JP2003134020A - Ground digital broadcasting retransmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground digital broadcasting retransmitter, in which ground digital broadcasting of a plurality of channels can be simultaneously received and retransmitted to an area with difficulty in viewing. SOLUTION: An input filter 11 selects the signal of ground digital broadcasting received by a receiving antenna by channels. In each of receiving units 12a-12n, the signal of each of channels selected by the input filter 11 is converted to an IF signal, amplified, afterwards converted to the frequency of the original channel again, and outputted. The output of each of receiving units 12a-12n is extracted through an RF filter 14, amplified by an RF terminal amplifier 15, and afterwards outputted from an output terminal 23 through an output filter 22. In an MPU 16, the gain of the RF terminal amplifier 15 is controlled on the basis of the level of the signal inputted from the RF terminal amplifier 15 through a BPF 18 and a detector 19 and status outputted from the receiving units 12a-12n.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terrestrial digital broadcasting retransmitting device for receiving terrestrial digital broadcasting and retransmitting it to a difficult-to-view area.

[0002]

2. Description of the Related Art Terrestrial digital (television) broadcasting (I
SDB-T: Terrestrial Integrated Services Digital
Broadcasting) is scheduled to start in 2003 in the Kanto, Kinki and Chukyo Wide Areas, and by 2006 in other areas.

In terrestrial digital broadcasting, radio waves with a high frequency such as UHF are used, so there is almost no diffraction of the radio waves, and if there is an obstacle such as a tall building, the radio waves will be blocked and a part of the service area will be provided. In some areas it is difficult to receive radio waves. For example, as shown in FIG. 3, a radio wave transmitted from the transmitting station 1 is blocked by an obstacle such as a tall building 2 in an urban area, and is blocked by an obstacle such as a mountain 3 in a mountain area.
An urban difficult-to-view area 4, a mountain difficult-to-view area 5, and the like are generated in which it is difficult to receive transmitted waves.

In order to eliminate such urban difficult areas 4 and mountain difficult areas 5, a transmitter 6 is installed on the roof of the building 2 in the urban areas, and at the top of the mountain 3 in the mountain areas. There is a system in which a re-transmitting device 6 is installed in such a place and the radio wave from the transmitting station 1 is re-transmitted to the urban difficult-to-view area 4 or the mountain difficult-to-view area 5. The retransmitting device 6 is the transmitting station 1
The radio wave from is received by the receiving antenna 7, amplified, and then retransmitted by the transmitting antenna 8 to the urban difficult viewing area 4 and the mountain difficult viewing area 5.

[0005]

As described above, in the digital terrestrial broadcasting, the retransmitting device 6 is provided on the roof of the building 2 or on the top of the mountain 3 in order to eliminate the urban difficult-to-view area 4 and the mountain difficult-to-view area 5. Although a system for installing the radio wave and relaying the radio wave from the transmission station 1 is considered, the retransmission device 6 is currently under development and has not yet been put into practical use.

The present invention has been made to solve the above problems, and it is possible to simultaneously receive terrestrial digital broadcasts of a plurality of channels and retransmit them to a difficult-to-view area, thereby eliminating the difficult-to-view area. It is an object to provide a broadcast retransmission device.

[0007]

A terrestrial digital broadcasting retransmitting apparatus according to a first aspect of the present invention includes a first filter for selecting a terrestrial digital broadcasting signal received by a receiving antenna for each channel, and the first input. A plurality of receiving units for receiving and amplifying and outputting signals for each channel selected by the filter, and a unit for selecting, extracting, mixing and outputting the signals amplified by the receiving units for each channel. A second filter, and a final stage amplifier for amplifying an output signal of the second filter,
A detector that detects the output signal of the final stage amplifier, a controller that controls the gain of the final stage amplifier based on the level of the signal detected by the detector, and all channels amplified by the final stage amplifier. And a third filter for selecting the signal of (1) and outputting to the transmitting antenna.

According to the above configuration, the terrestrial digital broadcast signal received by the receiving antenna is selected for each channel by the first filter, amplified by each of the plurality of receiving units, and then passed through the second filter. Mixed. The output signal of the second filter is amplified by the final-stage amplifier, then output through the third filter, and retransmitted by the transmitting antenna toward the difficult-to-view area. Further, the control device detects the output signal level of the final stage amplifier by the wave detector and controls so that the output signal of the final stage amplifier is always at a constant level. As described above, terrestrial digital broadcasting of a plurality of channels can be simultaneously received and re-transmitted to the difficult-to-view area, and the hard-to-view area can be eliminated.

A terrestrial digital broadcasting retransmitting apparatus according to a second aspect of the present invention includes a first filter for selecting a terrestrial digital broadcasting signal received by a receiving antenna for each channel.
A plurality of receiving units for receiving, amplifying and outputting signals for each channel selected by the first input filter, and outputting a receiving unit status;
A second filter that selects, extracts, mixes, and outputs the signals amplified by the receiving units for each channel, a final-stage amplifier that amplifies an output signal of the second filter, and an output of the final-stage amplifier A detector for detecting a signal, a controller for controlling the gain of the final stage amplifier based on the receiving unit status output from each of the receiving units and the level of the signal detected by the detector, and the final stage amplifier And a third filter for selecting the signals of all the channels amplified by and outputting them to the transmitting antenna.

According to the above configuration, the control device controls the amplification level of the final stage amplifier according to the output level of the final stage amplifier input through the detector, keeps the signal output level constant, and receives each signal. Based on the status sent from the unit, it is determined whether or not there is a channel for which digital broadcasting has ended, or whether or not there is a defective receiving unit, and the amplification degree of the final stage amplifier is controlled accordingly.
Therefore, even if there is a channel for which digital broadcasting has ended or a receiving unit has a failure, the signal of each channel output from the RF final stage amplifier can always be held in a stable state.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of a terrestrial digital broadcast retransmission device according to an embodiment of the present invention. In FIG. 1, 11 is an input filter,
The terrestrial digital broadcast wave received by the receiving antenna is input through the input terminal 10. The input filter 11 selects a signal of a designated band 6 MHz × n channel in the UHF-TV band of 470 MHz to 770 MHz, inputs it to the corresponding receiving units 12 a to 12 n, and inputs it to the spare receiving unit 13.

The receiving units 12a to 12n respectively receive terrestrial digital broadcast waves of different channels, and are set to, for example, about 6 to 9 units, and the RF signal input from the input filter 11 will be described later in detail. The (high frequency signal) is converted to an IF signal (intermediate frequency signal) and amplified, and then converted to the frequency of the original channel and output. Further, the receiving units 12a to 12n and the standby receiving unit 13 indicate the receiving unit status indicating the receiving state by a control device described later, for example, MPU (Microprocess).
ing unit) 16.

The RF signals output from the receiving units 12a to 12n and the standby receiving unit 13 are extracted by the RF filter 14 for each channel, mixed, and input to the RF final stage amplifier 15. RF final amplifier 1
5 has a wide band amplification characteristic of, for example, about 100 MHz, and its amplification degree is controlled by a level control signal from the MPU 16. A part of the output signal of the RF final stage amplifier 15 is branched to the MPU 16 by a branch circuit 17, and a wide band BPF (band filter) 18 and a detector 19 are provided.
Be entered via. The BPF 18 has a bandwidth corresponding to all channels output from the RF final stage amplifier 15. In addition, the MPU 16 includes the receiving units 12a to 12n and the standby receiving unit 13 as described above.
A receiving unit status indicating a receiving state is input from the device, and a status display 20 for displaying the status of the receiving units 12a to 12n and an annunciator 21 such as a speaker or a buzzer are connected.

The MPU 16 controls the amplification degree of the RF final-stage amplifier 15 according to the output level of the RF final-stage amplifier 15 input via the BPF 18 and the detector 19, and keeps the output level constant AGC. It has the function of. In this case, when one or a plurality of broadcast channels received by the receiving units 12a to 12n have finished broadcasting, or when the output signals disappear due to a failure of the receiving units 12a to 12n, the output signal level of the RF final stage amplifier 15 Therefore, there is a problem that the MPU 16 controls the gain of the RF final stage amplifier 15 so as to be larger than a normal value.

Therefore, in the present embodiment, the MPU 16 determines whether or not broadcasting has ended and whether or not there is a failure based on the statuses of the receiving units 12a to 12n and the standby receiving unit 13, and the channel that has finished broadcasting or the receiving unit that has failed is determined. In some cases, the level control of the RF final stage amplifier 15 is performed in consideration of it. That is, even if there is a channel that has finished broadcasting or a receiving unit that has a failure, the RF final stage amplifier 15 operates so as to operate normally.
It is controlled by the PU 16. For example, when one channel finishes broadcasting, the signal level of the output signal of the RF filter 14 is reduced by one receiving unit, so that the output signal of the RF final stage amplifier 15 is also reduced by one channel. The MPU 16 controls so as to stably operate in this state. Further, the MPU 16 includes the receiving unit 12a.
.About.12n, when an abnormality of the standby receiving unit 13 is detected, the alarm 21 notifies the occurrence of the abnormality.

The RF signal of each channel amplified by the RF final stage amplifier 15 is sent from the output terminal 23 to the transmitting antenna through the output filter 22, and is retransmitted from the transmitting antenna to the difficult-to-view area. It

Next, the detailed structure of the receiving units 12a to 12n will be described with reference to FIG. Figure 1 above
The signal from the input filter 11 shown in FIG.
Is input to the input mixer 33 via the input amplifier 32. In addition, a local oscillation signal is input to the input mixer 33 from a local oscillator 34 configured by using a PLL, for example. The RF signal amplified by the input amplifier 32 is converted into an IF signal (intermediate frequency signal) by the input mixer 33, and the IF amplifier 35, the SAW filter 36, the IF amplifier 37, the SAW filter 38, the IF amplifier 39, and the splitter 40. Is input to the output mixer 41 via.

A part of the IF signal output from the IF amplifier 39 is branched by the branching device 40 and the AGC detector 42.
Is input to the MPU 43 via. MPU43 is AG
The gain control signal AGC-1 for the input amplifier 32 is generated according to the level of the IF signal detected by the C detector 42, and the gain control signal AG for the IF amplifier 35 is generated.
C-2 is generated and input to the input amplifier 32 and the IF amplifier 35, respectively. That is, the MPU 43 controls the gains of the input amplifier 32 and the IF amplifier 35 so that the IF signal of the constant level is always output from the IF amplifier 39.
Further, the MPU 43 controls the oscillation frequency of the local oscillator 34.

The output mixer 41 converts the IF signal input from the IF amplifier 39 through the splitter 40 into the frequency of the original channel by mixing with the local oscillation signal from the local oscillator 34, and the RF amplifier 44. And to the output terminal 46 via the branching device 45. A part of the output signal of the RF amplifier 44 is branched by the branching device 45 and is sent to the MPU 43 through the output detecting wave detector 47.
The MPU 43 determines the state of the receiving unit from the output signal of the detector 47, and outputs the receiving unit status signal to the MPU 16 shown in FIG.

As described above, each receiving unit 12a-12
n is an IF amplifier 35, 3 that converts the RF signal input from the input filter 11 into an IF signal by the input mixer 33.
It is amplified by 7, 39, then returned to the frequency of the original channel by the output mixer 41 and output from the output terminal 46 via the RF amplifier 44. The MPU 43 controls the gains of the input amplifier 32 and the IF amplifier 35 based on the level of the IF signal output from the AGC detector 42, and the level of the output signal of the RF amplifier 44 detected by the detector 47. The state of the receiving unit is determined from the above and is output to the MPU 16 as the receiving unit status.

The backup receiving unit 13 has the same structure as the receiving units 12a to 12n, but it can receive a signal on the same channel as the receiving units 12a to 12n by adjusting the oscillation frequency of the local oscillator 34. It has become. Therefore, the spare receiving unit 13
Irrespective of which of the receiving units 12a to 12n has failed, it receives the RF signal on behalf of the failed receiving unit, amplifies and outputs it to the RF filter 14, and outputs the receiving unit status to the MPU 16. be able to.

The MPU 16 has a BPF 18 and a detector 19
The amplification level of the RF final-stage amplifier 15 is controlled in accordance with the output level of the RF final-stage amplifier 15 input via the input terminal, and the output level is kept constant, and each receiving unit 12a
Based on the status sent from ~ 12n, it is judged whether there is a channel for which digital broadcasting has ended, or whether there is a defective receiving unit, etc., and there is a channel for which digital broadcasting has ended or a defective receiving unit. Corresponding to the RF final amplifier 1
The output level of 5 is controlled so that the signal of each channel is always output from the RF final stage amplifier 15 in a stable state.

The terrestrial digital broadcasting retransmitting apparatus configured as described above is installed in the terrestrial digital broadcasting service area, for example, on the roof of the building 2 or on the top of the mountain 3 as shown in FIG. The terrestrial digital broadcast waves of a plurality of channels transmitted from 1 are received by the receiving antenna 7, converted into IF signals and amplified, and then returned to the frequency of the original channel, and by the transmitting antenna 8, the urban difficult-to-view areas 4 and mountains. Send to the difficult-to-view area 5. Therefore, even in the urban difficult-to-view area 4 and the mountain difficult-to-view area 5, it is possible to arbitrarily select and receive the radio wave retransmitted from the retransmission device 6. As a result, it is possible to surely eliminate the difficult-to-view area even in the urban area and the mountainous area in the service area.

In the case of digital broadcasting, even if the radio wave of the same frequency as that of the transmitting station 1 is retransmitted from the retransmitting device 6, both radio waves do not affect each other. Therefore, in the difficult-to-view area, the TV receiving the radio wave retransmitted from the retransmitting device 6
The receiver does not need to readjust the received frequency to the frequency of the retransmitted radio wave.

[0025]

As described in detail above, according to the present invention, it is possible to simultaneously receive terrestrial digital broadcasts of a plurality of channels and retransmit the terrestrial digital broadcasts to the difficult-to-view area, thereby eliminating the difficult-to-view area. A transmitter can be provided.

Further, the control unit (MPU 16) controls the amplification degree according to the output level of the RF final-stage amplifier input via the wave detector to keep the signal output level constant and at the same time each receiving unit. Based on the status sent from the device, it is determined whether there is a channel that has finished digital broadcasting, or whether there is a defective receiving unit, etc., so that the amplification degree of the RF final stage amplifier is controlled. Even if there is a channel that has finished broadcasting or a receiving unit that has failed, the signal of each channel output from the RF final-stage amplifier can always be held in a stable state.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a terrestrial digital broadcast retransmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a receiving unit in the same embodiment.

FIG. 3 is a diagram showing an example of a relay system using a terrestrial digital broadcast retransmission device.

[Explanation of symbols]

1 ... Transmitting station 2 ... Building 3 ... mountain 4 ... Urban difficult-to-view areas 5 ... Difficult to view areas in the mountains 6 ... Retransmission device 7 ... Receiving antenna 8 ... Transmission antenna 10 ... Input terminal 11 ... Input filter 12a to 12n ... Receiving unit 13 ... Spare receiving unit 14 ... RF filter 15 ... RF final stage amplifier 16 ... MPU 17 ... Branch circuit 18 ... BPF 19 ... Detector 20 ... Status indicator 21 ... Alarm 22 ... Output filter 23 ... Output terminal 31 ... Input terminal 32 ... Input amplifier 33 ... Input mixer 34 ... Local oscillator 35, 37, 39 ... IF amplifier 36, 38 ... SAW filter 40, 45 ... turnout 41 ... Output mixer 42, 47 ... Detector 43 ... MPU 44 ... RF amplifier 46 ... Output terminal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 7/08 H04B 7/15 Z 7/081 H04N 7/08 Z 7/16 (72) Inventor Makoto Watanabe 3-14-20 Higashi-Nakano, Nakano-ku, Tokyo F-term within Hitachi Kokusai Electric Co., Ltd. (reference) 5C063 AB03 AB05 AB06 AC01 AC05 CA21 5C064 BA01 BB05 BC11 BC14 5K060 CC04 HH08 HH11 HH16 HH32 LL01 5K061 AA11 BB06 CC52 CD04 JJ06 A24 BB03 BB04 BB14 BB27 CC34 DD15 EE19 GG01 GG14

Claims (4)

[Claims] 1. A first filter for selecting a terrestrial digital broadcasting signal received by a receiving antenna for each channel, and a signal for each channel selected by the first input filter is received, amplified, and output. A plurality of receiving units for outputting, a second filter for selecting, extracting, mixing and outputting the signals amplified by the receiving units for each channel, and a final stage for amplifying the output signals of the second filter. An amplifier, a detector that detects the output signal of the final amplifier, a controller that controls the gain of the final amplifier based on the level of the signal detected by the detector, and an amplifier that is amplified by the final amplifier. And a third filter for selecting signals of all channels and outputting them to a transmitting antenna. . 2. A first filter for selecting a terrestrial digital broadcasting signal received by a receiving antenna for each channel, and a signal for each channel selected by the first input filter is received, amplified and output. And a plurality of receiving units for outputting the receiving unit status, a second filter for selecting, extracting, mixing and outputting the signals amplified by the receiving units for each channel, and an output signal of the second filter. A final stage amplifier that amplifies the signal, a detector that detects the output signal of the final stage amplifier, the final stage based on the receiving unit status output from each receiving unit and the level of the signal detected by the detector. A control device that controls the gain of the amplifier and selects and sends the signals of all channels amplified by the final stage amplifier. A terrestrial digital broadcasting retransmitting device, comprising a third filter for outputting to a reception antenna. 3. The plurality of receiving units convert the signals of each channel selected by the first input filter into IF signals, amplify the signals, and then restore the frequencies of the original channels for output. Claim 1 characterized by the above-mentioned.
Or the terrestrial digital broadcasting re-transmission device according to 2. 4. The standby receiving unit is provided for the plurality of receiving units.
The terrestrial digital broadcasting retransmitting device described.