JPS643099B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reducing interference radio waves that go around from a transmitting antenna to a receiving antenna through space.

In the wireless relay method, in which a radio signal is received by a receiving antenna, and then retransmitted at the same frequency from a transmitting antenna after being amplified, a part of the signal emitted from the transmitting antenna is transmitted to the receiving antenna as a wraparound radio wave through space. It may be re-received at some point. In such a case, at the receiving antenna, the signal due to the regular incoming radio wave and the interference signal due to the detouring radio wave are added, which may become a factor that inhibits the function of the relay device. Conventionally, as a method of compensating for this interference signal, as shown in Figure 1, a feedback circuit that can adjust the amplitude and phase is installed between the transmitting end and the receiving end of the repeater, and the feedback signal is sent to the interfering signal with the opposite phase and equal amplitude. There is a configuration that cancels the interference signal by In the figure, 1 is a receiving antenna, 2 is a transmitting antenna, 3 is a relay amplifier, 5 is a semi-fixed phase shifter, 6 is a semi-fixed attenuator, and 4 is a feedback loop for interference compensation. Setting of the conditions of opposite phase and equal amplitude, which are the conditions for the feedback signal from the feedback loop 4 to cancel the interference signal, is performed by adjusting the semi-fixed phase shifter 5 and the semi-fixed attenuator 6. This adjustment is usually done manually using a measuring instrument, which is very inconvenient.
In addition, even if the adjustment is made well, the cancellation state between the interference signal and the feedback signal deteriorates due to variations in the amplifier characteristics and the propagation path characteristics between the transmitting and receiving antennas, so there is a drawback that compensation characteristics cannot be consistently obtained. .

In order to solve these drawbacks, the present invention transmits a pilot signal from a receiving antenna and detects the residual component of the pilot signal that cancels out the feedback loop signal and the interference signal, thereby determining the amplitude and phase of the feedback loop signal. The present invention provides an interference wave compensator that automatically realizes optimal compensation conditions through control and transmits a pilot signal from a receiving antenna to reduce the influence of the pilot signal on a transmitted signal.

The present invention will be explained in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which 1 is a receiving antenna, 2 is a transmitting antenna, 3 is a relay amplifier, and 4 is a transmitting antenna.
is a feedback loop, 7 is an equal amplitude 2-phase (0°, 90°) distributor, 8 is an equal amplitude 4-phase (0°, 90°, 180°, 270°) distributor, 9 is a pilot signal generator, 10 is a pilot signal remover, 11a and 11b are pilot signal detectors, 12 and 13 are signal band pass wavers, 14 is an amplifier for level adjustment, 15a and 15b are synchronous detectors, and 16a and 16b are voltage adders. 17 is a rectifier, 18 is an electrical variable attenuator, 1
9a and 19b are variable delay lines.

The signal received by the receiving antenna 1 is a combination of a signal due to a regular arriving radio wave (hereinafter referred to as a regular signal) and an interference signal that is emitted from the transmitting antenna 2 and then circulates through space. A feedback signal via a feedback loop 4 is further added to the input signal of the relay amplifier 3. Now, the present invention automatically realizes the conditions for canceling the interference signal and the feedback signal, and its operation is as follows. Now, consider a situation where a pilot signal of a single frequency is being transmitted from the receiving antenna 1. At this time, the output signal of the pilot signal detector 11a is a composite signal of the interference wave path signal propagated through the interference signal propagation path and the feedback signal, and this is shown by the vector diagram e _s in FIG.
Here, e〓 _i and e〓 _c in the same figure represent an interference wave path signal and a feedback signal, respectively. If this extracted pilot signal e _s is synchronously detected by synchronous detectors 15a and 15b using the in-phase and quadrature components of the signal branched from the pilot signal generator 9 as references, a vector is obtained.
The in-phase and quadrature components e _x and e _y of e〓 _s can be detected as DC voltages. Therefore, by further _adding the _vector −e〓 _s , which is the sign-inverted vector of _e . Specifically, this is achieved as follows. First, the in-phase component e _x and quadrature component e _y detected by the synchronous detectors 15 a and 15 b are input to voltage adders 16 a and 16 b, respectively, and the outputs thereof are used as the equal amplitude 4-phase divider 8 and the electrical variable attenuator 18. Drives a vector modulator consisting of Here, the diode 17 selects the polarity of the X-axis and Y-axis of the vector modulator according to the polarity of the output voltage of the voltage adders 16a and 16b.
For example, if e _x is positive, the π-phase signal path becomes conductive, and the level of the conductive signal is set by the electrical variable attenuator 18 so that it becomes the magnitude of the detected voltage, for example, |e _s |. In this way, the synchronous detector 15
It is possible to control the vector modulator in a negative feedback state with respect to the voltages detected at a and 15b. For example, as shown in the vector diagram in Figure 3, if e _x is detected as the in-phase component and e _y is detected as the orthogonal component of the pilot signal component extracted from the transmitting antenna, the vector modulator will detect that the output signal of the feedback loop is The output signal e〓 _c is further added with −e _xi −e _yj (where i and j are the unit vectors of the X-axis and Y-axis in FIG. 3, respectively), that is, −e〓 _s . Therefore, this control realizes suppression of the pilot signal in the signal received by the transmitting antenna 2.

Now, the propagation path and feedback loop of the interference signal transmitted from the transmitting antenna 2 and received by the receiving antenna 1 are both reversible, and the conditions for suppressing the pilot signal described above depend on the actual signal transmitted from the transmitting antenna 2. Since this satisfies the condition that the interference signal is canceled by the feedback signal, the present invention can be applied to an automatic compensation device for inter-antenna interference. At this time, the pilot signal remover 10 removes the pilot signal component in the main signal path, so that the residual pilot component appears on the output side and interferes with the pilot signal received from the transmitting antenna 2 through space. prevent this from happening. It should be noted that it is desirable that the approximation of the added control voltage to −e〓 _s is better because convergence will be faster, but even if the approximation is not good, since the control is negative feedback, it will converge and the interference signal will be suppressed. is possible. In addition, the synchronous detector 1
The phase synchronization between the reference signals and input signals of the vector modulators 5a and 15b and the output signal of the vector modulator is performed by adjusting the variable delay lines 19a and 19b, respectively.
Further, the pilot remover 10 is not necessary when the pilot signal can be sufficiently removed by the signal bandpass remover 12.

As explained above, by using the present invention, it is possible to automatically reduce the interference wave signal in the antenna reception signal regardless of the characteristic fluctuations of the propagation path between the antenna transmission and reception and the relay amplifier. It is possible to compensate for interference signals between transmitting and receiving antennas in a wireless relay system in which the transmitting and receiving antennas are the same, and it is possible to allocate more than the coupling attenuation between the transmitting and receiving antennas (the value when no interference compensation is used) as the amplification gain of the relay device. In addition, since the pilot signal is sent from the receiving antenna, the level of the pilot signal mixed in with the transmitted signal is extremely low, so inserting the pilot signal may cause interference distortion in the signal to be relayed and amplified. This has the advantage of preventing adverse effects from occurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional interference compensation device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a vector diagram of a received pilot signal. 1... Receiving antenna, 2... Transmitting antenna, 3... Relay amplifier, 4... Feedback loop, 5... Semi-fixed phase shifter,
6... Semi-fixed attenuator, 7... Equal amplitude two-phase distributor, 8...
Equal amplitude 4-phase distributor, 9...pilot signal generator,
10... Pilot signal remover, 11... Pilot signal detector, 12, 13... Signal bandpass waver, 14... Amplifier, 15a, 15b... Synchronous detector, 16a, 16b... Voltage adder, 17... Diode, 18...Electrical variable attenuator, 19a, 19
b...Variable delay line, 20...Extracted pilot signal vector, 21...Interference signal vector, 22...
Feedback signal vector, 23... Inverse vector of the pilot signal, 24... X component (in-phase component) of the pilot signal vector, 25... Y of the pilot signal vector
Components (orthogonal components), 26a, 26b...circulator.

Claims (1)

[Claims] 1. In a radio relay device that receives a radio signal with a receiving antenna, amplifies the received signal with an amplifier, and retransmits it as a transmitting signal from the transmitting antenna at the same frequency as the received signal, means for transmitting a pilot signal of a specific frequency from the receiving antenna. and means for extracting the pilot signal from the transmitting antenna;
means for removing the pilot signal that goes around to the received signal and applying the received signal to the amplifier; and a vector modulator for branching part of the pilot signal and the transmitted signal to adjust amplitude and phase. means for feeding back the transmitted signal output and the pilot signal output of the vector modulator to the received signal path and the transmitted signal path, respectively; It has means for detecting orthogonal components, and means for controlling the vector modulator based on information on the detected in-phase and orthogonal components, and reduces interference signals that return from the transmitting antenna to the receiving antenna through space. An interference wave compensator characterized in that it is configured to.