JP2556162B2 - Sidelobe canceller - Google Patents

Description

TECHNICAL FIELD The present invention relates to a side lobe canceller having an interference wave removing function.

[Conventional technology]

An example of a conventional side lobe canceller configured in an analog high frequency band is shown in FIG. In the figure, the main antenna 1 has a gain in the target direction, and the auxiliary antenna 2 is an antenna having a gain substantially equal to the side lobe level of the main antenna 1. The interference canceller 10 forms an optimum weighting coefficient so that both input signals at the main input terminal 11 and the auxiliary input terminal 12 minimize the signal power at the output terminal 13,
The input signal at the auxiliary input terminal 12 is weighted and the main input terminal is weighted.
This is a circuit that removes the interference wave by taking the difference from the input signal at 11.

That is, the signal received by the main antenna 1 is input to the main input terminal 11,
The signals received by the auxiliary antenna 2 are input to the auxiliary input terminals 12, respectively. The interference wave remover 10 is a weighting circuit 14 for weighting the input signal at the auxiliary input terminal 12, a difference circuit 15 for calculating the difference between the input signal at the main input terminal 11 and the output signal of the weighting circuit 14, and the auxiliary input. Multiplier for correlating the complex conjugate signal of the input signal at the end 12 and the output signal of the difference circuit 15
16, an amplifier 17 for amplifying the output signal of the multiplier 16, and a low-pass filter 18 for calculating a weighting coefficient by integrating the output signal of the amplifier 17 and generating a control signal for controlling the weighting circuit 14. There is.

FIG. 4 shows an example in which the side lobe canceller is digitally configured. In the figure, the main antenna 1 has a gain in the target direction, and the auxiliary antenna 2 is the main antenna 1
With a gain approximately equal to the sidelobe level of
Reference numerals 31 and 32 convert the received signals received by the main antenna 1 and auxiliary antenna 2 into video signals, and A / D converters 33 and 34 convert the video signals into digital signals.

The interference wave remover 20 calculates an optimum weighting coefficient from both input signals at the main input end 21 and the auxiliary input end 22 so as to minimize the signal power at the output end 23, and weights the input signal at the auxiliary input end 22. Further, it is a circuit for removing an interference wave by taking a difference from the input signal at the main input terminal 21.

That is, the signals output from the A / D converters 33 and 34 are supplied to the main input terminal 21 and the auxiliary input terminal 22, respectively. The interference wave remover 20 includes a weight calculator 28 that calculates a weighting coefficient from the input signals at the main input terminal 21 and the auxiliary input terminal 22, delay devices 26 and 27 that adjust the timing of each input signal, and a delay device 27.
A weighting circuit 24 for weighting the signal output from the
And a difference circuit 25 that takes the difference from the output signal of.

[Problems to be Solved by the Invention]

By the way, not only interference waves but also signals such as targets, clutter, and noise are superimposed on the main antenna received signal and the auxiliary antenna received signal. Further, since the main antenna and the auxiliary antenna are separate antennas, the interference wave signals received by the respective antennas have a phase difference based on the interference wave frequency and the arrival direction of the interference wave. Therefore, the weighting coefficient in the interference wave remover is obtained as a statistical value from both received signals within the range where the interference frequency does not change.

That is, in the conventional side lobe canceller of FIGS. 3 and 4 described above, in order to calculate the weighting coefficient,
The sample time for detecting the reception signal of each of the main antenna and the auxiliary antenna is fixedly set based on the above-mentioned statistical value. For example, in FIG. 3, the integration time of the low-pass filter 18 is fixed to a fixed value, and in FIG. 4, the sample time set by the weight calculator 28 is fixed to a fixed value.

However, there are many types of actual interference waves, such as a spot interference wave having a constant frequency, a sweep interference wave whose frequency changes every moment, and an interference wave in which short pulse interference is repeatedly generated. For this reason, the conventional one in which the sample time is fixed to a fixed value cannot suppress the sweeping interference wave whose frequency changes every moment, and can suppress the pulse interference wave shorter than the sample time. There is a problem that you cannot do it.

An object of the present invention is to provide a sidelobe canceller that adapts various interference waves.

[Means for solving the problem]

The side lobe canceller of the present invention is designed to remove an interference wave based on a weighting coefficient obtained from the reception signals of the main antenna and the auxiliary antenna, and an antenna for receiving the interference wave and a frequency of the received interference wave A means for measuring the pulse width, a means for controlling the sample time based on the frequency and the pulse width of the measured interference wave, and a main antenna for the time required by the means for measuring the interference wave and the sample time control means And a delay means for delaying the reception signal of the auxiliary antenna, and is configured to change and control the weighting coefficient in the interference wave remover based on the obtained sample time.

In this case, the analog canceller controls the low-pass filter of the interference canceller, and the digital canceller controls the weight calculator based on the obtained sample time.

Further, the sample time control means controls the sample time by the frequency and pulse width of the interfering wave and the maximum value of the sample time input in advance and an algorithm based on the maximum value.

[Action]

According to the present invention, by controlling the weighting coefficient in the interfering wave remover based on the sample time obtained from the frequency and pulse width of the interfering wave, the interfering wave whose frequency changes every moment or the short pulse interfering wave Even with respect to the above, it is possible to remove the interfering wave at each suitable sample time.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment in which the side lobe canceller of the present invention is configured by analog in a high frequency band.
In the figure, an interference wave receiving antenna 3 is newly provided in addition to the main antenna 1 and the auxiliary antenna 2. In addition, the main antenna 1 and the auxiliary antenna 2 are respectively connected with delay devices 4 and 5 and connected to the interference wave remover 10. The interference wave remover 10 is composed of a weighting circuit 14, a difference circuit 15, a multiplier 16, an amplifier 17, and a low-pass filter 18, like the conventional one shown in FIG.

On the other hand, the interference wave receiving antenna 3 is connected with an interference waveform side device 6 for measuring the frequency and pulse width of the received interference wave. Further, a sample time controller 7 is connected to control the sample time based on the measured frequency and pulse width of the interference wave and the predetermined minimum and maximum sample times. The output of the sample time controller 7 is input to the control input terminal 19 of the interference wave remover 10 to control the amplifier 17 and the low pass filter 18.

The sample time controller 7 obtains the sample time by the algorithm shown in Table 1.

In the present embodiment configured as described above, the main antenna 1
And the signal received by the auxiliary antenna 2 is the interference wave remover 10
Is input to The frequency and pulse width of the interfering wave received by the interfering wave receiving antenna 3 are measured by the interfering wave measuring device 6, and the sample time controller 7 is determined from the measured value and the maximum and minimum values of the sample time. At, the sample time is set by the algorithm shown in Table 1 and input to the interference wave canceller 10. At this time, the signals of the main antenna 1 and the auxiliary antenna 2 are delayed by the delay units 4 and 5 by the time required for the interference wave measuring device 6 and the sample time controller 7 to process, and the sample time Signal is input at the same timing.

The interference wave canceller 10 calculates an optimum weighting coefficient from the input signals at the main input end 11, the auxiliary input end 12 and the control input end 19 so as to minimize the signal power at the output end 13, and the input at the auxiliary input end 12 is calculated. It has a function of removing an interference wave by taking a difference from the signal. And here the amplifier
17 for the output signal of the multiplier 16, performs amplitude adjustment based on the input sample time, the low-pass filter 18 calculates the weighting coefficient by integrating the output signal of the amplifier 17 based on the sample time, The weighting circuit 14 is controlled.

As a result, the weighting circuit 14 can be controlled to follow an interference wave whose frequency changes every moment, and the interference wave suppression performance is improved. Further, it becomes possible to suppress even short pulse interference waves.

FIG. 2 shows a second embodiment in which the present invention is applied to a digital sidelobe canceller. The same parts as those in the conventional configuration shown in FIG. 4 are designated by the same reference numerals.

In this embodiment, similarly to the first embodiment, an interference wave receiving antenna 3 is newly provided, and an interference wave measuring instrument 6 for measuring the frequency and pulse width of the received interference wave and a sample time control for controlling the sample time are provided. A container 7 is provided. And
The output of the sample time controller 7 is input to the delay devices 26 and 27 and the weight calculator 28 of the interference wave remover 20. Also,
Main antenna 1 and auxiliary antenna 2 receive and A / D
The main antenna video signal and the auxiliary antenna video signal output by the converters 33 and 34 are provided with the delay units 4 and 5 for delaying the time required for the measurement of the interference wave and the control of the sample time, and the timing adjustment with the signal of the sample time is performed. Done.

According to this configuration, the main antenna 1 and the auxiliary antenna 2
The main antenna video signal and the auxiliary antenna video signal, which are respectively received by the receivers 31 and 32 through the A / D converters 33 and 34 and delayed by the delay units 4 and 5, respectively, The sample time obtained by the interference wave measuring instrument 6 and the sample controller 7 is controlled based on the interference waves input to the main input terminal 21 and the auxiliary force terminal 22 of the 20 and received through the interference wave receiving antenna 3. Input end
Entered in 29. The signals input to the main input terminal 21 and the auxiliary input terminal 22 are output from the output terminal 23 as before, but the weight calculation is performed based on the sample time input to the control input terminal 29 at this time. The weighting coefficient is controlled by the device 28, and at the same time, the delay time is controlled by the delay devices 26 and 27 according to the sample time.

As a result, similarly to the first embodiment, the weighting circuit 24 can be controlled to follow the interference wave whose frequency changes every moment, and the interference wave suppression performance is improved. Further, it becomes possible to suppress even short pulse interference waves.

〔The invention's effect〕

As described above, the present invention measures the frequency and pulse width of the interference wave, determines the sample time from this measurement value, and controls the weighting coefficient in the interference wave remover based on this sample time. Also, it is possible to improve the suppression performance of an interfering wave whose frequency changes every moment or a short pulse interfering wave.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment in which the sidelobe canceller of the present invention is configured in an analog high frequency band, and FIG. 2 is a block diagram of a second embodiment in which the sidelobe canceller of the present invention is configured in a digital high frequency band. FIG. 3 is a block diagram of a conventional analog high-frequency sidelobe canceller,
FIG. 4 is a block diagram of a conventional side lobe canceller for a digital high frequency band. 1 ... Main antenna, 2 ... Auxiliary antenna, 3 ... Interference wave receiving antenna, 4,5 ... Delay device, 6 ... Interference wave measuring instrument,
7: Sample time controller, 10: Interfering wave remover, 11 ...
… Main input end, 12 …… Auxiliary input end, 13 …… Output end, 14 ……
Weighting circuit, 15 ... Difference circuit, 16 ... Multiplier, 17 ... Amplifier, 18 ... Low-pass filter, 19 ... Control input terminal, 20
…… Interfering wave remover, 21 …… Main input end, 22 …… Auxiliary input end, 23 …… Output end, 24 …… Weighting circuit, 25 …… Difference circuit, 26,27 …… Delayer, 28 …… Weight calculator, 31,32 ... Receiver, 33,34 ... A / D converter.

Claims (3)

(57) [Claims] 1. A weighting coefficient is calculated from signals received by a main antenna and an auxiliary antenna, a reception signal of the auxiliary antenna is weighted based on the weighting coefficient, and a difference from the reception signal of the main antenna is calculated. In a side rope canceller equipped with an interfering wave remover that removes the interfering wave, an antenna that receives the interfering wave, a means for measuring the frequency and pulse width of the received interfering wave, and the frequency of the measured interfering wave A means for controlling the sample time based on the pulse width, a delay means for delaying the received signals of the main antenna and the auxiliary antenna by the time required for the measuring means of these interfering waves and the sample time controlling means,
A sidelobe canceller characterized by being configured to change and control a weighting coefficient in the interference wave remover based on the sample time obtained by the sample time control means. 2. The sidelobe canceller according to claim 1, wherein a low-pass filter for eliminating interference or a weight calculator is controlled based on the sample time obtained. 3. The sample time control means controls the sample time by the frequency and pulse width of the interfering wave and the maximum value of the sample time inputted in advance and an algorithm based on the maximum value. The side lobe canceller according to item 2.