JP2006203417A - Broadcast wave converting circuit and broadcast wave conversion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable it to receive a terrestrial digital broadcast automatically, without investigating a frequency which a televiewer can receive or without performing an operation of setting the frequency for each channel when the terrestrial digital broadcast is viewed and listened. <P>SOLUTION: A broadcast wave converting circuit 4 includes a tuner 41 which receives a terrestrial digital broadcast wave in a frequency band from 470 MHz to 770 MHz, a detector 42 which divides the frequency band into a plurality of frequency bands and detects whether it is contained in either of the plurality of the frequency bands by which the terrestrial digital broadcast wave received by the tuner 41 is divided, a variable downconverting circuit 43 which converts the terrestrial digital broadcast wave received by the tuner 41 into a broadcast wave having 322 MHz or less based on the detection result, and an amplifier circuit 44 which amplifiers and outputs the broadcast wave converted by the variable downconverting circuit 43. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a broadcast wave conversion circuit and a broadcast wave conversion device, and more particularly to a broadcast wave conversion circuit and a broadcast wave conversion device for converting a terrestrial digital television broadcast wave.

  In recent years, a terrestrial digital broadcast service has been started, and this terrestrial digital broadcast can be viewed even at home. On the other hand, it is becoming common sense to use a plurality of television receivers in one home as the price of the television receivers is reduced and the size and weight are reduced. That is, in addition to a stationary television receiver that is commonly viewed by family members, a television receiver that is viewed for each individual is used. The stationary television receiver can be viewed in a favorable reception environment because it is connected to an antenna installed outdoors by a coaxial cable or the like. However, many personal television receivers are portable and convenient because they can be carried anywhere in the home. It can be difficult. For example, in the case of a reinforced concrete apartment house such as an apartment, radio waves may not reach the room to be viewed.

  Such a problem occurs not only in terrestrial digital broadcasting but also in BS television broadcasting using satellites. Although it is not intended to improve the reception environment for BS TV broadcasts, satellite broadcast waves received by an outdoor BS antenna with high reception capability can be used to simplify installation and simplify wiring between devices. Has been proposed for transmitting a satellite wave to an indoor television receiver. In this proposal, some embodiments are shown, but the basic configuration is that a satellite wave received by a BS antenna connected to a main body mechanism unit installed outdoors is a VHF band or UHF band. The signal is down-converted and transmitted to an indoor television receiver via a VHF antenna or UHF antenna (see Patent Document 1). As shown in FIG. 2, the main body mechanism unit in this proposal has a receiving unit 11 that receives a BS broadcast wave, and a remote control receiving unit that receives a channel selection signal from a remote controller. 11 includes a tuner 12 that selects one channel from the channels received at 11, and a down converter 13 that down-converts the satellite wave output from the tuner 12 to the VHF band. Also, as shown in FIG. 3, a plurality of receiving units 11 that receive satellite waves of a plurality of channels, and a tuner that selects a channel set by the channel setting unit 12b from the channels received by each receiving unit 11. 12. A down converter 13 is provided for down-converting the satellite wave output from each tuner 12 to the VHF band set by the band setting unit 13b.

A technique for down-converting a high-frequency terrestrial digital broadcast wave to a low frequency is widely known, and there are many prior literatures on proposals related to down-conversion.
For example, in a proposed digital broadcasting receiver, a down-conversion circuit that generates a lower intermediate frequency from a desired signal selected from a digital broadcasting signal has a frequency of an oscillation signal output from a local oscillator. And an image rejection type mixer that generates an intermediate frequency having a frequency different from the frequency of the desired signal input to the down-conversion circuit and removes an image signal associated with the desired signal (Patent Document 2). ).
Japanese Patent No. 3446950 (Japanese Patent Laid-Open No. 2001-86020) JP 2000-68752 A

In terrestrial digital broadcasting, a frequency band of 300 MHz from 470 MHz to 770 MHz is used, and about 6 MHz is assigned to one broadcast wave (channel). Which band to use in the 300 MHz frequency band varies depending on the region. For example, one 100 MHz band is used from three 100 MHz bands of 470 MHz to 570 MHz, 570 MHz to 670 MHz, or 670 MHz to 770 MHz. Alternatively, a plurality of 6 MHz band channels (usually a maximum of 10 channels) are used from the 300 MHz frequency band of 470 MHz to 770 MHz. For this reason, even if the satellite wave conversion device proposed in Patent Document 1 is applied to improve the reception environment in terrestrial digital broadcasting, it is necessary to examine the frequency of the channel that the viewer can receive in his / her area. Since it is necessary to set the frequency examined for each channel, there is a problem that the investigation and setting of the channel is very troublesome.
The present invention is to solve such a conventional problem, and when viewing a terrestrial digital broadcast having a different frequency that can be received depending on a region, the frequency that can be received by the viewer is examined, or for each channel. An object of the present invention is to enable automatic reception of digital terrestrial broadcasting without performing an operation for setting the frequency.

  The broadcast wave conversion circuit according to claim 1 is a reception circuit that receives a terrestrial digital broadcast wave (corresponding to a terrestrial digital terrestrial broadcast wave in the embodiment) in a frequency band from 470 MHz to 770 MHz. In the embodiment, the frequency band is divided into a plurality of frequency bands (corresponding to three frequency bands of 100 MHz band in the embodiment) and the receiving circuit. A detection circuit (corresponding to the detection circuit 42 in FIGS. 2 and 5 in the embodiment) for detecting whether the received terrestrial digital broadcast wave is included in any of the divided frequency bands; Based on the detection result in the detection circuit, the terrestrial digital broadcast wave received by the reception circuit is released in the frequency band of 322 MHz or less. A variable down-conversion circuit (in the embodiment, corresponding to the variable down-conversion circuit 43 in FIGS. 2 and 5) for converting to a wave, and a broadcast wave converted by the variable down-conversion circuit at a predetermined level (implementation) (In the embodiment, it corresponds to a level of 500 μV / m or less permitted by the Radio Law) and amplifying circuit (in the embodiment, corresponding to the amplifying circuit 44 in FIG. 2) for output. It has become.

  The broadcast wave converter according to claim 2 is a receiving means for receiving a terrestrial digital broadcast wave (corresponding to a terrestrial digital terrestrial broadcast wave in the embodiment) within a frequency band from 470 MHz to 770 MHz. In the embodiment, the frequency band is divided into a plurality of frequency bands (corresponding to three frequency bands of the 100 MHz band in the embodiment) and the reception means. Detection means (corresponding to the detection circuit 42 in FIGS. 2 and 5 in the embodiment) for detecting whether the received terrestrial digital broadcast wave is included in any of the divided frequency bands; Based on the detection result of the detection means, the terrestrial digital broadcast wave received by the reception means is released within a frequency band of 322 MHz or less. Variable down-converting means (in the embodiment, corresponding to the variable down-converting circuit 43 in FIGS. 2 and 5) and a transmission antenna (in the embodiment, corresponding to the transmission antenna 5 in FIG. 2) for converting into a wave ), And a broadcast wave converted by the variable down-converting means is amplified to a predetermined level (corresponding to a level of 500 μV / m or less permitted by the Radio Law in the embodiment) and output by a transmitting antenna. Transmitting means (corresponding to the amplifying circuit 44 in FIG. 2 in the embodiment).

  The broadcast wave conversion circuit according to claim 3 is a plurality of terrestrial digital broadcast waves in a frequency band from 470 MHz to 770 MHz (corresponding to a broadcast wave of about 6 MHz band of terrestrial digital broadcast in the embodiment). And a detection circuit for detecting each frequency of a plurality of terrestrial digital broadcast waves received by the reception circuit (embodiment corresponds to the tuner 41 in FIGS. 7 and 9). And the frequency of each of the plurality of terrestrial digital broadcast waves received by the receiving circuit based on the detection result in the detecting circuit independently of 322 MHz or less. A plurality of down-conversion circuits (in the embodiment, the down-conversion circuits shown in FIGS. 7 and 9) for converting into broadcast waves in the frequency band. And a synthesis circuit for synthesizing a plurality of broadcast waves converted by a plurality of down-conversion circuits (in the embodiment, this corresponds to the synthesis circuit 47 in FIG. 7). And an amplification circuit (in the embodiment, which amplifies and outputs the broadcast wave synthesized by the synthesis circuit to a predetermined level (corresponding to a level of 500 μV / m or less permitted in the Radio Law in the embodiment). , Corresponding to the amplifier circuit 44 in FIG. 7).

  The broadcast wave converter according to claim 4 is a plurality of terrestrial digital broadcast waves in a frequency band from 470 MHz to 770 MHz (in the embodiment, this corresponds to a broadcast wave of about 6 MHz band of terrestrial digital broadcast). Receiving means (corresponding to the tuner 41 in FIG. 7 and FIG. 9 in the embodiment) and detecting means for detecting each frequency of a plurality of terrestrial digital broadcast waves received by the receiving means (embodiment) And the detection circuit 45 of FIG. 7 and FIG. 9), and the frequency of each of the plurality of terrestrial digital broadcast waves received by the reception means is independently 322 MHz or less based on the detection result of the detection means. A plurality of down-conversion means for converting into broadcast waves in the frequency band (in the embodiment, the down-conversion in FIGS. 7 and 9). And synthesizing means for synthesizing a plurality of broadcast waves converted by a plurality of down-converting means (in the embodiment, it corresponds to the synthesizing circuit 47 in FIG. 7). And a transmission antenna (corresponding to the transmission antenna 5 in FIG. 7 in the embodiment), and the broadcast wave synthesized by the synthesis means is transmitted at a predetermined level (in the embodiment, 500 μV / and a transmission means (corresponding to the amplifier circuit of FIG. 7 in the embodiment) that amplifies the signal to a level equal to or lower than m and outputs the result by a transmission antenna.

  According to the broadcast wave conversion circuit and the broadcast wave conversion device of the present invention, when viewing a terrestrial digital broadcast having a different frequency that can be received in each region, the frequency that can be received by the viewer is checked, or the frequency is set for each channel. There is an effect that digital terrestrial broadcasting can be automatically received without performing the setting operation.

A first embodiment and a second embodiment of a broadcast wave conversion circuit and a broadcast wave conversion device according to the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram showing an overall system configuration in each embodiment. In FIG. 1, a receiving antenna 1 receives a terrestrial digital broadcast in a frequency band of 470 MHz to 770 MHz and inputs it to a stationary television receiver 3 and a broadcast wave conversion circuit 4 in a house 2. The stationary television receiver 3 selects a broadcast wave of the selected channel according to the channel operation, performs predetermined signal processing such as decoding processing, displays video, and produces sound. The broadcast wave conversion circuit 4 down-converts the reception frequency of terrestrial digital broadcasting of 470 MHz to 770 MHz into a broadcast wave of a frequency band of 322 MHz or less, and outputs the broadcast wave to the house by the transmission antenna 5. The portable television receiver 6 receives the broadcast wave output from the transmission antenna 5 of the broadcast wave conversion circuit 4 by the rod antenna 7, performs predetermined signal processing such as decoding processing, displays video, and displays audio. Pronounce. That is, the broadcast wave conversion circuit 4 and the transmission antenna 5 constitute a broadcast wave conversion device.

  Next, a first embodiment of the present invention will be described. In the terrestrial digital broadcasting of 470 MHz to 770 MHz, the first embodiment is a frequency band of 470 MHz to 570 MHz, BAND (1), a frequency band of 570 MHz to 670 MHz, BAND (2), and a frequency band of 670 MHz to 770 MHz. This corresponds to the case where any of BAND (3) is used depending on the region.

  FIG. 2 is a schematic block diagram illustrating a configuration of a broadcast wave conversion apparatus including the broadcast wave conversion circuit 4 and the transmission antenna 5 according to the first embodiment. The broadcast wave conversion circuit 4 receives a terrestrial digital broadcast of 470 MHz or higher from the tuner 41 that receives the terrestrial digital broadcast from the broadcast wave reception antenna 1, the detection circuit 42 that detects the broadcast wave of the tuner 41, and the reception antenna 1. The variable down-conversion circuit 43 that converts the broadcast wave to 322 MHz or less, and the amplification circuit 44 that amplifies the broadcast wave output from the variable down-conversion circuit 43 and outputs the amplified wave from the transmission antenna 5.

  FIG. 3 shows a down-conversion state when BAND (2) which is a frequency band of 570 MHz to 670 MHz is used in a certain area and three channels of about 6 MHz band can be received. As shown in FIG. 3, the three channels are down-converted to a band of 222 MHz to 322 MHz. Furthermore, the electric field strength of the broadcast wave output from the transmission antenna 5 is amplified within the range of the electric field strength permitted by the weak radio wave law.

  FIG. 4 is a diagram showing a correspondence relationship between the allowable value of the electric field intensity at 3 m from the radio wave station and the frequency in the weak radio wave method. As shown in FIG. 4, at a frequency of 322 MHz or less, a broadcast wave can be transmitted with a maximum electric field strength of 500 μV / m. Therefore, the amplifier circuit 44 power-amplifies the broadcast wave output from the variable down-conversion circuit 43 to an electric field strength of 500 μV / m or less and outputs it.

  FIG. 5 is a block diagram showing the internal configuration of the detection circuit 42 and variable down-conversion circuit 43 in the first embodiment. The detection circuit 42 includes a control circuit 421, an ADC (analog / digital conversion circuit) 422, a VBPF (variable frequency bandpass filter) 423, a comparison circuit 424, and a reference value power source 425 that outputs a voltage reference value Vf. . The variable down-conversion circuit 43 includes three RF-BPFs (UHF band bandpass filters) 431, 432, 433, a VOSC (variable frequency oscillation circuit) 434, and a MIXER (mixer) 435.

Next, the operation of the broadcast wave conversion circuit 4 in the first embodiment will be described based on the configuration of FIG. 5 and the flowchart of FIG.
The control circuit 421 sets a variable n designating BAND () to 1 (step SA1), and detects a receivable frequency band while incrementing n. That is, a selection signal for selecting BAND (n) is given to the tuner 41 (step SA2). Therefore, the signal output from the tuner 41 is converted into a digital signal by the ADC 422 and input to the VBPF 423 that can vary the pass frequency. The control circuit 421 sets the passing frequency of the VBPF 423 to the frequency of BAND (n) (step SA3). The output of the VBPF 423 is input to the comparison circuit 424 and compared with the reference value Vf of the reference value power source 425.

  When the received value of BAND (n), which is the output of VBPF 423, is larger than the reference value Vf, the comparison circuit 424 outputs a 1 (high level) signal, and the received value of BAND (n) is less than or equal to the reference value Vf. In some cases, the comparison circuit 424 outputs a 0 (low level) signal. The control circuit 421 determines whether or not the received value of BAND (n) is larger than the reference value Vf according to the signal from the comparison circuit 424 (step SA4). If the received value of BAND (n) is less than or equal to the reference value Vf, the value of n is incremented (step SA5). Then, it is determined whether or not the value of n is larger than the maximum value (step SA6). That is, it is determined whether or not the value of n has become 4. If the value of n is 3 or less, the process proceeds to step SA2, a selection signal for selecting BAND (n) designated by n is given to the tuner 41, and the processing up to step SA4 is repeated.

  If the received value of BAND (n) is larger than the reference value Vf at step SA4, the control circuit 421 is one of the three RF-BPF (1) to RF-BPF (3) in the variable down-conversion circuit 43. A control signal En for enabling RF-BPF (n) specified by n is output (step SA7). Therefore, a broadcast wave of BAND (n) that can be received in this region is input to the MIXER 435 via the RF-BPF (n). The control circuit 421 sets the oscillation frequency of the VOSC 434 in the variable down-conversion circuit 43 in accordance with the receivable BAND (n) frequency band (step SA8). As a result, an oscillation signal having a set frequency is input from the VOSC 434 to the MIXER 435, and the broadcast wave of the terrestrial digital broadcast is down-converted to 322 MHz or lower, output from the MIXER 435, and input to the amplifier circuit 44.

  For example, as shown in FIG. 3, when the frequency band receivable in this region is BAND (2) of 570 MHz to 670 MHz, the control circuit 421 sets the oscillation frequency of the VOSC 434 to 350 MHz. As a result, the broadcast wave in the frequency band of 570 MHz to 670 MHz is down-converted to the broadcast wave in the frequency band of 220 MHz to 320 MHz, amplified by the amplifier circuit 44, and output from the transmission antenna 5.

As described above, according to the first embodiment, the broadcast wave conversion circuit 4 includes the tuner 41 that receives the terrestrial digital broadcast wave in the frequency band from 470 MHz to 770 MHz, and the frequency band is divided into a plurality of frequency bands. And the detection circuit 42 for detecting whether the terrestrial digital broadcast wave received by the tuner 41 is included in any of the divided frequency bands, and the tuner based on the detection result in the detection circuit 42. 41. A variable down-conversion circuit 43 that converts a terrestrial digital broadcast wave received by the receiver 41 into a broadcast wave in a frequency band of 322 MHz or less, and a broadcast wave converted by the variable down-conversion circuit 43 at a level of 500 μV / m or less. And an amplifier circuit 44 for amplifying and outputting the signal.
Therefore, when a terrestrial digital broadcast from 470 MHz to 770 MHz is divided into a plurality of frequency bands and the terrestrial digital broadcast is viewed in an area where only a specific frequency band can be received, the frequency that can be received by the viewer is set. Digital terrestrial broadcasting can be automatically received without checking or setting the frequency for each channel.

Further, since all or most of the broadcast wave conversion circuit 4 in the first embodiment can be configured by LSI, downsizing of the broadcast wave conversion apparatus including the broadcast wave conversion circuit 4 and the transmission antenna 5 is reduced. In addition, the weight can be reduced.
Therefore, the broadcast wave converter of the first embodiment can be arranged on the top surface of the stationary television receiver 3 shown in FIG. 1, and the electric field strength of 500 μV / m at the maximum in the frequency band of 322 MHz or less. Large broadcast waves can be output, so that the rod antenna 7 of the portable television receiver 6 in another room or the like can be sufficiently received.

  Next, a second embodiment of the present invention will be described. In the terrestrial digital broadcasting of 470 MHz to 770 MHz, the second embodiment corresponds to the case where the frequency band used according to the region is designated for each channel of the 6 MHz band. In addition, in 2nd Embodiment, the fundamentally same thing as the structure of 1st Embodiment is represented by the same code | symbol.

  FIG. 7 is a schematic block diagram illustrating a configuration of a broadcast wave conversion apparatus including the broadcast wave conversion circuit 4 and the transmission antenna 5 according to the second embodiment. The broadcast wave converting circuit 4 receives a terrestrial digital broadcast of 470 MHz or higher from the tuner 41 that receives the terrestrial digital broadcast from the broadcast wave receiving antenna 1, the detection circuit 45 that detects the broadcast wave of the tuner 41, and the receive antenna 1. A plurality of down-conversion circuits 46 for converting to a broadcast wave of 322 MHz or less, a synthesis circuit 47 for synthesizing a plurality of broadcast waves output from the plurality of down-conversion circuits 46, and a synthesized output outputted from the synthesis circuit 47 It comprises an amplifier circuit 44 that amplifies the broadcast wave and outputs it from the transmission antenna 5.

  FIG. 8 shows a state in which the frequencies fR1 to fR7 of the seven channels that can be received in a certain region are down-converted independently to a frequency of 322 MHz or less in a plurality of channels of terrestrial digital broadcasting of 470 MHz to 770 MHz. ing. In the frequency band of 322 MHz or less, various commercial and public radio waves are used. In FIG. 8, the frequency bands fIa, fIb, and fIc represent the frequencies of radio waves that are already used. Accordingly, the frequency that is already in use is regarded as a jamming radio wave, and down-conversion is performed while selecting a frequency that is not in use.

  FIG. 9 is a block diagram showing the internal configuration of the detection circuit 45 and the down-conversion circuit 46 in the second embodiment. The detection circuit 45 includes a control circuit 451, an ADC (analog / digital conversion circuit) 452, a VBPF (variable frequency bandpass filter) 453, a comparison circuit 454, a reference value power supply 455 that outputs a voltage reference value Vf, and a memory 456. Has been. The down-conversion circuit 46 includes a plurality of down-conversion circuits 461, 462, 463, etc. from the first to the N-th, and an RF-BPF (UHF band-pass filter) 464.

  The first down-conversion circuit 461 includes a variable frequency oscillation circuit VOSC (1), a mixer MIXER (1), and a VHF bandpass filter IF-BPF (1). The second down-conversion circuit 462 includes VOSC (2), MIXER (2), and IF-BPF (2). Similarly, the third and subsequent circuits not shown in the figure, for example, the n-th down-conversion circuit is composed of VOSC (n), MIXER (n), and IF-BPF (n). The last N-th down-conversion circuit 463 is composed of VOSC (N), MIXER (N), and IF-BPF (N).

Next, the operation of the broadcast wave conversion circuit 4 in the second embodiment will be described based on the configuration of FIG. 9 and the flowchart of FIG.
The control circuit 451 sets n, which designates the channel CH () of terrestrial digital broadcasting, and the variable m, which designates the VOSC () of the down-conversion circuit and the address AD () of the memory 456, to an initial value of 1. Set (step SB1). A receivable channel is detected while incrementing the value of n.
That is, a channel selection signal for selecting the channel CH (n) designated by n is given to the tuner 41 (step SB2). Therefore, the signal output from the tuner 41 is converted into a digital signal by the ADC 452 and input to the VBPF 453 that can vary the pass frequency. The control circuit 451 sets the passing frequency of the VBPF 453 to the frequency of CH (n) (step SB3). The output of VBPF 453 is input to comparison circuit 454 and compared with reference value Vf of reference value power supply 455 (step SB4).

  When the received value of the channel of CH (n), which is the output of VBPF 453, is larger than the reference value Vf, 1 and the frequency of channel CH (n) are written from the comparison circuit 454 to the address AD (m) of the memory 456 (step) SB5). On the other hand, when the received value of the channel of CH (n) is equal to or lower than the reference value Vf, 0 and the frequency of channel CH (n) are written from the comparison circuit 454 to the address AD (m) of the memory 456 (step SB6). Next, the value of m is incremented (step SB7), and the value of n is incremented (step SB8). At this time, it is determined whether or not the value of n has become larger than the maximum value (step SB9). That is, it is determined whether or not all channels have been detected. If the value of n is less than or equal to the maximum value, the process proceeds to step SB2, and the process up to step SB9 is repeated.

  When the value of n becomes larger than the maximum value in step SB9, that is, when the detection of all channels is completed, the control circuit 451 sets the value of m to 1 (step SB10), While incrementing the value, the data of the address AD (m) in the memory 456 is searched. That is, it is determined whether or not the AD (m) data is 1 (receivable channel) (step SB11). When the AD (m) data is 1, depending on the frequency of the AD (m) channel. Then, the oscillation frequency of VOSC (m) of the down-conversion circuit 46 is set (step SB12). As a result, the broadcast wave input to the MIXER (m) from the RF-BPF 464 is down-converted by the difference in the oscillation frequency of the VOSC (m), and only the channel that can pass through the IF-BPF (m) is combined. Is input.

  After setting the oscillating frequency of VOSC (m) in step SB12 or when the data of AD (m) is 0 (unreceivable channel) in step SB11, the control circuit 451 increments the value of m. (Step SB13), the next address of the memory 456 is designated. At this time, it is determined whether m is larger than the maximum value (step SB14). That is, it is determined whether or not retrieval of all data written in the memory 456 has been completed. If m is less than or equal to the maximum value, the process proceeds to step SB11 and the processes up to step SB14 are repeated. When m is larger than the maximum value, the down conversion setting for all receivable channels is completed.

  For example, when the frequency of the AD (m) channel is fR3 in FIG. 8, the VOSC (m) oscillation frequency is set to fL3. As a result, the fR3 channel input from the RF-BPF 464 to the MIXER (m) is down-converted to fI3 (fI3 = fR3-fL3) and output from the IF-BPF (m). When the frequency of the channel of AD (m) is fR4, when the oscillation frequency of VOSC (m) is set and the frequency fIa of the jamming radio wave is output from IF-BPF (m) by the setting, The oscillation frequency of VOSC (m) is set to a higher fL4, down-converted to a frequency fI4 (fI4 = fR4−fL4), and the frequency fIa of the jamming radio wave is skipped.

As described above, according to the second embodiment, the tuner 41 that receives a plurality of terrestrial digital broadcast waves in the frequency band from 470 MHz to 770 MHz, and the plurality of terrestrial digital broadcasts received by the tuner 41. A detection circuit 45 for detecting each frequency of the wave, and based on the detection result in the detection circuit 45, each frequency of the plurality of terrestrial digital broadcast waves received by the tuner 41 is independently within a frequency band of 322 MHz or less. A plurality of down-conversion circuits 461, 462, 463, etc. that convert into broadcast waves, a synthesis circuit 47 that synthesizes a plurality of broadcast waves converted by the plurality of down-conversion circuits 461, 462, 463, etc., and a synthesis circuit 47 Amplifying circuit 44 that amplifies the broadcast wave synthesized by the above to a level of 500 μV / m and outputs it Having.
Therefore, when the terrestrial digital broadcast from 470 MHz to 770 MHz is divided into channels for different frequencies, and the terrestrial digital broadcast is viewed in an area where only a specific channel can be received, the frequency that can be received by the viewer is examined. In addition, digital terrestrial broadcasting can be automatically received without performing an operation for setting the frequency for each channel.

Furthermore, since all or most of the broadcast wave conversion circuit 4 in the second embodiment can be configured by LSI, downsizing of the broadcast wave conversion apparatus including the broadcast wave conversion circuit 4 and the transmission antenna 5 is reduced. In addition, the weight can be reduced.
Therefore, the broadcast wave converter of the second embodiment can be arranged on the top surface of the stationary television receiver 3 shown in FIG. 1, and the electric field strength of 500 μV / m at the maximum in the frequency band of 322 MHz or less. Large broadcast waves can be output, so that the rod antenna 7 of the portable television receiver 6 in another room or the like can be sufficiently received.

In each of the above embodiments, the broadcast wave conversion circuit and the broadcast wave conversion device in the case of receiving terrestrial digital broadcasting have been described. However, the scope of application of the present invention is limited to the terrestrial digital broadcasting of each of the above embodiments. It is not something. It is obvious that the present invention can be applied to other types of digital broadcasting, that is, BS digital broadcasting, CS digital broadcasting, CATV digital broadcasting, and the like.
In each of the above embodiments, when converting a terrestrial digital broadcast wave from 470 MHz to 770 MHz into a frequency of 322 MHz or lower, the antenna gain of the receiver is proportional to the frequency, and the best reception state is obtained. You may comprise so that a transmission radio wave may be filled from the band above 322 MHz.

The figure which shows the whole system configuration | structure in 1st Embodiment and 2nd Embodiment of this invention. The schematic block diagram which shows the structure of the broadcast wave converter by the broadcast wave converter circuit and transmission antenna in 1st Embodiment. The figure showing the state of down conversion in case three channels can be received in the frequency band of 570 MHz-670 MHz in terrestrial digital broadcasting. The figure which showed the correspondence of the allowable value of the electric field strength in 3 m from a radio wave station, and a frequency in the weak radio wave method. The block diagram which shows the internal structure of the detection circuit and variable down-conversion circuit in 1st Embodiment. The flowchart which shows operation | movement of the broadcast wave conversion circuit in 1st Embodiment. The schematic block diagram which shows the structure of the broadcast wave converter by the broadcast wave converter circuit and transmission antenna in 2nd Embodiment. The figure which shows the state which down-converts the frequency of seven channels of terrestrial digital broadcasting independently. The block diagram which shows the internal structure of the detection circuit and several down conversion circuit in 2nd Embodiment. The flowchart which shows operation | movement of the broadcast wave conversion circuit in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reception antenna 3 Stationary type television receiver 4 Broadcast wave conversion circuit 5 Transmission antenna 6 Portable television receiver 41 Tuner 42, 45 Detection circuit 43 Variable down-conversion circuit 44 Amplification circuit 46 Multiple down-conversion circuits 47 Synthesis | combination Circuit 421, 451 Control circuit 422, 452 Analog / digital conversion circuit 423, 453 Variable frequency band pass filter 425, 455 Reference value power source 424, 454 Comparison circuit 456 Memory 431, 464 RF band pass filter 434 Variable frequency oscillation circuit 435 Mixer 461 , 462, 463 Down converter circuit

Claims (4)

A receiving circuit for receiving a terrestrial digital broadcast wave in a frequency band from 470 MHz to 770 MHz;
A detection circuit that divides the frequency band into a plurality of frequency bands, and detects whether a terrestrial digital broadcast wave received by the receiving circuit is included in any of the divided plurality of frequency bands;
A variable down-conversion circuit for converting a terrestrial digital broadcast wave received by the reception circuit into a broadcast wave in a frequency band of 322 MHz or less based on a detection result in the detection circuit;
An amplification circuit that amplifies the broadcast wave converted by the variable down-conversion circuit to a predetermined level and outputs it;
A broadcast wave conversion circuit. Receiving means for receiving a terrestrial digital broadcast wave in a frequency band from 470 MHz to 770 MHz;
Detecting means for dividing the frequency band into a plurality of frequency bands, and detecting whether the terrestrial digital broadcast wave received by the receiving means is included in any of the divided plurality of frequency bands;
Variable down-converting means for converting a terrestrial digital broadcast wave received by the receiving means into a broadcast wave in a frequency band of 322 MHz or less based on a detection result in the detecting means;
A transmission means comprising a transmission antenna, amplifying the broadcast wave converted by the variable down-conversion means to a predetermined level, and outputting by the transmission antenna;
A broadcast wave converter having A receiving circuit for receiving a plurality of terrestrial digital broadcast waves in a frequency band from 470 MHz to 770 MHz;
A detection circuit for detecting each frequency of a plurality of terrestrial digital broadcast waves received by the reception circuit;
A plurality of down-conversion circuits for independently converting respective frequencies of the plurality of terrestrial digital broadcast waves received by the reception circuit into broadcast waves in a frequency band of 322 MHz or less based on the detection result in the detection circuit; ,
A synthesis circuit for synthesizing a plurality of broadcast waves converted by the plurality of down-conversion circuits;
An amplification circuit that amplifies the broadcast wave synthesized by the synthesis circuit to a predetermined level and outputs it;
A broadcast wave conversion circuit. Receiving means for receiving a plurality of terrestrial digital broadcast waves in a frequency band from 470 MHz to 770 MHz;
Detecting means for detecting each frequency of a plurality of terrestrial digital broadcast waves received by the receiving means;
A plurality of down-converting means for independently converting each frequency of a plurality of terrestrial digital broadcast waves received by the receiving means into a broadcast wave in a frequency band of 322 MHz or less based on a detection result in the detection means; ,
Combining means for combining a plurality of broadcast waves converted by the plurality of down-converting means;
A transmitting means comprising a transmitting antenna, amplifying the broadcast wave synthesized by the synthesizing means to a predetermined level, and outputting by the transmitting antenna;
A broadcast wave converter having

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