JPH01194551A - Digital micro-wave communication system - Google Patents

Abstract

PURPOSE:To simplify a device and to cause a cost to be low by fixing the base band signal of a modulator to specified data at a trouble time and transmitting a non-modulating wave without a squelch oscillator. CONSTITUTION:A data signal is passed through a code converter 101 and a code processor 102 and inputted to a modulator 108. The demodulator 108 fixes the base band signal, which is inputted to an orthogonal modulator, to the specified data at the trouble time, outputs the non-modulating wave and outputs normal PSK and QAM modulating waves at a normal time by the output signal of a warning controller 109, which collects and controls warnings Thus, the squelch oscillator is eliminated and the device goes to be simple. Then, the cost goes to be low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital microwave communication system using n-value PSK and QAM modulation and demodulation, and particularly to a system for transmitting unmodulated waves in the event of a failure.

[Conventional explanation] In digital microwave communication, when a propagation path failure or equipment failure occurs, the output spectrum of the transmitter becomes abnormal, adversely affecting adjacent signals, or the SC signal is converted to PSK by FM modulation. .

In the QAM weight modulation system, even though the propagation path is normal and the demodulator of the opposite station is not faulty, the demodulator may have a pull-in failure and the SC signal cannot be reproduced. there were.

Therefore, conventionally, a method has been adopted for relief by providing a squelch oscillator, supplying the output signal of the squelch oscillator to a transmitter in the event of a failure, and transmitting an unmodulated signal.

For example, as shown in the example of the terminal equipment in FIG.

The data signal from the MUX at the carrier end is sent to the code converter 101.
, the signal passes through a transmission code processor 102, is input to a modulator 103, is orthogonally modulated by a carrier wave from an internal oscillator, becomes PSK and QAM modulated waves, and is supplied to a switch 106.

Further, one input of the switch 106 is connected to the modulator 103.
The output of a squelch oscillator 105 which oscillates at approximately the same frequency as the oscillator of the code converter 101. An alarm controller 104 that collects and controls the alarms of the code processor 102 and the modulator 103 selects the output signal of the modulator 103 in normal times and the output signal of the squelch oscillator 105 in the event of a failure and supplies them to the transmitter 107. .

[Problems to be solved] The conventional method described above requires a squelch oscillator that is not always needed, which increases the complexity of the device and increases the
There was also a problem that the price was high.

The present invention has been made in view of the above problems, and is designed to generate unmodulated harmonics and provide relief by fixing the baseband signal of the modulator to specific data without providing a squelch oscillator. The purpose is to provide a digital microwave communication system that enables

[Means for solving the problem] The digital microwave communication system of the present invention uses n-value PSK,
In digital microwave communication using the QAM modulation/demodulation method, when there is a device failure or a propagation failure, the baseband signal of the modulator is fixed to specific data to transmit unmodulated waves.

[Example] Next, an example of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram of a terminal equipment used in an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of the configuration of the same modulator.

In FIG. 1, a data signal is passed through a code converter 101 and a code processor 102 to a modulator 108 as in the conventional case.
is input to.

Then, the modulator 108 fixes the baseband signal input to the quadrature modulator at a fault to specific data by the output signal of the alarm controller 109 that compiles and controls alarms, and outputs an unmodulated wave. Outputs PSK and QAM modulated waves.

This modulator 10B is configured as shown in FIG. 2. Input data is subjected to a predetermined logical operation in a code converter 115, and there are cases in which the input data is output as is by an external control signal. , is input to the reset circuit 116 which has two cases of outputting a specific fixed value. The output signal of the reset circuit 116 is sent to the D/A converter 117. The signal passes through a low-pass filter 118, is orthogonally modulated in a quadrature modulator 119 using an output signal from a local oscillator 120, and is amplified to a specified level in an amplifier section 121 to become an output signal.

- the output signal of the modulator 108 is fed to the transmitter 107;
It is transmitted after being amplified.

FIG. 3 is a block diagram used when implementing the present invention in a relay station device. In the circuit configuration of this relay station device, a code converter 101 is connected to a receiver 110, and a code processor 1 is connected to a receiver 110.
The configuration is substantially the same as that shown in FIG. 1, except that 02 is replaced by a demodulator 111.

[Effects of the Invention] As explained above, in the present invention, by fixing the baseband signal of the modulator at failure to specific data, it is possible to transmit an unmodulated wave without a squelch oscillator.
This has the effect that the device can be made simple and can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a terminal station device used in an embodiment of the present invention, FIG. 2 is a block diagram of the same modulator, FIG. 3 is a blow diagram of a relay station device, and FIG. 4 is a conventional block diagram. A block diagram of each terminal equipment used is shown. 101: Code converter 102: Code processor 107: Transmitter 108: Modulator 109: Alarm controller 115: Code converter 116: Reset circuit 117: D/A converter 118: Low-pass filter 119: Quadrature modulator 120 : Local oscillator 121: Amplifier section representative Patent attorney Kihei Watanabe Figure 3 Figure 4 1'O5

Claims (1)

[Claims] In digital microwave communication using n-value PSK and QAM modulation/demodulation systems, a digital microwave communication system is characterized in that, in the event of equipment failure or propagation failure, unmodulated waves are transmitted by fixing the baseband signal of the modulator to specific data. Microwave communication method.