JPS5840857B2 - Multiplex wireless relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wireless relay device that uses a phase synchronization circuit and can directly relay a received signal without converting it to an intermediate frequency.

In recent years, the development of devices that can amplify microwave signals has flourished, and as a result, it has become possible to directly relay microwave received signals without converting and amplifying them to an intermediate frequency as in the case of conventional relay equipment. be.

However, a major problem with this direct relay is how to synchronize the phase relationship between the input received signal and the output received signal.

A first object of the present invention is to provide a wireless relay device that enables direct relay in microwaves by using a phase synchronization circuit.

A second object of the present invention is to provide a relay device using the direct relay method, which prevents malfunction of the phase synchronization circuit by detecting the amplitude of a received signal.

Furthermore, the prevention of malfunction of the phase synchronization circuit is performed by detecting a pilot signal included in the received signal.
The third step is to provide a relay device using the above direct relay method.
The purpose of

The present invention will be described in detail below using the drawings.

FIG. 1 is a configuration diagram of a wireless relay device according to the present invention,
Frequency modulated signal Fr received from antenna A1
is introduced into the phase locked circuit PLL via a mixer MIX into which the outputs of the bandpass filter BPF1, the amplifier AMP1, and the shift oscillator SFO are input.

PLL circuit consists of phase comparator PD1 voltage controlled oscillator VCO1
Directional coupler DCP1? It is composed of a wave amplifier FA.

In addition, the PLL circuit output is output from the amplifier AMP2 and the bandpass filter BP.
It is transmitted from antenna A2 via F2 at frequency Ft.

NPD is a received signal amplitude detector, the output of which is led to a sweep oscillator SWP and a transmission circuit cutoff switch SW.

When the reception amplitude by antenna A1 becomes smaller than a predetermined value due to fading or equipment failure, amplitude detector MPD generates an output and operates sweep oscillator SWP and transmission circuit cutoff switch SW.

Since the sweep oscillator SWP controls the voltage controlled oscillator ■CO, the output frequency of ■CO is swept, and when the above-mentioned condition is restored, it can immediately synchronize with the received input and perform normal operation of the PLL.

Further, the transmission circuit cutoff switch SW prevents the output of the voltage controlled oscillator VCO, which is not synchronized with the received signal, from being transmitted from the antenna A2 as an unnecessary wave.

Therefore, since the PLL circuit obtains a signal synchronized with the received signal and uses it as the transmitted signal, there is no need for local oscillators for transmitting and receiving, and it has the advantage of having a band-limiting effect on the received signal in terms of operation. Despite its configuration, it is extremely useful.

However, as mentioned above, if the received amplitude becomes small and PL
If the L operation is disturbed, it means that the voltage controlled oscillator ■CO'I
Since this is to output phase liquid oscillation due to J phase oscillation, if this is transmitted from antenna A2 to the next station, normal close band communication will be disturbed.

Therefore, even if normal operation of the PLL can be quickly restored, it is absolutely necessary to detect abnormal operation immediately when it occurs.

Therefore, it is preferable that the above-mentioned received signal amplitude detector MPD has a hysteresis characteristic in order to eliminate the unstable range of the operating point, but if the detector starts operating too early for fear of interference, recovery may be delayed. If the operating point is moved to speed up recovery, interference to the next station is likely to occur.

FIG. 2 is a block diagram showing the main parts of a second embodiment of the present invention which further improves such drawbacks.

PLD is a pilot signal detection device that is connected to the input terminal of the voltage controlled oscillator ■CO in the PLL circuit, and is composed of a pilot signal extraction band generator PPP and a diode DD, and its output is connected to the transmission circuit breaker SW. ing.

In normal wireless communications, pilot signals are included in modulated waves and used to monitor communication paths, but if they are not used, they are included on the transmitting side.

Therefore, if the amplitude of the received signal is greater than the expected value, the PLL
The operation of the filter amplifier FA returns to normal state, and the output point P of the filtering amplifier FA is changed so that the frequency of the received signal applied to the phase comparator PD and the output frequency of the voltage controlled oscillator CO extracted by the directional coupler DCP match. The potential changes minutely.

That is, the demodulated wave of the received signal is obtained at point P. The pilot signal included in the demodulated wave is rectified by the diode DD detected by the filter PPP, and its output signal is in the state that the transmitting circuit breaker SW is closed. do.

Next, when the received amplitude becomes less than the expected value or the amplitude becomes zero for some reason, the PLL becomes inoperable, so there is no signal that can pass through the pilot signal extraction band generator PPP, and the transmitting circuit breaker SW is forced to operate. It is said to be open to the public.

In this case, even if the distortion controlled oscillator ■CO oscillates at an abnormal frequency, it will not be transmitted from the antenna A2.

Whether the PLL operation is abnormal or normal can be clearly distinguished depending on whether the PLL is in synchronization or not, so the fact that the pilot signal is obtained always accurately detects the normal state of the PLL operation. It happens.

In addition to the above-mentioned transmission circuit breaker SW, a so-called "restorer" (squelch circuit) is used as a means to prevent the output of the voltage-controlled oscillator ■CO included in the PLL from being sent out when the PLL operates abnormally. It is possible to use a transmission cut-off circuit called .

Such a "restorer" is equipped with a standby oscillator that oscillates at the specified transmission frequency of the repeater, and for example, a changeover switch for switching between the output of the amplifier AMP2 and the output of the standby oscillator is provided on the input side of the bandpass filter BPF2 shown in FIG. establish.

As mentioned above, when the output of the pilot signal detection device PLD decreases, this changeover switch is switched to the standby oscillator output side, and the carrier wave output of the specified transmission frequency is transmitted from the antenna A2 via the bandpass filter BPF2. become.

Here, since the carrier wave output from the relay device is not cut off, it is possible to continue operating the automatic gain control circuit (AGC circuit) in the downstream station of the relay device at a predetermined gain.

In that case, the automatic gain control circuit in the downstream station continues its normal operation, which is convenient for maintenance of the downstream station.

FIG. 3 is a configuration diagram showing the main parts of a third embodiment of the present invention.

SWP in FIG. 3 is a sweep oscillator, which controls whether or not the voltage controlled oscillator (CO) operates based on the output of the pilot signal detection device PLD.

That is, when the PLD output disappears, the sweep oscillator SWP
starts and causes the voltage controlled oscillator ■CO to continuously oscillate a frequency within a predetermined range.

Therefore, when the reception amplitude recovers, the PLL operation immediately follows the reception frequency.

Note that when the sweep oscillator SWP is activated, it is necessary to open the transmission circuit breaker SW at the same time as shown by the broken line.

The reason for this is that the abnormal frequency is not transmitted from antenna A2.

In the embodiment of the present invention, the received signal is shifted and then added to the PLL circuit, but the shift circuit may be placed after the PLL circuit, or a wireless relay in which the receiving frequency and the transmitting frequency are the same without using a shift circuit is used. Of course, a device may also be used.

In this way, according to the present invention, a signal synchronized with the received signal is obtained and used as the transmitted signal only by using the PLL circuit, so there is no need for a transmitting/receiving local oscillator that requires stabilization, and the received signal It also has the advantage of having a band-limiting effect, making it an extremely useful wireless relay device.

Moreover, since the presence or absence of a pilot signal detects whether or not the PLL operation is normal due to changes in the installation location or line conditions, etc., the PLL can be activated without waiting for hysteresis characteristics even in the case of a gradual decrease in reception amplitude. The operating status of the device can be clearly determined.

Therefore, it is easy to use it in a wireless relay device to enable communication without interfering with adjacent channels.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a wireless relay device according to a first embodiment of the present invention,
FIGS. 2 and 3 are configuration diagrams showing the main parts of second and third embodiments of the present invention. AI, A2...Antenna, BPF...
Bandpass filter, PLL... Phase synchronization circuit, PD.
...Phase comparator, vCO...Voltage controlled oscillator, FA...Filtering amplifier, DCP...
・Directional coupler, SWP...Sweep oscillator, PL
D...Pilot signal detection device, PPP...
...Pilot signal extraction bandpass filter, DD...
・Diode, SW...Transmission circuit breaker.

Claims (1)

[Claims] 1. A phase comparator that compares the phase of a frequency-modulated received signal with an oscillation output signal of a voltage-controlled oscillator without converting it to an intermediate frequency and generates a control signal according to the phase difference between the two signals. and the voltage controlled oscillator whose oscillation frequency is controlled in accordance with the control signal, the oscillation output of the voltage controlled oscillator or the amplified oscillation output of the voltage controlled oscillator being used as a relay transmission output. A wireless relay device characterized by: 2. A phase comparator that compares the phase of the frequency-modulated received signal with the oscillation output signal of the voltage-controlled oscillator without converting it to an intermediate frequency and generates a control signal according to the phase difference between the two signals, and a phase comparator that generates a control signal according to the phase difference between the two signals. a phase-locked circuit comprising the voltage-controlled oscillator whose oscillation frequency is controlled by the voltage-controlled oscillator, means for detecting received signal amplitude, and an output of the voltage-controlled oscillator is transmitted between the voltage-controlled oscillator and the relay transmitter. In the radio relay device, the radio relay device is equipped with a means for preventing the above-described voltage-controlled oscillator from occurring, and in which the oscillation output of the voltage-controlled oscillator is used as the relay transmission output, detecting that the amplitude of the received signal has become smaller than a predetermined value. A wireless relay device, characterized in that when the means detects the detection, the detecting means operates means for preventing the output of the voltage controlled oscillator from being transmitted. 3. A phase comparator that receives frequency modulation and compares the phase of the received signal including the pilot signal with the oscillation output signal of the voltage controlled oscillator without converting it to an intermediate frequency and generates a control signal according to the phase difference between the two signals. A phase locked loop comprising the voltage controlled oscillator whose oscillation frequency is controlled in accordance with the control signal, and preventing the output of the voltage controlled oscillator from being transmitted between the voltage controlled oscillator and the relay transmitter. and in which the oscillation output of the voltage controlled oscillator is used as the relay transmission output, further comprising means for detecting a pilot signal extracted from a part of the phase synchronization circuit, the detecting means comprising: A radio relay device, wherein when the disappearance of the pilot signal is detected, the detecting means operates a means for preventing the output of the voltage controlled oscillator from being transmitted.