JP5180244B2 - Retransmission device - Google Patents

Description

  The present invention relates to a retransmission apparatus that modulates the contents of a digital terrestrial broadcast program in an analog broadcast system in a television broadcast joint reception system, and more particularly to a retransmission apparatus that performs retransmission on the same channel as an analog broadcast channel.

  In recent years, digitalization of television broadcasting has been progressing worldwide. In Japan, analog broadcasting is scheduled to be stopped on July 24, 2011 due to the conversion of terrestrial digital broadcasting. After analog broadcasting is stopped, the VHF band is newly used for other purposes such as digital radio. Is going to be. Due to the analog broadcasting stoppage, many existing analog broadcast television receivers are required to be updated to digital broadcast compatible television receivers.

  However, it is difficult to replace and update the number of installed television receivers for analog broadcasting-compatible television receivers already installed in facilities such as hospitals, schools, and hotels at once. This is because a special device suitable for the environment is used, for example, a television receiver such as a hospital or a hotel is small and has a simple function or is used via a terminal with limited operation.

  Therefore, it is conceivable to introduce a re-transmission device that converts terrestrial digital broadcasting into analog broadcasting and performs re-broadcasting within the facility.

  FIG. 5 is a block diagram showing a schematic configuration of a general television broadcast re-transmission apparatus. This retransmission apparatus includes an input terminal 1 to which a UHF signal (digital terrestrial broadcasting) is input, a booster 2 for correcting distribution loss of the input signal, and a distributor 3 that distributes a signal amplified by the booster 2. And digital broadcast demodulators 4a to 4n corresponding to terrestrial digital broadcast corresponding to each channel of terrestrial digital broadcast, analog modulators 5a to 5n corresponding to each channel of analog broadcast, and analog modulators 5a to 5n. The mixer 6 that mixes the modulated signal and the output terminal 7 that outputs the signal mixed by the mixer 6 are configured.

  In the above configuration, the existing digital terrestrial broadcast signal input from the input terminal 1 is amplified by the booster 2 and distributed to the digital broadcast demodulators 4 a to 4 n by the distributor 3. The digital broadcast demodulators 4a to 4n correspond to each channel (physical channel) of terrestrial digital broadcast, and demodulate the terrestrial digital broadcast. The signals demodulated by the digital broadcast demodulators 4a to 4n are remodulated by the analog modulators 5a to 5n configured for each physical channel in the channel of the terrestrial analog broadcast frequency band, mixed by the mixer 5, and output. Output from terminal 7.

  As described above, in the retransmission apparatus, digital broadcast is converted into analog broadcast and re-transmission is performed, but in an area called a strong electric field, that is, an area close to a broadcasting station and an electric field of television broadcasting is very strong, When the output channel of the retransmission device is set to the channel preset in the current analog television receiver, the analog broadcast wave is mixed into the demodulator in the television receiver and the vertical synchronization is disturbed, resulting in horizontal stripes on the screen. Failure (beat failure) appears. This occurs because the phase of the signal retransmitted from the retransmission apparatus is shifted from the phase of the analog broadcast wave. Due to this phenomenon, the output channel of the retransmission apparatus cannot be set to the same channel as the analog broadcast wave in the strong electric field area, and it has been necessary to change to another empty channel.

  Further, as a known technique related to the present invention, in a television signal processing device used for a head-end device of a joint viewing facility, re-transmission is performed at the same frequency as the carrier frequency of the received television broadcast wave signal, and a ghost There are various TV signal processing techniques such as removal and audio level adjustment for adjacent channel transmission (see, for example, Patent Document 1), and there are specific channels with a low reception level and a channel group that does not differ much in reception level. In a digital television broadcast reception area, a plurality of channels received by an antenna are collectively amplified by a wideband amplifier, and a specific channel having a low reception level is amplified to an appropriate level by a single channel amplifier. Techniques for frequency re-transmission to a frequency range that does not affect the broadcast signal etc. (See, for example, Patent Document 2), and a technique (for example, see Patent Document 3) that can control the level of an output signal and prevent the influence on other channels when the output frequency is changed is known. It has been.

JP-A-7-162324 JP 2006-229590 A JP 2005-79796 A

  As described above, in the conventional retransmission apparatus, when the output channel of the retransmission apparatus is set to the channel preset in the current analog television receiver, the broadcast wave is transmitted in an area where the electric field of the television broadcast is very strong. However, there is a problem that the vertical synchronization is disturbed by mixing in the demodulator in the television receiver and a horizontal stripe beat failure appears on the screen.Therefore, in the strong electric field area, the output channel of the retransmission device is set to the same channel as the analog broadcast wave. It was impossible to set, and it was necessary to change to another empty channel or to change the setting of the reception channel of the television receiver.

  The present invention has been made to solve the above-described problems, and there is no fear of causing a failure in an analog television receiver even in a strong electric field region, and the reception channel of the television receiver is adjusted to the same channel as an analog broadcast wave. An object of the present invention is to provide a re-transmission apparatus that can perform the above-described process.

  In addition, the present invention can block the VHF band frequency signal generated after the analog broadcast is stopped from the main body of the apparatus and output a retransmitted signal without distortion, and can reliably prevent a failure in the television image. An object is to provide a transmission device.

  The present invention is a retransmission apparatus that converts a digital broadcast into an analog broadcast frequency band and retransmits the first broadcast amplifier, which receives and amplifies the digital broadcast wave, and receives and amplifies the analog broadcast wave. A second amplifier; a digital broadcast demodulator that demodulates a video signal and an audio signal from the digital broadcast wave amplified by the first amplifier; and a video carrier signal from the analog broadcast wave amplified by the second amplifier. A carrier extraction unit for extraction, an analog modulation unit that remodulates the video signal and audio signal demodulated by the digital broadcast demodulation unit, converts the signal to a retransmission signal in the same frequency band as the analog broadcast wave, and crystal oscillation Using a real-time clock circuit that is driven by a long-life battery using a child as a reference signal source, the timer time is set by a microcomputer controlled with the analog broadcast stop date set. Power supply control for supplying operating power to the first circuit and the second amplifier, and shutting off the operating power of the second amplifier by a signal output from the timer circuit on the analog broadcast stoppage day The analog modulation unit remodulates the video signal demodulated by the digital broadcast demodulation unit in synchronization with the video carrier signal extracted by the carrier extraction unit, It is a retransmission signal having the same frequency and phase as the video carrier signal of the wave.

  According to the present invention, the retransmission signal is a signal having the same frequency and phase as the analog broadcast wave video carrier signal, so that even if the broadcast wave is mixed in the demodulator in the television receiver, the vertical synchronization is disturbed. This prevents the occurrence of horizontal stripes and other obstacles on the screen, and converts the digital broadcast to the analog broadcast signal format without changing the channel preset of the current analog broadcast compatible television receiver. Introduction and operation of a retransmission apparatus for transmission can be started.

  In addition, a new VHF band frequency signal generated after the analog broadcasting is stopped can be cut off from the main body of the apparatus, and a retransmitted signal without distortion can be output. To a television image by a VHF band frequency signal generated after the analog broadcasting is stopped Can be reliably prevented.

It is a block diagram which shows the whole structure of the retransmission apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the detailed structure of the retransmission apparatus in the same embodiment. It is a block diagram which shows the detail of the analog modulation part and carrier extraction part in the embodiment. It is a figure which shows the structure of the input distribution part and power supply control part of the retransmission apparatus which concern on 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the conventional common retransmission apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of a retransmission apparatus 10 according to the first embodiment of the present invention. The retransmission apparatus 10 according to the present invention includes an input distribution unit 11, a digital broadcast demodulation unit 12a, an analog modulation unit 13a, a carrier extraction unit 14a, and an output mixing unit 15.

  The input distributor 11 inputs, for example, the terrestrial digital broadcast radio wave received by the antenna to the digital broadcast demodulator 12a˜, and inputs the current analog broadcast radio wave received by the antenna to the analog modulator 13a˜. Further, the input distribution unit 11 outputs the received terrestrial digital broadcast radio wave as it is to the output mixing unit 15 by the digital broadcast wave pass-through circuit 16.

  The digital broadcast demodulating units 12a to 12 are composed of, for example, a tuner module, an OFDM demodulating unit LSI, an MPEG decoder, and the like, and have a number that can sufficiently correspond to the number of terrestrial digital broadcast channels in each region. Each of the digital broadcast demodulation units 12a˜ decodes the terrestrial digital radio signal of each channel, extracts the video signal, the audio signal, and the control signal from the TS data and decodes them, thereby converting the analog signal into an analog modulation unit. Output to 13a-. The audio signals include L / M (left / main) and R / S (right / sub) signals, and the audio system currently receiving from the digital broadcast demodulator 12a to mono, stereo, and audio multiplexing. An audio system identification signal for identifying the signal is output as an audio control signal to the analog modulators 13a.

  Also, the carrier extraction unit 14a˜ extracts the received analog broadcast radio wave carrier signal for each channel, converts it to, for example, a 45.75 MHz IF video carrier signal, and supplies it to the analog modulation unit 13a˜ as an IF video carrier signal. . The analog modulation unit 13a˜ includes a video modulation unit 21, an audio modulation unit 22, and a frequency conversion unit 23, and the IF video carrier signal transmitted from the carrier extraction unit 14a˜ is input to the video modulation unit 21.

  The video modulation unit 21 remodulates the video signal demodulated by the digital broadcast demodulation unit 12a˜ with VSB (Vestigial Side Band) -AM of NTSC specification. When modulating the video signal, the video modulation unit 21 performs modulation processing with the IF video carrier signal sent from the carrier extraction unit 14 and modulates the video carrier signal in synchronism with the analog broadcast wave video carrier signal. .

  The audio modulation unit 22 performs FM modulation on the audio signal demodulated by the digital broadcast demodulation units 12a to 12 and converts the audio signal into, for example, a 41.25 MHz IF audio signal. In this case, the audio modulation unit 22 performs the L / M (left / main) and R / S (right / sub) based on the audio control signal (audio system identification signal) sent from the digital broadcast demodulation unit 12a. The audio signal is automatically switched to monaural, stereo, and audio multiplexing.

  The frequency conversion unit 23 mixes the video signal modulated by the video modulation unit 21 and the audio signal modulated by the audio modulation unit 22, and then converts the mixed signal into the same frequency as the channel of the current analog broadcast, and the cable television broadcast. A video signal and an audio signal of analog broadcasting compliant with the law are output to the output mixing unit 15.

  The output mixing unit 15 mixes the analog signal of each channel modulated by the analog modulation units 13a to the digital broadcast wave sent from the input distribution unit 11 via the digital broadcast wave pass-through circuit 16, and retransmits the signal. Output to the outside.

  Although not shown, the retransmission signal output from the output mixing unit 15 is distributed to a plurality of television receivers installed in each room or the like by a hearing system in, for example, a hospital, a school, a hotel, or the like.

  Next, details of each part of the retransmission apparatus 10 will be described.

  FIG. 2 is a block diagram showing a detailed configuration of the retransmission apparatus 10. The input distribution unit 11 includes an input terminal 31 to which a digital terrestrial broadcast wave (UHF) received by an antenna is input and an input terminal 41 to which an analog broadcast wave received by the antenna is input.

  The terrestrial digital broadcast wave input to the input terminal 31 is output to the monitor terminal 37 via the branch circuit 32 and to the amplifier 33. The amplifier 33 amplifies each terrestrial digital broadcast wave and outputs the amplified terrestrial digital broadcast wave to the digital broadcast demodulator 12a- through, for example, a 3-distributor 34 and 5-distributors 35 and 36.

  The analog broadcast wave input to the input terminal 41 is output to the monitor terminal 47 via the branch circuit 42 and input to the amplifier 43. The amplifier 43 amplifies the analog broadcast wave input to the input terminal 41, and outputs the amplified analog broadcast wave to the carrier extraction units 14a to via the 2-distribution distributor 44 and the 5-distribution distributors 45 and 46, for example.

  The input distributor 11 distributes the digital broadcast wave amplified by the amplifier 33 to the digital broadcast wave pass-through circuit 16 by the distributor 34. The digital broadcast wave pass-through circuit 16 includes, for example, an input connector and an output connector at both ends of a coaxial cable, and the terrestrial digital broadcast wave distributed to the terminal 17 of the input distribution unit 11 is directly supplied to the terminal 18 of the output mixing unit 15. Connecting.

  The digital broadcast demodulation units 12a to 12 are provided with a number sufficient to accommodate the number of terrestrial digital broadcast channels in each region, for example, 10 digital broadcast demodulation units 12a to 12j. In the Kanto region, the digital broadcasting demodulation units 12a to 12j are, for example, 21 to 28, 30, 32 channels, that is, 1, 3, 4, 6, 8, 10, 12, 16, 38, 38 of analog television broadcasting. It is preset so that digital terrestrial broadcasting corresponding to 42 channels can be received. Each of the digital broadcast demodulation units 12a to 12j demodulates the video signal and the audio signal, and outputs them to the analog modulation units 13a to 13j, respectively.

  Also, the carrier extraction units 14a to 14 include a number of carrier extraction units 14a to 14j corresponding to the digital broadcast demodulation units 12a to 12j, and extract video carrier signals of analog broadcast channels in each region. That is, in the NTSC system, since there is a video carrier signal at a position of 1.25 MHz from the lower end of each channel, this is extracted. The carrier extraction units 14a to 14j convert the extracted video carrier signal of each channel into an IF band signal of 45.75 MHz, for example, and supply it to the analog modulation units 13a to 13j as an IF video carrier signal IFvc signal.

  The analog modulation units 13a to 13a are configured by the number of analog modulation units 13a to 13j corresponding to the digital broadcast demodulation units 12a to 12j. Each of the analog modulation units 13a to 13j modulates the audio signal demodulated by the digital broadcast demodulation units 12a to 12j, and converts the video signal to the IF video carrier signal IFvc supplied from the carrier extraction units 14a to 14j. The signal is modulated in synchronism, converted to the same frequency as the current analog broadcast wave, and output to the output mixing unit 15.

  The output mixing unit 15 mixes the analog broadcast waves of the respective channels modulated by the analog modulation units 13 a to 13 j by the mixers 51 and 52, and then inputs them to the mixer 53. The output mixing unit 15 takes out the digital broadcast wave output from the terminal 18 of the digital broadcast wave pass-through circuit 16 by the U / V mixer 54 and inputs the digital broadcast wave to the mixer 53. In this case, since the U / V mixer 54 is used to extract the UHF band digital broadcast wave, the terminal on the VHF side is grounded via the load resistor R. The value of the load resistance R is set to 75Ω, for example, according to the impedance of the line.

  The mixer 53 mixes the analog broadcast wave mixed by the mixers 51 and 52 and the digital broadcast wave taken out via the U / V mixer 54, and re-mixes from the output terminal 56 via the branch circuit 55. Output as a transmission signal. The mixed signal of the analog broadcast wave and the digital broadcast wave output from the mixer 53 is output to the output monitor terminal 57 via the branch circuit 55.

  The analog modulation unit 13 (13a to 13j) and the carrier extraction unit 14 (14a to 14j) will be described in detail with reference to FIG.

  In the carrier extraction unit 14, the analog broadcast wave distributed from the input distribution unit 11 is input via an input terminal 61 to a bandpass filter (BPF) 62 having a bandwidth of 6 MHz. This band pass filter 62 is for selecting each channel of the analog broadcast wave, and a frequency band is set according to the channel to be selected. For example, when selecting one channel of an analog broadcast wave, it is set to 90 to 96 MHz.

  The signal selected by the band pass filter 62 is amplified by the amplifier 63 and then input to one input terminal of the mixer 64. The mixer 64 constitutes a frequency conversion circuit that converts the analog broadcast wave selected by the band-pass filter 62 into an IF frequency of 45.75 MHz. The other input terminal receives a local oscillation signal (local signal) from the analog modulation unit 13. Signal) LoF is supplied. The frequency of the local oscillation signal is set to a frequency higher by 45.75 MHz than the video carrier signal to be extracted. For example, when extracting a video carrier signal of one channel, the frequency of the local oscillation signal LoF is set to “91.25 + 45.75 MHz = 137 MHz”.

  After the analog broadcast wave and the local oscillation signal LoF are mixed by the mixer 64 and converted into an IF signal, the band is limited by the 45.75 MHz crystal filter 65 and the video carrier signal is extracted. The video carrier signal extracted from the crystal filter 65 is amplified by amplifiers 66 and 67 and then divided into two by a two-distribution circuit 68. One of the signals is a voltage-controlled oscillator (PLL) by a PLL (Phase-Locked Loop) circuit 69. VCO (Voltage Controlled Oscillator) 70 is used to control the oscillation frequency. The voltage controlled oscillator 70 is a local oscillator that oscillates at a frequency of 45.75 MHz, and its oscillation output is returned to the PLL circuit 69 to constitute a loop circuit. The PLL circuit 69 synchronizes the oscillation signal output from the voltage controlled oscillator 70 with the analog broadcast wave image carrier signal output from the amplifiers 66 and 67 and the oscillation signal from the voltage controlled oscillator 70 to synchronize with the analog broadcast wave. The 45.75 MHz local oscillation signal is generated. A local oscillation signal synchronized with the analog broadcast wave is input to one terminal of the changeover switch 71 as a video carrier signal IFvc.

  A reference signal of 45.75 MHz is input to the other terminal of the changeover switch 71 from a crystal oscillator 75 having a crystal resonator 74. The crystal oscillator 75 outputs a stable IF band video carrier signal of 45.75 MHz by the crystal oscillator 74.

  The other signal divided by the two distribution circuit 68 is detected by the detector 72 and inputted to the (+) input terminal of the comparator 73. The (−) input terminal of the comparator 73 has a certain level. The reference signal is input. The signal output from the comparator 73 is input to the changeover switch 71 as a change control signal. This switching control signal is at a high level when the analog broadcast wave video carrier signal is extracted, the switch 71 is switched to the voltage controlled oscillator 70 side, the analog broadcast wave is stopped, and the video carrier signal is extracted. If not, the changeover switch 71 is switched to the crystal oscillator 75 side.

  The IF band video carrier signal selected by the selector switch 71 is sent to the analog modulator 13 and input to the video input terminal 81 of the video modulator 21.

  In addition, the audio modulation unit 22 of the analog modulation unit 13 includes audio input terminals 82 and 83 and a control terminal 84, and video signals transmitted from the corresponding digital broadcast demodulation units 12 a to 12 j, respectively. An audio signal and an audio control signal are input. In this case, the audio input terminal 82 has an L / M (left / main) audio signal, the audio input terminal 83 has an R / S (right / sub) audio signal, and the control terminal 84 has the audio signal L / M. , An audio control signal for selecting R / S is input.

  The video signal input to the video input terminal 81 is sent to the analog modulator 85, and analog-modulated using the video carrier signal in the IF band sent from the carrier extraction unit 14 as a carrier for video modulation. The analog-modulated video signal is amplified by an amplifier 86, band-limited by a SAW (Surface Acoustic Wave filter) filter 87, and input to one input terminal of a mixer 89 via a mixer 88. The SAW filter 87 has a pass band of 4 MHz and outputs a signal in the IF band of 43.75 to 47.75 MHz.

  The L / M (left / main) and R / S (right / sub) audio signals input to the audio input terminals 82 and 83 are sent to the multiplexer (MPX) 91. The multiplexer 91 selects the audio signals L / M and R / S based on the audio control signal input via the control terminal 84, and performs automatic switching between monaural, stereo, and audio multiplexing.

  The audio signal output from the multiplexer 91 is amplified by the amplifier 92 and then input to the voltage controlled oscillator 93. This voltage-controlled oscillator 93 is a local oscillator that oscillates at a frequency of 41.25 MHz. The oscillation frequency is locked by a reference signal of, for example, 8 MHz of the reference oscillator 95 by the PLL circuit 94, and the center oscillation frequency is 41.25 MHz. Keep stable.

  The audio signal output from the amplifier 92 is input to the voltage controlled oscillator 93 as a modulation signal, and the oscillation signal of the oscillator is FM-modulated and input to the mixer 88 via the 41.25 MHz SAW filter 96. The mixer 88 mixes the video signal output from the SAW filter 87 and the audio signal output from the SAW filter 96 and inputs the mixed signal to one input terminal of the mixer 89.

The reference signal output from the reference oscillator 95 is input to the PLL circuit 97. The PLL circuit 97 locks the oscillation frequency of the voltage controlled oscillator 98 to a predetermined value based on the reference signal. The voltage-controlled oscillator 98 is a local oscillator for converting the frequency of the IF signal to the frequency of analog broadcasting in each region, and can select, for example, an oscillation frequency of 137 to 263 MHz for channels 1 to 12 with a switch. . In this case, the oscillation frequency of the voltage controlled oscillator 98 is set to a frequency 45.75 MHz higher than the frequency of the video carrier signal in each of the current analog broadcast waves. For example, as shown below, 1 channel: 137 MHz
2 channels: 143 MHz
3 channels: 149MHz
4 channels: 217 MHz
6 channels: 229 MHz
12 channels: 263MHz
Set to

  The local oscillation signal LoF output from the voltage controlled oscillator 98 is divided into two by the two distribution circuit 99 and input to the mixer 64 in the carrier extraction unit 14 and the mixer 89 in the analog modulation unit 13.

  The mixer 89 mixes the video and audio IF signals output from the mixer 88 and the local oscillation signal LoF output from the voltage controlled oscillator 98, and converts them to the same frequency as each channel in the analog broadcast wave. The signal converted by the mixer 89 is band-limited by a bandpass filter (BPF) 101 and extracted. The bandpass filter 101 has a bandwidth of 6 MHz, and the frequency band is set according to each channel as with the bandpass filter 62 in the carrier extraction unit 14.

  The band-limited signal by the band-pass filter 101 is level-adjusted by the level adjuster 102, amplified by the amplifier 103, further push-pull amplified by the amplifiers 104 and 105, and passed through the band-pass filter 106. The output is output from the output terminal 107 to the output mixing unit 15 (see FIG. 2). Similar to the bandpass filter 101, the frequency band of the bandpass filter 106 is set according to each channel.

  In the above configuration, in a state where analog broadcasting is being performed, an analog broadcast wave is input to the input terminal 61 of the carrier extraction unit 14. The analog broadcast wave input to the input terminal 61 is band-limited by the band pass filter 62, and a signal of a predetermined channel is selected. The analog broadcast wave of a predetermined channel selected by the band pass filter 62 and from which unnecessary waves are removed is amplified by the amplifier 63 and input to the mixer 64. The mixer 64 mixes the analog broadcast wave selected by the band-pass filter 62 and the local oscillation signal LoF sent from the voltage controlled oscillator 98 of the analog modulation unit 13 and converts it to a video IF signal of 45.75 MHz.

  The video IF signal output from the mixer 64 is band-limited by a 45.75 MHz crystal filter 65 to extract a video carrier signal. The video carrier signal output from the crystal filter 65 is amplified by the amplifiers 66 and 67 and then input to the PLL circuit 69 via the two distribution circuit 68. The PLL circuit 69 synchronizes the oscillation signal output from the voltage controlled oscillator 70 with the video carrier signal of the analog broadcast wave, and generates a 45.75 MHz video carrier signal IFvc synchronized with the analog broadcast wave.

  The video carrier signal IFvc output from the voltage controlled oscillator 70 is selected by the changeover switch 71 and supplied to the analog modulator 85 of the analog modulator 13 as a video carrier signal.

  The analog modulator 85 analog-modulates the baseband video signal sent from the corresponding digital broadcast demodulation units 12a to 12j to the video input terminal 81 in synchronization with the video carrier signal. The analog modulator 85 outputs an IF band IF video signal IFv. The IF video signal IFv is amplified by the amplifier 86, band-limited by the SAW filter 87, and input to the mixer 88.

  On the other hand, the multiplexer 91 selects the audio signals L / M and R / S sent from the corresponding digital broadcast demodulation units 12a to 12j to the audio input terminals 82 and 83 by the audio control signal input from the control terminal 84. Automatically switch between mono, stereo, and audio multiplexing. The audio signal output from the multiplexer 91 is amplified by the amplifier 92 and then input to the voltage control terminal of the voltage controlled oscillator 93. An IF audio signal IFa that has been FM-modulated at an IF frequency of 41.25 MHz is sent to the mixer 88 via the SAW filter 96 as an output signal of the voltage controlled oscillator 93.

  The mixer 88 mixes the IF video signal IFv output from the SAW filter 87 and the IF audio signal IFa output from the SAW filter 96 and inputs them to the mixer 89. The mixer 89 mixes the video and audio IF signals mixed by the mixer 88 and the local oscillation signal LoF for each channel output from the voltage-controlled oscillator 98, and converts it to the same frequency as each channel in the analog broadcast wave. .

  The signal converted by the mixer 89 is taken out through the band pass filter 101 and input to the level adjuster 102 to adjust the signal level. The signal level-adjusted by the level adjuster 102 is amplified by the amplifier 103, further push-pull amplified by the amplifiers 104 and 105, and output from the output terminal 107 to the output mixing unit 15 via the band pass filter 106. The

  As described with reference to FIG. 2, the output mixing unit 15 receives the analog signal of each channel modulated by each of the analog modulation units 13 a to 13 j and the digital signal transmitted from the input distribution unit 11 via the digital broadcast wave pass-through circuit 16. The broadcast wave is mixed and output from the output terminal 56 as a retransmission signal.

  Further, when the analog broadcast is stopped at night or in 2011, the carrier extraction unit 14 cannot extract the video carrier signal of the analog broadcast wave, so the output signal of the comparator 73 becomes low level, and the changeover switch 71 is connected to the crystal oscillator 75 side. The 45.75 MHz oscillation signal output from the crystal oscillator 75 is sent to the analog modulator 85 of the analog modulator 13 as a carrier signal for video modulation. As a result, even when analog broadcasting stops at night or in 2011, the analog modulator 85 can modulate the video signal without any problem.

  As described above, the retransmission signal output from the output mixing unit 15 of the retransmission apparatus 10 is a signal having the same frequency and phase as the video carrier signal of the analog broadcast wave. Even if it is mixed in the demodulator in the receiver, it is possible to prevent the disturbance of vertical synchronization and to prevent horizontal stripes from occurring on the screen, and to operate without changing the channel preset of the television receiver. Can start.

  For example, in the conventional retransmission apparatus shown in FIG. 5, when the D / U ratio (Desire to Undesire signal ratio) is 55 dB or more, a beat failure appears on the television screen. In the re-transmission apparatus 10 shown in FIG. 5, beat failure does not appear at a D / U ratio of 25 dB, and the D / U ratio can be reduced by 30 dB.

  Even if a retransmission signal in the same frequency band as an analog broadcast wave is output from the retransmission apparatus 10 as described above, it is possible to prevent the occurrence of a beat failure. For example, analog installed in hospitals, schools, hotels, etc. Without changing the channel preset of the broadcast television receiver, the retransmission signal can be received normally in the current state. Therefore, it is not necessary to add an expensive digital broadcast receiving tuner or the like to an existing television receiver, and the system can be constructed very economically.

  In addition, the retransmission signal output from the retransmission apparatus 10 includes an analog broadcast wave and a terrestrial digital broadcast wave of the same channel as the current analog broadcast wave. However, even in a facility where television receivers having a reception function for digital terrestrial broadcasting are mixed, it is possible to receive television broadcasting as it is.

  Even when analog broadcasting stops at night or in 2011 and the video carrier signal cannot be extracted, the changeover switch 71 is automatically switched to the crystal oscillator 75 side and the video carrier signal output from the crystal oscillator 75 is output. Is sent to the analog modulation unit 13, so that the modulation processing on the video signal and the audio signal output from the digital broadcast demodulation unit 12a can be normally performed.

  In the above embodiment, the detector 72 is provided in the preceding stage of the PLL circuit 69 to detect the presence or absence of the video carrier signal, and when the analog broadcast wave video carrier signal disappears, the changeover switch 71 is switched and the crystal oscillator 75 The output signal of the local oscillator is automatically selected. Alternatively, for example, it may be automatically switched by a timer with a calendar function at a preset time.

  In the above embodiment, the case where the digital broadcast wave sent from the input distribution unit 11 to the output mixing unit 15 via the digital broadcast wave pass-through circuit 16 is extracted by the U / V mixer 54 has been described. A digital broadcast wave may be extracted using a filter instead of the V mixer 54.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a diagram illustrating the configuration of the input distribution unit 11 and the power supply control unit 110 of the retransmission apparatus according to the second embodiment of the present invention. In the second embodiment, in the retransmission apparatus 10 shown in the first embodiment, a power control unit 110 that controls an operation power supplied to the input distribution unit 11 is provided, and the input distribution unit 11 is stopped when analog broadcasting is stopped. The power supply to is controlled. Note that the input distribution unit 11 has the same configuration as that shown in FIG. 2 of the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted. The configuration of each circuit provided in the subsequent stage of the input distribution unit 11 is the same as that of the first embodiment, and thus detailed description thereof is omitted.

  The power control unit 110 includes a standard radio wave receiving unit 111 that receives standard radio waves (40 kHz, 60 kHz) from a radio station (JJY (registered trademark)) that broadcasts Japan Standard Time, a standard radio wave receiving antenna 112, a timer circuit 113, The power supply control circuit 114 supplies operation power to the digital broadcast wave amplification amplifier 33 and the analog broadcast wave amplification amplifier 43 provided in the input distribution unit 11 through power supply lines 115 and 116. The antenna 112 is built in the retransmission apparatus 10.

  The standard radio wave receiving unit 111 receives a standard radio wave transmitted from a radio station by the antenna 112 and outputs a time signal to the timer circuit 113. The timer time of the timer circuit 113 is set at midnight on July 24, 2011 when the analog broadcast is stopped, that is, when the analog broadcast is stopped. The timer circuit 113 operates in accordance with the time signal output from the standard radio wave receiving unit 111 and outputs a signal to the power supply control circuit 114 when the set time is reached. Until the operation signal is output from the timer circuit 113, the power supply control circuit 114 is connected to the digital broadcast wave amplification amplifier 33 and the analog broadcast wave amplification amplifier 43 provided in the input distribution unit 11 with the power supply line 115, When the operation power is supplied from the timer circuit 113 and an operation signal is output from the timer circuit 113, the operation power for the analog broadcast wave amplification amplifier 43, that is, the power supply on the power line 116 side is cut off. In this case, the operating power for the digital broadcast wave amplification amplifier 33 is continuously supplied as it is.

  In the above configuration, the timer circuit 113 performs a time measuring operation based on the standard radio wave received by the standard radio wave receiving unit 111, but does not output an operation signal until midnight on July 24, 2011. The power supply control circuit 114 supplies operation power to the digital broadcast wave amplification amplifier 33 and the analog broadcast wave amplification amplifier 43 provided in the input distributor 11 until an operation signal is output from the timer circuit 113. To do. Accordingly, the amplifier 33 amplifies the digital broadcast wave, and the amplifier 43 amplifies the analog broadcast wave and outputs it to the subsequent circuit.

  Then, at midnight on July 24, 2011, which is the set time of the timer circuit 113, an operation signal is output from the timer circuit 113 and sent to the power supply control circuit 114. When the operation signal is output from the timer circuit 113, the power supply control circuit 114 cuts off the operation power supply (power supply line 116) for the analog broadcast wave amplification amplifier 43. As a result, the amplifier 43 stops the amplification operation.

  On the other hand, the operational power is continuously supplied from the power control circuit 114 to the amplifier 33 for digital broadcast wave amplification. Therefore, the digital broadcast wave is amplified by the amplifier 33, demodulated by the subsequent digital broadcast demodulation units 12a to 12j shown in FIG. 2, and sent to the analog modulation units 13a to 13j. At this time, a 45.75 MHz video carrier signal, which is the output of the crystal oscillator 75, is given to the analog modulation units 13a to 13j from the carrier extraction unit 14 (14a to 14j) via the changeover switch 71 as shown in FIG. Therefore, the analog modulation operation is performed without any trouble.

  As described above, when the analog broadcast is stopped, the operating power of the analog broadcast wave amplification amplifier 43 provided in the input distribution unit 11 is shut off to newly generate the frequency of the VHF band after the analog broadcast is stopped. The signal (carrier wave) can be cut off from the apparatus main body. For this reason, a retransmitted signal without distortion can be output from the retransmitting device 10, and it is possible to surely prevent a television image from being disturbed by a frequency signal in the VHF band that occurs after the analog broadcast is stopped.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. For example, date and time information can be set for a long time by microcomputer control using a real-time clock circuit driven by a long-life battery such as a lithium battery using a crystal oscillator as a reference signal source instead of the standard radio wave receiving unit 111 of the above embodiment The power supply control circuit 114 can be controlled by a simple timer circuit, and the power supply similar to that described above can be shut off at the date and time when the analog broadcast stops.

  DESCRIPTION OF SYMBOLS 10 ... Retransmission apparatus, 11 ... Input distribution part, 12a-12j ... Digital broadcast demodulation part, 13, 13a-13j ... Analog modulation part, 14, 14a-14j ... Carrier extraction part, 15 ... Output mixing part, 16 ... Digital Broadcast wave pass-through circuit, 21... Video modulation unit, 22... Audio modulation unit, 23... Frequency conversion unit, 31 ... input terminal, 32 ... branch circuit, 33 ... amplifier, 34 to 36 ... distributor, 37 ... monitor terminal, 41 DESCRIPTION OF SYMBOLS ... Input terminal, 42 ... Branch circuit, 43 ... Amplifier, 44-46 ... Distributor, 47 ... Monitor terminal, 51-53 ... Mixer, 54 ... U / V mixer, 55 ... Branch circuit, 56 ... Output terminal, 57 ... Output monitor terminal, 61 ... Input terminal, 62 ... Band pass filter, 63 ... Amplifier, 64 ... Mixer, 65 ... Crystal filter, 66, 67 ... Amplifier, 68 ... Distribution circuit, 69 ... PLL 70, voltage controlled oscillator, 71 ... changeover switch, 72 ... detector, 73 ... comparator, 74 ... crystal oscillator, 75 ... crystal oscillator, 81 ... video input terminal, 82, 83 ... audio input terminal, 84 ... control Terminal: 85 ... Analog modulator, 86 ... Amplifier, 87 ... SAW filter, 88 ... Mixer, 89 ... Mixer, 91 ... Multiplexer, 92 ... Amplifier, 93 ... Voltage controlled oscillator, 94 ... PLL circuit, 95 ... Reference oscillator, 96 ... SAW filter, 97 ... PLL circuit, 98 ... Voltage controlled oscillator, 99 ... Distribution circuit, 101 ... Band pass filter, 102 ... Level adjuster, 103 ... Amplifier, 104, 105 ... Amplifier, 106 ... Band pass filter, 107 DESCRIPTION OF SYMBOLS ... Output terminal, 110 ... Power supply control part, 111 ... Standard radio wave receiving unit, 112 ... Antenna, 113 ... Timer circuit, 11 ... the power supply control circuit, 115, 116 ... power line.

Claims (1)

A retransmission device that converts digital broadcasts into analog broadcast frequency bands and retransmits them,
A first amplifier for receiving and amplifying a digital broadcast wave;
A second amplifier for receiving and amplifying an analog broadcast wave;
A digital broadcast demodulator that demodulates a video signal and an audio signal from the digital broadcast wave amplified by the first amplifier;
A carrier extraction unit for extracting a video carrier signal from the analog broadcast wave amplified by the second amplifier;
An analog modulation unit that remodulates the video signal and the audio signal demodulated by the digital broadcast demodulation unit, converts the signal to a retransmission signal in the same frequency band as the analog broadcast wave; and
Using a real-time clock circuit driven by a long-life battery with a crystal oscillator as a reference signal source, a timer circuit with a microcomputer control in which the timer time is set to an analog broadcast stoppage date,
A power control circuit for supplying operating power to the first amplifier and the second amplifier, and shutting off the operating power of the second amplifier according to a signal output from the timer circuit on the analog broadcast stoppage date; And
The analog modulation unit remodulates the video signal demodulated by the digital broadcast demodulation unit in synchronization with the video carrier signal extracted by the carrier extraction unit, A retransmission apparatus characterized in that the retransmission signal has the same frequency and phase.

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