JPS63276924A - Jamming eliminating device - Google Patents

Abstract

PURPOSE:To eliminate a disturbing radio wave with the same frequency as that of a desired wave but in different direction by converting a disturbing wave input to one of two antennas installed at a prescribed interval into a signal of the same level but with a phase difference of 180 deg. and mixing the result. CONSTITUTION:The antennas 8, 9 are installed at a prescribed interval. When the frequency of the desired wave and that of the disturbing wave are the same and the incoming direction differs, the output of the antenna 9 is given to an attenuator 11, an amplifier 12 and a phase shifter 13 so as to adjust the output of the disturbing wave to be of the same level as the output of the disturbing wave from the antenna 8 with a phase different by 180 deg.. Then the output is mixed with the output of the antenna 8 at a mixer 14 to cancel the disturbing wave. On the other hand, since the phase angle of the desired wave differs from that of the disturbing wave, it is not cancelled. Thus, the disturbing wave is eliminated without deteriorating the quality of the desired wave.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for removing interference waves of the same frequency arriving from different directions, and in particular, by adjusting the level and phase shift of two antenna output signals. The present invention relates to an interference removal method in which two signals having a phase difference of 18° are generated with respect to an interference wave signal, and the two signals are combined to cancel out and eliminate the interference wave.

(Prior Art) Interfering waves in wireless communication are generally removed using a filter, but it is impossible to remove interference waves of the same frequency using a filter.

Conventionally, as such a same-frequency interference wave removal means, the fourth
There is something called a beat canceller as shown in the figure.

This splits the signal containing both the desired signal and the interference signal into two,
One branch signal is transferred to a π/4 phase shifter 11 phase detector 2. One branch of the matrix circuit 5 is connected through a low-pass filter (LPF) 3 and a phase adjuster 4, and the other branch (a is π/4
After passing through the phase shifter Bi, phase detector 2°, LPF 3° and π/2 phase adjuster 4°, the f-matrix circuit 5 is manually operated, and furthermore, the phase detector 2.2° is The comparison signal is a voltage controlled oscillator VCO 7 which is controlled by a voltage obtained by removing noise from the output voltage of the π/2 phase adjuster 4'', that is, the output voltage of the second L P F 3° by the loop filter 6. This is the human output of the output.

According to this beat canceller, each filter 1□P V 3 and 1,1)T when synchronized with the desired wave part -;
=' The outputs Io and Qo of 3° are expressed as follows, and both have a phase difference of π/2.

Therefore, by shifting the phase of Qo by π/2, combining it with 10 in the matrix circuit 5, and finding the sum or difference between the two, it is possible to cancel and remove only the interference wave.

゛ However, in such conventional beat cancellers, the received signal is converted into a one-way intermediate frequency signal, and after further detection, the interference signal is removed, so in image processing, the desired signal and the interference signal are separated. Wave signals are mixed together, and due to the nonlinearity of the circuit that converts to an intermediate frequency signal, the detection circuit, etc., mixing of both signals, that is, two-signal interference and cross-modulation occurs, and the quality of the extracted desired wave signal is significantly reduced. There were flaws that worsened.

(9, Akira's)) The present invention was made in order to eliminate the drawbacks of such conventional interference wave removal means. The purpose of this invention is to provide an interference cancellation method that does not cause two-signal interference as shown in l=by eliminating the waves.

(Summary of the Invention) In order to achieve the object No. 8, the present invention feeds the outputs of two antennas arranged at a predetermined interval, one directly and the other through a level adjustment means and a phase adjustment means, respectively. In this coupler, the interference signals from both F2 antennas are made to have the same level and a 180° difference in phase, thereby canceling out the interference signals.

In addition, when transmitting via such an antenna and interference removal device, or when there is no need to remove interference waves, a bus route is added to bypass these devices and connect to the other antenna.

(Example) An example of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the principle of the present invention, in which antennas 8.9 are installed at a predetermined distance d, and the output of one antenna 9 is divided into two parts by a first race switch 15, one of which is divided into two parts by an attenuator 11.9. Mixer 1 via amplifier 12 and phase shifter 13
4. I will do it alone.

Attenuator 11 and amplifier 12 constitute level adjuster 10 .

= On the other hand, the other output of the antenna is used as the other input of the direct mixer 14, and the output of this mixer 14 and the other branch signal separated by the relay switch 15 are selected by the second relay switch 15°. It is configured so that it can be output in a realistic manner.

In this configuration, if the angle formed by the direction of arrival of the desired wave and the inter-frequency interference wave U is θ, then if the sources of both types of waves are sufficiently far away from the distance between the two antennas (j), both antennas The two antennas are incident at almost the same angle, and the difference in distance from the signal source to both antennas, that is, the geometric length β shown in the figure is.

ρ=dsinθ...(1) becomes.

Therefore, the phase of the interference wave U incident on the antenna 9 is delayed by β compared to that incident on the antenna 8. If this t/z is φ, it is expressed as φ=(27C/λ)−dsinθ−−(2).

Therefore, the 4-channel signal to antenna 9 is transmitted to attenuator II and amplifier 1.
2 and a level adjuster 10 and a phase shifter 13, so that the phase difference between the interference waves of the signals of both antennas 8 and 9 in the mixer 14 becomes 180°, and the interference waves are canceled out by each other. Remove waves.

In this case, since the desired wave differs from the interfering wave by θ, it will not be out of phase and will hardly be affected.

Next, when transmitting radio waves through this device, or in case of power supply trouble or other failure, the first and second relay switches 15 and 15 degrees are driven to adjust the phase shifter and level adjustment block. is connected to one antenna 9 via a bypass route.

With this configuration, interference waves having the same frequency as the desired wave or extremely close frequencies can be removed without converting to an intermediate frequency, so that there is no influence on the desired wave signal generated by the relationship between the two signals.

Further, FIG. 2 is a block diagram showing one embodiment of the present invention. In other words, the marks 8 and 9 are placed at the required interval.
After the output signals of the antennas 8 and 9 are converted to a frequency that is easy to perform one-step phase shift operation in frequency conversion circuits 16 and 17, the interference waves are removed by the above method, and the original signal is transferred to the frequency conversion circuit 18 again. It is constructed to restore the frequency to .

In addition, these three frequency conversion circuits 16, 17 and 18
is supplied with a signal 5 from the local oscillator 19.

According to such a configuration, since it is possible to remove the interference wave at +iij passing through a non-linear circuit such as a detection circuit, it is possible to eliminate the 2f:X interference as in the conventional case.

Historically, in the case of all-knee F communication where the transmitter and receiver work simultaneously as shown in Fig. 3, the requirements for the antenna feeder line connected to the transmitter with one antenna in the device of the present invention described above are known. It may be configured such that a signal obtained by branching a part of the transmission output from the section via a feeder is extracted as the output of the two antennas L1. This utilizes a positional delay commensurate with the branching point distance of the antenna feed line, and simultaneously cancels out and removes the radio waves from the transmitter that go around from the nearby transmitting antenna to the receiving antenna. This eliminates the influence on the driving receiving section.

(Effects of the Invention) As explained above, the present invention utilizes the phase difference between two signals caused by different directions of arrival, and adjusts the level and phase of these two signals to eliminate the interference waves described above. By making the signal levels from both antennas almost equal and having a phase difference of 180 degrees, only the interference waves are canceled out, so interference waves of the same frequency do not degrade the quality of the desired signal. It can be removed without any problem.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the principle of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, and Fig. 3 is a block diagram showing an embodiment of the invention. Fig. 4 is a block diagram showing a conventional technique, 8.9... Antenna % 11... Attenuator, 12...
・Amplifier, 13... Phase shifter, 14... Mixer, 10
,15° ・・・Relay switch

Claims (2)

[Claims] (1) By inputting one of the two antennas arranged at a predetermined interval directly and the other to the mixing means through the level adjustment means and the phase shifting means, interference signals of the same frequency and from different directions are removed. 1. An apparatus for canceling negative phase interference, characterized in that a frequency conversion means is inserted at each of the two antenna output terminals and the mixing means output terminal. (2) If one of the two antennas is a receiving antenna and the other is a transmitting antenna, the receiving antenna output and a portion of the transmitting output branched from the feeder line from the transmitter to the transmitting antenna 2. The interference removal device according to claim 1, wherein both outputs of and are used as the outputs of the two antennas.