JPS581574B2 - Multiplex wireless relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, there is no risk of abnormal operation even when the received wave disappears or decreases.

The present invention relates to a multiplex radio relay device that performs amplification or noise removal using a phase-locked loop (hereinafter abbreviated as PLL).

After receiving the received wave as it is or after shifting the frequency appropriately,
Synchronize the VCO with the input signal by inputting it to a PLL consisting of a phase detector, loop filter, loop amplifier, and voltage-controlled oscillator (hereinafter referred to as vCO), and output the output of the CO directly or with an appropriate frequency shift as a relay output. A multiplex radio repeater used as a direct repeater is already known as a direct repeater that processes input microwave signals as they are as microwaves without converting them into intermediate frequency signals.

Such a relay device can use a loop filter in the control loop of the CO, so it has a band limiting effect to some extent, and since the output of the VCO becomes the output of the relay device, it cannot have an amplification effect. It has advantages such as:

On the other hand, such relay devices have the following various drawbacks.

That is, when the received wave decreases due to fading or the like, the PLL becomes uncontrollable, and unnecessary waves may be transmitted from the VCO.

Furthermore, under such conditions, CO is drawn into the interference waves,
The interference wave may be amplified and transmitted.

In any of these cases, a false signal is emitted from the relay device, which may cause interference not only with the own line but also with other lines, causing great confusion.

Furthermore, if vCO is drawn into the interference wave as described above, even if the received wave recovers, it is likely to be difficult to draw it back into the received wave.

Furthermore, the pull-in time for received waves is generally long, especially ■C
When the capture range of O is narrow, there are many problems such as not being able to pull in unless a sweep is performed, and the above-mentioned relay device was not necessarily practical.

In contrast, in the past, after amplifying the input signal, only the desired received signal was extracted using an appropriate filter, and when the signal level was detected and fell below a certain reference level, a switch was operated to detect the transmitted signal. VC with another oscillator (restorer) that can disconnect or generate a carrier wave.
Methods such as switching O were used, but none of them could be called a perfect solution.

The present invention is a novel invention that solves the drawbacks of the prior art, and its purpose is to eliminate the risk of emitting a fraudulent signal from the CO even when the received wave drops, and to quickly recover the received wave. An object of the present invention is to provide a multiplex wireless relay device that can establish synchronization.

In order to achieve this object, the multiplex radio relay device of the present invention stores the CO control voltage during normal operation, and fixes the VCO control voltage to the voltage just before it was stored when the received wave drops. It is characterized by:

Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 is a block diagram showing the configuration of an embodiment of a multiplex radio relay device of the present invention.

In the figure, a received wave f1 input from a receiving antenna 1 passes through a bandpass filter 2 and an amplifier 3, removes unnecessary waves, and is appropriately amplified.
The signal is mixed with the shifted frequency signal f8 (=fl to f2) and converted into a signal of frequency f2, and after its level is made constant by the amplifier 6 with AGC, it is input to the phase detector 7.

The phase detector 7 compares the phases of the input signal f2 from the amplifier 6 and the output signal of the VCO 8, and generates an output signal according to the phase difference.

The output signal of the phase detector 7 removes unnecessary components with a loop filter 9, is amplified with a DC amplifier 10, and is then supplied as a control signal to the VCO 8, where a round of feedback control is performed to control its oscillation frequency. In a sufficiently controlled state, the signal generated by vcos has the same frequency and constant phase as the input signal f2 from the amplifier 6.

The output signal f2 of the VCO 8 is amplified to a required level by the amplifier 11, unnecessary wave components are removed by the band pass filter 12, and then sent out from the transmission amplifier 13.

On the other hand, the output signal f2 from the amplifier 6 removes unnecessary waves by the bandpass filter 14, and then is detected by the detector 15. When the detected output exceeds a certain level, the Schmitt circuit 16 is triggered, and the Schmitt circuit is output from the Schmitt circuit. is generating output.

Further, the output voltage of the DC amplifier 10, which is the control input of the CO8, is stored in the voltage storage circuit 17 every moment.

Using the voltage stored in the voltage storage circuit 17, the constant voltage drive circuit 18 generates a voltage equal to the stored voltage and supplies it to the switch 19.

However, when the input level of the received wave is sufficiently high and the Schmitt circuit 16 is generating an output signal, the switch 19 is opened thereby, so that the output voltage of the constant voltage drive circuit 18 is not connected to the VCO 8.

When the received wave falls below a certain level, the Schmitt circuit 16
is inverted and no longer generates an output signal, so memory circuit 1
7 is held at its previous value, the switch 19 is closed, and the output of the constant voltage 1 drive circuit 18 is connected to the VCO 8.

The output of the constant voltage drive circuit 18 is low impedance,
Since the output of the DC amplifier 10 is configured to have high impedance, the VCOB is controlled by the output voltage of the constant voltage drive circuit 18, and therefore the signal frequency generated by the VCO 8 is the VCO oscillation frequency just before the received wave drops. Since the signal is fixed to , there is no risk of generating an unauthorized signal.

Further, this fixed oscillation frequency is close to the oscillation frequency at which the received wave is recovered again and the switch 19 is opened and the PLL returns to its normal control state, so that the PLL can be re-engaged easily.

In the above embodiment, it goes without saying that the frequency shift may be performed using the output of the CO, or that the frequency shift may not be performed.

FIG. 2 is a block diagram showing the configuration of another embodiment of the multiplex radio relay device of the present invention.

In the figure, the meanings of symbols 1 to I1 and 14 to 17 are the same as in FIG. 1.

A voltage comparison circuit 20 compares the voltage stored in the voltage storage circuit 17 and the output voltage of the amplifier 10, and generates an error output according to the difference.

The error output is amplified by the amplifier 21 and returned to the input of the loop filter 9 via the switch 22 to perform a series of feedback controls so that both inputs to the voltage comparator circuit 20 are equalized.

As a result, even when there is no received wave, the signal frequency generated by ■Co8 is fixed to the ■CO oscillation frequency immediately before the received wave drops, so there is no risk of generating a fraudulent signal.

Furthermore, when the received wave is restored again, the PLL can be re-engaged easily.

As explained above, according to the multiplex radio relay device of the present invention, when the received wave decreases due to fading etc.
Since there is no risk of unnecessary waves or interference waves being generated from the PLL, and synchronization to the received wave is easily performed when the received wave is recovered, it is possible to configure a practical repeater using PLL. Therefore, it is possible to realize a multiplex radio relay device that utilizes the amplification effect and band limiting effect of the PLL, and excellent effects can be obtained.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are block diagrams each showing the configuration of an embodiment of a multiplex radio relay device of the present invention. 1... Receiving antenna, 2... Band pass filter, 3... Amplifier, 4... Mixer, 5... Shift oscillator, 6 ...AG
Amplifier with C, 7... Phase detector, 8...
...VC0,9...Loop filter, 10...
...DC amplifier, 11...Amplifier, 12...
... Bandpass filter, 13... Transmission antenna, 14... Bandpass filter, 15.
...Detector, 16...Schmitt circuit,
17... Voltage storage circuit, 18... Constant voltage drive circuit, 19... Switch, 20...
...Voltage comparator circuit, 21...Amplifier, 22...
····switch.

Claims (1)

[Claims] 1 Comprising a phase comparison means that compares the phases of a human input signal and an oscillation output signal of a voltage-controlled oscillator and generates an output signal according to the phase difference, and a voltage-controlled oscillator that changes the oscillation frequency according to a control input voltage. a phase-locked circuit that synchronizes the frequency of the output signal of the voltage-controlled oscillator with the input signal by controlling the voltage-controlled oscillator using the output signal of the phase comparison means; In a multiplex radio relay device that amplifies or removes noise from a received signal by storage means for retaining the immediately previous stored value when the output of the level determination means disappears, and a control input of the voltage controlled oscillator depending on the presence or absence of the output of the level determination means, respectively, and the output of the phase comparison means and the storage 1. A multiplex radio relay device comprising: switching means for switching between the output of the means and the output of the means.