JPH05107334A - Side lobe canceller - Google Patents

Abstract

PURPOSE:To improve the ability of restraining unnecessary waves by providing a pulse generating circuit to generate a sample hold pulse and a sample hold circuit to hold correlative components in a correlative loop. CONSTITUTION:A pulse generating circuit 9 to generate a sample hold pulse after detecting unnecessary waves received from an auxiliary antenna 2 and sample hold circuits 7, 8 which are operated by a sample hold pulse Tb are provided. A reset pulse Ta is also provided to reset the time constants of reducing filters 10, 11 and the circuit 9 for each beam scanning. As a result, correlative components in a correlative loop right before there is no pulse for pulse-like unnecessary waves are held to make response to the correlative loop faster. In addition, when new correlative operation is required for each beam scanning in one-dimensional and two-dimensional phased array antennas, the correlative loop is initiated to allow a new loop to be made, so that a correlative group is combined to improve the ability of restraining the unnecessary waves of a side lobe canceller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sidelobe canceller (hereinafter referred to as CSLC), and more particularly to improvement of a correlation loop.

[0002]

CSLCs are mainly used in radar receivers.

The basic function of the radar receiver is to receive a reflection signal from a target object, perform required reception processing, and output the signal to a radar target detection device such as an indicator.

Unwanted waves such as interference waves are often incident on the radar receiver from the side lobes. Therefore, the unnecessary wave component in the received signal from the main antenna is estimated by extracting the correlation component with the reference signal for the unnecessary wave received from the auxiliary antenna, and unnecessary by subtracting this from the received signal from the main antenna. CSLC that suppresses wave components is used.

FIG. 6 is a system diagram of a conventional CSLC. 2, FIG. 3, and FIG. 7 are diagrams for explaining the operation,
FIG. 2 is a diagram showing the antenna patterns of the main antenna and the auxiliary antenna, FIG. 3 is a conceptual diagram of one-dimensional and two-dimensional phased array antenna beam scanning, and FIG. 7 is a waveform diagram of each signal.

In the figure, 1 is a main antenna and 2 is an auxiliary antenna. Received signal u received by the main antenna 1
Passes through the subtractor 3 and becomes a z signal. Reference numerals 5, 6 are multipliers, and the signal z is obtained. To the other inputs of the multipliers 5 and 6, the signal x received by the auxiliary antenna 2 and the signal obtained by converting the signal x into x _Q by the π / 2 transporter 4 are input. 1
Reference numerals 0 and 11 are low-pass filters, and outputs r _I and r _Q of the multipliers 5 and 6 are input to extract desired correlation signals t _I and t _Q. Reference numerals 40 and 41 denote correlators, which are combinations of the multipliers 5 and 6 and the low-pass filters 10 and 11. 12,
A DC amplifier 13 amplifies the correlation signals t _I and t _Q , and outputs signals w _I and w _Q. Reference numerals 14 and 15 denote multipliers, which receive the signals w _I and w _Q and the signals x and x _Q. Reference numeral 16 denotes an adder, which adds the outputs of the multipliers 14 and 15 into a signal y, which is input to the subtractor 3.

In this configuration, the subtractor 3 to the multiplier 5,
The loop that passes through 6 and reaches the subtractor 3 again is called a correlation loop.

Further, the outputs of the multipliers 5 and 6 are converted into the multiplier 1
Up to the input of 4 and 15, it is the baseband processing area.

Next, the operation will be described. One-dimensional and two
If there is only one source of unwanted waves that are incident on the main antenna 1 and the auxiliary antenna 2 that are dimensional phased arrays, it can be said that the mutually received unwanted waves are correlated. The output signal z and the unnecessary wave reference signal x in this perspective, by adding x _Q to the correlator 40 and 41, and extracts correlation undesired wave, i.e. the phase and the amplitude difference.

The signals t _I and t from the correlators 40 and 41 are
Signal w _I of the complex load from _Q, to generate a w _Q, unwanted wave reference signal x from the auxiliary antenna 2, x _Q and complex multiplication, the same IF unnecessary wave component included in the received signal u from the main antenna 1 The signal y is obtained, and the subtractor 3 subtracts the unwanted wave from the main antenna 1.

The output of the subtractor 3 passes through the multipliers 5 and 6 again to form a correlation loop which returns to the subtractor 3.

[0012]

Since the conventional CSLC is configured as described above, as shown in FIG. 7, when a pulse-shaped unnecessary wave is input, the correlation loop receives the pulse wave. There is a problem that it takes a long time to stabilize by repeating the closed loop when the pulse wave is not input and the open loop when the pulse wave is not input, and it takes a long time to suppress the unwanted wave. In addition, when the beam is scanned in the one-dimensional and two-dimensional phased array main antenna, the phase and amplitude of the unwanted wave change uncorrelatedly due to the change of the antenna pattern in the incoming direction of the unwanted wave. Therefore, there is a problem that it takes a long time for the correlation operation to occur and the correlation loop becomes stable, and it takes a long time to suppress unnecessary waves as described above.

The present invention has been made to solve the above problems, and the suppression time of the unnecessary wave is short even when a pulsed unnecessary wave is input or when beam scanning is performed. The purpose is to obtain CSLC.

[0014]

A CSLC according to the present invention
Includes a pulse generation circuit that detects an unwanted wave received from an auxiliary antenna and generates a sample hold pulse, and a sample hold circuit that is controlled by the pulse generation circuit and holds a correlation component in a correlation loop. ..

Further, the pulse generation circuit and the low-pass filter in the correlation loop are reset by a reset pulse.

[0016]

According to the present invention, a pulse creating circuit for detecting an unwanted wave received from the auxiliary antenna and generating a sample hold pulse, and a sample holding circuit for holding the correlation component in the correlation loop controlled by the pulse creating circuit. Since the correlation loop does not become an open loop even when there is no unnecessary wave, the correlation loop can be focused in a short time and suppression can be performed in a short time.

Further, since the pulse generation circuit and the low-pass filter in the correlation loop are reset by the reset pulse, when a new correlation operation is required by the beam scanning, the pulse scanning circuit is reset at the beam scanning interval to perform the correlation. By initializing the correlation loop voltage in the loop, the correlation loop can be focused in a short time and suppressed in a short time.

[0018]

1 is a system diagram of a CSLC according to an embodiment of the present invention. FIG. 4 is a waveform diagram of each signal.

In the figure, the same reference numerals as those in FIG. 6 indicate the same or corresponding portions, and 9 is a pulse generation circuit for detecting an unnecessary wave from the received signal of the auxiliary antenna 2 and generating a sample hold pulse Tb. Reference numerals 7 and 8 denote sample and hold circuits which receive the sample and hold pulse Tb and the signals r _I and r _Q and output the signals s _I and s _Q. Low pass filter 1
0 and 11 are input with the signals s _I and s _Q and the reset pulse Ta. The reset pulse Ta is a signal that resets the time constant circuits of the low-pass filters 10 and 11 and the pulse generation circuit 9 at beam scanning intervals. Reference numerals 30 and 31 denote correlators, and multipliers 5, 6, sample and hold circuits 7, 8
And the low-pass filters 10 and 11 are combined.
The correlators 30 and 31 extract desired correlation signals t _I and t _Q.

In this configuration, the subtractor 3 to the multiplier 5,
A loop that passes through 6 and reaches the subtractor 3 again is called a correlation loop. Also, from the outputs of the multipliers 5 and 6, the multipliers 14 and 15
Up to the input of is the baseband processing area.

Next, the operation will be described. Multipliers 5 and 6
The operation is the same as that of the conventional technique up to the point where the orthogonal components r _I and r _Q of the baseband band are obtained as the output of.

The pulse generation circuit 9 detects the reception signal of the auxiliary antenna 2 and converts it from analog to digital, and sets it as a sample signal "H" when there is an unnecessary wave and holds "L" when there is no unnecessary wave. Then, the sample hold pulse Tb is generated by performing an OR operation with the reset pulse Ta for each beam scanning interval.

The outputs r _I and r _Q of the multipliers 5 and 6 are supplied to the sample and hold circuits 7 and 8, and the sample and hold circuits 7 and 8 generate r _I and r _Q by the sample and hold pulse Tb of the pulse generation circuit 9. It is held for a predetermined time and output to the low-pass filters 10 and 11.

That is, as shown in FIG. 4, the signals r _I , r
_Q is sampled by the sample and hold circuits 7 and 8 by the sample and hold pulse Tb for a time period in which there is an unwanted wave, and the unwanted wave component immediately before the unwanted wave disappears, that is, the final voltage when there is an unwanted wave is held. As a result, as shown in FIG. 4, signals s _I and s _Q are obtained, and the correlation loop is prevented from opening even when there is no unnecessary wave, and signals w _I ,
w _Q stands up. After that, the same operation as the conventional technique is performed.

When a new correlation operation is required for each beam scanning in the one-dimensional and two-dimensional phased array antennas, the correlation loop is initialized (reset) by the reset pulse Ta to cancel the loop, and a new loop is created. make. That is, the output s _I of the sample hold circuits 7 and 8
The s _Q is added to the low-pass filters 10 and 11 and the correlation component is processed and output as signals t _I and t _Q. The low-pass filters 10 and 11 are C amplifiers including an op amp.
It has a time constant circuit by R and determines the response time of the correlation loop. The reset pulse Ta for each beam scanning is operated to reduce the time constant of the time constant circuit,
Initialize the correlation loop voltage. Then, the correlators 30, 3
After the output to 1, the same operation as the conventional technique is performed.

As described above, according to this embodiment, the pulse generation circuit 9 for detecting the unwanted wave received from the auxiliary antenna and generating the sample and hold pulse, and the sample and hold circuits 7 and 8 which operate with the sample and hold pulse Tb are provided. A reset pulse Ta which is provided and resets the time constants of the low-pass filters 10 and 11 and the pulse generation circuit 9 for each beam scanning.
The correlation component in the correlation loop immediately before the pulse of the pulse-like unwanted wave disappears can be retained, and the response of the correlation loop can be speeded up. Also, beam scanning in the one-dimensional and two-dimensional phased array antenna When a new correlation operation is required for each time, the correlation loop can be initialized (reset) and a new loop can be created, and the correlation loop can be converged in a short time to improve the CSLC unnecessary wave suppression capability. Can be planned.

FIG. 5 shows a CSL according to another embodiment of the present invention.
It is a system diagram of C, and in the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions.

In the above-mentioned embodiment, the input of the pulse generating circuit 9 is the received signal x, but it may be x _Q , and the same effect is obtained.

[0029]

As described above, according to the CSLC according to the present invention, a pulse generating circuit for detecting an unnecessary wave received from an auxiliary antenna and generating a sample hold pulse, and a pulse loop controlled by the pulse generating circuit in a correlation loop. Since it is equipped with a sample hold circuit that holds the correlation component of, the correlation component in the correlation loop immediately before the pulse of the pulse-shaped unnecessary wave disappears, the correlation loop is focused in a short time, and the unnecessary wave suppression capability is improved. Has the effect of improving.

Further, since the pulse generation circuit and the low-pass filter in the correlation loop are reset by the reset pulse, when a new correlation operation is required by the beam scanning, the correlation is reset by the beam scanning interval. There is an effect that a loop can be initialized, a new correlation loop can be focused in a short time, and suppression can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a system diagram of a CSLC according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of FIGS. 1 and 6.

FIG. 3 is a diagram for explaining the operation of FIGS. 1 and 6.

FIG. 4 is a CSLC waveform diagram according to an embodiment of the present invention.

FIG. 5 is a system diagram of a CSLC according to another embodiment of the present invention.

FIG. 6 is a system diagram of a conventional CSLC.

FIG. 7 is a waveform diagram of a conventional CSLC.

[Explanation of symbols]

 1 Main Antenna 2 Auxiliary Antenna 3 Subtractor 4 π / 2 Phase Shifter 5, 6, 14, 15 Multiplier 7, 8 Sample Hold Circuit 9 Pulse Creating Circuit 10, 11 Low-pass Filter 12, 13 DC Amplifier 16 Adder

Claims (2)

[Claims] 1. A correlation loop for suppressing a received signal of an unnecessary wave incident from a side lobe of a main antenna,
In a side lobe canceller that performs suppression in the correlation loop using a reference signal for an unwanted wave received from an auxiliary antenna, a pulse generation circuit that detects the unwanted wave received from the auxiliary antenna and generates a sample hold pulse, A side-lobe canceller, comprising: a sample-hold circuit which is controlled by the pulse generation circuit and holds a correlation component in the correlation loop. 2. A correlation loop for suppressing a received signal of an unnecessary wave incident from a side lobe of a main antenna,
In a side lobe canceller that performs suppression in the correlation loop using a reference signal for the unwanted wave received from the auxiliary antenna, the unwanted wave received from the auxiliary antenna is detected, and a sample hold pulse is generated from the unwanted wave and the reset pulse. And a sample hold circuit that is controlled by the pulse generation circuit and holds the correlation component in the correlation loop, and a low-pass filter in the correlation loop that is reset by the reset pulse. A sidelobe canceller characterized by that.