JP2006270228A - Relay transmission system, transmitter switching apparatus, and switching method of transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relay transmission system capable of preventing affect onto a transmission radio wave and uninterruptibly switching and outputting radio waves outputted from two transmitters and to provide a transmitter switching apparatus and switching method. <P>SOLUTION: A phase shifter 52 is inserted between an output terminal 1o of a 90-degree hybrid 51 receiving radio waves transmitted from first and second transmitters 1, 2 and one input terminal 1i of a 90-degree hybrid 54 the output terminal of which is connected to an antenna 7, a phase shifter 53 is inserted between the other input terminal 2i and an output terminal 2o, and setting the phase setting of the phase shifter 52 to 180° or 0° switches an output of the first transmitter 1 or an output of the second transmitter 2 for the radio wave output from the hybrid 54 to the antenna 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a relay transmission system, a transmitter switching device, and a transmitter switching method for relaying a digital broadcast program signal.

  In recent years, public broadcasting has become digital. For example, when the broadcast program signal is wirelessly relayed and transmitted from the studio to the transmitting station, a redundant relay transmission system that switches between two transmitters is used so that the broadcast is not interrupted. And since the relay transmission system digitizes broadcasts and further relays high-definition video signals, it is required to switch without interruption at the baseband bit unit level so that visual anomalies are not recognized at the time of switching. Has been. For this reason, some relay transmission systems employ a non-instantaneous switching method that accurately controls switching timing between two transmitters (for example, Patent Document 1).

  FIG. 4 is a functional block diagram showing a transmitter switching system in a conventional relay transmission system.

  4, the conventional relay transmission system includes a first transmitter 10, a second transmitter 20, two transmitters 10, and a transmitter 20 that transmit signals input from the first system and the second system. Are provided with a switching unit 50 that switches the transmission radio wave to be output to the antenna 70, a switching control unit 60 that supplies a switching control signal to the switching unit 50, an antenna 70, and a load 80.

  The switching unit 50 includes, for example, a diode switch 51 to which transmission radio waves from the first transmitter 1 and the second transmitter 2 are input. One output terminal of the diode switch 51 is connected to the antenna 70 and the other output terminal. Are connected to a dummy load 80.

However, in the conventional switching method of the relay transmission system, a diode switch or a mechanical switch by mechanical contact is used for the switching unit, so noise is generated in the transmission radio wave due to the transient phenomenon of the high frequency signal accompanying switching of two transmitters. This easily affects the demodulated signal on the receiving side. As a result, the conventional relay transmission system has a problem that an uninterruptible switching failure in which an error occurs in a broadcast program signal due to the fact that the demodulator of the receiver that receives the relay radio wave cannot accurately detect and demodulate.
Japanese Patent No. 3485993 (page 10, FIG. 1)

  In a transmission apparatus that relays and transmits a conventional broadcast program, when two transmitters are switched, noise is easily generated in a transmission radio wave. In addition, although the demodulator of the receiver is in a short time, it cannot accurately detect and demodulate, so that there is a problem that switching noise that causes an error in the broadcast program signal occurs.

  The present invention has been made in order to solve the above-described problem. A relay transmission system and a transmitter switching which can prevent the transmission radio waves from being affected and can switch the radio waves output from the two transmitters without interruption. An object is to provide an apparatus and a switching method.

  In order to achieve the above object, the relay transmission system of the present invention is a relay transmission system that outputs either one of the first and second transmitter outputs having the same frequency and phase to the antenna via the switching unit. The first and second transmitters, a frequency / phase control unit that performs monitoring control to align the frequency and phase of the first and second transmitters, and the frequency / phase control unit performs the monitoring control. A switching control signal for switching from the output of the transmitting transmitter to the output of the other transmitter of the two units by a switching command generated when an abnormality is detected or a switching command input by an input means such as a switch And a switching control unit that outputs the first transmitter output to one input terminal and the second transmitter output to the other input terminal. The first A first phase shifter that is connected to one output terminal of the 90-degree hybrid and receives a switching control signal for setting the phase setting to 180 ° or 0 ° from the switching control unit; and the first 90-degree A second phase shifter connected to the other output terminal of the hybrid and having a phase set to 0 °; an output of the first phase shifter is input to one input terminal; and the second phase shifter is The second 90-degree hybrid is connected to the antenna, and one output terminal is connected to the antenna.

  Further, in the transmitter switching device of the relay transmission system of the present invention, the first and second frequency / phase control units that perform monitoring and control of the output radio wave have the same frequency and phase of the radio wave output from each. In the switching device of the transmitter of the relay transmission system that outputs any one of the radio waves output from the transmitter to the antenna via the switching unit, when the frequency / phase control unit detects the abnormality by the monitoring control A switching control signal for switching from the output of the transmitting transmitter of the two units to the output of the other transmitter is output to the switching unit by a generated switching command or a switching command input by an input means such as a switch. A switching control unit configured to switch the first transmitter output to one input terminal and the second transmitter output to the other input terminal. A first phase shifter which is connected to one output terminal of the first 90-degree hybrid, and to which a switching control signal for setting the phase setting to 180 ° or 0 ° is input from the switching control unit; A second phase shifter connected to the other output terminal of the first 90-degree hybrid and having a phase set to 0 °; and an output of the first phase shifter is input to one input terminal; The second phase shifter is connected to the other input terminal, and one output terminal is composed of a second 90-degree hybrid connected to the antenna.

  Furthermore, the transmitter switching method of the relay transmission system according to the present invention is a relay transmission system that outputs either one of the first and second transmitter outputs having the same frequency and phase to the antenna via the switching unit. In the transmitter switching method, the relay transmission system includes first and second transmitters, a frequency / phase control unit, a switching control unit, and a switching unit, and the frequency / phase control unit includes: The first and second transmitters, when the monitoring control detects an abnormality, generates a switching command and outputs the switching command to the switching control unit, the switching control unit, the output switching command, or A switching control signal for switching from the output of the transmitting transmitter of the two units to the output of the other transmitter is output to the switching unit by a switching command input by an input means such as a switch, and the switching control signal is input. Said said The conversion unit includes a first 90-degree hybrid in which the first transmitter output is input to one input terminal and the second transmitter output is input to the other input terminal, and one of the first 90-degree hybrid. To a first phase shifter to which a switching control signal for setting the phase setting to 180 ° or 0 ° is input from the switching control unit, and to the other output terminal of the first 90-degree hybrid. A second phaser connected and having a phase set to 0 °; an output of the first phaser is input to one input terminal; the second phaser is connected to the other input terminal; A second 90-degree hybrid connected to the antenna, and the switching control unit, when outputting the first transmitter output to the antenna, to the switching unit The switching system for setting one phase shifter to 180 ° When the control signal is output and the second transmitter output is output to the antenna, the switching control signal for setting the first phase shifter to 0 ° is output to the switching unit. .

  According to the present invention, there are provided a relay transmission system, a transmitter switching device, and a transmitter switching method capable of preventing the transmission radio waves from being affected and switching the radio waves output from two transmitters without interruption. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a functional configuration of a relay transmission system according to an embodiment of the present invention. Hereinafter, processing and operation of each component of the relay transmission system will be described with reference to FIG. In FIG. 1, a relay transmission system is used to align the transmission frequency and phase between a first transmitter 1, a second transmitter 2, a reference oscillator 3 that supplies reference clocks for both transmitters, and two transmitters. A frequency / phase control unit 4, a switching unit 5 that switches transmission radio waves of two transmitters, a switching control unit 6 that outputs a switching control signal to the switching unit 5, an antenna 7, a load 8, and a self-diagnosis unit 9 are provided. ing.

  The switching unit 5 includes phase shifters 52, 53, and two phase shifters 52, 53 connected to two outputs of the 90 degree hybrid 51 and the 90 degree hybrid 51 to which transmission radio waves from the first transmitter 1 and the second transmitter 2 are input, respectively. A 90-degree hybrid 54 to which the outputs of the phase shifters 52 and 53 are input is provided. One output terminal of the 90-degree hybrid 54 is connected to the antenna 7 and the other output terminal is connected to the dummy load 8.

  Each of the first transmitter 1 and the second transmitter 2 receives a digital signal from each system, that is, a first modulator and a second modulator (not shown). The first transmitter 1 and the second transmitter 2 receive the reference clock of the reference oscillator 3 in order to synchronize the transmission frequency and phase of the two units so that the digital signal can be switched seamlessly and instantaneously even when switching. . Each transmitter operates in synchronism.

  Note that the modulators 1 and 2 (not shown) also operate in synchronization with the reference oscillator 3 in principle. Further, the first transmitter 1 may incorporate a first modulator, and the second transmitter may incorporate a second modulator.

  The outputs of the first and second transmitters 1 and 2 are input to the frequency / phase control unit 4 by means such as a coupler. Then, feedback control is performed so that either one of the transmitting transmitters has the same frequency and phase, and the outputs of the two transmitters input to both the 1i and 2i input terminals of the 90-degree hybrid 51 are synchronized with high accuracy. is doing.

  The switching control unit 6 outputs a switching control signal to the phase shifter 52 so that the output of any transmitter is output to the antenna 7. This switching control signal is input by a switching command from the self-diagnosis unit 9 of the two transmitters, or an input unit such as a switch (not shown) provided in the switching control unit 6 by an operator of the transmission system. Is output by

  The frequency / phase control unit 4 performs high-precision synchronization control so that the digital signals transmitted by the phases of the radio waves output by the two transmitters can be synchronized in bit units of the baseband, and between the transmission radio waves Phase difference information is output to the self-diagnosis unit 9. The self-diagnosis unit 9 outputs a switching command signal to the switching control unit 6 when it is determined that the frequency or phase difference is equal to or greater than a predetermined value and the transmitting transmitter is abnormal.

  Which output of the two transmitters is input to the antenna 7 is performed by controlling the phase amount of the phase shifter 52 provided between the 90-degree hybrid 51 and the 90-degree hybrid 54. For example, when the output of the first transmitter 1 is input, the phase change amount of the phase shifter 52 is set to 180 °, and when the output of the second transmitter 2 is input, it is set to 0 °. The phase shifter 53 is inserted in order to make the signal levels from the two transmitters input to the 90-degree hybrid 54 uniform, but the phase change is zero when the phase of the phase shifter 52 is set to 0 °. An attenuator or the like that adjusts the level may be used as long as the angle is uniform.

FIG. 2 is a diagram illustrating the first phase change at the positions “A” to “D” in FIG. 1 when the phase change amount of the phase shifter 52 is set to 180 ° (the radio wave of the transmitter 1 is transmitted from the antenna 7). It is a figure explaining the phase of the electromagnetic wave output from 1 transmitter.
In FIG. 2, the radio wave output from the first transmitter 1 is input to the position “A”, that is, the input terminal 1 i of the 90-degree hybrid 51 and is equally divided.

  At one output terminal 1o of the 90-degree hybrid 51 at the position “B”, the phase remains the same and the power is halved and output. Further, the power is output to the other output terminal 2o by 1/2 and the phase is shifted by 90 degrees (here, the delay is expressed). (Although the electric power and amplitude of the radio wave are halved, in FIG. 2 and FIG. 3 described later, the amplitude is drawn constant in order to explain the phase.)

  The radio wave input from the output terminal 1o to the phase shifter 52 is input to one input terminal 1i of the 90-degree hybrid 54 at the position “C” with a phase delay of 180 degrees and to one output terminal 1o of the 90-degree hybrid 54. While maintaining the phase, the level is equally divided to the other output terminal 2o, and the phase is output delayed by 90 degrees.

  On the other hand, the radio wave output from the other output terminal 2 o of the 90-degree hybrid 51 is input via the phase shifter 53 to the position “C”, that is, the other input terminal 2 i of the 90-degree hybrid 54. Then, the power is equally divided and output to the other output terminal 2o of the 90-degree hybrid 54 with the phase unchanged, and the remainder of the equally divided power is output to one output terminal 1o with a phase delay of 90 degrees. The The output terminal 1o of the 90-degree hybrid 54 is connected to the antenna 7, but here, since the radio waves input to the two input terminals of the 90-degree hybrid 54 are aligned in phase, finally, the first transmitter 1 is transmitted from the antenna 7 with 1/2 of the power output by 1.

  The radio wave output to the output terminal 2o is supplied to the dummy load 8 and consumed.

FIG. 3 shows the first change at the positions “A” to “D” in FIG. 1 when the phase change amount of the phase shifter 52 is set to 0 ° (the radio wave of the transmitter 1 is not transmitted from the antenna 7). It is a figure explaining the phase of the electromagnetic wave output from 1 transmitter.
In FIG. 3, the radio wave output from the first transmitter 1 is input to the input terminal 1 i of the 90-degree hybrid 51 at the position “A”, that is, output in half. At one output terminal 1o of the 90-degree hybrid 51 at the position “B”, the phase remains the same and the power is halved and output. The other output terminal 2o is output with a power of 1/2 and a phase shifted by 90 degrees (here, a delay is expressed). The radio wave input from the output terminal 1o to the phase shifter 52 is input to one input terminal 1i of the 90-degree hybrid 54 at the position “C” as it is, and the phase is shifted to one output terminal 1o of the 90-degree hybrid 54. At the same time, the level is equally divided to the other output terminal 2o, and the phase is output with a delay of 90 degrees.

  On the other hand, the radio wave output from the other output terminal 2 o of the 90-degree hybrid 51 is input via the phase shifter 53 to the position “C”, that is, the other input terminal 2 i of the 90-degree hybrid 54. Then, the electric power is equally divided and outputted without changing the phase to the other output terminal 2o of the 90-degree hybrid 54, and the remainder after the equal division of the electric power is delayed by 90 degrees in the one output terminal 1o. Is output. Since the radio waves that have reached the output terminal 1o of the 90-degree hybrid 54 are in reverse phase, the radio waves output by the first transmitter 1 cancel each other and are not transmitted from the antenna 7.

  When the first transmitter 1 is selected, the radio wave output from the second transmitter 2 cancels out at the output terminal 1o of the 90-degree hybrid 54 and does not output to the antenna 7, Details can be easily inferred from processing of the radio wave output from the first transmitter in FIG.

  As described above, the switching of the transmitter according to the present invention in combination with the phase shifter and the two 90-degree hybrids is different from the method using the switching switch by the diode switch or the mechanical contact, so that the transient phenomenon accompanying the switching is small. Noise generation accompanying transmitter switching can be suppressed to a low level, and seamless uninterrupted switching can be provided.

The block diagram which shows the function structure of the relay transmission system concerning the Example of this invention. The figure explaining the phase relationship of the electromagnetic wave in case the output of the 1st transmitter of FIG. 1 is transmitted from an antenna. The figure explaining the phase relationship of the electromagnetic wave when the 1st transmitter output of FIG. 1 is not transmitted from an antenna. The block diagram which shows the function structure of the conventional relay transmission system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st transmitter 2 2nd transmitter 3 Reference oscillator 4 Frequency / phase control part 5 Switching part 51, 54 90 degree hybrid 52, 53 Phaser 6 Switching control part 7 Antenna 8 Load 9 Self-diagnosis part

Claims (3)

In the relay transmission system that outputs one of the first and second transmitter outputs having the same frequency and phase to the antenna via the switching unit,
First and second transmitters;
A frequency / phase control unit that performs supervisory control to align the frequency and phase of the first and second transmitters;
The output of the transmitting transmitter of the two units by a switching command generated when the frequency / phase control unit detects the abnormality by the monitoring control or a switching command input by an input means such as a switch. A switching control unit that outputs a switching control signal to switch to the output of the other transmitter to the switching unit,
The switching unit is
A first 90 degree hybrid in which the first transmitter output is input to one input terminal and the second transmitter output is input to the other input terminal;
A first phase shifter connected to one output terminal of the first 90-degree hybrid and to which a switching control signal for setting a phase setting to 180 ° or 0 ° is input from the switching control unit;
A second phaser connected to the other output terminal of the first 90-degree hybrid and having a phase set to 0 °;
An output of the first phase shifter is input to one input terminal, the second phase shifter is connected to the other input terminal, and one output terminal is connected to the antenna; A relay transmission system comprising: One of the radio waves output by the first and second transmitters, whose frequency and phase of the radio waves output by each are aligned by the frequency / phase control unit for monitoring and controlling the output radio waves, is switched to the antenna. In the switching device of the transmitter of the relay transmission system that is output via
The output of the transmitting transmitter of the two units by a switching command generated when the frequency / phase control unit detects the abnormality by the monitoring control or a switching command input by an input means such as a switch. A switching control unit for outputting a switching control signal for switching to the output of the other transmitter from the switching unit,
The switching unit is
A first 90 degree hybrid in which the first transmitter output is input to one input terminal and the second transmitter output is input to the other input terminal;
A first phase shifter connected to one output terminal of the first 90-degree hybrid and to which a switching control signal for setting a phase setting to 180 ° or 0 ° is input from the switching control unit;
A second phase shifter connected to the other output terminal of the first 90-degree hybrid and having a phase set to 0 °; and an output of the first phase shifter is input to one input terminal; A transmitter switching device for a relay transmission system, comprising: a second 90-degree hybrid in which two phase shifters are connected to the other input terminal and one output terminal is connected to the antenna. In the transmitter switching method of a relay transmission system that outputs either one of the first and second transmitter outputs having the same frequency and phase to the antenna via the switching unit,
The relay transmission system includes:
First and second transmitters;
A frequency / phase control unit;
A switching control unit;
A switching unit,
The frequency / phase controller is
When the first and second transmitters detect and control the abnormality, a switching command is generated and output to the switching control unit,
The switching controller is
A switching control signal for switching from the output of the transmitting transmitter to the output of the other transmitter of the two units by the output switching command or the switching command input by an input means such as a switch to the switching unit. Output,
The switching unit to which the switching control signal is input,
The first transmitter output is input to one input terminal, the second transmitter output is input to the other input terminal, and the first 90 degree hybrid is input to one output terminal of the first 90 degree hybrid. Connected to the first phaser to which a switching control signal for setting the phase setting to 180 ° or 0 ° is input from the switching control unit, and to the other output terminal of the first 90-degree hybrid. And a second phase shifter set to 0 °, an output of the first phase shifter is input to one input terminal, the second phase shifter is connected to the other input terminal, and one output terminal Having a second 90 degree hybrid connected to the antenna,
When outputting the first transmitter output to the antenna, the switching control unit outputs the switching control signal for setting the first phase shifter to 180 ° to the switching unit,
When outputting the second transmitter output to the antenna, the switching control unit outputs the switching control signal for setting the first phase shifter to 0 ° to the switching unit. A method for switching a transmitter of a transmission system.

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