JP5051895B2 - Gap filler device - Google Patents

Description

  The present invention relates to a gap filler device used for relaying digital broadcasts, and more particularly to a gap filler device applicable to relaying to a difficult-to-view area in a closed space such as a building or an underground mall.

  In digital broadcasting such as a terrestrial digital broadcasting system, a gap filler device is used in a relay station for the purpose of expanding a broadcasting service area and eliminating difficult viewing areas. As this type of gap filler device, for example, a device as disclosed in Patent Document 1 is disclosed.

FIG. 13 is a diagram showing a configuration of a conventional gap filler device described in Patent Document 1. In FIG. This gap filler device distributes broadcast waves received by the receiving antenna 11 into two systems by the distributor 12, and supplies one to the amplifier 13 and the other to the analog TV detection circuit 14. Here, the presence or absence of an analog TV signal is detected by the analog TV detection circuit 14. Based on the detection result, the filter control circuit 18 controls the pass band of the filter circuit 15 by turning off the power of the band filters 151 to 15n corresponding to the frequency band of the analog TV signal. Thereby, the frequency band of the analog broadcast wave is cut off from the broadcast wave received by the receiving antenna 11, the analog TV signal is removed, and only the digital broadcast signal is retransmitted.
JP 2006-287342 A

  The gap filler device of the above conventional example is to retransmit and relay to a wide area of open space, and it is necessary to strictly observe the characteristics such as CNR defined as a relay device for a wide area, It must be equipped with a filter with high precision pass / cut characteristics. Further, in contrast to the fact that the channel arrangement of analog broadcast waves varies from region to region, the conventional example is configured to change the combination of filters by turning off the power of the band filter corresponding to the frequency band of the analog broadcast wave. . For this reason, when installing in each region, prepare a filter for all frequency bands and turn off the band filter corresponding to the analog broadcast channel arrangement in the region, or replace the band filter for each region. Need to be configured. For these reasons, since a large number of high-performance and large-scale filters are required, the system of the relay apparatus becomes expensive and the apparatus becomes large.

  For example, when it is applied to relay to a difficult viewing area in a closed space such as a building or an underground shopping center, re-transmission conforming to the regulations is not obligatory. There is no merit. Further, when analog TV broadcasting ends in 2011, the function of removing analog broadcast waves is not necessary. For this reason, a simple device specified only in a closed space is promising as market needs, has a function of removing analog broadcast waves and retransmitting desired digital broadcast waves, and is inexpensive and easy to install and maintain It can be said that a relay device is preferable.

  The present invention has been made in view of the above circumstances, and can be applied to relay to a difficult viewing area in a narrow closed area, and can remove unnecessary analog broadcast waves and retransmit a desired digital signal. An object is to provide a small and inexpensive gap filler device.

The gap filler device of the present invention includes a receiving unit that receives a signal including a broadcast wave, and each frequency band of an analog broadcast wave and a digital broadcast wave in the broadcast wave in the frequency spectrum of the received signal received by the receiving unit. Based on the detection result of the frequency detection unit for detecting the frequency, the filter unit for blocking the unnecessary frequency band in the frequency spectrum of the received signal and having variable frequency characteristics to pass the desired frequency band, and the detection result of the frequency detection unit A filter control unit that controls frequency characteristics of the filter unit, removes a frequency band of the detected analog broadcast wave as an unnecessary wave, and passes a frequency band including the digital broadcast wave as a desired wave; and the filter unit A transmitter for retransmitting the output signal of
The filter unit includes a band-pass filter that passes a frequency band of a desired wave including a plurality of the digital broadcast waves having continuous frequency bands, and a narrow-band band pass that passes a frequency band of the desired wave by the single digital broadcast wave And a filter
The filter control unit, when there are a plurality of the digital broadcast waves that are continuous in a predetermined channel frequency band, passes the frequency bands of the corresponding digital broadcast waves by the band pass filter, When the single digital broadcast wave is present and the analog broadcast wave is present in the vicinity of the digital broadcast wave, the narrowband bandpass filter passes the frequency band of the corresponding single digital broadcast wave. is there.

  The present invention is the gap filler device described above, wherein the filter unit further includes a band elimination filter that removes an analog broadcast wave that exists between frequency bands of a desired wave including the digital broadcast wave, When the analog broadcast wave exists between the plurality of digital broadcast waves or between the plurality of digital broadcast waves and the single digital broadcast wave, the filter control unit uses the band elimination filter. Includes those that remove the frequency band of the corresponding analog broadcast wave.

  Further, the present invention is the gap filler device described above, wherein the filter unit further includes an eraser that erases an analog broadcast wave existing in a frequency band of a desired wave including the plurality of continuous digital broadcast waves. The filter control unit includes a unit that erases the frequency band of the corresponding analog broadcast wave by the eraser when the analog broadcast wave exists in the plurality of continuous digital broadcast waves.

  With the above configuration, the use of relatively inexpensive variable-type bandpass filters, band elimination filters, erasers, etc. without using many high-performance and large-scale filters enables different broadcast wave channel arrangements in each region. It is possible to flexibly deal with unnecessary analog broadcast waves and to retransmit digital signals including desired digital broadcast waves. Therefore, it is possible to reduce the size and space of the apparatus and achieve cost reduction. Such a configuration is applicable to relaying to difficult viewing areas in a narrow closed space, and is a small and inexpensive gap filler that can remove unnecessary analog broadcast waves and retransmit a desired digital signal. A device can be realized. Therefore, for example, when installing as a relay device in a narrow area of a closed space such as in a building, it is possible to realize a simple gap filler device that is inexpensive and does not require installation work and subsequent maintenance.

The present invention is the gap filler device described above, wherein the filter unit includes an equalizer that varies the pass frequency characteristic of the output signal and adjusts the signal level within the band of the output signal to be substantially flat. It shall be further provided.
With the above configuration, since the frequency spectrum of the output signal to be retransmitted is flattened and relayed and transmitted, the sensitivity difference for each channel can be reduced on the receiving side, and a stable reception environment can be provided.

Further, the present invention is the gap filler device described above, wherein the frequency detection unit includes a synthesizer that generates a local frequency signal used for detection of the received signal, and the local frequency signal is 4.5 MHz in the synthesizer. Including an FM modulator for applying FM modulation.
With the above configuration, when detecting an analog broadcast wave in which the carrier wave is arranged at an interval of 4.5 MHz, it is not necessary to determine the frequency interval of each carrier wave, and the analog broadcast wave is determined at one signal level. Can be detected.

Further, the present invention is the gap filler device described above, wherein the frequency detection unit detects a signal of a predetermined level or more as the analog broadcast wave or the digital broadcast wave in the detection signal detected from the received signal, Among these, the signal which discriminate | determines the signal more than a predetermined threshold as said analog broadcast wave is included.
With the above configuration, analog broadcast waves and digital broadcast waves can be easily classified and detected according to the magnitude of the signal level of the detected signal obtained by detecting the received signal.

Moreover, this invention is said gap filler apparatus, Comprising: It comprises as an integrated module containing the said filter part, This module is removable with respect to the apparatus main body containing the said receiving part and the said transmission part. Including things.
With the above configuration, for example, when the analog broadcast wave ends in the future and the filter function that eliminates unnecessary waves becomes unnecessary, it can be removed and operated, so the system configuration can be easily adapted to changes in the environment. Can be made.

  According to the present invention, there is provided a small and inexpensive gap filler device that can be applied to relay to a difficult viewing area in a narrow closed space area and can remove unnecessary analog broadcast waves and retransmit a desired digital signal. Can be provided.

  FIG. 1 is a diagram illustrating a configuration of a relay system including a gap filler device according to an embodiment of the present invention. The relay system according to the present embodiment includes a receiving antenna 21, an E / O (electrical-optical conversion) device 22, an optical fiber 23, an O / E (optical-electrical conversion) device 24, and a power amplifier (PA). 25 and a transmission antenna 26. In this relay system, a received signal including a digital broadcast wave received by the receiving antenna 21 is converted into an optical signal by the E / O device 22, transmitted through the optical fiber 23, and then converted into an electric signal by the O / E device 24. The power is amplified by the power amplifier 25 and retransmitted from the transmission antenna 26. In the present embodiment, the E / O device 22 on which the function of the gap filler device is mounted will be described in detail.

  FIG. 2 is a diagram showing a configuration of an E / O device including a gap filler device according to the present embodiment. The E / O device 22 is configured to have the function of a gap filler device, removes signals in the frequency band of analog broadcast waves in the frequency spectrum of the received signal, and emits only desired digital signals such as digital broadcast waves. Convert to signal and output. The E / O device 22 includes a low noise amplifier (LNA) 31, a filtering circuit 32, an equalizer 33, an eraser 34, a scanner 36, and an electro-optical conversion circuit 35. In the above configuration, the low noise amplifier 31 realizes the function of a receiving unit, and the electro-optical conversion circuit 35 realizes the function of a transmitting unit. The filtering circuit 32, the equalizer 33, and the eraser 34 realize a function of a filter unit that cuts off an unnecessary frequency band and allows a desired frequency band to pass therethrough. The scanner 36 realizes a function of a frequency detection unit that detects each frequency band of an analog broadcast wave and a digital broadcast wave among broadcast waves in the frequency spectrum of the reception signal received by the reception unit.

  The filter unit 90 including the filtering circuit 32, the equalizer 33, the eraser 34, and the scanner 36 is integrated into a module configuration, and this module corresponds to the apparatus main body of the E / O device 22 including the electro-optical conversion circuit 35 and the like. It can also be configured to be removable. As described above, the filter unit 90 is configured to be detachable separately, so that it can be removed when the filter function becomes unnecessary.

  FIG. 3 is a diagram showing the configuration of the main part of the gap filler device according to this embodiment. In FIG. 3, the detailed structural example of the filtration circuit 32 of the E / O apparatus 22, the equalizer 33, and the scanner 36 is shown.

  The filtering circuit 32 passes a desired digital signal (desired wave, desired digital wave) according to the channel arrangement of the terrestrial digital broadcast wave of the received signal, and an unnecessary signal (unnecessary wave, unnecessary analog wave) such as an analog broadcast wave. And a plurality of variable filters that cut off the wave). The plurality of variable filters include a variable bandpass filter (BPF) 42 that passes a frequency band block of a terrestrial digital broadcast signal, and a variable band filter that blocks a frequency band of an unnecessary analog wave such as an analog broadcast signal. Nation filter (BEF: Band Elimination Filter) 43 and variable narrow band pass filter (Narrow BPF, narrow band BPF) 44 dedicated to an isolated channel that passes an isolated frequency band such as a single channel in a terrestrial digital broadcast signal And.

  The equalizer 33 includes a plurality of variable filters for adjusting the frequency characteristics of the pass frequency band of the received signal. As the plurality of variable filters, a first variable filter 45, a second variable filter 46,..., An nth variable filter 47 are provided.

  The scanner 36 includes a mixer 54, a filter 55, a detector 56, an AD converter (ADC) 57, and a local frequency signal for detection, which constitute a detection circuit for detecting a reception signal distributed and input from the distributor 41. Are provided with a distributor 58, a frequency divider 59, an oscillator 60, a PLL (phase locked loop) 61, a reference signal generator 62, and an FM modulator 63. The scanner 36 also includes a control unit 64 composed of a microcomputer or the like that performs digital wave / analog wave determination and variable filter control, and converts the filter control signal from the control unit 64 into an analog signal to convert the filter circuit 32 and the equalizer 33. DA converters (DACs) 48 to 53 that supply the variable filters. In the above configuration, the control unit 64 controls the frequency characteristics of the filter unit based on the detection result of the frequency detection unit, removes the detected analog broadcast wave frequency band as an unnecessary wave, and includes a digital broadcast wave. Filter control unit that allows the filter to pass as a desired wave The function of the filter control unit is realized.

  Next, the operation of the gap filler device of this embodiment will be described in detail. FIG. 4 is a diagram illustrating an example of a frequency spectrum of a received signal including a digital broadcast wave and an analog broadcast wave. Conventionally used analog broadcast waves exist in frequency bands (such as 520 to 620 MHz) to which terrestrial digital broadcast signals are assigned. FIG. 4 shows an example of frequency distribution in a certain broadcast area, where band D is a frequency band to which a digital broadcast wave is assigned, and band A is a frequency band to which an analog broadcast wave is assigned.

  An analog broadcast wave is transmitted in a state where a video carrier wave (P wave) and an audio carrier wave (S wave) are arranged at an interval of 4.5 MHz in one channel (6 MHz band). The energy of one carrier appears greatly. A digital broadcast wave is transmitted by an OFDM (Orthogonal Frequency Division Multiplexing) method with a bandwidth of 6 MHz assigned to one channel, and a digital signal of a desired channel is obtained by extracting and demodulating a signal for each band of 6 MHz in a received signal. Get a signal. Terrestrial digital broadcasting has 13 segments per channel, and one-segment broadcasting uses one of these segments.

  The gap filler apparatus of this embodiment removes an analog TV broadcast signal (analog broadcast wave) from the received signal as shown in FIG. 4 as an unnecessary analog wave, and converts a terrestrial digital broadcast signal (digital broadcast wave) to a desired digital signal. Pass through as a wave and retransmit.

  FIG. 5 is a diagram for explaining the filtering method of each variable filter in the filtering circuit 32. The filtering circuit 32 removes unnecessary analog waves according to the channel arrangement of the broadcast wave at the reception point and outputs the desired digital wave through a plurality of variable filters including a variable BPF 42, a variable BEF 43, and a variable narrow band BPF 44. .

  FIG. 5A shows an example of the frequency characteristic of the variable BPF 42. The variable BPF 42 passes a frequency band block in which a plurality of channels of terrestrial digital broadcast waves exist. Therefore, the pass characteristic of the variable BPF 42 is set so as to pass a desired digital wave continuous in a predetermined channel frequency band. Thereby, only desired digital waves such as a plurality of continuous channels can be passed, and unnecessary analog waves existing in other frequency bands (outside and behind the band, in the vicinity) can be blocked and made non-passable.

  FIG. 5B shows an example of frequency characteristics of the variable BEF 43. This variable BEF 43 cuts off a frequency band in which an analog broadcast wave exists. Therefore, the pass characteristic of the variable BEF 43 is set so as to pass through the frequency band of the desired digital wave and to block unnecessary analog waves in a specific frequency band. Thereby, an unnecessary analog wave can be blocked.

  FIG. 5C shows an example of frequency characteristics of the variable narrow band BPF 44. The variable narrow band BPF 44 allows a single channel and an isolated frequency band of a digital terrestrial broadcast wave to pass through. Therefore, the pass characteristic of the variable narrow band BPF 44 is set so as to pass a desired digital wave in a specific narrow band frequency band. Thereby, only the desired digital wave of a specific isolated channel such as the desired digital wave sandwiched between unnecessary analog waves can be passed, and the adjacent unnecessary analog waves can be blocked and made non-passable.

  A filter control signal from the control unit 64 is input to the variable BPF 42, the variable BEF 43, and the variable narrow band BPF 44 via the DA converters 48 to 50, respectively, and the pass frequency characteristics of each filter are controlled.

  FIG. 6 is a diagram for explaining the configuration and operation of the scanner 36, and FIG. 7 is a diagram showing an example of scan information obtained by the scanner 36. The scanner 36 scans the frequency of the received signal and outputs the detection output as scan information, and individually and automatically discriminates which band is a desired digital wave and which band is an unnecessary analog wave. It has a function to do. The control unit 64 has a function of optimally controlling settings such as the pass characteristics of the variable filter of the filter circuit 32 described above from the obtained scan information based on the detection output of the scanner 36.

  The scanner 36 operates on the same principle as a general spectrum analyzer and has a similar configuration. The RF band received signal distributed and input by the distributor 41 is mixed with the local frequency signal by the mixer 54 and converted to the IF band, and only a desired frequency band is passed by the filter 55, and the detector 56 detects the signal. Is done. This detection output is output to the control unit 64 as scan information. The control unit 64 outputs a control signal for setting the frequency division ratio of the frequency divider 59 for determining the scan frequency. A synthesizer including a distributor 58, a frequency divider 59, an oscillator 60, a PLL 61, and a reference signal generator 62 generates and outputs a predetermined local frequency signal for detection, and the frequency is controlled by a feedback loop of the PLL 61. Is done. In the present embodiment, an FM modulator 63 is provided, and 4.5 MHz FM modulation is applied to the oscillator 60 so that the local frequency signal is a 4.5 MHz FM modulated wave.

  The carrier energy of an analog broadcast wave is mainly composed of a video carrier and an audio carrier, and these carriers are arranged at an interval of 4.5 MHz. Therefore, an FM of 4.5 MHz is added to a local frequency signal mixed with a received signal. By applying modulation, it is possible to simultaneously detect two signal levels of a video carrier and an audio carrier at an intermediate scan frequency.

  The detection output of the scanner 36 can be obtained over the entire band as shown in FIG. 7B by finely scanning at predetermined frequency intervals as shown in FIG. 7A. Here, in the received signal, the analog broadcast wave has a large signal level, and the digital broadcast wave has a signal level lower than that of the analog broadcast wave. Therefore, the scanner 36 can discriminate and detect the unnecessary analog wave and the desired digital wave, respectively, based on the signal level of the detection signal of the received signal obtained as the scan information. At this time, the scanner 36 detects a signal having a predetermined level or more as a broadcast wave by an analog broadcast wave or a digital broadcast wave in the detection signal obtained by detecting the received signal, and determines a signal having a predetermined threshold value or more as an analog broadcast wave. By doing so, analog broadcast waves and digital broadcast waves can be classified and detected. Note that the frequency interval scanned by the scanner 36 is implemented in 6 MHz steps, which are channel intervals of terrestrial digital broadcasting, or at an interval of 1 / integer of this frequency (6 MHz).

  The equalizer 33 is configured to include n variable filters 45 to 47, and the pass frequency characteristics can be freely changed in a band of 470 to 770 MHz. Each variable filter has a plurality of basic elements arranged side by side in the form of a traveling wave amplifier, and the pass frequency characteristics are varied by the varicap control voltage of each basic element. Filter control signals from the control unit 64 are input to the variable filters 45 to 47 of the equalizer 33 via the DA converters 51 to 53, respectively, and the pass frequency characteristics of each filter are controlled to adjust the frequency characteristics of the equalizer 33. Is done.

  FIG. 8 is a diagram illustrating an example of frequency characteristics of the equalizer 33. The broadcast signal at the reception point has a different reception level for each channel depending on the distance from the transmission antenna and the surrounding environment. For this reason, the equalizer 33 performs filtering on the frequency spectrum of the output signal from the filtering circuit 32 so as to flatly shape the output level of the OFDM subcarrier group of the desired digital wave. As a result, the frequency spectrum of the output signal to be retransmitted can be flattened and relay transmission is performed, so that the sensitivity difference for each channel on the receiving side can be reduced, and a stable reception environment can be provided.

  FIG. 9 is a diagram for explaining the configuration and operation of the eraser 34. 9, (a) is a block diagram showing a configuration of the eraser 34, and (b) to (d) are diagrams showing signal examples of respective parts. The eraser 34 has a function of removing (erasing) unnecessary analog waves of a specific narrow band by performing subtraction processing of unnecessary wave components. The eraser 34 of the present embodiment includes amplifiers 72 and 73, a distributor 74, a mixer 75, a distributor 71, a local frequency oscillator 70, an amplifier 76, a SAW type bandpass filter (SAW-BPF) 77, an amplifier 78, a mixer 79, A gain control unit 80, a phase control unit 82, and an adder 81 are included.

  There may be an unnecessary analog wave for only one channel in a band in which the desired digital wave is continuous. In such a case, the unnecessary analog wave cannot be sufficiently suppressed by the filtering circuit 32 and the equalizer 33. Further, it is technically difficult to realize a filter having a very steep Q that removes only adjacent frequency bands in channels arranged every 6 MHz. That is, in such a situation, it is almost impossible to cope with any frequency filtering mechanism. Therefore, in the present embodiment, the unnecessary analog wave adjacent to the desired digital wave can be erased by subtracting only the target channel by the eraser 34.

  In the eraser 34 shown in FIG. 9A, the received signal passes through the amplifiers 72 and 73, is amplified, and is distributed by the distributor 74. Here, as shown in FIG. 9B, the received signal is a signal in which an unnecessary analog wave is mixed for only one channel between continuous desired digital waves. One signal is gain-adjusted to a predetermined gain by the gain control unit 80 based on a gain control signal from the control unit 64 and input to one of the adders 81.

  The other signal is mixed with the local frequency signal generated by the local frequency oscillator 70 and supplied via the distributor 71 in the mixer 75 and converted from the RF band to the IF band. Here, the local frequency signal is set to the frequency of the channel to be erased + 57 MHz, and the received signal is converted into an IF band of 57 MHz. Thereafter, only the band of the unnecessary analog wave is passed by the SAW-BPF 77. At this time, although the desired digital wave is arranged in the adjacent band of the unnecessary analog wave, only the unnecessary analog wave can be filtered by using the SAW-BPF 77 for 57 MHz OFDM-IF having a steep attenuation characteristic. Since the filter can sharply attenuate when the frequency band is lowered, such filtering is possible. The output of the SAW-BPF 77 is amplified by an amplifier 78, mixed in the mixer 79 with the same local frequency signal generated by the local frequency oscillator 70 and supplied via the distributor 71, and reconverted to the original RF band. .

  The output signal of the mixer 79 is an inverted signal, which is a signal of only unnecessary analog waves not including the desired digital wave, and is an inverted signal as shown in FIG. 9C. By adding the inverted signal of the unnecessary analog wave with the other RF signal previously distributed by the adder 81, it is possible to eliminate only the unnecessary analog wave. Therefore, as shown in FIG. 9 (d), it is possible to output only a desired digital wave continuous as an eraser output from the eraser 34.

  At this time, in order to completely subtract unnecessary analog waves in the eraser 34, the delay amounts of the two signal systems must be the same, opposite in phase, and the signal level must be the same. Therefore, the signal gain and phase are adjusted by the gain control unit 80 and the phase control unit 82 based on the control signal from the control unit 64. It is a known condition that the analog wave video carrier and audio carrier are 4.5 MHz apart, and the phase difference is set so that the integral multiple of the beat frequency due to the difference is 4.5 MHz. If set, the video carrier and the audio carrier can be suppressed simultaneously. For example, when the delay difference between two signal systems is set to 2.0 μsec, the frequency beat is generated in a 500 kHz cycle, and the phase condition capable of suppressing the video carrier becomes the condition capable of suppressing the audio carrier.

  FIG. 10 is a flowchart showing a processing procedure in the gap filler device of this embodiment.

  First, in the scanner 36, a frequency division ratio is set from the control unit 64 to the frequency divider 59, and the received signal is scanned at 470 to 770 MHz in 6 MHz steps (or steps of 1 / integer of 6 MHz). 64, the detection result of the scan result obtained from the AD converter 57 is compared with the frequency at that time (step S11).

  Then, the control unit 64 determines in which frequency band an analog wave (unnecessary analog wave) and a digital wave (desired digital wave) exist based on the detection level of the scan result of the scanner 36. This determination is repeated to determine the channel arrangement status of each analog wave / digital wave and obtain it as scan information (step S12).

  Next, the control unit 64 determines whether or not there is a continuous broadcast wave of analog waves or digital waves (2 waves or more: one that is continuous at 6 MHz intervals) for the scan information (step S13). Here, if there is a continuous broadcast wave, it is determined whether an analog wave exists in the continuous broadcast wave (step S14).

  If it is determined in step S14 that an analog wave is present in the continuous broadcast wave, the control unit 64 controls the eraser 34, and the eraser 34 erases an unnecessary analog wave in the desired digital wave (step S14). S15). On the other hand, when it is determined in step S14 that no analog wave exists, it is determined whether or not there are other such continuous digital waves (step S16).

  In step S16, when there is no other continuous digital wave (including a case where a single digital wave exists), the control unit 64 determines whether an analog wave exists between these digital waves. (Step S17). Here, when there is no analog wave between the digital waves, the control unit 64 controls the variable BPF 42 of the filter circuit 32 and passes these desired digital waves through the variable BPF 42 (step S18). On the other hand, when an analog wave exists between the digital waves, the control unit 64 controls the variable BEF 43 of the filtering circuit 32, and blocks the unnecessary analog wave between the digital waves by the variable BEF 43 (step S19).

  If there are other continuous digital waves in step S16, the control unit 64 determines whether an analog wave exists between these continuous digital waves (step S20). Here, when an analog wave exists between continuous digital waves, an unnecessary analog wave between the digital waves is blocked by the variable BEF 43 in step S19. On the other hand, if there is no analog wave between successive digital waves, these desired digital waves are passed through the variable BPF 42 in step S18.

  Next, the control unit 64 determines whether there is any other single digital wave (step S21). Here, if there is a single digital wave, it is determined whether there is an analog wave in the vicinity of this digital wave (step S22). When there is an analog wave in the vicinity of the digital wave, the control unit 64 controls the variable narrow band BPF 44 of the filtering circuit 32, and passes only the digital wave through the variable narrow band BPF 44, thereby removing the unnecessary analog wave in the vicinity. Shut off (step S23). Thereafter, the control unit 64 controls the equalizer 33 and adjusts the frequency characteristics so that the output level of the desired digital wave that is passed through the equalizer 33 becomes flat (step S24). On the other hand, if no other single digital wave exists in step S21, or if no analog wave exists in the vicinity of the digital wave in step S22, the variable narrowband BPF 44 is not used, and the desired digital signal is obtained by the equalizer 33 in step S24. The frequency characteristic of the wave is adjusted to be substantially flat.

  11 and 12 are diagrams showing examples of channel arrangements of desired digital waves and unnecessary analog waves. In the case of the first example shown in FIG. 11, since the analog wave A11 exists in the continuous digital waves D11 and D12, the unnecessary analog wave A11 is erased by the eraser 34 in step S15. At this time, since the analog wave A11 exists in one channel (6 MHz width) between the digital waves D11 and D12, in step S13, these broadcast waves are recognized as a continuous broadcast wave, and then in step S14, these waves are recognized. A determination is made as to whether there are analog waves in the continuous broadcast waves. Further, since the analog wave A12 exists between the continuous digital waves D11 and D12 and the single digital wave D13, the unnecessary analog wave A12 is blocked by the variable BEF 43 in step 19. After that, in step S18, the continuous digital waves D11 and D12 and the single digital wave D13 are passed by the variable BPF 42. Furthermore, since there is another single digital wave D14, and analog waves A13 and A14 exist in the vicinity (both sides) of the digital wave D14, only the digital wave D14 is allowed to pass through the variable narrowband BPF 44 in step S23 to Unnecessary analog waves A13 and A14 are blocked.

  In the case of the second example shown in FIG. 12, since the analog wave A21 exists in the continuous digital waves D21 and D22, the unnecessary analog wave A21 is erased by the eraser 34 in step S15. In addition to the continuous digital waves D21 and D22, there is a continuous digital wave D23, and an analog wave A22 exists between these continuous digital waves D21 and D22 and the digital wave D23. The unnecessary analog wave A22 is blocked by the BEF43. Then, in step S18, the continuous digital waves D21 and D22 and the other continuous digital waves D23 are passed by the variable BPF 42.

  In the gap filler device of the present embodiment as described above, the channel of the broadcast wave at the installation location can be obtained by using a relatively inexpensive BPF or BEF variable filter, eraser, or the like without using a high-performance and large-scale filter. Corresponding to the arrangement, unnecessary analog broadcast waves can be removed, and a digital signal including a desired digital broadcast wave can be transmitted and retransmitted. Therefore, the apparatus size can be reduced to reduce the size and the space, and the cost can be reduced.

  The variable filter used in this embodiment has a pass frequency characteristic controlled by a control unit such as a microcomputer, and the cutoff band can be varied after determination of an unnecessary wave or a desired wave. Is possible. At this time, in order to remove unnecessary analog broadcast waves, it is possible to retransmit and transmit the received RF signal as it is without modulating even unnecessary analog broadcast waves during conversion to an optical signal. In other words, the RF information obtained at the reception point is basically retransmitted at the transmission point as it is, so the configuration does not depend on the modulation method, and the operation conforms to each region without changing the device hardware configuration such as the filter configuration. Is possible. Therefore, even if it does not comprise as a specification which changes for every area, it is possible to constitute and ship with the specifications common to all areas in the whole country etc.

  Here, when the optical signal is converted into an optical signal and transmitted in the relay device, if the modulation degree of the laser converted from electricity to light is set to 100% or more, the transmission characteristic is remarkably deteriorated. For this reason, the unnecessary wave can be stably relayed by removing it from the object to be modulated as much as possible. In this embodiment, it is necessary to use a variable band filter that can obtain sufficient optical transmission characteristics without completely removing unnecessary waves, without using an expensive filter having a steep pass band characteristic. A gap filler device having a sufficient function can be realized. The configuration of the present embodiment can be sufficiently put into practical use even if a simple variable filter is used in applications such as relaying one-segment broadcasting to difficult-to-view areas in closed spaces such as buildings and underground shopping streets. It is.

  In addition, by making the filter unit including the variable filter removable as an integrated module configuration, when the filter function becomes unnecessary, it can be removed and operated, and the system configuration can be easily adapted to changes in the environment. Can be matched. When an analog broadcast wave is stopped after 2011, a filter function for removing the analog broadcast wave as an unnecessary wave is not necessary. Therefore, if the filter unit can be removed, maintenance is easy and wasteful power consumption. Can also be eliminated. According to the present embodiment, it is possible to realize a simple gap filler device that is as inexpensive as possible and that does not require installation labor and subsequent maintenance. In addition, it is possible to avoid the introduction of an expensive and large system due to functions that will become unnecessary in the future. From such a thing, the appeal effect to a user becomes a high thing.

  In the scanner of this embodiment, the local frequency signal for detection is an FM modulated signal of 4.5 MHz, and broadcast waves are detected from the received signal. For this reason, when detecting an analog broadcast wave in which a carrier wave is arranged at an interval of 4.5 MHz, it is not necessary to determine the frequency interval of each carrier wave. Can be detected. Therefore, the processing time in broadcast wave detection can be shortened.

  Note that the gap filler device of this embodiment can also be configured to have a function of relaying a wireless communication signal for mobile communication such as a mobile phone. That is, this embodiment can be applied to a relay device for mobile communication. In this case, an analog broadcast wave is removed as an unnecessary analog wave, and a desired digital wave including a digital broadcast wave and a mobile communication signal is retransmitted and relayed.

  It should be noted that the present invention is not limited to those shown in the above-described embodiments, and those skilled in the art can also make changes and applications based on the description in the specification and well-known techniques. Yes, included in the scope of protection.

  INDUSTRIAL APPLICABILITY The present invention can be applied to relay to a difficult viewing area in a narrow closed space, and can provide a small and inexpensive gap filler device that can remove unnecessary analog broadcast waves and retransmit a desired digital signal. It has an effect and is useful as a gap filler device used for relaying digital broadcasts that can be applied to relaying to difficult-to-view areas in closed spaces such as buildings and underground malls.

The figure which shows the structure of the relay system containing the gap filler apparatus which concerns on embodiment of this invention. The figure which shows the structure of the E / O apparatus containing the gap filler apparatus which concerns on this embodiment The figure which shows the structure of the principal part of the gap filler apparatus which concerns on this embodiment. The figure which shows an example of the frequency spectrum of the received signal containing a digital broadcast wave and an analog broadcast wave The figure explaining the filtering system of each variable filter in the filtration circuit of this embodiment It is a figure explaining the structure and operation | movement of a scanner in this embodiment. The figure which shows the example of the scan information obtained by the scanner in this embodiment The figure which shows an example of the frequency characteristic of the equalizer in this embodiment The figure explaining the structure and operation | movement of an eraser in this embodiment The flowchart which shows the process sequence in the gap filler apparatus of this embodiment. The figure which shows an example of the channel arrangement of a desired digital wave and an unnecessary analog wave The figure which shows an example of the channel arrangement of a desired digital wave and an unnecessary analog wave The figure which shows the structure of the gap filler apparatus of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Reception antenna 22 E / O (electro-optical conversion) apparatus 23 Optical fiber 24 O / E (photo-electric conversion) apparatus 25 Power amplifier 26 Transmission antenna 31 Low noise amplifier 32 Filtration circuit 33 Equalizer 34 Eraser 35 Electro-optical conversion circuit 36 Scanner 42 Variable bandpass filter (BPF)
43 Variable Band Elimination Filter (BEF)
44 Variable Narrow Bandpass Filter (Narrow BPF)
45 to 47 Variable filter 48 to 53 DA converter 54 Mixer 55 Filter 56 Detector 57 AD converter 58 Divider 59 Divider 60 Oscillator 61 PLL
62 Reference signal generator 63 FM modulator 64 Controller 70 Local frequency oscillator 71, 74 Distributor 75, 79 Mixer 77 SAW-BPF
80 gain control unit 81 adder 82 phase control unit 90 filter unit

Claims (7)

A receiver for receiving signals including broadcast waves;
In the frequency spectrum of the received signal received by the receiver, a frequency detector that detects each frequency band of the analog broadcast wave and the digital broadcast wave of the broadcast wave;
In the frequency spectrum of the received signal, a filter unit that blocks an unnecessary frequency band and has a variable frequency characteristic that allows a desired frequency band to pass through;
Controls the frequency characteristics of the filter unit based on the detection result of the frequency detection unit, removes the detected analog broadcast wave frequency band as an unnecessary wave, and passes the frequency band including the digital broadcast wave as a desired wave A filter control unit,
A transmission unit for retransmitting the output signal of the filter unit,
The filter unit includes a band-pass filter that passes a frequency band of a desired wave including a plurality of the digital broadcast waves having continuous frequency bands, and a narrow-band band pass that passes a frequency band of the desired wave by the single digital broadcast wave And a filter
The filter control unit, when there are a plurality of the digital broadcast waves that are continuous in a predetermined channel frequency band, passes the frequency bands of the corresponding digital broadcast waves by the band pass filter, When the single digital broadcast wave is present and the analog broadcast wave is present in the vicinity of the digital broadcast wave, the gap filler that allows the corresponding single digital broadcast wave to pass through the narrowband bandpass filter. apparatus. The gap filler device according to claim 1,
The filter unit further includes a band elimination filter that removes an analog broadcast wave existing between frequency bands of desired waves including the digital broadcast wave,
When the analog broadcast wave exists between the plurality of digital broadcast waves or between the plurality of digital broadcast waves and the single digital broadcast wave, the filter control unit uses the band elimination filter. Gap filler device that removes the frequency band of the corresponding analog broadcast wave. The gap filler device according to claim 1 or 2,
The filter unit further includes an eraser that erases an analog broadcast wave existing in a frequency band of a desired wave including the plurality of continuous digital broadcast waves,
The said filter control part is a gap filler apparatus which erase | eliminates the frequency band of a corresponding analog broadcast wave by the said eraser, when the said analog broadcast wave exists in the said several continuous digital broadcast wave. The gap filler device according to any one of claims 1 to 3,
The said filter part is a gap filler apparatus further provided with the equalizer which varies the pass frequency characteristic of an output signal, and adjusts the signal level in the zone | band of this output signal so that it may become substantially flat. The gap filler device according to claim 1,
The said frequency detection part has a synthesizer which produces | generates the local frequency signal used for the detection of the said received signal, A gap filler apparatus provided with the FM modulator which applies FM modulation of 4.5 MHz to the said local frequency signal in this synthesizer. The gap filler device according to claim 5,
The frequency detection unit detects a signal having a predetermined level or higher as the analog broadcast wave or the digital broadcast wave in the detection signal obtained by detecting the received signal, and determines a signal having a predetermined threshold value or higher as the analog broadcast wave. Gap filler device. The gap filler device according to any one of claims 1 to 6,
A gap filler device configured as an integrated module including the filter unit, the module being detachable from the apparatus main body including the receiving unit and the transmitting unit.

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