example of the form in FIG. 7, after receiving a broadcast wave by the television receiving antenna 100 installed on the roof or the like, the signal is amplified by the booster 101, Distribution is supplied to the televisions 104 in each room via a distributor 102 and a plurality of coaxial cables 103.
In addition, although not shown, in the case of joint reception at buildings, condominiums, etc., the broadcast wave received by the antenna of the joint reception facility is transmitted to each home, either directly or after frequency conversion, via a cable, Then, the transmitted signal is distributed and supplied to the receivers in each room using the same means as in FIG.
[0003]
The reception form described above is basically the same even when it is a terrestrial DTV. This reception form has the following problems.
1) Recently, the number of TVs used indoors has increased due to the spread of LCD TVs. Under such circumstances, indoor wiring of the coaxial cable becomes complicated, and further, installation of a booster and wiring work are involved. In addition, since the cable is exposed in each room, the beauty of the fashionable television is lost.
2) It is thought that the number of TVs that can be viewed while moving from the installation location will increase further in the future. However, in that case, it is not always possible to connect the antenna cable to the television at the destination, so that in practice, the installation location cannot be freely selected.
3) Terrestrial DTV is also expected to be received by mobile terminals. However, since the radio waves coming directly from the station are weak indoors, reception is difficult in most areas.
[0004]
As one means for solving the above problems, as shown in FIG. 8, a signal received by an outdoor antenna (not shown) is transmitted to an indoor television broadcast receiver 106 via a relay device 105 and its antenna 105a. A re-transmission method has been proposed for analog television broadcasting (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-10-013368 [0006]
[Problems to be solved by the invention]
However, it is practically difficult to apply the above method directly to terrestrial DTV broadcasting. That is, since the frequency range applied to the DTV broadcast wave is 470 MHz to 770 MHz in the UHF band, this DTV broadcast wave is clearly shown in FIG. The above-mentioned allowable electric field strength of is 35 μV / m at a point 3 m away. Therefore, when the above method is adopted for terrestrial DTV broadcasting, the radio wave retransmitted from the indoor relay apparatus becomes very weak and can hardly be received by a normal DTV receiver. In addition, since the radio wave transmitted from the indoor repeater and the radio wave directly arriving indoors from the antenna of the broadcasting station have the same frequency, there is a problem that interference occurs.
[0007]
As another method, recently, it has been proposed to use a wireless liquid crystal television having a configuration in which a tuner section and a display section are separated. This television demodulates and digitally compresses the radio waves received by the tuner, and transmits the signals obtained thereby into the room as 2.4 GHz band or 5 GHz band radio waves based on the IEEE802.11a standard.
[0008]
However, in this method, since it is necessary to compress video / audio on the tuner side, normally only one channel can be transmitted, and therefore, there is a drawback that the display of any room is the same channel. Furthermore, in addition to having to install a transmitter / receiver in the GHz band, there is a problem in terms of cost and standardization because the television receiver becomes special.
[0009]
In view of the above-described problems of the conventional technology, the present invention provides a transmission apparatus and a reception apparatus capable of effectively receiving a terrestrial DTV broadcast wirelessly by a plurality of indoor receivers and portable terminals. It is intended to provide.
[0010]
[Means for Solving the Problems]
The present invention is a transmission apparatus that relays a UHF band signal received by a receiving antenna for digital terrestrial television broadcast waves in a house and retransmits it to a television receiver, and receives the UHF band existing at 470 MHz or higher. A frequency conversion circuit that converts the frequency of the signal to a VHF band of 90 MHz to 222 MHz, a mid band band, or a super high band frequency of 322 MHz or less, and an amplification circuit that amplifies the signal converted by the frequency conversion circuit; And a retransmission antenna that emits radio waves having a prescribed electric field intensity in response to the output of the amplifier circuit.
[0011]
The frequency conversion circuit, the amplification circuit, and the retransmission antenna can be mounted on a digital television broadcast receiver. The radio wave emitted from the re-transmission antenna is set so that the electric field intensity at a distance of 3 meters is 500 μV / m or less in accordance with radio wave regulations.
[0012]
The present invention converts a received digital terrestrial television broadcast wave into a signal having a frequency of a VHF band, a mid band band or a super high band band of 322 MHz or less by a frequency conversion pass-through method, and transmits the signal through a cable. A transmission device applied to a facility, an amplification circuit that amplifies a signal transmitted through the cable as it is, and a retransmission antenna that receives an output of the amplification circuit and emits a radio wave of a prescribed electric field strength, It is characterized by providing.
[0013]
Also in the present invention, the frequency conversion circuit, the amplifier circuit, and the retransmission antenna can be mounted on a digital television broadcast receiver. The radio wave emitted from the re-transmission antenna is set so that the electric field intensity at a distance of 3 meters is 500 μV / m or less in accordance with radio wave regulations.
[0014]
A receiving apparatus for digital terrestrial television broadcasting according to the present invention includes an antenna for receiving radio waves emitted from the transmission apparatus, and a desired receiving frequency range connected to the antenna and extended to a predetermined frequency of 322 MHz or less. And a channel selection unit for selecting a channel.
[0015]
Furthermore, the digital terrestrial television broadcasting receiver according to the present invention includes an antenna for receiving radio waves emitted from the transmission device, and a frequency before the frequency conversion of the frequency of the received signal input from the antenna. A frequency conversion circuit that reconverts the signal into a normal terrestrial digital television broadcast receiver, and is configured to input the reconverted signal to the television broadcast receiver. Yes.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing an embodiment of a transmission apparatus and reception apparatus for digital terrestrial television broadcasting according to the present invention.
In FIG. 1, a UHF band terrestrial DTV broadcast wave (with a peripheral frequency band included in 470 MHz to 770 MHz) emitted from a transmission antenna 1 of a broadcasting station is received outdoors (usually a roof). The signal is received by the antenna 2 and guided to the wireless transmission device 4 by the lead-in cable 3.
[0017]
The wireless transmission device 4 uses the frequency conversion circuit 5 to convert the input DTV broadcast wave band to either a VHF band of 90 MHz to 222 MHz, a midband band (MID band), or a super high band band (SHB band) of 322 MHz or less. The broadcast wave signal having been converted into the predetermined band is amplified by the amplifier 6 and then emitted as a weak radio wave from the small transmission antenna 7 serving as a retransmission antenna. The reason for frequency conversion is as follows.
[0018]
(1) Ensuring radio wave emission strength:
The required electric field strength of the DTV receiver is generally 50 dBμV / m. If the electric field is weaker than this, no received video appears, but if the electric field is higher than this, it is possible to receive a high-quality video with almost no image quality degradation. In analog broadcasting, since the received image quality depends on the electric field strength, a considerable electric field strength is required to receive high image quality.
Considering that this device is a device for home use, it must be a weak radio station without a license. As a result of studying under such conditions, it is difficult to secure the above-described electric field with an allowable electric field strength of 35 μV / m. For this reason, it is necessary to perform frequency conversion to 322 MHz or less where the allowable electric field strength is 500 μV / m (see FIG. 9).
[0019]
(2) Sharing receivers by coordinating with cable TV for joint reception etc .:
As for CATV retransmission of terrestrial DTV, a pass-through method in which a DTV broadcast wave is directly sent to each house is considered as one effective method. In facilities where the band of the cable system extends to 770 MHz, it is simple because UHF waves can flow as they are based on this method. However, most cable facilities cover only a bandwidth of 450 MHz or less, and therefore, a frequency conversion pass-through system that converts the frequency of the transmitted wave to 450 MHz or less is considered promising.
The receiver in each home is generally considered to have a UHF band of 470 MHz or higher as its reception frequency range, so there is a possibility that it does not support frequencies below that. Therefore, the related organizations are requesting manufacturers to produce receivers that also support VHF, MID, SHB bands, and the like.
Therefore, it is expected that receivers that can cope with the frequency conversion pass-through method as described above will become widespread in the future. The receiver according to the present invention can directly use this frequency conversion pass-through method.
[0020]
From the viewpoints of (1) and (2) above, the conversion frequency is suitably 322 MHz or less, and for example, a MID band of 108 MHz to 170 MHz is conceivable. For example, in the case of the Kanto wide area, 20 ch. To 27ch. Since the frequency range is the UHF band of 512 MHz to 560 MHz, the frequency range is converted to the MID band of 110 to 158 MHz as shown in the frequency allocation of FIG.
[0021]
For example, the radio wave 8 emitted from the small transmission antenna 7 of the wireless transmission device 4 is set to have a frequency of 110 MHz to 158 MHz in the MID band, and the electric field strength at a point 3 m away is 500 μV / m or less. Is set.
Television receivers 9, 10, 11, home server 12, etc. installed in each room receive the radio wave 8. Since the television receiver 9 has a built-in small receiving antenna 9a and has a configuration compatible with the frequency conversion pass-through method, it can be used as it is.
[0022]
Since the television receiver 10 does not have a built-in antenna, it can be received by connecting a commercially available indoor antenna 13 to the antenna terminal. Moreover, since the television receiver 11 does not have an antenna and does not support the frequency conversion pass-through method, a converter 14 that performs frequency conversion opposite to the frequency conversion in the wireless transmission device 4 is prepared. It can be received by connecting to the input together with the indoor antenna 15.
[0023]
The server 12 may be installed in the home in the future. Although the server 12 does not include a display unit, the server 12 can be used by providing the tuner unit with the same function as the television receiver. Furthermore, since the mobile phone 16 having a DTV reception function naturally has an antenna built therein, it can be easily used at home simply by setting the input reception frequency range so as to be compatible with the VHF band and the like. Is possible.
[0024]
FIG. 3 shows an example of the configuration of a television receiver with a built-in wireless transmission device.
The wireless transmission device 4 in FIG. 1 is configured as a unit independent of the television receiver. However, as shown in FIG. 3, the frequency conversion circuit 5 and amplification of the wireless transmission device 4 are added to a television receiver (a normal DTV receiver having a digital television circuit, a display unit, etc.) placed in a home living room or the like. Realizing a television receiver having a wireless transmission function that does not require a separate unit by mounting a frequency conversion circuit 5 ′, an amplification circuit 6 ′, and a small transmission antenna 7 ′ corresponding to the circuit 6 and the small transmission antenna 7. Can do.
[0025]
FIG. 4 is a schematic view showing another embodiment of the present invention. In addition, the case where it receives through a joint reception facility in a building, a condominium, etc. or a cable television company is demonstrated here.
Broadcast waves in the UHF band emitted from the transmission antenna 17 of the broadcast station are captured by the reception antenna 19 of the joint reception facility 18 and input to the frequency conversion pass-through device 21 via the lead-in cable 20. In the frequency conversion pass-through device 21, when the band of the cable system of the joint reception facility 18 cannot cover the UHF band (80% in Japan corresponds to this), the facility 18 has the frequency of the received broadcast wave. The frequency is converted into a frequency within the bandwidth, for example, a frequency of 110 MHz to 160 MHz in the MlD band.
[0026]
The signal frequency-converted by the pass-through device 21 is distributed to each home by the distribution cable 22 and guided from the entrance 23 of each door to the indoor wireless transmission device 24. In this case, since the wireless transmission device 24 inputs a DTV broadcast wave signal that has already been frequency-converted to the MID band, it is only necessary to amplify the signal by the amplifier 25.
[0027]
The signal amplified by the wireless transmission device 24 is supplied to a small transmission antenna 26 as a re-transmission antenna, and is emitted from the antenna 26 as a radio wave of 500 μV / m or less that conforms to a specified value according to the Radio Law. The radio wave emitted from the antenna 26 is received by the television receiver 27 equipped with the receiving antenna 27a, the television receiver 29 equipped with the indoor antenna 28, and the like, similarly to the radio wave 8 shown in FIG.
[0028]
The wireless transmission device 24 that inputs a DTV signal frequency-converted by cable distribution can be configured very simply with only an amplifier circuit. Of course, if the wireless transmission device 4 having the frequency conversion circuit 5 described with reference to FIG. 1 is provided with a cable input terminal and a switch for passing through the conversion circuit, the wireless transmission device 4 is also applied to the frequency-converted DTV signal. It becomes possible to apply.
[0029]
FIG. 5 shows a specific example of a receiving apparatus according to the present invention. This DTV broadcast receiving apparatus basically includes a channel selection unit 30, an OFDM (Orthogonal Frequency Division Multiplexing) demodulation unit 31, and signal processing elements (error correction unit 32, demultiplexing unit) that process the output signal of the OFDM demodulation unit 31. 33, a moving picture experts group (MPEG) decoding unit 34, an image superimposing unit 35), and a display unit 36.
[0030]
In this receiving apparatus, a radio wave received by an internal or external indoor antenna 37, that is, a DTV broadcast wave that has already been converted to a frequency such as MID, VHF, or SHB is input to the channel selection unit 30. The channel selection unit 30 is configured to provide channel selection data from the CPU 37 to the PLL circuit, for example, to control the frequency of the local oscillator, and to select a desired channel in the DTV wave by the control. That is, the channel selection unit 30 is configured to be able to select a desired channel in the reception frequency range extended to a predetermined use frequency of 322 MHz or less.
[0031]
Since this receiving apparatus has the same configuration as that of a normal DTV receiver except that the input frequency range is different, it is connected here to each of the signal processing elements 32 to 35, a telephone line, the Internet, or the like. A description of the configuration and operation related to the communication unit 38, the remote control light receiving unit 39, and the like is omitted.
[0032]
FIG. 6 shows an embodiment of a receiving apparatus according to the present invention using a normal commercial DTV receiver 40. The receiving device 43 has a configuration in which the receiving antenna 41 and the frequency conversion circuit 42 are unitized.
In this receiving apparatus, a frequency-converted DTV broadcast wave emitted from a wireless transmission apparatus (for example, the wireless transmission apparatus 4 in FIG. 1) is received by the receiving antenna 41, and the frequency band of this DTV broadcast wave is converted in frequency. The circuit 42 converts the DTV broadcast wave into the original frequency band, and the converted frequency signal is supplied to the antenna terminal of the DTV receiver 40.
[0033]
【The invention's effect】
According to the digital terrestrial broadcast transmission apparatus and reception apparatus according to the present invention, it is possible to wirelessly receive the broadcast anywhere in an area where terrestrial DTV broadcasts can be received. At the same time, it can meet the demands of the times when many televisions such as LCD televisions are installed at home.
In addition, any number of wireless television receivers can be used indoors, and it is easy to view the television receiver by freely changing the installation position of the television receiver in the home.
[0034]
Furthermore, since the portable receivers to be commercialized in the future can be used at home or in buildings, the effect is enormous. Also, when receiving through a cable system such as joint reception, indoor wireless reception is possible, so that a distributor and an indoor distribution cable are not required, and the indoor aesthetics can be maintained. In this case, since it can be a very simple wireless transmission apparatus having only an amplifier circuit, economical home distribution is possible.
[0035]
The present invention effectively uses the features of terrestrial DTV broadcasting in the following points, and has significant features that cannot be obtained by conventional analog broadcasting.
{Circle around (1)} If the electric field strength is equal to or higher than a predetermined level, high image quality and high sound quality with almost no deterioration can be obtained, so that high performance reception performance can be obtained indoors.
{Circle around (2)} Since transmission is performed by OFDM modulation, even if some reflected waves exist, the multipath rejection capability is high, so there is no interference.
Further, according to the present invention, since the UHF band DTV wave is converted to a lower frequency and transmitted, the effect based on the property that the spatial propagation loss is reduced as the frequency is lower, that is, a wider indoor reception area is realized. The effect that it can be obtained. Furthermore, since the frequency of the radio wave from the broadcasting station is different from the frequency of the indoor transmission radio wave, it is possible to configure a system that does not have any fear of interference.
As described above, the present invention can greatly contribute to the spread of terrestrial DTV broadcasting because it can obtain significant effects in terms of functionality and performance.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a digital terrestrial television broadcast transmission apparatus and reception apparatus according to the present invention.
FIG. 2 is a diagram illustrating frequency allocation.
FIG. 3 is a block diagram illustrating a configuration example of a television receiver including a wireless transmission device.
FIG. 4 is a schematic diagram showing an embodiment of a transmission apparatus and reception apparatus for digital terrestrial television broadcasting according to the present invention.
FIG. 5 is a block diagram showing a specific example of a receiving apparatus according to the present invention.
FIG. 6 is a schematic diagram showing another embodiment of a receiving apparatus according to the present invention using a normal commercial digital television receiver.
FIG. 7 is a block diagram showing a typical example of a reception form of the current analog television broadcast.
FIG. 8 is a schematic diagram showing a retransmission method applied to the current analog television broadcast.
FIG. 9 is a graph showing the allowable electric field strength of a weak radio station that does not require a license according to radio wave regulations;
[Explanation of symbols]
1,17 Transmitting antenna 2 UHF receiving antenna 4, 24 Wireless transmission device 5, 5 ', 42 Frequency conversion circuit 6, 6' Amplifier 7, 7 ', 26 Small transmitting antenna 8 Radio wave 9, 10, 11, 27, 29 Television Receiver 12 Home server 13, 15, 37 Indoor antenna 14 Converter 16 Mobile phone 18 Joint reception facility 19, 41 Receiving antenna 21 Frequency conversion pass-through device 22 Distribution cable 30 Tuning section 40 Digital television receiver 43 Receiver

Claims (8)

A transmission device that relays a UHF band signal received by a receiving antenna for terrestrial digital television broadcast waves in a house and retransmits the signal to a television receiver,
A frequency conversion circuit that converts the frequency of the received signal in the UHF band existing at 470 MHz or higher into a VHF band, a midband band of 90 MHz to 222 MHz, or a super high band frequency of 322 MHz or lower;
An amplification circuit for amplifying the signal converted by the frequency conversion circuit;
A re-transmission antenna that receives the output of the amplifier circuit and emits radio waves of a prescribed electric field strength;
A terrestrial digital television broadcast transmission device comprising: The terrestrial digital television broadcast transmission apparatus according to claim 1, wherein the frequency conversion circuit, the amplification circuit, and the retransmission antenna are mounted on a digital television broadcast receiver. The terrestrial digital television broadcast transmission apparatus according to claim 1, wherein the retransmission antenna emits a radio wave having an electric field strength of 500 μV / m or less at a distance of 3 meters. The terrestrial digital television broadcast wave received is converted into a signal having a VHF band, midband band or super high band frequency of 322 MHz or less by a frequency conversion pass-through method, and applied to a joint reception facility that transmits the signal through a cable. A transmission device comprising:
An amplification circuit that amplifies the signal transmitted through the cable as it is;
A re-transmission antenna that receives the output of the amplifier circuit and emits radio waves of a prescribed electric field strength;
A terrestrial digital television broadcast transmission device comprising: 5. The digital terrestrial television broadcast transmission apparatus according to claim 4, wherein the frequency conversion circuit, the amplification circuit, and the retransmission antenna are mounted on a digital television broadcast receiver. 6. The terrestrial digital television broadcast transmission apparatus according to claim 4, wherein the retransmission antenna emits a radio wave having an electric field strength of 500 [mu] V / m or less at a distance of 3 meters. An antenna for receiving radio waves emitted from the transmission device according to claim 1;
A channel selection unit that is connected to the antenna and selects a desired channel in a reception frequency range extended to a predetermined frequency of 322 MHz or less;
A terrestrial digital television broadcast receiver characterized by comprising: An antenna for receiving radio waves emitted from the transmission device according to claim 1;
A frequency conversion circuit that reconverts the frequency of the reception signal input from the antenna to the frequency before the frequency conversion;
A terrestrial digital television broadcast receiver connected to a normal terrestrial digital television broadcast receiver and configured to input the reconverted signal to the television broadcast receiver.

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