JP7469199B2 - Relay transmitter - Google Patents

Description

The present invention relates to a relay transmitter for terrestrial digital broadcasting, and in particular to a relay transmitter that can reduce the work and labor required for installation and maintenance, significantly improve the efficiency of maintenance work, and further improve the soundness of the device.

Description of the Prior Art
In terrestrial digital broadcasting, due to the structure of the broadcasting network, relay stations are often set up and operated in locations far from the broadcasting station, such as on top of mountains.
Installation and maintenance of digital terrestrial broadcasting relay transmitters (relay transmitters, relay devices) is often carried out during periods when broadcasting is not taking place, and at such times it is necessary to check the operation of the system.

Conventionally, when checking the operation of a relay transmitter, a signal generator that generates a signal equivalent to a broadcast signal is prepared, and the signal from the signal generator is input to the relay transmitter to check the operation.
However, in that case, the signal generator must be carried to the top of the mountain where the relay transmitter is installed. The signal generator weighs about 15 kg, and in many cases the journey to the relay transmitter is on foot, which is time-consuming and difficult.

In addition, the terrestrial digital broadcasting relay transmitter (relay transmitter) is a two-unit system for redundancy. Normally, the PA (Power Amplifier) on the non-operating side (standby side) is stopped and stands by, and a self-check is performed periodically to check its operation by automatic control.
In the self-check, the standby PA is periodically started and operated to check its soundness.
However, if the self-check is performed during a break in broadcasting, the PA will only start and stop, and it cannot be confirmed whether the output is normal.

[Configuration of a conventional relay transmission device: FIG. 7]
Here, the configuration of a conventional relay transmitter will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram showing a schematic configuration of a conventional relay transmitter. Fig. 7 shows the state of the conventional relay transmitter during operation check.
The digital terrestrial broadcasting relay transmitter is a two-unit system, providing redundancy to the system.

As shown in FIG. 7, the conventional relay transmitter 3 includes an input filter 31, a distributor 32, basic sections 33 and 34, PAs 35 and 36, a switching control section 37, output filters 38 and 39, and a dummy load 40.
During operation check, the signal generator 2 is connected to the input terminal, and a pseudo OFDM signal is input to operate each section, thereby checking the operation.

The input filter 31 limits the band of the input signal.
The distributor 32 distributes the band-limited signal into two.
The basic unit and PA have a redundant configuration, with the basic unit 33 and PA 35 being the No. 1 system, and the basic unit 34 and PA 36 being the No. 2 system.

The basic units 33 and 34 are sections that perform basic processing of the relay transmitter, and after performing FFT (Fast Fourier Transform) on the input OFDM signal, they perform equalization processing to remove the effects of interference waves, etc., and generate an OFDM signal again, thereby generating a transmission signal.
A reference signal (10 MHz) for clock generation is input to the basic units 33 and 34, and the reference signal is used when no broadcast wave is input. The No. 1 reference signal is input to the basic unit 33, and the No. 2 reference signal is input to the basic unit 34.

The PAs 35 and 36 amplify a transmission signal, and one of them operates as an active system, while the other is in a stopped state and stands by.
The switching control unit 37 receives an amplified transmission signal from either the PA 35 of the No. 1 system or the PA 36 of the No. 2 system, and outputs it to the output filter 38 under normal circumstances, and to the output filter 39 when checking operation.

The output filter 38 receives an ordinary broadcast signal, performs band restriction, and outputs a transmission signal to the shared transmission unit 4 .
The output filter 39 receives an untransmittable signal such as a pseudo signal from the signal generator 2 , limits the band, and outputs the signal to a dummy load 40 .
The dummy load 40 is a resistor with a large capacity, and acts as a pseudo load to absorb the energy of the input signal.

[Signal generation function]
The relay transmitter is provided with a function for outputting a pseudo signal (pseudo broadcast wave signal, pseudo OFDM signal) for a short period of time only.
This has the role of complementing the waveform to continue broadcasting in the event of a momentary interruption in the input signal during operation, and its duration is 250 msec.

Because it is used as a waveform complement, it will be interrupted after only one time. In other words, the pseudo signal generator that generates the pseudo signal outputs a pseudo signal when it detects a momentary interruption in the broadcast wave input, and cuts off the output 250 msec after the output starts.

[Related Technology]
Incidentally, conventional techniques relating to wireless relay devices include JP 2001-309201 A “STL/TTL relay device” (Patent Document 1), JP 2005-210299 A “wireless relay system” (Patent Document 2), and JP 2009-182943 A “relay transmission device” (Patent Document 3).

Patent Document 1 describes an STL/TTL repeater device in which an IF band filter for a broadcasting device is configured with a digital filter, and which extracts only a desired channel with stable characteristics during multi-channel transmission repeat.
Patent document 2 describes a method in which an interference signal is generated when a synchronization signal is detected from the output of an FM demodulation circuit, and the interference signal is used to determine whether an analog FM modulated signal is received on the same channel when a digitally modulated signal is received.
Patent Document 3 describes a configuration for a relay transmitting device using a loop interference canceller, which prevents repeated system switching of the transmitting device due to oscillation.

JP 2001-309201 A JP 2005-210299 A JP 2009-182943 A

As described above, with conventional relay transmitters, when checking the operation during a broadcast interruption, it was necessary to transport the signal generator to the installation site of the equipment and connect it there, which required time and effort and reduced the efficiency of maintenance work.
Furthermore, in the conventional relay transmitter, when a self-check is performed during a broadcast break, it is not possible to check the output of the standby PA.

Note that Patent Documents 1 to 3 do not mention that the basic section of the relay transmitter has a test mode that continuously outputs a pseudo broadcast wave signal (pseudo broadcast wave signal), and that when the test mode is set, the pseudo broadcast wave signal is output to the downstream PA.

The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a relay transmitter that eliminates the need for a signal generator during operation check and can significantly improve the efficiency of maintenance work.
Another object of the present invention is to provide a relay transmitter that can improve the soundness of the device by checking the output of the standby side PA during a self-check.

The present invention, which aims to solve the problems of the above-mentioned conventional examples, is a relay transmitter that relays broadcast wave signals, and comprises a basic unit that performs relay processing by demodulating, equalizing, and remodulating the received broadcast wave signal before outputting it, an amplifier unit that amplifies the output signal from the basic unit, and a control unit that controls the basic unit. The present invention comprises two sets of basic units and amplifier units, one of which is an operational system and the other a standby system. The basic unit has an operational mode in which relay processing is performed, and a test mode in which a pseudo broadcast wave signal is output in place of the broadcast wave signal. When the test mode is set when no broadcast wave signal is input , the control unit controls the basic unit to continuously generate pseudo broadcast wave signals and output them to the amplifier unit, and periodically causes the basic unit and amplifier unit of the standby system to perform self-checks to check their operation. When the self-check begins, the control unit detects whether a broadcast wave signal is input, and if a broadcast wave signal is not input, the control unit sets the test mode and causes the basic unit of the standby system to continuously output the pseudo broadcast wave signal .

The present invention is also characterized in that, in the relay transmitter, when the test mode is set, the control unit controls the basic unit to re-modulate the signal to a pseudo broadcast wave signal using pseudo data carriers and pseudo control information generated internally, instead of the data carriers and control information extracted from the signal obtained by demodulating and equalizing the broadcast wave signal, to generate a pseudo broadcast wave signal.

The present invention is also characterized in that in the relay transmitter, when the control unit receives an external command to switch to the test mode, it detects whether or not a broadcast wave signal is being input, and if a broadcast wave signal is being input, it controls the basic unit to maintain the operation mode without setting the test mode.

In addition, the present invention relates to a relay transmitter in which the basic unit includes a clock extraction unit that extracts a broadcast wave synchronization signal from the orthogonally demodulated broadcast wave signal, a demodulation and equalization processing unit that OFDM demodulates and equalizes the orthogonally demodulated signal, a data extraction unit that extracts a data carrier from the equalized signal, a control information extraction unit that extracts control information other than the data carrier from the equalized signal, a remodulation processing unit that OFDM modulates the input signal, a clock generation unit that generates a clock based on a reference signal input from the outside, a first switch that is connected to the output of either the clock extraction unit or the clock generation unit and outputs a clock to be used for internal signal processing, and a pseudo data carrier that replaces the data carrier extracted from the equalized signal. The device is characterized in that it includes a pseudo signal generating unit, a second switch that outputs the output of either the data extracting unit or the pseudo signal generating unit to the remodulation processing unit, a control information generating unit that generates pseudo control information in place of the control information extracted from the equalized signal, and a third switch that outputs the output of either the control information extracting unit or the control information generating unit to the remodulation processing unit, and that when the operation mode is set, the control unit switches the first switch to the clock extracting unit side, the second switch to the data extracting unit side, and the third switch to the control information extracting unit side, and when the test mode is set, the control unit switches the first switch to the clock generating unit side, the second switch to the pseudo signal generating unit side, and the third switch to the control information generating unit side.

According to the present invention, a relay transmitter for relaying a broadcast wave signal includes a basic section for performing relay processing of demodulating, equalizing, and remodulating the received broadcast wave signal and outputting it, an amplifier section for amplifying the output signal from the basic section, and a control section for controlling the basic section . The relay transmitter includes two sets of a basic section and an amplifier section, one of which is an active system and the other is a standby system. The basic section has an active mode for performing relay processing and a test mode for outputting a pseudo broadcast wave signal instead of the broadcast wave signal, and when the test mode is set in a state where no broadcast wave signal is input, the control section controls the control section to continuously generate the pseudo broadcast wave signal and output it to the amplifier section , and periodically causes the standby system basic section and amplifier section to perform self-checks to check their operation, and a security function is provided. When the self-check begins, the relay transmitter detects whether a broadcast wave signal is being input, and if no broadcast wave signal is being input, it sets the test mode and continuously outputs a pseudo broadcast wave signal from the basic unit of the standby system. Therefore, when installing or maintaining the relay transmitter, it is possible to check the operation of the amplifier unit using the pseudo broadcast wave signal output from the basic unit without having to carry a large, heavy signal generator to the top of a mountain where the relay transmitter is installed, and the efficiency of maintenance work can be greatly improved . Furthermore, even if the timing of the self-check is during a broadcast break, the pseudo broadcast wave signal can be used to operate the PA and check the output characteristics, which has the effect of improving the soundness of the device .

In addition, according to the present invention, when the control unit receives an external command to switch to the test mode, the relay transmitter detects whether or not a broadcast wave signal is being input, and if a broadcast wave signal is being input, the relay transmitter controls the basic unit to maintain the operation mode without setting the test mode, which has the effect of preventing a pseudo broadcast wave signal from being output from the relay transmitter.

FIG. 2 is an explanatory diagram showing a schematic configuration of the present relay transmitter. FIG. 2 is a block diagram showing the configuration of the basic part of the present relay transmitter. FIG. 4 is an explanatory diagram of an input detection and display control circuit. FIG. 4 is an explanatory diagram of a UNIT display control circuit. FIG. 4 is an explanatory diagram of a mode switching control circuit. FIG. 4 is an explanatory diagram of an abnormality detection circuit. FIG. 1 is an explanatory diagram showing a schematic configuration of a conventional relay transmitter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
The relay transmitter of the embodiment of the present invention (this relay transmitter) has, as basic operating modes, an operation mode and a simple SG (Signal Generator) mode that outputs a pseudo broadcast wave signal (pseudo OFDM signal), and a mode change switch provided on the top panel makes it possible to switch between the operation mode and the simple SG mode. When the simple SG mode is set, the control unit causes the pseudo signal generation unit to continuously output pseudo data signals, and the remodulation processing unit combines control information obtained in advance from the received signal with the pseudo data signal to perform OFDM remodulation to generate and output a pseudo OFDM signal. This makes it possible to output a pseudo OFDM signal to a connected PA to check its operation even without a signal generator, thereby improving the efficiency of maintenance work.

In addition, in this relay transmitter, the control unit determines whether or not a broadcast wave signal is being input when the standby PA self-check begins, and if there is no input, it sets the simple SG mode and outputs a pseudo-OFDM signal. Therefore, even if the self-check occurs during a broadcast outage, the pseudo-OFDM signal can be input to the PA to operate it and the output signal can be checked, improving the health of the standby PA.

[Configuration of this repeater transmitter: Figure 1]
The configuration of this relay transmitter will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing the schematic configuration of this relay transmitter.
As shown in FIG. 1, the basic configuration of this relay transmitter 1 is a redundant configuration similar to that of the conventional relay transmitter 3 shown in FIG. 7, and includes an input filter 11, a distributor 12, basic units 13 and 14, PAs 15 and 16, a switching controller 17, output filters 18 and 19, and a dummy load 20.
Among these components, the configuration and operation of the basic units 13 and 14 are partially different from the conventional ones, while the configuration and operation of the other units are the same as the conventional ones, and therefore the description thereof will be omitted.

The basic units 13 and 14 are basic units with a signal generating function that have a function (signal generating function) of outputting a pseudo broadcast wave signal as a simple signal generator.
The signal generation function is a function for outputting a pseudo OFDM signal as a pseudo broadcast wave signal used for checking the operation of the device when installing or maintaining a relay transmitter.

When the relay transmitter is installed or maintained, pseudo OFDM signals can be output from the basic units 13 and 14 to operate the downstream PAs 15 and 16, thereby enabling confirmation of the output.
Therefore, with this repeater transmitter, there is no need to connect a signal generator when checking the operation.

This makes it possible to check the operation of a large, heavy signal generator without having to transport it up the mountain where the relay transmitter is installed, reducing the amount of work required and shortening the time required for installation and maintenance work, thereby making it possible to improve the efficiency of the work.
Furthermore, since there is no need to wait for one's turn using the limited number of signal generators, the operation of a plurality of relay transmitters can be checked simultaneously, thereby further improving efficiency.

[Configuration of the basic part of this repeater transmitter: Figure 2]
The configuration of the basic unit 13 of this broadcast repeater will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of the basic unit of this repeater transmitter. Note that although the basic unit 13 will be described here, the basic unit 14 has the same configuration and operation.
As shown in FIG. 2, the basic unit 13 includes a signal receiving unit 71 , an A/D (Analog/Digital) conversion unit 72 , a digital processing unit 73 , and a D/A (Digital/Analog) conversion unit 74 .

Furthermore, this relay transmitter is equipped with a control signal output unit 75 that controls the basic units 13 and 14. Note that the control signal output unit 75 corresponds to the control unit described in the claims, and controls both the basic units 13 and 14, and is shown in FIG. 2 for the sake of explanation.

Furthermore, the digital processing unit 73 includes an orthogonal demodulation unit 51, a clock extraction unit 52, an FFT unit 53, an equalization processing unit 54, a data extraction unit 55, a data storage unit 56, a remodulation processing unit 58, an orthogonal modulation unit 59, a clock generation unit 61, a pseudo signal generation unit 62, and switches S1, S2, and S3.

Each part of the basic unit 13 will be described.
The signal receiving unit 71 receives the signal output from the distributor 12 of FIG.
The A/D converter 72 performs A/D conversion on the received signal.
The digital processing unit 73 demodulates the received signal, performs equalization processing, and then modulates it again to generate a signal for transmission.
The D/A conversion unit 74 performs D/A conversion on the signal to be transmitted.

The control signal output unit 75 is a characteristic part of this relay transmitter, and manages the operating mode of the basic units 13 and 14, and switches and sets the operating mode to "operation mode" or "simple SG mode" depending on the state of the mode change switch provided on the top plate. Note that the "simple SG mode" is sometimes called the "test mode." The simple SG mode corresponds to the test mode described in the claims.

"Operation mode" is an operation mode that relays broadcast waves during normal operation, while "simple SG mode" is an operation mode that outputs a pseudo-OFDM signal to the downstream PA during device installation or maintenance, and does not relay broadcast waves.

The control signal output section 75 controls each section of the basic sections 13 and 14, and controls the switches S1, S2, and S3 of the digital processing section 73 in accordance with the set operation mode.
Furthermore, the control signal output unit 75 displays the current operating mode and the input and output states on an LED display unit provided on the top panel of the basic unit.

Furthermore, although not shown in the figure, in this repeater transmitter, the control signal output unit 75 also controls a self-check similar to the conventional method. Specifically, it periodically starts up the standby basic unit and PA that are in a stopped state to check their operation.
In this case, if a broadcast wave signal is input to this relay transmitter, it checks its operation using the broadcast wave signal as in the conventional case, and if the broadcast wave signal is not input due to a broadcast interruption, etc., it sets the simple SG mode and outputs a pseudo-OFDM signal from the basic unit 13 or 14 on the standby side.
This allows the PA 15 or 16 at the rear stage of the standby basic unit 13 or 14 to carry out an amplification operation and check the output. The operation of the control unit 75 will be described later.

Each part of the digital processing unit 73 will now be described.
The quadrature demodulation unit 51 performs quadrature demodulation on the A/D converted input signal and outputs an I signal and a Q signal.
The clock extraction unit 52 extracts the clock of the broadcast wave synchronization signal from the quadrature demodulated signal.
The clock generating unit 61 generates a clock based on a reference signal input from the outside.

The switch S1 outputs either the clock signal from the clock extraction unit 52 or the clock signal from the clock generation unit 61 for use in signal processing within the device.
The switch S1 is switched by a switch change-over signal from a control signal output unit 75, which will be described later.

The FFT unit 53 receives the I and Q signals and performs a fast Fourier transform to generate a carrier symbol in the frequency domain.
The equalization processing unit 54 performs equalization processing to remove the influence of the diffraction wave.
The combination of the FFT section 53 and the equalization processing section 54 corresponds to a demodulation and equalization section recited in the claims.
The data extraction unit 55 extracts data carriers from the equalized carrier information and stores them in the data storage unit 56, and also reads out the data carriers from the data storage unit 56 and outputs them.
The data storage unit 56 stores the extracted data carriers.

The pseudo signal generating unit 62 outputs pseudo data, outputting pre-stored data as a data carrier (pseudo data signal). The stored data may be data extracted from previously received signals, or may be newly generated data arbitrarily by the pseudo signal generating unit 62. The internally generated pseudo data described in the claims corresponds to the data output from the pseudo signal generating unit 62.

In this relay transmitter, when the simple SG mode is set, the pseudo signal generating section 62 continues to output data carriers continuously without interruption in response to an instruction from the control signal output section 75 .
In addition, in conventional relay transmitters, the pseudo signal generating unit 62 operates for only 250 msec to output a data carrier when the input of the broadcast wave is momentarily interrupted, but the present relay transmitter also operates in the same manner in the operation mode.

In addition, the pseudo signal generating unit 62 is capable of not only outputting a data carrier for generating an OFDM modulated signal, but also outputting an unmodulated CW (Continuous Wave), and the CW is output directly to the output terminal of the basic unit 13.
As described later, in the simple SG mode, this repeater transmitter has a modulated wave output mode that outputs a modulated wave and a CW output mode that outputs a CW, and can be set according to the type of test required.

The switch S 2 outputs either the data carrier from the data extraction unit 55 or the data carrier from the pseudo signal generation unit 62 to the remodulation processing unit 58 .
The switch S 2 is switched by a switch change-over signal from the control signal output unit 75 .

The control information extraction unit 57 extracts carrier information (control information) other than the data carrier from the equalized carrier information.
The control information generating unit 63 outputs pre-stored control information (pseudo control information) as carrier information other than the data carrier. The stored control information may be control information extracted from previously received broadcast wave signals, or may be control information newly generated by the control information generating unit 63. The pseudo control information generated internally as described in the claims corresponds to the control information stored in the control information generating unit 63.

Then, the switch S 3 outputs either the control information from the control information extraction unit 57 or the control information from the control information generation unit 63 to the remodulation processing unit 58 .
The switch S 3 is also switched by a switch change-over signal from the control signal output section 75 .

The remodulation processing unit 58 performs IFFT (Inverse Fast Fourier Transform) processing using the data carrier input via switch S2 and the control information input via switch S3 to generate an OFDM signal.
The orthogonal modulation section 59 performs orthogonal modulation on the OFDM signal to generate data for transmission.

[Toggle switch]
Next, the switching of the switches S1, S2, and S3 of the digital processing unit 73 will be described with reference to FIG.
The operation mode set in the control signal output unit 75 is normally the "operation mode."
In the "operation mode", the switch S1 is switched to the clock extraction unit 52 side, the switch S2 is switched to the data extraction unit 55 side, and the switch S3 is switched to the control information extraction unit 57 side.

In other words, in the operational mode, the broadcast wave synchronization signal extracted by the clock extraction unit 52 is used as a clock, the received broadcast wave signal is equalized, and the signal is re-modulated using the data carrier extracted by the data extraction unit 55 and the control information extracted by the control information extraction unit 57 to obtain transmission data.
As a result, in an operation mode in which broadcast waves are relayed, a digitally equalized broadcast wave signal is output from the basic unit 13 as a transmission signal, which is amplified and then radiated from the antenna.

On the other hand, when the mode change switch provided on the top panel of this relay transmitter is pressed and the simple SG mode is turned ON, the control signal output unit 75 switches and sets the operating mode to "simple SG mode" and outputs a switch change signal (SW change signal) to switches S1, S2, and S3.
The simple SG mode is set when the device is installed or during maintenance, and usually when no broadcast wave signal is input, such as during a broadcast break.
Specifically, when the simple SG mode is turned on, the switch S1 is switched to the clock generating unit 61 side, the switch S2 is switched to the pseudo signal generating unit 62 side, and the switch S3 is switched to the control information generating unit 63 side.

In other words, in the simple SG mode, since there is no input of a broadcast wave signal, the clock generated by the clock generating unit 61 is used to re-modulate the data to be transmitted using the data carrier (or newly generated data carrier) previously stored in the pseudo signal generating unit 62 and the control information (or newly generated control information) previously stored in the control information generating unit 63.
As a result, in the simple SG mode, a pseudo-OFDM signal generated by the basic unit 13 is output as a pseudo broadcast wave signal, and even when broadcasting is suspended, the operation of the downstream PA 15 can be checked and the output characteristics can be obtained.

[Various controls in the control signal output section: Figures 3 to 6]
Next, the control by the control signal output unit 75 will be described.
Inside the top panel of the basic unit, there are LEDs labeled "input detection,""outputdetection,""referencesignal,""equalization,""synchronization," and "UNIT" to indicate the operating status of the basic unit, and each of them lights up red or green or flashes depending on the status. The control signal output unit 75 controls the display of these.

In particular, this relay transmitter has a new operating mode called simple SG mode, so to ensure that workers are aware that it is in simple SG mode, a display format different from conventional methods is used. This makes it possible to alert workers without adding additional LEDs to the top panel of the device.

The control signal output unit 75 also controls mode switching and abnormality detection in relation to the simple SG mode. The control signal output unit 75 is equipped with control circuits that perform these controls, and each control circuit will be described using Figures 3 to 6.

[Input detection and display control circuit: Figure 3]
The input detection and display control circuit will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram of the input detection and display control circuit.
The control signal output unit 75 detects whether or not a broadcast wave signal is being input, and controls the display of the "input detection" LED display unit. In this broadcast wave repeater, the "input detection" LED display unit is used to display that the "simple SG mode" is set.
As shown in FIG. 3, the input detection display control circuit includes AND circuits 81, 83 and an inversion circuit 82, and receives as inputs an input detection signal and a simple SG mode ON signal. The output of the AND circuit 81 is connected to a green (G) input detection LED, and the output of the AND circuit 83 is connected to a red (R) input detection LED.

The input detection signal is then branched into two, one of which is input to one input terminal of an AND circuit 81 , and the other branched input detection signal is input to one input terminal of an AND circuit 83 via an inversion circuit 82 .
The other input terminals of the AND circuits 81 and 83 receive an inverted simple SG mode ON signal.

As a result, when there is an input signal and the simple SG mode is not ON (when in the operation mode), the input detection LED lights up in green.
Also, if there is no input signal and the simple SG mode is not ON, this indicates an input abnormality and the input detection LED lights up in red.

Furthermore, when there is no input signal and the simple SG mode is ON, the input detection LED is turned off without lighting up either red or green.
In other words, the input detection LED, which would conventionally be lit in either red or green, is now off, thereby making it possible to notify the operator that the simple SG mode is in effect.

[UNIT display control circuit: Figure 4]
Next, the UNIT display control circuit of the control signal output unit 75 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram of the UNIT display control circuit.
4, the UNIT display control circuit includes an inversion circuit 84, AND circuits 85 and 86, and an OR circuit 87, and receives the device abnormality signal and the simple SG mode ON signal as inputs. The AND circuit 85 also receives a clock that turns on and off at 0.5 sec intervals.

The device abnormality signal is branched into two, one of which is output to a red UNIT display LED, and the other of which is inverted by an inverter circuit 84 and input to one input terminal of each of AND circuits 85 and 86 .
The simple SG mode ON signal is input to the other input terminal of the AND circuit 85 and is inverted and input to the other input terminal of the AND circuit 86 .

As a result, the LED on the UNIT lights up red when an abnormality occurs in the device, and lights up green when the device is normal and the simple SG mode is OFF.
In addition, when the device is normal and the simple SG mode is ON, the UNIT LED will flash green to notify the operator that the device is in maintenance mode and to draw his or her attention.

[Mode switching control circuit: Figure 5]
Next, the mode switching control circuit of the control signal output unit 75 will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram of the mode switching control circuit, where (a) is a simple SG mode switching circuit, and (b) is a CW mode switching circuit.
In this relay transmitter, when a broadcast wave signal is being input, the control signal output unit 75 controls the mode switching control circuit so as not to turn on the simple SG mode.
As shown in FIG. 5A, the mode switching control circuit has an AND circuit 91, and when the simple SG mode switch (corresponding to the above-mentioned "mode switching switch") is turned ON, if the input detection signal is OFF, the simple SG mode is turned ON.

Even if the simple SG mode switch is turned ON, if the input detection signal is ON, the simple SG mode remains OFF and the operation mode is maintained.
As a result, even if the simple SG mode switch is pressed while broadcast waves are being input, the generation of the pseudo signal is stopped and the relaying of the broadcast waves is continued, so that pseudo data from the pseudo signal generating unit 62 is not output from the relay transmitter.

In addition, in the simple SG mode, this repeater transmitter allows testing with not only modulated waves (MOD) but also continuous waves (CW), and is equipped with a MOD/CW changeover switch (simple SG CW mode switch) on the top panel of the basic unit 13.
5B, the CW mode setting circuit includes an AND circuit 92. When the simple SG mode switch is turned ON and the simple SG CW mode switch is turned ON, the simple SG mode is switched to CW mode, and the control signal output unit 75 controls the pseudo signal generating unit 62 to output CW.

[Abnormality detection circuit: Figure 6]
Next, the abnormality detection circuit of the control signal output unit 75 will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram of the abnormality detection circuit.
As shown in FIG. 6, the abnormality detection circuit includes an EXOR circuit 93 and an AND circuit 94. The EXOR circuit 93 receives the input of the input detection signal and the output detection signal. The AND circuit 94 receives the output of the EXOR circuit 93 and the ON signal of the simple SG mode. The output of the AND circuit 94 is connected to the device abnormality.

The EXOR circuit 93 outputs "1" when only one of the input detection and output detection is ON, and in the operation mode (simple SG mode is OFF), when only one of the input and output is detected, an apparatus abnormality signal is output.
However, when the simple SG mode is ON, the output from the AND circuit 94 is always "0" and no device abnormality signal is output. This is because in the simple SG mode, "input is not detected, but output is detected" is a state, and this state is not detected as a device abnormality.

[Self-check operation]
Furthermore, in this relay transmitter, the standby basic unit 13 or 14 and the PA 15 or 16 are periodically started up to check their operation.
When the self-check timing arrives, the control signal output unit 75 judges whether or not there is an input detection, and if there is an input detection, carries out a self-check on the standby side while maintaining the operation mode.
In this case, the basic unit and PA on the standby side check their operation using broadcast wave signals.

In addition, if no input is detected due to a broadcast interruption or the like, the control signal output unit 75 turns on the simple SG mode, switches the operating mode from the operational mode to the simple SG mode, switches S1, S2, and S3, and causes the pseudo signal generating unit 62 to continuously output data carriers for the pseudo signal.
As a result, even if the timing of the self-check overlaps with a broadcasting break, the operation of the standby PA can be checked up to the point of output, thereby improving the soundness of the device.

[Mutual complementation of reference signals]
Furthermore, in this repeater transmitter, if an abnormality occurs in the local oscillator that generates the reference signal, the basic units of the redundant configuration are arranged to mutually complement each other's reference signals.
Specifically, as shown in FIG. 1, reference signal No. 1 is input to basic unit 13, and reference signal No. 2 is input to basic unit 14, but in this relay transmitter, each basic unit is provided with a terminal for outputting a reference signal to the other basic unit, and a terminal for inputting a reference signal from the other basic unit (not shown).

That is, the basic unit 13 has a No. 1 reference signal output terminal that outputs the No. 1 reference signal to the basic unit 14 and a No. 2 reference signal input terminal that inputs the No. 2 reference signal from the basic unit 14 .
Similarly, the basic unit 14 is provided with a No. 2 reference signal output terminal that outputs the No. 2 reference signal to the basic unit 13 , and a No. 1 reference signal input terminal that inputs the No. 1 reference signal from the basic unit 13 .

For example, if No. 1 (basic unit 13 and AMP 15) of the redundant configuration is in operation and No. 2 (basic unit 14 and AMP 16) is in standby, if an abnormality occurs in the No. 1 reference signal, the system will switch to No. 2 and continue operation.
At that time, the No. 1 basic unit 13 temporarily restores the frequency conversion function by using the No. 2 reference signal input from the No. 2 basic unit 14 in place of the No. 1 reference signal that has become abnormal locally.

This means that, for example, if an abnormality occurs in AMP16 of No. 2 while it is in operation (No. 2 reference signal is normal), as long as No. 1 is able to convert the frequency normally, it will be possible to switch back to No. 1 and continue operation.

[Effects of the embodiment]
According to this relay transmitter, the basic units 13, 14 have operating modes including an operation mode and a simple SG mode in which a pseudo broadcast wave signal (pseudo OFDM signal) is output, and a mode change switch provided on the top panel makes it possible to switch between the operation mode and the simple SG mode. When the simple SG mode is set, the control signal output unit 75 causes the pseudo signal generation unit 62 to continuously output data carriers of the pseudo signal, and the remodulation processing unit 58 combines the control information acquired in advance from the received signal with the pseudo signal to perform OFDM remodulation to generate and output a pseudo OFDM signal. This makes it possible to output a pseudo OFDM signal to the connected PAs 15, 16 to check operation even without a signal generator, and has the effect of significantly reducing the labor required for maintenance work, shortening time, and improving efficiency.

In addition, with this relay transmitter, the control signal output unit 75 determines whether or not a broadcast wave signal is input when the standby PA self-check begins, and if there is no input, it sets the simple SG mode and outputs a pseudo-OFDM signal. Therefore, even if the self-check occurs during a broadcast halt, the pseudo-OFDM signal can be input to the PA to operate it and check the output signal, which has the effect of improving the health of the standby PA.

In addition, with this relay transmitter, even when the mode change switch on the top panel is pressed to instruct switching to simple SG mode, the control signal output unit 75 determines whether a broadcast wave signal is being input, and if a broadcast wave signal is being input, it does not switch to simple SG mode and controls the pseudo signal generation unit 62 not to output continuous data carriers, which has the effect of preventing meaningless pseudo data from being output.

In addition, with this relay transmitter, when the simple SG mode is ON, the control signal output unit 75 turns off the "input detection" LED on the top panel of the device and blinks the green "UNIT" LED, providing a display in a manner not seen in the past, thereby informing the operator that the simple SG mode for maintenance is set and encouraging them to be careful.

The present invention is suitable for relay transmitters, which can significantly improve the efficiency of maintenance work and further improve the soundness of the equipment.

1, 3... relay transmitter, 2... signal generator, 4... transmission duplexer, 11... input filter, 12... distributor, 13, 14... basic unit with signal generation function, 15, 16... PA (amplification unit), 17... switching control unit, 18... output filter (normal), 19... output filter (spare), 20... dummy load, 51... quadrature demodulation unit, 52... clock extraction unit, 53... FFT unit, 54... equalization processing unit, 55... data extraction unit, 56... data storage unit, 57... control information extraction unit, 58... remodulation processing unit, 59... quadrature modulation unit, 61... clock generation unit, 62... pseudo signal generation unit, 63... control signal generation unit, 71... signal receiving unit, 72... A/D conversion unit, 73... digital processing unit, 74... D/A conversion unit 81, 83, 85, 86, 91, 92, 94...AND circuit, 82, 84...inverting circuit, 87...OR circuit, 93...EXOR circuit

Claims (4)

A relay transmitter that relays a broadcast wave signal,
A basic unit that performs relay processing by demodulating, equalizing, and remodulating the received broadcast wave signal and outputting it;
an amplifier section for amplifying an output signal from the fundamental section;
A control unit that controls the basic unit,
two sets of the basic unit and the amplifier unit, one set being an active system and the other set being a standby system;
The basic unit has an operation mode in which the relay process is performed and a test mode in which a pseudo broadcast wave signal is output instead of a broadcast wave signal,
A relay transmitter characterized in that, when the control unit is set in a state where the broadcast wave signal is not input, the control unit controls the unit to continuously generate the pseudo broadcast wave signal and output it to the amplifier unit, periodically causes the basic unit and amplifier unit of the standby system to perform self-checks to confirm their operation, detects whether the broadcast wave signal is being input when the self-check starts, and if the broadcast wave signal is not being input, sets the test mode and causes the basic unit of the standby system to continuously output the pseudo broadcast wave signal . The relay transmitter according to claim 1, characterized in that, when the test mode is set, the control unit controls the basic unit to re-modulate the signal to a pseudo broadcast wave signal using pseudo data carriers and pseudo control information generated internally instead of the data carriers and control information extracted from the demodulated and equalized broadcast wave signal. The relay transmitter according to claim 1 or 2, characterized in that the control unit detects whether a broadcast wave signal is being input when an external command is issued to switch to the test mode, and if the broadcast wave signal is being input, controls the basic unit not to set the test mode and to maintain the operation mode. A clock extraction unit that extracts a broadcast wave synchronization signal from the broadcast wave signal that has been quadrature demodulated by the basic unit;
a demodulation and equalization processing unit that performs OFDM demodulation and equalization on the orthogonally demodulated signal;
a data extractor for extracting a data carrier from the equalized signal;
a control information extraction unit for extracting control information other than the data carrier from the equalized signal;
a remodulation processing unit that performs OFDM modulation on an input signal;
a clock generating unit that generates a clock based on a reference signal input from an external device;
a first switch that is connected to an output of either the clock extraction unit or the clock generation unit and outputs a clock used for internal signal processing;
a pseudo signal generator for generating pseudo data representing the data carriers extracted from the equalized signal;
a second switch that outputs an output of either the data extraction unit or the pseudo signal generation unit to the remodulation processing unit;
a control information generating unit for generating pseudo control information in place of the control information extracted from the equalized signal;
a third switch that outputs an output of either the control information extraction unit or the control information generation unit to the remodulation processing unit;
A relay transmitter as described in any one of claims 1 to 3, characterized in that when an operation mode is set, a control unit switches the first switch to the clock extraction unit side, the second switch to the data extraction unit side, and the third switch to the control information extraction unit side, and when a test mode is set, the control unit switches the first switch to the clock generation unit side, the second switch to the pseudo signal generation unit side, and the third switch to the control information generation unit side.

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