JP3233965B2 - Wireless communication device and its receiving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus used in a backbone communication path of a digital communication network, and more particularly to a digital microwave radio apparatus capable of switching between an active apparatus and a standby apparatus without any trouble. Wireless communication device and its
Related to a receiving device .

[0002]

2. Description of the Related Art In recent years, various communication systems have been developed with an increase in communication needs and development of communication technology, and among them, there is a digital microwave radio communication system. This type of system wirelessly transmits digital data by modulating a carrier wave composed of, for example, a microwave using a quadrature phase modulation (QPSK) system or a multi-level quadrature amplitude modulation (multi-level QAM) system. Compared to transmission systems and wired digital transmission systems, high-quality data transmission is possible at lower cost.

By the way, in this type of system, a service is provided in order to remedy deterioration of transmission quality or line disconnection caused by fading in a transmission line or a failure of a device constituting the transmission line, or to perform test and repair of a device or a line. In order to prevent interruption of transmission, important devices on the transmission line are usually provided with spare devices.

FIG. 3 shows a conventional system in which such a spare device is arranged. Fig. 3 shows a system in which two systems of wireless devices are prepared, one is used for working and the other is used for spare, and one system is switched to the other system when a failure occurs or maintenance and inspection is required. FIG. 3 shows a digital microwave radio apparatus employing a set backup method. In FIG. 3, reference numeral 21 denotes an input terminal, 22 denotes a baseband signal switch, and 20a
Is an active transmission system, and 20b is a standby transmission device. Also, 2
3, 23 'are transmission digital signal processing circuits;
′ Is a modulation circuit, 25 and 25 ′ are transmission microwave circuits,
6 is a changeover switch, and 36 is an antenna.

The active transmission system 20a includes a transmission digital signal processing circuit 23, a modulation circuit 24, and a transmission microwave circuit 25.
The standby transmission device 20b includes a transmission digital signal processing circuit 23 ', a modulation circuit 24', and a transmission microwave circuit 25 '.

The baseband signal switch 22 has an input terminal 2
The transmission digital signal processing circuits 23 and 23 'are for switching the transmission signal input from 1 to either the active transmission system 20a or the standby transmission device 20b for input. The transmission signal input via the signal switch 22 is converted into a digital signal and output.

The modulation circuits 24 and 24 'modulate and output digital signals output from the transmission digital signal processing circuits 23 and 23', and include an error correction circuit encoder. An error correction code is added to the digital signal to be modulated and then modulated and output. This enables the error correction decoding process on the receiving side.

The transmission microwave circuits 25 and 25 'convert the modulated signal into a microwave and output the microwave.
The changeover switch 26 switches the microwave output from the transmission microwave circuit 25 or 25 ′ to switch the antenna 36.
It leads to. The guided microwave is antenna 3
It is released into the air from 6.

Reference numeral 37 denotes an antenna, 27 denotes a high-frequency changeover switch, 40a denotes an active receiving system, 40b denotes a standby receiving system, 28 and 28 'receive microwave circuits, and 29 and 29'.
Is a demodulation circuit, 30 and 30 'are differential conversion circuit decoders, 3
2, 32 'are error correction circuit decoders, 33, 33' are reception digital signal processing circuits, 34 is a baseband signal switch, and 35 is an output terminal.

The active receiving system 40a includes the receiving microwave circuit 28.
, Demodulation circuit 29, differential conversion circuit decoder 30, error correction circuit decoder 32, reception digital signal processing circuit 3
The standby receiving system 40b comprises a receiving microwave circuit 28 ', a demodulating circuit 29', a differential converting circuit decoder 30 ', an error correcting circuit decoder 32', and a receiving digital signal processing circuit. 33 '.

The antenna 37 receives the microwave transmitted from the antenna 36 of the transmitting station, and the power distributor 27 distributes the microwave received by the antenna 37 to the active receiving system 4a and the standby receiving device 40b. Is what you do.

The receiving microwave circuits 28 and 28 'return the receiving microwave distributed by the high-frequency switch 27 to a current signal, and the demodulating circuits 29 and 29' demodulate the current signal and transmit the signal. This is a circuit for returning to a signal (to which a digital signal and an error correction code have been added). The differential conversion circuit decoders 30 and 30 ′ perform a difference operation on the demodulated transmission signal to decode it into the original digital signal. Error correction circuit decoders 32 and 32 'are circuits for correcting the error of the decoded signal with reference to the error correction code and decoding the signals, and receive digital signal processing circuits 33 and 3'.
Reference numeral 3 'denotes a circuit for processing the error-corrected signal and outputting it as an original baseband signal. The baseband signal switch 34 includes these digital signal processing circuits 33, 3
3 'is a switching circuit for sending an output from one of the terminals 3' to the output terminal 35.

In such a configuration, at the time of normal operation, the digital microwave radio apparatus of the present invention operates in the active transmission system 20.
It is assumed that digital signals are transmitted and received using a and the current receiving system side 40a.

In this state, for example, when the transmitting station performs maintenance and inspection work on the constituent elements of the active system, in this case, the maintenance worker, while starting work, communicates between the transmitting and receiving stations, After switching from the device to the standby device, the signal can be transmitted using the standby system, and then maintenance and inspection work of the active device starts.

At the time of this switching, the standby devices 20b and 40b are activated on each side of the transmitting station, and when the preparation is complete, the transmitting station switches the switch 22 and the changeover switch 26 to the side of the standby transmitting system 20b. At the receiving station side, the high-frequency switch 27 and the switch 34 are switched to the standby receiving system 40b.

As a result, both the transmitting station and the receiving station are switched to the standby system. After the transmitting station processes the transmission signal by the transmission digital signal processing circuit 23 ', error correction coding is performed by the modulation circuit 24'. The signal is modulated after being applied to the microwave transmission circuit 25 '. Then, the signal is converted into a microwave by the microwave transmission circuit 25 ′, sent out to the antenna 26 via the changeover switch 26, and transmitted.

The transmitting microwave is received by an antenna 37 at a receiving station, sent to a microwave receiving circuit 28 'via a high-frequency changeover switch 27, and converted into an electric signal. The signal is sent to the demodulation circuit 29 '. The demodulation circuit 29 'synchronously detects this signal, returns it to the in-phase and quadrature-phase baseband signal components, and further performs a summation operation to obtain in-phase and quadrature component identification data.

Accordingly, the identification data is subjected to a difference operation in the differential conversion decoder 30 'to restore the original data, and thereafter, the error is corrected and decoded in the error correction circuit decoder 32'. Then, the received digital signal is processed by a received digital signal processing circuit 33 'to restore the original baseband signal, and then output as a received decoded signal to a signal output terminal 35 via a switch 34.

As described above, in the conventional system, the carrier recovery method in the demodulation circuits 29 and 29 'of the receiving apparatus is as follows.
The synchronous detection method was adopted. For this reason, a disadvantage of the demodulation circuit of the synchronous detection method, which is weak against instantaneous interruption of the received signal and fluctuation of the frequency, is inherent.

That is, in the wireless device of the set-standby system as shown in FIG. 3, when switching from the active system to the standby system, the switch 26
In the switching operation, instantaneous interruption of the transmission signal occurs, and since the modulation circuit and the transmitter frequency are different between the active device and the standby device, the problem that the synchronous detection circuit in the receiving side demodulation circuit loses synchronization can be avoided. Absent.

This means that at the time of system switching, the signal input to the demodulation circuit of the synchronous detection system is out of phase due to the difference between the delay times of the active transmitting device and the standby transmitting device. The loss of the synchronization signal due to the instantaneous interruption causes an instantaneous change in the phase of the reproduced carrier wave due to the synchronous detection, and exceeds the synchronization holding limit of the phase locked loop (PLL) of the demodulation circuit of the synchronous detection method. As a result, it is inevitable that a loss of synchronization occurs.

In this type of apparatus, when switching from the active system to the standby system at the time of maintenance and inspection, an error occurs in the number of bits transmitted during an elapsed time from when synchronization is lost to when synchronization is restored.

FIG. 4 shows a synchronous detection type demodulation circuit.
FIG. 5 shows a demodulation circuit of the delay detection system. In the figure, 61 and 71 are demodulation circuit input terminals, 70 is a hybrid circuit, 62, 62 ', 72 and 72' are detection circuits, 6
3, 73 are power phase shift distributors, 66 is a carrier recovery circuit, 7
6 is a delay circuit for one clock time, 64 and 74 are clock recovery circuits, 65, 65 ', 75 and 75' are demodulated digital signal discrimination circuits, 67 and 77 are differential logic circuits, and 68 and 6
Numerals 8 ', 78 and 78' denote demodulation circuit output terminals, respectively. In the synchronous detection type demodulation circuit shown in FIG.
2, 62 'and a carrier recovery circuit 66 constitute a phase locked loop. And the demodulation circuit input terminal 61
Phase locked to the input signal.

That is, in the demodulation circuit of the synchronous detection system shown in FIG. 4, a multi-valued QAM signal output from an intermediate frequency amplifier (not shown) and input to an input terminal 61 as shown in FIG. After being branched into two, the signals are guided to two synchronous detection circuits 62 and 62 'for in-phase and quadrature phases, where they are synchronously detected. Then, the in-phase and quadrature-component baseband signals obtained by synchronous detection by these synchronous detection circuits 62 and 62 'are guided to identification circuits 65 and 65', respectively.

The discriminating circuits 65 and 65 'are each composed of, for example, an A / D converter. In these discriminating circuits 65 and 65', a clock reproduced by the clock reproducing circuit 64 from the baseband signal is used. In synchronization, each of the in-phase and quadrature-component baseband signals is A / D-converted and converted into a digital value corresponding to the level, and the converted digital value is used as identification data for the in-phase and quadrature-component baseband signals. Input to the circuit 67.

The differential logic circuit 67 performs differential logic processing (here, a sum operation) on the identification data of the baseband signal of the in-phase and quadrature components, thereby obtaining demodulated digital data of the in-phase and quadrature components. The identification data output from each of the identification circuits 65 and 65 ′ is input to a carrier recovery circuit 66.

The carrier recovery circuit 66 includes a logic circuit,
It has a DC amplifier having a built-in loop filter and a voltage controlled oscillator (VCO).
Restores the reference carrier. Then, the reference carrier is connected to the reference carrier having the same phase by the power phase shifter 63,
After being branched into a reference carrier wave shifted by 90 °, the signals are supplied to the synchronous detection circuits 62 and 62 ′, respectively, whereby synchronous detection is performed.

That is, in the demodulation circuit adopting the synchronous detection system, a PLL (Phase Locked Loop) circuit is constituted by the synchronous detection circuits 62 and 62 'and the carrier recovery circuit 66, and the multi-valued QAM signal is formed by the PLL circuit. QA according to a reference carrier whose phase is always locked
Synchronous detection of the M signal is performed.

On the other hand, the demodulation circuit includes a delay detection type demodulation circuit as shown in FIG. 5 as another system. In this delay detection type demodulation circuit, the modulation signal inputted from the input terminal 71 is divided into two. Thereafter, one of them is divided into two signals having phases different from each other by 90 ° in the hybrid circuit 70, and supplied to the local ports of the detection circuits (multiplier; double-bounced mixer) 72 and 72 ', respectively.

On the other hand, the other of the two modulated signals is delayed by one bit in a delay circuit 76 to become a reference carrier. Then, the reference carrier is branched into a reference carrier having the same phase and a reference carrier having a phase shifted by 90 ° by the phase shift distributor 73, and supplied to the high-frequency ports of the detection circuits 72 and 72 ', respectively.

In these detection circuits 72 and 72 ', the in-phase reference carrier and the anti-phase reference carrier supplied from the hybrid circuit 70 are mixed and detected with the reference carrier, and the in-phase and quadrature-phase baseband signals are detected. Get. The baseband signals of the respective phases thus obtained are input to demodulated digital signal discriminating circuits 75 and 75 'each including an A / D converter. These discriminating circuits 75 and 75 ′ convert the baseband signals output from the detection circuits 72 and 72 ′ into digital signals in synchronization with the clock reproduced by the clock reproducing circuit 74, so that the baseband signals The signal level is identified for each axis direction of the quadrature modulation, and the identification output is input to the differential logic circuit 77. The differential logic circuit 77 performs predetermined logic processing (sum operation processing) on the discrimination output, and thereby demodulates data in each axis direction (in-phase component and quadrature component) of the quadrature modulation for each axis. Output terminal 7
8, 78 '.

The above is the configuration example and operation example of the demodulation circuit of the synchronous detection system and the delay detection system. As described above, since the active transmitting apparatus and the standby transmitting apparatus do not have a synchronous relationship, there is inevitably a delay time difference, and thus the active transmitting apparatus having the delay time difference transmits the standby transmitting apparatus. When switching to the device, the receiving device of the synchronous detection system switches and inputs a signal having a different delay time from the input terminal, thereby exceeding the period holding limit of the phase lock loop and becoming out of synchronization. Moreover, since the input is switched with an instantaneous interruption, the synchronization is reliably lost.

On the other hand, in the delay detection system of FIG. 5, the input signal of the demodulation circuit is delayed by one clock by the delay circuit 76 and supplied to the detection circuits 72 and 72 '. Since the detection is performed based on the signal delayed by the clock time, a synchronization circuit is not required, and therefore, there is no element that causes loss of synchronization.

However, since the delay detection system does not have a synchronous system, the error rate is relatively large as compared with the synchronous detection system. Therefore, it is impossible to entirely employ a delay detection type demodulation circuit in place of the synchronous detection type demodulation circuit when the decoding accuracy thereof must be ensured.

[0035]

As described above, in a receiving system in a quadrature modulation type microwave radio communication system, a synchronous detection system is employed as a carrier recovery system in a demodulation circuit. In this system, two systems of wireless devices are prepared, one is used for operation, the other is used for spare, and when one of them is broken or needs maintenance and inspection, it is switched to the other system for operation. In this type of microwave radio communication system employing the set-backup method, the synchronous detection method is used as the carrier recovery method in the demodulation circuit in the reception system. Detachment occurs and becomes a problem.

That is, when the microwave radio communication system is switched from the working system to the protection system for operation, an instantaneous interruption occurs in the transmission microwave for the switching operation time of the transmission-side changeover switch. Since the modulation circuit and the transmitter frequency are different between the system and the delay time difference between the active device and the standby device, the phase lock loop in the demodulation circuit on the receiving side exceeds the synchronization holding limit,
Loss of synchronization is inevitable.

Once the synchronization is lost, an error occurs in the number of bits of the signal transmitted during the time until the synchronization is restored, and a correct received signal cannot be obtained.

Thus, the object of the present invention is to
Comprises a working system and a standby system, the radio apparatus capable of switching use, during maintenance, when switched to the standby system from the working and can be switched to smoothly protection system to prevent desynchronization radio Communication device and its
A receiving device is provided.

[0039]

In order to achieve the above object, the present invention is configured as follows. That is, the transmitting device and the receiving device each have an active system and a standby system,
The transmission device is provided with a transmission system switching means for switching between the working system and the protection system, and the reception device is provided with a reception system switching means for switching between the working system and the protection system. In a wireless communication apparatus capable of switching and using an active system and a standby system by a switching unit,
At least the working system of the receiving apparatus is configured such that the demodulation means is a synchronous detection system, and the protection system of the receiving apparatus is provided with a synchronous detection type demodulation circuit and a delay detection type demodulation circuit as the demodulation means. Further, when switching from the active system to the standby system, until the synchronization of the synchronous detection type demodulation circuit of the standby system receiving device is established, the demodulation output of the delay detection system is selected, and after the synchronization is established, And a selection control means for selecting and outputting a demodulated output of the synchronous detection type demodulation circuit. Further, the transmission device is provided with a means for adding an error correction code to the transmission signal, and the output of the demodulation means is provided with error correction decoding means for performing correction processing based on the error correction code. An error correction means for receiving an output of the means and performing error correction processing based on the error correction code, and a processing means for obtaining a demodulated output from a signal after error correction by the error correction means are provided.

Secondly, the transmitting apparatus is provided with means for adding an error correction code to a transmission signal, and
At least the working system receiving apparatus uses the synchronous detection system for the demodulation means, and receives the output of the demodulation means and provides a working system error correction decoding means for performing correction processing based on the error correction code. The receiving apparatus is provided with a synchronous detection type demodulation circuit and a delay detection type demodulation circuit as demodulation means, and performs a sum operation on an output of the delay detection type demodulation circuit to perform a demodulation output of the delay detection type. And a delay detection system differential conversion means for outputting the demodulated output of the delay detection system until the synchronization of the synchronous detection type demodulation circuit of the standby system reception system is established when switching from the active system to the standby system. After the synchronization is established, selection control means for selecting and outputting the demodulation output of the demodulation circuit of the synchronous detection system, and receiving the output of the selection control means, and correcting the error based on the error correction code. A second error correction means for processing,
A second operation for performing a difference operation on the signal after the error correction is performed.
And a differential conversion means.

[0041]

In the above configuration, transmission from the transmitting device side is performed.
The received signal is received by the active receiver on the receiving side.
To perform synchronous detection, return to the baseband signal, and
I do. When switching from the active system to the standby system,
Two demodulation circuits for the standby system by switching the switching means for the reception system
Are operated together, but at the initial stage of switching, the selection control means
Are the synchronous detection type demodulation circuit and the delay detection type demodulation circuit.
Among them, select the output of the demodulation circuit of the delay detection method
Switching, synchronization of demodulation circuit of synchronous detection system is established
Until the delay detection system demodulation output is selected and
After the period is established, the demodulation output of the demodulation circuit of the synchronous detection system
Works to select. Alternatively, the transmitting apparatus adds an error correction code to the transmission signal and transmits the transmission signal. On the receiving side, the active receiving apparatus receives the signal, performs synchronous detection, corrects the error based on the error code, and then corrects the baseband signal. And return to the reception output. When switching from the working system to the protection system, the switching means for the reception system is switched to activate both the two demodulation circuits of the protection system. Of the demodulation circuits of the system, switching to select the output of the demodulation circuit of the delay detection system, until the synchronization of the demodulation circuit of the synchronous detection system is established, select the demodulation output of the delay detection system, After the synchronization is established, it operates to select the demodulation output of the demodulation circuit of the synchronous detection system. for that reason,
In the early stage of switching, which becomes unstable in the synchronous detection method, use a delay detection type demodulation circuit that does not cause a loss of synchronization at the initial stage, and switch to the delay detection type demodulation circuit when synchronization of the synchronous detection method demodulation circuit is established. Therefore, it is possible to switch from the active system to the standby system without causing loss of synchronization.

In the case of the first configuration, the demodulated output is
The error correction means performs error correction processing based on the error correction code, and the error-corrected code is converted into a baseband signal by the processing means to become a reception demodulated output.

As described above, the output of the demodulation circuit is subjected to the error correction processing based on the error correction code, further subjected to the difference operation processing, and then converted to the baseband signal to obtain the reception output. The switching from the working system to the standby system (effect by suppressing the loss of synchronization) can be performed while suppressing (effect by error correction processing) and without loss of synchronization.

When switching from the active system to the standby system, the demodulation output of the delay detection system is selected until the synchronization of the synchronous detection type demodulation circuit of the standby receiving device is established. In the case of the configuration of the above, the output of the demodulation circuit of the delay detection system is summed by the differential conversion system of the delay detection system to obtain a demodulated output of the delay detection system, and this is output to the error correction code by the second error correction unit. , And the output after the error correction processing is subjected to a difference operation processing by the second differential conversion means, and then converted into a baseband signal to be a reception output. When the synchronization of the synchronous detection type demodulation circuit of the standby receiver is established, the selection control means switches from the delay detection type demodulation output to the synchronous detection type demodulation circuit demodulation output. The demodulated output of the demodulation circuit of the system is supplied to a second error correction means, which performs an error correction process based on the error correction code. The signal is subjected to the difference calculation processing by the differential conversion means, and then converted to a baseband signal by the processing means to be a received demodulated output.

As described above, according to the present invention, in the microwave radio communication system of the set protection system in which the working system and the protection system are provided, at least the demodulation circuits of the synchronous detection system and the delay detection system are used as the demodulation circuits on the receiving side of the protection system. In the initial stage of switching to the standby system, the output of the demodulation circuit of the delay detection method is used, and the output of the demodulation circuit of the synchronous detection method is used when synchronization is established, which may cause loss of synchronization. In addition, the standby system can be started up and switched, and the output of the demodulation circuit of the delay detection system is subjected to summation processing through differential conversion means, and the error correction processing is performed based on the error correction code. Further, after performing a difference calculation process, the signal is converted into a baseband signal to obtain a reception output, and the output of the demodulation circuit of the synchronous detection system is converted to an error correction code. Error correction processing, further differential processing, and then converted to a baseband signal to obtain a reception output, thereby suppressing transmission path errors (the effect of the error correction processing) and causing loss of synchronization. The switching from the working system to the standby system (effect by suppressing the loss of synchronization) can be performed without causing the problem.

In the difference calculation processing by the second differential conversion means, if an error occurs due to noise or waveform distortion due to fading or the like in the transmission path, the error is doubled. Before the error increases in the conversion means,
Since the error is corrected by the error correcting means, the error correcting capability can be secured and the reliability can be secured.

Therefore, according to the present invention, in a microwave radio apparatus provided with an active system and a standby system and made available for switching, loss of synchronization is prevented when switching from the active system to the standby system during maintenance. It is possible to provide a microwave radio device capable of smoothly switching to the standby system.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
Is a signal input terminal, 2 is a signal distributor, and 3 and 3 'are transmission digital signal processing circuits. The transmission digital signal processing circuit 3 is for an active system device, and the transmission digital signal processing circuit 3 '.
Indicates that it is for a standby system device and the one with the suffix "'" below indicates that it is for the standby system device, and the one without the suffix "'" indicates that it is for the active device. .

4, 4 'are modulation circuits, 5, 5' are microwave transmission circuits, 6 is a high-frequency switch, 7 is a high-frequency switch, 8, 8 'are microwave reception circuits, and 9, 9' are synchronous detection systems. 9 "is a delay detection type demodulation circuit used only in the standby device, 10 and 10 'are error correction circuit decoders, and 11' is a synchronous detection type demodulation circuit 9 'in the standby device.
Switch for switching between the demodulation circuit 9 "and the delay detection system, 12 and 12 'are differential conversion circuit decoders (difference operation circuit), 12" is differential conversion circuit decoder (sum operation circuit),
13, 13 'are reception digital signal processing circuits, 14 is a changeover switch, 15 is a signal output terminal, 16 and 17 are antennas, 18 is a changeover request switch, 19 and 20 are control circuits,
Are respectively shown.

The signal distributor 2 is a switch for supplying the transmission signal input from the signal input terminal 1 to either the working system or the protection system, and the transmission digital signal processing circuits 3, 3 ' This is a circuit that performs a predetermined digital signal processing on the transmission signal transmitted via the distributor 2.

The modulation circuits 4 and 4 'are circuits for modulating the output of the transmission digital signal processing circuits 3 and 3' (for example, orthogonal transform modulation such as 16QAM) and outputting the modulated signals. The output from the transmission digital signal processing circuits 3 and 3 'is processed after adding an error correction code, and then modulated and output. This enables the error correction decoding process on the receiving side.

The microwave transmission circuits 5 and 5 'are circuits for converting the modulated signal into a microwave signal and outputting it. The changeover switch 6 is a selection switch for selecting one of the output of the microwave transmission circuit 5 and the output of the microwave transmission circuit 5 ′ and sending it out to the antenna 16. This is a command switch that is operated when it is desired to switch the transmission system. The control circuit 19 is the center of control on the transmitting device side. When an alarm is generated, a switching request signal is sent on the control channel to the receiving side, and the switching is performed when a switching response is received from the receiving side. In addition to performing control such as switching the switch 6 to switch the transmission system from the working system to the protection system (or vice versa), when the switch request switch 18 is operated, the switch request signal is put on the control channel and received. Side, and at the time of receiving a switching response from the receiving side, switches the switch 6 to perform a control of switching the transmission system from the working system to the protection system (or vice versa).

The antenna 17 is a receiving antenna.
The high-frequency changeover switch 7 is a changeover switch capable of leaking electric power, and is a changeover switch for supplying the microwave received by the antenna 17 to the active system receiving device or the standby system receiving device. The high-frequency changeover switch 7 can switch the path between the working system and the protection system, and is configured such that the input signal leaks to the other side and is output while being switched to one side.

The microwave receiving circuits 8 and 8 'convert received microwaves transmitted through the high frequency changeover switch 7 into electric signals and output the electric signals. The demodulation circuits 9 and 9 of the synchronous detection system are used. 'Demodulates and outputs the outputs of the corresponding microwave receiving circuits 8, 8'. The demodulation circuit 9 "of the delay detection system is for detecting the output of the corresponding microwave receiving circuit 8 'by delay detection, demodulating the output, and outputting the demodulated signal.

The differential conversion decoder (sum operation circuit) 12 "sums and outputs the output data (demodulated data) of the delay detection type demodulation circuit 9" and outputs the changeover switch 11 '. Is the differential conversion decoder 12 "and the demodulation circuit 9 '
Is a path switch for selecting one of the outputs.

Since the differential detection demodulation circuit 9 "performs the differential operation simultaneously with the detection, the differential conversion code is provided after the delay detection circuit 9" to match with the synchronous detection type demodulation circuit 9 'side. Unit (sum operation circuit) 12 ″ is arranged,
This summation operation does not hinder the processing in the subsequent stage.

An error correction decoder (FEC DEC) 10 'performs error correction decoding on data output through the changeover switch 11', and a differential conversion circuit decoder (differential operation circuit) 12 ' ′ Is for differentially converting and decoding the output of the error correction decoder 10 ′, and the reception digital signal processing circuit 13 ′ receives the output of the differential conversion circuit decoder 12 ′ and processes the signal to obtain the original signal. The baseband signal switch 14 is a switching circuit that receives the output from the digital signal processing circuits 13 and 13 ′, switches to select one of them, and sends it to the output terminal 35. .

The error correction decoder 10 performs error correction decoding on the output data of the demodulation circuit 9 of the synchronous detection system, and a differential conversion circuit decoder (differential operation circuit) 12
Is for differentially converting and decoding the output of the error correction decoder 10 ', and the reception digital signal processing circuit 13 receives the output of the differential conversion circuit decoder 12 and processes the signal to obtain the original baseband signal. And outputs the result.

The control circuit 20 plays a central role in controlling the receiving apparatus, and is constituted by a microprocessor (CPU). When receiving a command, the control circuit 20 switches the changeover switch 11 'of the standby receiving circuit section to a differential conversion circuit. At the same time as switching to the decoder 12 ″ system, the baseband signal switch 15 is switched to the standby system side, and thereafter, the switching switch 11 ′ of the standby receiving circuit unit is switched to the synchronous detection system demodulator 9 ′ side.

Next, the operation of the system of the present invention will be described with reference to the operation flow of FIG. At the time of normal operation, the digital microwave radio apparatus is configured such that the active transmitting apparatus 200a (constituent elements 1, 2, 3, 4, 5, and 6) and the active receiving apparatus 400a shown in FIG.
(Components 7, 8, 9, 10, 12, 13, 14, 1
It is assumed that digital signals are transmitted and received using 5).

For example, in this state, if the transmitting station performs maintenance and inspection work on the constituent elements of the active system, in this case, the maintenance worker first enters the work from the active system to the standby system. Is switched to the standby side so that the signal can be transmitted using the standby side, and then the maintenance and inspection work of the active system apparatus is started. In this switching, the maintenance worker sends a switching command, which is issued by operating a switching request switch 18 provided in the transmitting device.

When the switching request switch 18 is operated, a switching command is issued to the control circuit 19. Then, upon receiving this switching command, the control circuit 19 of the present device activates the device of the standby transmission device 20b. That is, the control circuit 19 on the transmitting station side checks whether an alarm has occurred (S9a),
The switch request switch 18 is checked (S9b). When the switch request switch 18 is turned on, a switch request signal is output to the control channel to transmit the switch request signal, and the switch is sent to the transmission digital signal processing circuit 3 of the active system. give.

Thus, the active transmission digital signal processing circuit 3 inserts this switching request signal into the control channel and outputs it, and the modulation circuit 4 performs error correction coding on the transmission signal including this output. Then, these are modulated and given to the microwave transmission circuit 5. The microwaves are converted into microwaves by the microwave transmission circuit 5, sent out to the antenna 16 via the changeover switch 6, and transmitted.

At the receiving station, the transmitting microwave is received by an antenna 17, sent to a microwave receiving circuit 8 via a high-frequency switch 7, converted into an electric signal, and then demodulated by a synchronous detection method. It is sent to the circuit 9. The demodulation circuit 9 synchronously detects this signal, corrects the error in an error correction circuit decoder 10, and then decodes the signal. Then, the differential conversion decoder 12 performs a difference operation, and the received digital signal processing circuit 13 performs signal processing to convert the signal to a baseband signal, which is output to a signal output terminal 15 via a switch 14.

On the receiving side, a control channel signal is extracted from the baseband signal, and the control circuit 20
Give to.

The control circuit 20 monitors the switching request signal from the signal of the control channel (S10a). If the switching request signal is detected, the standby system 200b of the receiving device is activated, and then the switching switch 11 'is operated. The control circuit 20 switches to the side of the dynamic conversion circuit decoder 12 ″ (S10b). When this is completed, the control circuit 20 gives a command to its own transmission device to generate a switch response signal. The transmitting device of the station inserts the switching response signal into the control channel, modulates the converted signal into a microwave, and transmits the microwave to the partner station (the transmitting station) (S10e).

In the transmitting station receiving the signal, the receiving system of the own station demodulates the signal and gives the control channel information to the control circuit 19.
The control circuit 19 monitors the reception of the switching response signal (S
9d), upon receiving the switching response signal, control is performed so as to switch the changeover switches 2 and 6, respectively, and the transmitting device is switched from the active system 20a to the standby system 20b (S9e). Therefore, after this,
The transmitting apparatus sends the input transmission signal to the standby system, modulates the signal in the standby system 20b, converts the signal into a microwave, and transmits the microwave.

On the other hand, on the receiving station side, the standby receiving device 20
When 0b is activated, the active receiver 200a and the standby receiver 200b enter a parallel receiving state. That is, the received microwave is given to the working-system receiving device 200a and the standby-system receiving device 200b by the high-frequency switch 7 capable of leaking power.
The receiving device 200a and the standby receiving device 200b perform the receiving operation, respectively, and detect / demodulate the received signal to output.

At this time, the demodulation circuits 9 'and 9 "operate in the standby receiving apparatus 200b, respectively, but the control circuit 20 switches the changeover switch 11' to the differential conversion circuit decoder 12" side, and the demodulation circuit Is switched to the differential detection side. Accordingly, in this state, a signal obtained by performing a sum operation on the signal demodulated by the differential detection method in the differential conversion circuit decoder 12 ″ is supplied to the error correction circuit decoder 1 via the changeover switch 11 ′.
0 ', where it is subjected to error correction processing and then decoded, and further to a differential conversion circuit decoder (difference calculation circuit) 12'
, And is returned to the original baseband signal by the reception digital signal processing circuit 13 '.
4 given.

The control circuit 20 sees that the baseband signal is output from the reception digital signal processing circuit 13 ', and
The switch 14 is switched from the active receiver 200a to the standby receiver 200b at an appropriate time. The active receiver 200a is still in a parallel operation state at this point. Therefore, the switching of the switching unit 14 switches the reception output of the active system to the reception output of the standby system.

Further, the control circuit 20 monitors the synchronization establishment state of the synchronous detection type demodulation circuit 9 '(S10f), and when the synchronization is established, switches the switch 11' to the synchronous detection type demodulation circuit 9 'side. The changeover switch 11 'is switched to be controlled (S10g). As a result, the reception processing can be performed by switching the standby receiving apparatus 200b to the system of the demodulation circuit 9 'of the synchronous detection method without occurrence of synchronization loss.

As described above, in the present system, in the initial stage of the switching, the delay detection system is used, and after the synchronization of the synchronous detection system is established, the system is switched to the synchronous detection system, and the standby system is switched by the synchronous detection system. It is intended to be used eventually. In this way, delay detection is used at the initial stage of switching, because synchronization is not taken in delay detection unlike synchronous detection, so even if there is an instantaneous interruption on the transmission side, frequency shift, etc. This is because out-of-synchronization does not occur, and therefore, switching from the active system device to the standby system device can be performed without any problem.

By switching to the synchronous detection system after the synchronization of the synchronous detection system is established, it is possible to switch from the active system to the standby system without generating an error bit during maintenance and inspection. I do.

That is, when switching from the active system device to the standby system device, when the transmission-side switch 6 is switched, the time during which the power of the transmission signal is cut off during the switching operation of the switch 6 is determined. Will happen. Also, it is difficult to make the transmission frequency of the active device and the transmission frequency of the backup device completely the same frequency, and they are slightly different. Also,
There is a delay time difference between the active system device and the standby system device.

For these reasons, when the synchronous detection method is employed in the demodulation circuit of the receiving device, the synchronization is lost when the transmitting device is switched from the working system to the standby system. The digital signal transmitted during this out-of-synchronization period becomes erroneous.

According to the present invention, upon such switching, first, a receiving process is performed by using a demodulation circuit of a delay detection system, and a demodulation circuit 9 'of a synchronous detection system in the standby receiver 200b is also activated to synchronize. Wait for establishment. And
If synchronization of the synchronous detection type demodulation circuit 9 'is established (S
10f), the control circuit 20 switches the changeover switch 11 'to the side of the synchronous detection type demodulation circuit 9' (S10g). Thus, after the synchronization is established, the demodulated output of the demodulation circuit 9 'of the synchronous detection system is supplied to the processing circuits below the error correction circuit decoder 10', error-corrected and decoded, the difference operation is performed, the signal processing is performed, and The signal can be converted into a band signal and obtained as a reception output, and thereafter, it is possible to shift to a reception process using a demodulation circuit output by synchronous detection. As a result, it is possible to shift to the standby system without risk of loss of synchronization.

In the demodulation circuit 9 "of the delay detection system, the differential calculation is performed simultaneously with the detection. Therefore, in order to match the demodulation circuit 9 'of the synchronous detection system, the differential conversion encoder ( A summation operation circuit) 12 "is arranged so that the summation operation does not hinder the processing in the subsequent stage.

An error correction decoder () is provided after the changeover switch 11 'for switching the system on the side of the synchronous detection circuit 9' and the system for the output of the summation operation circuit 12 "of the output of the delay detection circuit 9". FEC DEC) 10 'and a differential conversion circuit decoder (differential operation circuit) 12' are arranged so that a transmission line in a demodulated signal input to the differential conversion circuit decoder (differential operation circuit) 12 '. At the error correction decoder 1
Error correction decoding is performed at 0 'to remove the error.

As described above, after removing the transmission line error from the demodulated signal, the differential conversion circuit decoder (difference calculation circuit) 1
2 ', which is converted to a baseband signal, which is more rational than a method of performing a differential operation on a demodulated signal (in this case, a transmission path error increases) and then performing error correction decoding. In this case, the accuracy of error correction is improved. That is, in the case of correcting an error with an increased error, the error correction capability is reduced as compared with the method of the present system, but such a problem is eliminated in the method of the present system in which error correction is performed first and then the difference operation is performed. .

The supplementary explanation that the summation operation after the delay detection circuit 9 ″ has the effect of reducing errors will be described below.

Now, the signal value of the transmission signal every moment is represented by x ₀ , x
_{1, x 2, ..., x} n, ... and then, sum calculation value of the signal value _{(y n = x n + y} n-1); y 0, y 1, y 2, ...,
y _n ,... The difference operation value of the signal value after sent the transmission line _{(Zn = y n -y n-} 1); Z
₀ , Z ₁ , Z ₂ ,..., Z _{n ,.}
= A _{z n + W n-1)} ; W 0, W 1, W 2, ..., W n,
...

[0082] Here, it is assumed that one symbol error occurs in _{y n.} The value _Z n of yn is the 1 symbol error difference calculation _result, thereby spreading the error _{Z n + 1.}

[0083] _{Z n = (y n) -y} n-1 Z n + 1 = y n + 1 - (y n) However, the formula shown above values _{Z n,} a _{Z n + 1} represents surrounds those produced errors in () It is.

[0084] As can be seen, one symbol error yn that spread to _{Z n} and _{Z n + 1} is composed of sign is the reverse.
Of re sum calculation result, the _{Z n} and _{Z n + 1} is _{concerned, W n, W n + 1} , W n + 2 ... a. _{Therefore, W n = Z n + W} n-1 = (y n) -y n-1 + W n-1 , and becomes one symbol error.

[0085] _{However, W n + 1 = Z n} + 1 + W n = y n + 1 - in _{(y n) + (y n} ) -y n-1 + W n-1, the error is canceled. Thus becomes no error in _{W n + 2 = z n +} 2 + W n + 1 = y n + 2 -y n + 1 + W n + 1, W n + 3 ... even after all become faultless later, sum calculation on after a delay detection circuit 9 "reduces the error It turns out that there is an effect.

In the receiving apparatus of this embodiment, a leak-type switch is used as the high-frequency switch 7, so that the received transmission signal is supplied to the standby receiver 400b without interruption when the switch 7 is switched. Will be done. For this reason, no bit error occurs in the transmission signal when the changeover switch 7 is switched, and the switching can be performed smoothly from the active receiver 400a to the standby receiver 400b.

Therefore, for example, even if the changeover switch 6 of the transmitting apparatus is changed without sufficient time from the changeover time of the changeover switch 7, the bit error of the transmission signal is generated only by the changeover switch 6. That is,
The bit error is suppressed to within 2 bits that can be corrected by the error correction circuit 10 ', and there is no problem in demodulating data. In other words, there is no need to perform control to sufficiently delay the switching timing of the changeover switch 6 of the transmission device from the changeover timing of the changeover switch 7 of the reception device, thereby simplifying the switching control of the control circuit 19 of the transmission device. Will be able to

By the way, when a leak type switch is not used as the changeover switch 7, that is, when a non-leakage type switch generally used as a microwave switch is used, the reception transmission signal is also changed when the changeover switch 7 is changed over. Since an instantaneous interruption occurs, the total bit error generated in the received transmission signal at the time of switching becomes 4 bits even if there are simply 2 bits at each switch,
The error correction capability of the error correction circuit 12 'will be exceeded. For this reason, the switching timing of the changeover switch 6 of the transmission device must be sufficiently delayed from the changeover timing of the changeover switch 7, and the control circuit 19 of the transmission device needs control for that. As a result, the control becomes complicated. This is not the case when a leak-type switch is used.

As described above, the present system has an active system and a standby system as a transmitting apparatus and a receiving apparatus, respectively. The transmitting apparatus is provided with a transmission system switching means for switching between the active system and the standby system. In the microwave radio communication device, the receiving device side is provided with a receiving system switching unit for switching between the working system and the standby system, and the switching unit can operate by switching between the working system and the standby system. The transmitting apparatus is provided with a means for adding an error correction code to the transmission signal, and at least the receiving apparatus serving as the working system uses the synchronous detection method as the demodulating means and receives the output of the demodulating means. A working system error correction decoding means for performing correction processing based on the error correction code is provided, and the protection system receiving apparatus includes a synchronous detection type demodulation circuit and a delay detection type demodulation circuit as demodulation means. And a delay detection system differential conversion means for summing the output of the delay detection type demodulation circuit and outputting the result as a delay detection system demodulation output, and switching from the working system to the standby system. At this time, the demodulation output of the delay detection system is selected until the synchronization of the demodulation circuit of the synchronous detection system of the standby receiving device is established, and after the synchronization is established, the demodulation output of the demodulation circuit of the synchronous detection system is established. And select
A selection control means for outputting, and a second means for receiving an output of the selection control means and performing error correction processing based on the error correction code.
And a second differential converter for performing a difference calculation process on the signal after the error correction.

The transmitting apparatus adds an error correction code to the transmission signal and transmits the transmission signal. On the receiving side, the active receiving apparatus receives the signal, performs synchronous detection, and corrects the error based on the error code. The signal is returned to the baseband signal and the reception output is set. When switching from the working system to the protection system, the switching means for the reception system is switched to operate both the two demodulation circuits of the protection system. The demodulation circuit of the synchronous detection system and the demodulation circuit of the delay detection system are switched to select the output of the demodulation circuit of the delay detection system, and the delay detection is performed until the synchronization of the demodulation circuit of the synchronous detection system is established. After the demodulation output of the system is selected and the synchronization is established, control is performed so as to select the demodulation output of the demodulation circuit of the synchronous detection system. For this reason, the synchronous detection method becomes unstable. In the initial stage of switching, a delay detection method demodulation circuit that does not cause loss of synchronization is used, and if the synchronization of the synchronous detection method demodulation circuit is established, the delay detection method synchronization is established. Since the switching to the demodulation circuit of the detection method is performed, it is possible to switch from the working system to the standby system without causing loss of synchronization.

When switching from the active system to the standby system, the demodulation output of the delay detection system is selected until the synchronization of the demodulation circuit of the synchronous detection system of the standby system receiver is established. The output of the demodulation circuit of the detection system is summed by the differential detection system differential conversion means to obtain a demodulated output of the delay detection system, which is subjected to error correction processing by the second error correction means based on the error correction code. Further, the output after the error correction processing is subjected to a difference operation processing by the second differential conversion means, and then converted into a baseband signal to be a reception output. When the synchronization of the synchronous detection type demodulation circuit of the standby receiver is established, the selection control means switches from the delay detection type demodulation output to the synchronous detection type demodulation circuit demodulation output.
The demodulated output of the demodulation circuit of the synchronous detection system that has been established in synchronization is given to the second error correction means, and the second error correction means performs error correction processing based on the error correction code,
Further, the output after this error correction processing is subjected to a difference operation processing by the second differential conversion means, and then converted into a baseband signal to become a reception output.

As described above, according to the present invention, in the microwave radio communication system of the set protection system in which the working system and the protection system are provided, at least the demodulation circuits of the synchronous detection system and the delay detection system are used as the demodulation circuits of the protection system. In the initial stage, when switching to the standby system, the output of the demodulation circuit of the delay detection method (poor error rate characteristics but no loss of synchronization) is used, and the output of the demodulation circuit of the synchronous detection method is used when synchronization is established. In this way, the standby system can be started up and switched without loss of synchronization, and the output of the demodulation circuit of the delay detection system is subjected to a sum operation through differential conversion means. This is subjected to an error correction process based on the error correction code, further subjected to a difference operation process, and then converted into a baseband signal to obtain a reception output. Since the output of the demodulation circuit of the system is subjected to error correction processing based on the error correction code, further subjected to difference calculation processing, and converted to a baseband signal to obtain a reception output, errors are not amplified, and In addition, it is possible to correct transmission path errors (effects of error correction processing) and perform instantaneous interruption switching (effects of loss of synchronization suppression) during maintenance.

In the difference calculation processing by the second differential conversion means, if an error due to noise or waveform distortion due to fading or the like occurs in the transmission path, the error is doubled. Before the error increases in the conversion means,
Since the error is corrected by the error correcting means, the error correcting capability can be secured and the reliability can be secured.

Therefore, according to the present invention, in a microwave radio apparatus which is provided with an active system and a standby system and which can be switched and used, loss of synchronization is prevented when switching from the active system to the standby system during maintenance. It is possible to smoothly switch to the standby system.

The present invention is not limited to the embodiments described above and shown in the drawings, but can be appropriately modified within the scope not changing the gist of the present invention. The working receiver is a synchronous detection type demodulation circuit only, and the protection receiver is a combination of a synchronous detection method and a delay detection type demodulation circuit. Then, when switching from the standby system to the active system, the same switching operation control as in the case of the standby system can be performed, and it is not necessary to use the standby system and the working system in particular. Needless to say.

In the above embodiment, the case where the present invention is applied to switching from the active system to the standby system has been described as an example. However, the present invention is also applied to a case where the standby system is returned to the active system as an application example of the present invention. It is possible.

In addition, the type of the changeover switch, the configuration of the demodulation circuit adopting the delay detection system, the configuration of the demodulation circuit adopting the synchronous detection system, the switching control procedure and the control contents do not depart from the gist of the present invention. Various modifications can be made.

[0098]

As described above, according to the present invention, the synchronous detection system and the delay detection system are provided as the demodulation circuits of the standby system receiver, and these two systems can be selected, and the error correction circuit encoder is provided on the transmission side. Is provided and subjected to an error correction code addition process, and then transmitted. On the receiving side, a correction process based on the error correction code is performed, and then the difference is processed by a differential conversion circuit encoder for differential calculation. Instantaneous interruption switching can be performed at the time of maintenance or the like without lowering the error correction capability.

Therefore, according to the present invention, a radio communication device which is provided with an active system and a standby system and which can be switched and used.
When switching from the active system to the standby system at the time of maintenance, it is possible to provide a wireless communication apparatus and a receiving apparatus thereof that can prevent loss of synchronization and can smoothly switch to the standby system. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure for switching from an active system to a standby system.

FIG. 3 is a block diagram showing a configuration of a demodulation circuit of a synchronous detection system.

FIG. 4 is a block diagram showing a configuration of a delay detection type demodulation circuit.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

1 ... signal input terminal, 2 ... baseband signal switch, 3,
3 ': transmission digital signal processing circuit; 4, 4': modulation circuit with built-in error correction circuit encoder; 5, 5 ': transmission microwave circuit; 6, 26: switch (diode switch); 7: high frequency switch Switch, 8, 8 '... receiving microwave circuit, 9, 9' ... synchronous detection type demodulation circuit, 9 "
... Delay detection type demodulation circuit, 10, 10 '... Error correction circuit decoder, 11' ... Changeover switch, 12,12 '... Differential conversion circuit decoder (differential operation circuit), 12 "... Differential conversion circuit code (Sum operation circuit), 13, 13 ': reception digital signal processing circuit, 14: baseband signal switcher, 1
5 ... signal output terminal, 16, 17 ... antenna, 61,71
... demodulation circuit input terminals, 62, 62 ', 72, 72' ... detection circuits, 63, 73 ... power phase distributors, 66 ... carrier recovery circuits, 76 ... 1 clock time delay circuits, 64, 74
... Clock recovery circuit, 65, 65 ', 75, 75' ... Demodulated digital signal identification circuit, 67, 77 ... Differential conversion circuit decoder (differential operation circuit), 68, 68 ', 78, 78'
... Demodulation circuit output terminal.

Continuation of front page (72) Inventor Hirofumi Hoshino 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-3-182144 (JP, A) JP-A-62-135047 (JP, A) JP-A-4-200038 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 27/00-27/38

Claims (9)

(57) [Claims] A transmitting system and a receiving system each have an active system and a standby system. The transmitting device is provided with a transmission system switching means for switching between the working system and the standby system, and the receiving device is provided with a switching system. Is provided with a receiving system switching means for switching between the working system and the standby system, and a wireless communication apparatus capable of operating by switching between the working system and the standby system by these switching means, wherein at least the working system of the receiving device is The demodulation means is a synchronous detection method, and the standby system of the receiving apparatus is provided with a synchronous detection method demodulation circuit and a delay detection method demodulation circuit as demodulation means, and switches from the active system to the standby system. Until the synchronization of the demodulation circuit of the synchronous detection system of the standby receiving device is established, the demodulation output of the delay detection system is selected, and after the synchronization is established, the synchronous detection system is used. Radio communication apparatus characterized by regulating selects the demodulated output of the circuit, the selection control means for outputting, which is configured by providing the. 2. The transmitting apparatus according to claim 1, wherein the transmitting apparatus has means for adding an error correction signal to the transmission signal, wherein a working system of the receiving apparatus performs demodulation by at least a synchronous detection method; A first error correction means for receiving an output of a circuit and performing a correction process based on the error correction code; a standby system of the receiving apparatus; a synchronous detection demodulation circuit for performing demodulation by a synchronous detection method; A delay detection demodulation circuit that performs demodulation by a detection method, and a demodulation output of the delay detection demodulation circuit is selected until synchronization of the synchronous detection demodulation circuit is established when switching from a working system to a standby system. After establishment, a selection control means for selecting and outputting a demodulation output of the synchronous detection demodulation circuit, and a standby error correction decoding means for receiving an output of the selection control means and performing a correction process based on the error correction code, Have The wireless communication device according to claim 1, wherein: 3. The wireless communication apparatus according to claim 1, wherein said transmitting apparatus issues a switching request to said transmitting apparatus.
A transmission control means for controlling the transmission signal by adding a switching command signal to the transmission signal in response to the command of the switching request and transmitting the response signal to the switching command, and for controlling the transmission apparatus to switch to the standby system; 2. The wireless communication device according to claim 1, further comprising a response signal transmission control unit that transmits the response signal to a transmission device when the switching command signal is received. 4. The switching means for the receiving system switches the path between the active system and the standby system of the receiving apparatus on the input side and the output side, and switches the input side to a non-transmitting side path for the input side. The wireless communication device according to claim 1, wherein the wireless communication device is configured using a leak-type switch capable of causing a leak. 5. A transmitting apparatus and a receiving apparatus each having an active system and a standby system. The transmitting apparatus is provided with transmission system switching means for switching between the working system and the standby system. Is a wireless communication apparatus comprising a receiving system switching means for switching between the working system and the protection system, and switching between the working system and the protection system by using these switching means, wherein at least the receiving device serving as the working system is provided. The synchronous receiving system is used for the demodulation means, and the standby system receiving device is provided with a demodulation circuit of a synchronous detection system and a demodulation circuit of a delay detection system as its demodulation means. Differential detection system differential conversion means for differentially calculating the output of the circuit and outputting the result as a demodulated output of the delay detection system; and synchronous detection of the standby system reception device when switching from the active system to the standby system. Selection control means for selecting the demodulation output of the delay detection system until the synchronization of the demodulation circuit of the system is established, and selecting and outputting the demodulation output of the demodulation circuit of the synchronization detection system after the synchronization is established. A wireless communication apparatus comprising: a second error correction unit; and a second differential conversion unit that performs a differential operation on an output signal of the selection control unit. 6. The transmitting device has means for adding an error correction signal to a transmission signal, wherein the working system of the receiving device performs at least a working demodulation circuit for performing demodulation by a synchronous detection method; A first error correction means for receiving an output of a circuit and performing a correction process based on the error correction code; a standby system of the receiving apparatus; a synchronous detection demodulation circuit for performing demodulation by a synchronous detection method; A delay detection demodulation circuit that performs demodulation by a detection method, and a demodulation output of the delay detection demodulation circuit is selected until synchronization of the synchronous detection demodulation circuit is established when switching from a working system to a standby system. After establishment, a selection control means for selecting and outputting a demodulation output of the synchronous detection demodulation circuit, and a standby error correction decoding means for receiving an output of the selection control means and performing a correction process based on the error correction code, Have The wireless communication device according to claim 5, wherein 7. The receiving system switching means switches paths between an active system receiving apparatus and a standby system receiving apparatus on an input side and an output side thereof, and switches a part of an input to a non-selection side for path switching on an input side. 6. The wireless communication device according to claim 5, wherein the wireless communication device is configured by using a leak-type switch that can leak to a path. 8. The differential detection system differential conversion means performs a sum operation on the output of the delay detection type demodulation circuit and outputs the result as a delay detection system demodulation output. 6. The wireless communication apparatus according to claim 5, wherein a difference calculation process is performed on an output signal of the selection control unit. 9. A receiving apparatus for a radio communication apparatus having at least an active system and a standby system and operating by switching between the active system and the standby system, wherein the standby system has a synchronous detection demodulation using a synchronous detection system as demodulation means. Circuit, a delay detection demodulation means using a delay detection method as a demodulation means, and when switching from the working system to the protection system, the output of the delay detection demodulation means until the synchronization of the synchronous detection demodulation circuit is established. And a selection control means for selecting and outputting the output of the synchronous detection and demodulation means after the synchronization of the synchronous detection and demodulation means is established.