JPH05199270A - Digital microwave radio equipment - Google Patents

Abstract

PURPOSE:To prevent the out of synchronism and to attain smooth changeover by using also an output of a demodulation circuit of the delay detection system just after a standby system is selected and selecting an output of a demodulation circuit of the synchronization detection system in the stage when the synchronization is estab lished CONSTITUTION:When a receiver 400b of a standby system is started, a demodulation circuit 9' of the synchronization detection system and a demodulation circuit 9'' of the delay detection system are respectively operated. A control circuit 20 controls the equipment to select an output of the demodulation circuit 9'' just after the standby system is selected and switches a changeover switch 11' to the position of the demodulation circuit 9' in the stage that the synchronization is established. Then a demodulation output of the demodulation circuit 9' is given to processing circuits after an error correction circuit decoder 10'. Thus, no out of synchronism takes place even in the presence of a momentary interruption or frequency deviation or the like at transmitters 100a, 100b by employing delay detection in the initial stage of the switching of the receiver 400b of the standby system and the receiver 400a of the active system and then the changeover of the receivers 400a, 400b is smoothly implemented.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, various communication systems have been developed in response to an increase in communication needs and the 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, for example, a microwave using a quadrature phase modulation (QPSK) system or a multilevel quadrature amplitude modulation (multilevel QAM) system. Compared with the transmission system and the wired digital transmission system, it is possible to transmit high quality data at low cost.

By the way, in this type of system, a service is provided in order to remedy the deterioration of transmission quality and disconnection of the line caused by fading in the transmission line or the failure of the device constituting the transmission line, or when performing test repair of the device or line. In order to prevent interruptions, important devices on the transmission line are usually equipped 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 of which is the current system and the other of which is the standby system, and when one fails or needs to be inspected, the system is switched to the other system for operation. FIG. 3 shows a digital microwave radio apparatus adopting a set spare method, in FIG. 3, 21 is an input terminal, 22 is a baseband signal switcher, and 20a.
Is a working transmission system, and 20b is a standby transmission device. Also, 2
3, 23 'are transmission digital signal processing circuits, 24, 24
′ Is a modulation circuit, 25, 25 ′ is a transmission microwave circuit, 2
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.
Further, 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
1 is for switching the input of the transmission signal input from the active transmission system 20a or the standby transmission device 20b to the input, and the transmission digital signal processing circuits 23 and 23 'are The transmission signal input through the signal switch 22 is converted into a digital signal and output.

The modulation circuits 24, 24 'modulate the signals output from the digital transmission signal processing circuits 23, 23' by converting them into digital signals and output the signals. An error correction code is added to the modulated digital signal, which is 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 it.
The change-over switch 26 switches the microwave output from the transmission microwave circuit 25 or 25 ′ to change the microwave output from the antenna 36.
It leads to. The guided microwave is the antenna 3
It is released from 6 into the air.

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

The active reception system 40a is a reception microwave circuit 28.
, Demodulation circuit 29, differential conversion circuit decoder 30, error correction circuit decoder 32, and reception digital signal processing circuit 3
3, the standby reception system 40b includes a reception microwave circuit 28 ', a demodulation circuit 29', a differential conversion circuit decoder 30 ', an error correction circuit decoder 32', and a reception 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 working receiving system 4a and the standby receiving device 40b. To do.

The reception microwave circuits 28 and 28 'return the reception microwaves distributed by the high-frequency changeover switch 27 to a current signal, and the demodulation circuits 29 and 29' demodulate the current signal and perform original transmission. This is a circuit for returning to a signal (digital signal and error correction code added), and the differential conversion circuit decoders 30 and 30 'perform a differential operation on the transmission signal obtained by this demodulation to decode it into the original digital signal. The error correction circuit decoders 32 and 32 'are circuits that perform error correction on the decoded signal with reference to an error correction code and decode the received signal.
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 is provided with these digital signal processing circuits 33, 3
3'is a switching circuit for sending the output from one side to the output terminal 35.

Further, in such a configuration, during normal operation, the present digital microwave radio device has the working transmission system 20.
It is assumed that digital signals are exchanged using a and the active reception system side 40a.

In this state, for example, suppose that the transmitting station side performs maintenance and inspection work on the active system side constituent devices. In this case, when the maintenance worker enters the work, the maintenance worker keeps contact with the transmitting and receiving stations while the active system side After switching from the equipment to the equipment side of the standby system so that the signal can be transmitted using the equipment of the standby system, the maintenance and inspection work of the active equipment is started.

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

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

This transmitting microwave is received by the antenna 37 at the receiving station, sent to the microwave receiving circuit 28 'via the high frequency changeover switch 27, converted into an electric signal there, and then subjected to the synchronous detection method. It is sent to the demodulation circuit 29 '. In the demodulation circuit 29 ', this signal is synchronously detected, returned to the in-phase and quadrature-phase baseband signal components, and further subjected to the sum calculation processing to become in-phase and quadrature component identification data.

Therefore, this identification data is subjected to difference calculation by the differential conversion decoder 30 'and returned to the original, and then error-corrected by the error correction circuit decoder 32' and then decoded. Then, the received digital signal processing circuit 33 'performs signal processing to restore the original baseband signal, and then outputs it as a received decoded signal to the signal output terminal 35 via the switch 34.

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

That is, in the wireless device of the set spare system as shown in FIG. 3, the changeover switch 26 is used at the time of switching the transmitting side when switching from the active system to the standby system.
It is possible to avoid the problem that the transmission signal is interrupted during the switching operation and the frequency of the modulation circuit and the transmitter is different between the active device and the standby device, which causes the synchronous detection circuit in the receiving side demodulation circuit to become out of synchronization. Absent.

This is because at the time of switching the system, the signal input to the demodulation circuit of the synchronous detection system has a phase shift due to the difference in delay time between the transmitter of the active system and the transmitter of the standby system. The loss of the sync signal due to the instantaneous interruption causes an instantaneous change in the phase of the reproduced carrier wave due to the coherent detection, and exceeds the sync holding limit of the phase locked loop (PLL) of the demodulator circuit of the coherent detection method. Due to this, it is unavoidable that the loss of synchronization occurs.

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

FIG. 4 shows a demodulation circuit of the synchronous detection system,
FIG. 5 shows a demodulation circuit of the differential 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, and 6
3, 73 is a power phase shift distributor, 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 demodulation digital signal identification circuits, 67 and 77 are differential logic circuits, and 68 and 6
Reference numerals 8 ', 78 and 78' respectively denote output terminals of the demodulation circuit. In the synchronous detection system demodulation circuit of FIG.
2, 62 'and the carrier recovery circuit 66 form a phase-locked loop. Then, the demodulation circuit input terminal 61
The phase is locked to the signal that is input more.

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

The discrimination circuits 65 and 65 'are each composed of, for example, an A / D converter. In the discrimination circuits 65 and 65', the clock regenerated by the clock regeneration circuit 64 is used as the clock regenerated from the baseband signal. The baseband signals of the in-phase and quadrature components are A / D-converted in synchronism with each other, and converted into digital values corresponding to the levels, and are used as differential logic as identification data of the baseband signals of the in-phase and quadrature components. 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 signals of the in-phase and quadrature components to obtain 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 the carrier wave reproduction circuit 66.

The carrier recovery circuit 66 includes a logic circuit,
The carrier recovery circuit 66 includes a direct current amplifier having a loop filter and a voltage controlled oscillator (VCO).
The reference carrier wave is reproduced by. Then, this reference carrier wave is in-phase with the reference carrier wave by the power phase shift distributor 63,
After being branched to the 90 ° phase-shifted reference carrier wave, they are supplied to the synchronous detection circuits 62 and 62 ', respectively, whereby synchronous detection is performed.

That is, in the demodulation circuit adopting this synchronous detection method, a PLL (Phase Locked Loop) circuit is constituted by the synchronous detection circuits 62, 62 'and the carrier wave recovery circuit 66, and this PLL circuit makes it possible to obtain a multilevel QAM signal. Multi-valued QA according to a reference carrier whose phase is always locked against
Synchronous detection of the M signal is performed.

On the other hand, there is a differential detection system demodulation circuit as shown in FIG. 5 as another system in the demodulation circuit. In this differential detection system demodulation circuit, the modulation signal input from the input terminal 71 is branched into two. After that, one of them is branched by a hybrid circuit 70 into two signals whose phases are different from each other by 90 ° and supplied to local ports of a detection circuit (multiplier; double-bounce mixer) 72, 72 '.

On the other hand, the other of the two branched modulation signals is delayed by one bit in the delay circuit 76 and becomes a reference carrier. Then, the reference carrier wave is branched by the phase shift distributor 73 into the in-phase reference carrier wave and the 90 ° phase-shifted reference carrier wave 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 respectively supplied from the hybrid circuit 70 and the reference carrier are mixed and detected, and in-phase and quadrature-phase baseband signals are detected. To get Then, the baseband signals of the respective phases thus obtained are input to the demodulation digital signal identification circuits 75 and 75 'which are A / D converters. These identification circuits 75 and 75 'convert the baseband signals output from the detection circuits 72 and 72' into digital signals in synchronization with the clocks reproduced by the clock reproduction circuit 74, thereby converting the baseband signals The signal level is identified for each axial direction of quadrature modulation, and the identification output is input to the differential logic circuit 77. In the differential logic circuit 77, a predetermined logical process (a sum calculation process) is performed on the identification output, whereby demodulated data in each axis direction (in-phase component and quadrature component) of quadrature modulation is separated for each axis. Output terminal 7
Obtained from 8,78 '.

The above is the configuration example and the operation example of the demodulation circuit of the synchronous detection system and the differential detection system. As described above, since the active transmission device and the standby transmission device are not in a synchronous relationship, there is inevitably a delay time difference, and thus the active transmission device having the delay time difference transmits the standby system transmission. When switching to the device, a signal with a different delay time is switched and input from the input terminal on the side of the receiving device of the synchronous detection system, which exceeds the period holding limit of the phase lock loop and becomes out of synchronization. Moreover, since the input is switched with a momentary interruption, the synchronization is surely lost.

On the other hand, in the differential detection system shown in FIG. 5, the input signal of the demodulation circuit is delayed by the delay circuit 76 for a time of one clock and applied to the detection circuits 72 and 72 '. Since it is a method of detecting by a signal delayed by a clock time, a synchronizing circuit is not required, and therefore, there is no element that causes loss of synchronization.

However, since the differential detection system has no synchronous system, the error rate is relatively large as compared with the synchronous detection system. Therefore, it is not possible to totally adopt the demodulation circuit of the differential detection system instead of the demodulation circuit of the synchronous detection system when it is necessary to secure the decoding accuracy.

[0035]

As described above, in the reception system in the quadrature modulation type microwave radio communication system, the synchronous detection method is adopted as the carrier wave reproduction method in the demodulation circuit. Then, two systems of wireless devices are prepared, one of which is the current system and the other of which is the standby system, and when one fails or needs to be inspected, the system is switched to the other system for operation. In this type of microwave wireless communication system that employs the set standby system, the synchronous detection system is used as the carrier recovery system in the demodulation circuit in the receiving system. It comes off and becomes a problem.

That is, when the microwave radio communication system is switched from the active system to the standby system for operation, a momentary interruption occurs in the transmission microwave for the switching operation time of the changeover switch on the transmission side, and the active system and the standby system. Since the modulation circuit and the transmitter frequency are different in the system, and the delay time difference between the active device and the standby device is different, the phase-locked loop in the demodulation circuit on the receiving side exceeds its synchronization holding limit,
It is unavoidable that the synchronization is lost.

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.

Therefore, the object of the present invention is to
In a microwave radio device equipped with an active system and a standby system that can be switched and used, when switching from the active system to the standby system during maintenance, loss of synchronization can be prevented and the standby system can be switched smoothly. The present invention provides a microwave radio device.

[0039]

In order to achieve the above object, the present invention is configured as follows. That is, each of the transmitter and the receiver has an active system and a standby system,
The transmitting device side is provided with a transmitting system switching means for switching between the active system and the standby system, and the receiving device side is provided with receiving system switching means for switching between the active system and the standby system. In a microwave radio communication device capable of operating by switching a working system and a standby system by switching means, firstly, the transmitting device is provided with means for giving an error correction code to a transmission signal, and , At least the receiving device to be the active system uses the demodulation means as a synchronous detection system, and is provided with an active system error correction decoding means for receiving the output of the demodulation means and performing correction processing based on the error correction code, The system receiver is configured by providing a demodulation circuit of a synchronous detection system and a demodulation circuit of a differential detection system as its demodulation means, and the synchronization of the standby system reception device when switching from the active system to the standby system. Until synchronization of the demodulation circuit in the wave system is established, it selects the demodulated output of the delay detection system,
After the synchronization is established, the demodulation output of the demodulation circuit of the synchronous detection method is selected and output, and a second error for receiving an output of the selection control means and performing error correction processing based on the error correction code. A correction means and a processing means for obtaining a demodulated output from the signal after the error correction are provided.

Secondly, the transmitting apparatus is provided with means for giving an error correction code to the transmission signal, and
At least the receiving device serving as the working system uses the demodulation means as a synchronous detection system, and is provided with working system error correction decoding means for receiving the output of the demodulation means and performing correction processing based on the error correction code, and the standby system. The receiving device is configured by providing a demodulation circuit of a synchronous detection system and a demodulation circuit of a differential detection system as its demodulation means, and the output of the demodulation circuit of the differential detection system is summed to perform a demodulation output of a differential detection system. And a differential detection system differential conversion means for outputting as a differential detection system, and a demodulation output of the differential detection system until the synchronization of the synchronous detection system demodulation circuit of the standby system reception device is established when switching from the active system to the standby system. After the synchronization is established, the demodulation output of the demodulation circuit of the synchronous detection system is selected and output, and the output of the selection control means is received, and the error correction code based on the error correction code is received. A second error correction means for processing,
The second that performs difference calculation processing on the signal after this error correction
And differential conversion means of the above.

[0041]

In the above structure, the transmitting device adds an error correction code to the transmission signal and transmits the signal, and the receiving side receives this by the receiving device of the active system and synchronously detects the error correction code based on the error code. After that, it is returned to the baseband signal and used as the reception output. Then, when switching from the active system to the standby system, the receiving system switching means is switched to operate the two demodulation circuits of the standby system together, but at the initial stage of switching, the selection control means causes the synchronous detection type demodulation circuit and the delay detection circuit to operate. Among the demodulation circuits of the system, switching to select the output of the demodulation circuit of the differential detection system, until the synchronization of the demodulation circuit of the synchronous detection system is established, select the demodulation output of the differential detection system,
After the synchronization is established, it operates so as to select the demodulation output of the demodulation circuit of the synchronous detection system. Therefore, if the synchronous detection method becomes unstable, a delay detection method demodulation circuit that does not cause loss of synchronization at the beginning of switching is used, and if synchronization of the synchronous detection method demodulation circuit is established, the delay detection method synchronization is established. Since it is switched to the demodulation circuit of the detection system, it is possible to switch from the active system to the standby system without causing loss of synchronization.

Further, in the case of the first configuration, the demodulation output is
The error correction means performs error correction processing on the basis of the error correction code, and the error-corrected processing is converted into a baseband signal by the processing means to be a reception demodulation output.

As described above, the output of the demodulation circuit is subjected to error correction processing based on the error correction code, and further subjected to difference calculation processing, and then converted into a baseband signal to be a reception output. It is possible to suppress (effect of error correction processing) and to switch from the active system to the standby system (effect of suppressing loss of synchronization) without causing loss of synchronization.

Also, when switching from the active system to the standby system, the demodulation output of the differential detection system is selected until the synchronization of the demodulation circuit of the synchronous detection system of the standby system receiver is established. In the case of the above configuration, the output of the differential detection type demodulation circuit is summed by the differential detection system differential conversion means and is used as the demodulated output of the differential detection system, and this is output by the second error correction means. Error correction processing is performed based on the above, and the output after this error correction processing is subjected to difference calculation processing by the second differential conversion means, and then converted into a baseband signal to be a reception output. When the synchronization of the demodulation circuit of the coherent detection system of the standby receiver is established, the selection control means switches from the demodulation output of the delay detection system to the demodulation output of the demodulation circuit of the coherent detection system. The demodulation output of the demodulation circuit of the system is given to the second error correction means, the second error correction means performs error correction processing based on the error correction code, and the output after this error correction processing is the second output. After the differential calculation processing is performed by the differential conversion means, it is converted into a baseband signal by the processing means and becomes a reception demodulation output.

As described above, according to the present invention, in the microwave radio communication system of the set standby system in which the active system and the standby system are provided, at least the demodulation circuit of the synchronous detection system and the delay detection system is used as the demodulation circuit of the receiver side of the standby system. The delay detection method demodulation circuit output is used at the beginning when switching to the standby system, and the synchronous detection method demodulation circuit output is used when synchronization is established. Instead, the standby system can be started and switched, and the output of the demodulation circuit of the differential detection system is subjected to the sum operation processing through the differential conversion means, and the error correction processing is performed based on the error correction code. Then, the difference calculation processing is further applied, and then it is converted to a baseband signal to be the reception output, and the output of the demodulation circuit of the synchronous detection method is converted into an error correction code. The error correction processing is performed first, and then the difference calculation processing is performed, and then the baseband signal is converted to the reception output, so that the transmission path error is suppressed (effect of the error correction processing) and the synchronization is lost. It is possible to switch from the active system to the standby system (the effect of suppressing the loss of synchronization) without causing the error.

Further, in the difference calculation processing by the second differential conversion means, if an error due to noise such as fading or a waveform distortion occurs on the transmission line, the error will be doubled. Before the error is increased by the conversion means,
Since the error is corrected by the error correction means, the error correction capability can be secured and the reliability can be secured.

Therefore, according to the present invention, in a microwave radio apparatus having a working system and a standby system, which can be switched and used, loss of synchronization is prevented when switching from the working system to the standby system during maintenance. A microwave radio device capable of smoothly switching to the standby system can be provided.

[0048]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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 a current system device, and the transmission digital signal processing circuit 3 '
Indicates that it is for a standby system device, and those with the reference symbol "'" are for the standby system device, and those without the symbol "'" are for the current device. ..

4, 4'is a modulation circuit, 5, 5'is a microwave transmission circuit, 6 is a high-frequency switch, 7 is a high-frequency changeover switch, 8, 8'is a microwave reception circuit, and 9, 9'is a synchronous detection system. Demodulation circuit, 9 "is a delay detection type demodulation circuit used only in the spare device, 10 and 10 'are error correction circuit decoders, and 11' is a synchronous detection type demodulation circuit 9'in the spare device.
And a switch for switching the delay detection type demodulation circuit 9 ″, 12 and 12 ′ are differential conversion circuit decoders (difference arithmetic circuits), 12 ″ are differential conversion circuit decoders (summation arithmetic circuits),
Reference numerals 13 and 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 shown respectively.

The signal distributor 2 is a switch for giving 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 and 3'are provided with this signal. It is a circuit that processes a transmission signal sent via the distributor 2 into a predetermined digital signal.

The modulation circuits 4 and 4'are circuits for modulating the outputs of the transmission digital signal processing circuits 3 and 3 '(for example, quadrature conversion modulation such as 16QAM) and outputting them, and have a built-in error correction circuit encoder. However, the output from the transmission digital signal processing circuits 3 and 3'is configured to be processed by adding an error correction code and then modulated and output. This enables the error correction decoding process on the receiving side.

The microwave transmitting 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 to the antenna 16, and the changeover request switch 18 is changed from the current system to the standby system. This is a command switch to be operated when switching the transmission system to. The control circuit 19 is the center of control on the side of the transmitter. When an alarm occurs, a switching request signal is placed on the control channel and sent to the receiving side, and 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 backup system (or vice versa), when the switching request switch 18 is operated, a switching request signal is received on the control channel. It has a function of performing control such that the transmission system is sent to the side, and the changeover switch 6 is switched when a switching response is received from the reception side to switch 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 applying the microwave received by the antenna 17 to the receiving device of the working system or the receiving device of the standby system. The high-frequency changeover switch 7 can switch the route between the working system and the standby system, and is configured so 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 the received microwaves sent through the high frequency changeover switch 7 into electric signals and output the electric signals. The demodulating circuits 9 and 9 of the synchronous detection system. ′ Is for demodulating and outputting the outputs of the corresponding microwave receiving circuits 8 and 8 ′. The differential detection type demodulation circuit 9 ″ is configured to detect the output of the corresponding microwave reception circuit 8 ′ by delay detection, demodulate and output.

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

Since the differential detection type demodulation circuit 9 "is configured to perform the differential calculation simultaneously with the detection, in order to match the differential detection type demodulation circuit 9'side, the differential conversion code is provided after the differential detection circuit 9". Place a vessel (summing arithmetic circuit) 12 ″,
This sum calculation does not hinder the processing in the subsequent stage.

An error correction decoder (FEC DEC) 10 'is for performing error correction decoding on the data output through the changeover switch 11', and a differential conversion circuit decoder (differential operation circuit) 12 ′ Is for differential conversion decoding of 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 ′, processes the signal, and The baseband signal switcher 14 is a circuit that outputs a baseband signal, and the baseband signal switcher 14 is a switching circuit that receives outputs from the digital signal processing circuits 13 and 13 ′, switches one of them to be selected, and sends the output 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 the differential conversion circuit decoder (difference calculation 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 performs signal processing to obtain the original baseband signal. It is a circuit that outputs.

The control circuit 20 plays a central role of control on the side of the receiving device, and is composed of 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, it has a function of switching the baseband signal switching device 15 to the backup system side, and then switching the changeover switch 11 ′ of the standby system receiving circuit section 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 chart of FIG. During normal operation, this digital microwave radio device has a working system transmitting device side 200a (components 1, 2, 3, 4, 5, 6) and a working system receiving device side 400a of FIG.
(Components 7, 8, 9, 10, 12, 13, 14, 1
It is assumed that the digital signal is exchanged using 5).

For example, in this state, if the transmitting station side performs maintenance and inspection work on the active system side constituent devices, in this case, the maintenance worker first starts from the active system device to the standby system device. Side, so that the signal can be transmitted using the standby system side, and then maintenance work of the active system device is started. Upon this switching, the maintenance worker sends a switching command, which is instructed by operating the switching request switch 18 provided in the transmission side device.

When the change request switch 18 is operated, a change command is issued to the control circuit 19. When the switching command is received, the control circuit 19 of this device activates the standby transmission device 20b. That is, the control circuit 19 on the transmitting station side checks whether or not an alarm is generated (S9a),
The switch request switch 18 is checked (S9b). If 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 active digital signal processing circuit 3 is sent. give.

As a result, 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. Then, the microwave transmission circuit 5 converts the microwave into a microwave, which is sent to the antenna 16 via the changeover switch 6 and transmitted.

This transmitting microwave is received by the antenna 17 in the receiving station, sent to the microwave receiving circuit 8 via the high frequency changeover switch 7, converted into an electric signal there, and then demodulated by the synchronous detection method. Sent to the circuit 9. The demodulation circuit 9 synchronously detects this signal, and the error correction circuit decoder 10 corrects the error before decoding. Then, the differential conversion decoder 12 calculates the difference, and the reception digital signal processing circuit 13 processes the signal to convert it into a baseband signal, which is then output to the signal output terminal 15 via the switcher 14.

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

The control circuit 20 monitors the switching request signal from the signal of this control channel (S10a), and if it detects the switching request signal, it activates the standby system 200b of the receiving device, and then switches the selector switch 11 '. The switching circuit is switched to the dynamic conversion circuit decoder 12 ″ (S10b). When this is completed, the control circuit 20 gives a command to the transmitting device of its own station to generate a switching response signal. The transmitting device of the station inserts the switching response signal into the control channel, modulates the signal to convert it into microwaves, and then transmits the microwaves to the partner station (the transmitting station) (S10e).

In the transmitting station which received this, the receiving system of its own station demodulates 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), when the changeover response signal is received, the changeover switches 2 and 6 are controlled to be changed respectively, and the transmitting device is changed over from the active system 20a to the standby system 20b (S9e). So after this,
The transmitter transmits the input transmission signal to the standby system, which is modulated in the standby system 20b, converted into microwaves and transmitted.

On the other hand, on the receiving station side, the receiving device 20 of the standby system
Since 0b is activated, the active reception device 200a and the standby reception device 200b enter the parallel reception state. That is, the received microwaves are given to the receiving device 200a of the active system and the receiving device 200b of the standby system by the high-frequency changeover switch 7 capable of leaking power, and the receiving device of the active system is supplied.
The receiving device 200b of the standby system 200a and the receiving device 200b of the standby system respectively perform reception operation, detect and demodulate the received signal, and output it.

At this time, although the demodulation circuits 9'and 9 "operate in the standby receiver 200b, 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 system side. Therefore, in this state, the signal demodulated by the differential detection method is summed by the differential conversion circuit decoder 12 ″, and the result is summed by the error correction circuit decoder 1 through the changeover switch 11 ′.
0 ', is subjected to error correction processing here, is then decoded, and is also a differential conversion circuit decoder (difference calculation circuit) 12'.
After being subjected to the difference calculation processing in step S1, the receiving digital signal processing circuit 13 'restores the original baseband signal, and the switch 1
Given to 4.

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

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

As described above, in this system, the delay detection system is used in the initial stage of switching, the system is switched to the synchronous detection system after the synchronization of the synchronous detection system is established, and the standby system is used in this synchronous detection system. It is intended to be used finally. In this way, differential detection is used at the initial stage of switching because differential detection does not synchronize unlike synchronous detection, so even if there is a momentary interruption on the transmission side or 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 waiting for the establishment of synchronization of the synchronous detection system, it is possible to switch from the active system device to the standby system device without generating an error bit during maintenance and inspection. To do.

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

Due to these causes, when the synchronous detection method is adopted in the demodulation circuit of the receiving device, the synchronization is lost when the transmitting device is switched from the active system to the standby system. Then, the digital signal transmitted during this period of being out of synchronization becomes erroneous.

In the present invention, at the time of such switching, the reception processing is first performed using the delay detection type demodulation circuit, and the synchronous detection type demodulation circuit 9'in the standby system receiving device 200b is also activated and synchronized. Wait for the establishment of. And
If the synchronization of the demodulation circuit 9'of the synchronous detection system is established (S
10f), the control circuit 20 switches the changeover switch 11 'to the side of the demodulation circuit 9'of the synchronous detection system (S10g). As a result, after the synchronization is established, the demodulation output of the demodulation circuit 9'of the synchronous detection system is given to the processing circuit below the error correction circuit decoder 10 ', and the error is corrected and decoded, the difference is calculated, the signal is processed, and the base is processed. A band signal can be obtained and obtained as a reception output, and thereafter, reception processing using a demodulation circuit output by synchronous detection can be performed. As a result, it is possible to switch to the standby system without the risk of out of sync.

Since the differential detection type demodulation circuit 9 "is configured to perform the differential calculation simultaneously with the detection, in order to match the differential detection type demodulation circuit 9'side, the differential conversion encoder ( A summing arithmetic circuit) 12 ″ is arranged so that the arithmetic processing does not interfere with the subsequent processing.

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

In this way, the differential conversion circuit decoder (difference calculation circuit) 1 is used after the transmission path error is removed from the demodulated signal.
Since it is given to 2'and is converted into a baseband signal, it is more rational than the method of performing error calculation decoding after the difference calculation of the demodulated signal (in this case, the transmission line error increases). , The accuracy of the correction is improved. That is, in the case of correcting an error with an increased error, the error correction capability is lower than that of the system of the present system, but such a problem is eliminated in the system of the present system in which the error is corrected first and the difference is then calculated. ..

In addition, it will be supplementarily described below that the addition operation after the differential detection circuit 9 "has an effect of reducing errors.

Now, the signal value of the transmission signal every moment is; x ₀ , x
₁ , x ₂ , ..., X _n , ... And the sum operation value (y _n = x _n + y _n−1 ) of this signal value; y ₀ , y ₁ , y ₂ ,.
_Let 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 , ..., and the sum calculation value (W _n
= Z _n + W _n−1 ); W ₀ , W ₁ , W ₂ , ..., W _n ,
...

Here, it is assumed that a 1-symbol error occurs in y _n . This one-symbol error yn spreads the error to the difference calculation result values Z _n and Z _{n + 1} .

Z _n = (y _n ) −y _n−1 Z _{n + 1} = y _{n + 1} − (y _n ) However, the above formulas indicating the values Z _n and Z _{n + 1} are represented by enclosing the error in brackets (). There is.

As can be seen from the above, the one-symbol error yn that affects Z _n and Z _{n + 1} has the opposite sign.
Among the re-summation calculation results, W _n , W _{n + 1} , W _{n + 2,} ... Are related to Z _n and Z _{n + 1} . _{Therefore, W n = Z n + W} n-1 = (y n) -y n-1 + W n-1 , and becomes one symbol error.

However, the error is canceled by W _{n + 1} = Z _{n + 1} + W _n = y _{n + 1} − (y _n ) + (y _n ) −y _n−1 + W _n−1 . Therefore, there is no error in W _{n + 2} = z _{n + 2} + W _{n + 1} = y _{n + 2} −y _{n + 1} + W _{n + 1} , and W _{n + 3} ... No error after all, and eventually the sum operation after the delay detection circuit 9 ″ reduces the error. You can see that it is effective.

In the receiving apparatus of this embodiment, since the leak type switch is used as the high frequency switching switch 7, the reception transmission signal is supplied to the standby receiving apparatus 400b without instantaneous interruption when the switching switch 7 is switched. Will be done. Therefore, a bit error of the transmission signal does not occur when the changeover switch 7 is switched, and thus the active receiver 400a can be smoothly switched to the standby receiver 400b.

Therefore, for example, even if the changeover switch 6 of the transmission device is changed over a short time after the changeover switch 7 is changed, only the changeover switch 6 causes the bit error of the transmission signal. That is,
Bit errors can be suppressed within 2 bits that can be corrected by the error correction circuit 10 ', so that no problem occurs in data demodulation. In other words, it is not necessary to perform control for sufficiently delaying the changeover timing of the changeover switch 6 of the transmitter from the changeover timing of the changeover switch 7 of the receiver, which simplifies the changeover control of the control circuit 19 of the transmitter. You will be able to.

By the way, when the leak type switch is not used as the changeover switch 7, that is, when the non-leakage type switch which is generally used as the microwave switch is used, the received transmission signal of the received transmission signal is changed even when the changeover switch 7 is changed. Since a momentary interruption occurs, the total number of bit errors generated in the received transmission signal at the time of switching is 4 bits even if each switch has 2 bits.
The error correction capability of the error correction circuit 12 'is exceeded. Therefore, the changeover 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, resulting in complicated control. However, this is not the case when using a leaky switch.

As described above, this system has a working system and a standby system as a transmitting device and a receiving device, respectively, and a transmitting system switching means for switching between the working system and the standby system is provided on the transmitting device side. In the microwave radio communication device, the receiving device side is provided with receiving system switching means for switching between the active system and the standby system, and the active system and the standby system can be switched and operated by these switching means. The transmitting device is configured by providing a means for giving an error correction code to the transmission signal, and at least the receiving device which is the active system uses the demodulating means as a synchronous detection system and receives the output of the demodulating means, An active system error correction decoding means for performing a correction process based on the error correction code is provided, and the standby system receiving device has a synchronous detection system demodulation circuit and a delay detection system recovery circuit as its demodulation means. A differential detection means for converting the output of the delay detection type demodulation circuit to a sum and performing output operation as a demodulation output of the delay detection system, and switching from the active system to the standby system. At this time, the demodulation output of the differential detection system is selected until the synchronization of the demodulation circuit of the synchronous detection system of the standby system receiver is established, and after the synchronization is established, the demodulation output of the demodulation circuit of the synchronous detection system Select
Second selection control means for outputting and second output for receiving an output of the selection control means and performing error correction processing based on the error correction code
The error correction means and the second differential conversion means for performing a difference calculation process on the signal after the error correction are provided.

Then, the transmitting apparatus adds an error correction code to the transmission signal and transmits the signal, and the receiving side receives this by the receiving apparatus of the active system and performs synchronous detection, and after error correction based on the error code. The baseband signal is returned to the reception output, but when switching from the active system to the standby system, the receiving system switching means is switched to operate the two demodulation circuits of the standby system together, and the selection control means operates at the initial stage of switching. Between the synchronous detection type demodulation circuit and the differential detection type demodulation circuit, the output of the differential detection type demodulation circuit is switched to be selected, and the delayed detection is performed until the synchronization of the synchronous detection type demodulation circuit is established. After the demodulation output of the system is selected and the synchronization is established, the demodulation output of the synchronous detection type demodulation circuit is controlled to be selected. Therefore, if the synchronous detection method becomes unstable, a delay detection method demodulation circuit that does not cause loss of synchronization at the beginning of switching is used, and if synchronization of the synchronous detection method demodulation circuit is established, the delay detection method synchronization is established. Since it is switched to the demodulation circuit of the detection system, it is possible to switch from the active system to the standby system without causing loss of synchronization.

Also, when switching from the active system to the standby system, the demodulation output of the differential 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 detection type demodulation circuit is summed by the differential detection system differential conversion means to be a delayed detection system demodulation output, which is subjected to error correction processing based on the error correction code by the second error correction means. Further, the output after the error correction processing is subjected to difference calculation processing by the second differential conversion means, and then converted into a baseband signal to be a reception output. When the synchronization of the demodulation circuit of the synchronous detection system of the standby receiver is established, the selection control means switches from the demodulation output of the differential detection system to the demodulation output of the demodulation circuit of the synchronous detection system.
The demodulation output of the demodulation circuit of the synchronous detection system in which the synchronization is established 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 difference calculation processing by the second differential conversion means and then converted into a baseband signal to be a reception output.

As described above, according to the present invention, in the set standby type microwave radio communication system in which the active system and the standby system are provided, at least a demodulation circuit of the synchronous detection system and the delay detection system is provided as a demodulation circuit on the receiving side of the standby system. The delay detection method demodulation circuit output (the error rate characteristic is bad but there is no loss of synchronization) is used at the beginning when switching to the standby system, and the synchronization detection method demodulation circuit output is used when synchronization is established. With this, it is possible to start and switch the standby system without causing loss of synchronization, and for the output of the demodulation circuit of the differential detection system, the sum calculation processing is performed via the differential conversion means, This is subjected to error correction processing based on the error correction code, further subjected to difference calculation processing, and then converted to a baseband signal to be received output, and synchronous detection is also performed. The output of the demodulation circuit of the system is subjected to error correction processing based on the error correction code, and further subjected to difference calculation processing, and then converted to the baseband signal to be the reception output, so that the error is not amplified and It is possible to correct a transmission path error (effect of error correction processing), and perform non-interruptive switching (effect of suppression of synchronization loss) during maintenance.

Further, in the difference calculation processing by the second differential conversion means, if an error due to noise such as fading or a waveform distortion occurs in the transmission line, the error is doubled. Before the error is increased by the conversion means,
Since the error is corrected by the error correction means, the error correction capability can be secured and the reliability can be secured.

Therefore, according to the present invention, in a microwave radio apparatus having a working system and a standby system, which can be switched and used, loss of synchronization can be prevented when switching from the working system to the standby system during maintenance. It becomes 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 and carried out without departing from the scope of the invention. For example, the above embodiments are The active receiver only had a synchronous detection type demodulator circuit, and the standby receiver had a combination of a synchronous detection system and a differential detection system demodulator circuit.Of course, the active system also had a delayed detection system demodulator circuit. Then, when switching from the standby system to the active system, it is possible to implement the same switching operation control as in the case of the standby system, and there is no particular need to distinguish between the standby system and the active system. Needless to say.

In the above embodiment, the case where the present invention is applied to the switching from the active system to the standby system has been described as an example, but it is also applied to the 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 types of changeover switches, the configuration of the demodulation circuit adopting the differential detection method, the configuration of the demodulation circuit adopting the synchronous detection method, the switching control procedure, the control contents, etc. are also within the scope of the present invention. Can be modified in various ways.

[0098]

As described above, according to the present invention, the demodulation circuit of the standby system receiver is provided with the synchronous detection system and the differential detection system, the two systems can be selected, and the error correction circuit encoder is provided on the transmission side. Since the error correction code is added and transmitted, and the receiving side performs a correction process based on this error correction code, the differential conversion circuit encoder for difference calculation processes it. It becomes possible to perform non-instantaneous interruption switching at the time of maintenance without lowering the error correction capability.

Therefore, according to the present invention, in the microwave radio equipment provided with the working system and the standby system, which can be switched and used, the system is switched from the working system to the backup system at the time of maintenance. It is possible to provide a microwave radio device capable of preventing disconnection and smoothly switching to the standby system.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a procedure for controlling switching from the active system to the 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 the configuration of a differential detection type demodulation circuit.

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

[Explanation of symbols]

1 ... Signal input terminal, 2 ... Baseband signal switcher, 3,
3 '... transmission digital signal processing circuit, 4, 4' ... error correction circuit encoder built-in modulation circuit, 5, 5 '... transmission microwave circuit, 6, 26 ... changeover switch (diode changeover switch), 7 ... high frequency changeover Switch, 8, 8 '... Reception 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 (difference arithmetic circuit), 12 "... differential conversion circuit code Receiver (summing operation circuit), 13, 13 '... Received digital signal processing circuit, 14 ... Baseband signal switcher, 1
5 ... Signal output terminals, 16, 17 ... Antennas, 61, 71
... Demodulation circuit input terminal, 62, 62 ', 72, 72' ... Detection circuit, 63, 73 ... Power phase shift distributor, 66 ... Carrier recovery circuit, 76 ... 1 clock time delay circuit, 64, 74
... clock recovery circuit, 65, 65 ', 75, 75' ... demodulation digital signal identification circuit, 67, 77 ... differential conversion circuit decoder (difference operation circuit), 68, 68 ', 78, 78'
… Demodulator output terminal.

Front Page Continuation (72) Inventor Hirofumi Hoshino 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (6)

[Claims] 1. A transmission device and a reception device each have an active system and a standby system, and the transmission device side is provided with a transmission system switching means for switching between the active system and the standby system, and the reception device side. Is a microwave radio communication device equipped with receiving system switching means for switching between the active system and the standby system, and switching between the active system and the standby system by these switching means. A means for adding an error correction code to the signal is provided, and at least the receiving device to be the active system uses the demodulation means as a synchronous detection system and receives the output of the demodulation means to convert the error correction code into the error correction code. An active system error correction decoding means for performing correction processing based on the above is provided, and the standby system receiving device is configured by providing a synchronous detection type demodulation circuit and a differential detection type demodulation circuit as its demodulation means. Further, when switching from the active system to the standby system, until the synchronization of the demodulation circuit of the synchronous detection system of the standby system receiver is established, the demodulation output of the differential detection system is selected, and 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 second error correction means for receiving the output of the selection control means and performing error correction processing based on the error correction code, A digital microwave radio communication apparatus comprising: a processing unit for obtaining a demodulated output from an error-corrected signal. 2. The digital microwave radio communication apparatus according to claim 1, wherein the transmitting device issues a switching request, and the switching command signal is added to the transmission signal when the switching request is issued. In addition to the control, a transmission control means is provided for controlling the transmitting device to switch to the standby system when receiving the response signal to the switching command, and the receiving device transmits the response signal to the transmitting device when receiving the switching command signal. A digital microwave radio communication device characterized by comprising a control means. 3. The receiving system switching means performs path switching between the active system receiving device and the standby system receiving device on the input side and the output side thereof, and part of the input is deselected on the input side route switching. 3. A leak-type switch capable of leaking to a path is used for construction.
The described digital microwave radio communication device. 4. A transmitting system and a receiving device each have an active system and a standby system, and the transmitting device side is provided with a transmitting system switching means for switching between the active system and the standby system, and the receiving device side. Is a microwave radio communication device equipped with receiving system switching means for switching between the active system and the standby system, and switching between the active system and the standby system by these switching means. A means for adding an error correction code to the signal is provided, and at least the receiving device which is the active system uses the demodulation means as a synchronous detection system and receives the output of the demodulation means to convert the error correction code into the error correction code. An active system error correction decoding means for performing correction processing based on the above is provided, and the standby system receiving device is configured by providing a synchronous detection type demodulation circuit and a differential detection type demodulation circuit as its demodulation means. And a differential detection system differential conversion means for differentially calculating the output of the differential detection type demodulation circuit and outputting it as a demodulation output of the differential detection system, and the standby system receiver when switching from the active system to the standby system Until the synchronization of the demodulation circuit of the synchronous detection method is established, select the demodulation output of the differential detection system,
After the synchronization is established, the demodulation output of the synchronous detection type demodulation circuit is selected and output, and a second error for receiving an output of the selection control means and performing error correction processing based on the error correction code. Correction means and second for performing differential arithmetic processing on the signal after the error correction
And a processing means for obtaining a demodulated output from the signal after the differential arithmetic processing, the digital microwave radio communication apparatus. 5. The receiving system switching means switches the route between the active system receiving device and the standby system receiving device on the input side and the output side thereof, and when switching the input side route, a part of the input is deselected. The digital microwave radio communication device according to claim 4, wherein the digital microwave radio communication device is configured by using a leak type switch capable of leaking to a path. 6. The differential detection system differential conversion means sums and outputs the output of the differential detection type demodulation circuit as a demodulation output of the differential detection system, and the second differential conversion means produces an error. 5. The digital microwave radio communication device according to claim 4, wherein the corrected signal is subjected to difference calculation processing.