JPH06109831A - Pseudotarget signal generation apparatus - Google Patents

Abstract

PURPOSE:To uniformly distribute a signal on an array antenna by a method wherein an attenuator which controls the amplitude of a pseudotarget signal, an electric power distributor, the array antenna, an antenna for calibration, a correction table and the like are provided. CONSTITUTION:A correction table which corresponds to the transmission frequency of a radar is held in an attenuator table 19 and a distributor table 19, and it is fixed to a frequency band as an object during an adjustment. Correction data which corresponds to a pseudotarget position is sent to an attenuator correction part 16 and a distributor correction part 17 from a table as an object, and the data is corrected and processed here. The corrected data acts to supplement the linearlity and the flatness of the characteristic of a level control part, and a level radiated from an array antenna 6 is brought close to a definite value. The reception level of a pseodutarget signal measured by an antenna 12 for calibration and by a receiver 13 is fed back to a table correction part 20, the corrected data is changed according to it, the data is measured again and an optimum correction value is found.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pseudo target signal generator for improving the radiation level accuracy of a pseudo target signal by compensating for fluctuations in the power level of the signal.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration of a conventional pseudo target signal generator, FIG. 4 is a diagram for explaining the operation of a distributor which is a part thereof, and FIG. 5 is a method of radiating a pseudo target signal. It is a figure for explaining. In FIG. 3, 1 is a radio wave source for generating a pseudo target signal corresponding to the pseudo target distance and speed, 2 is an attenuator for attenuating the signal power of the pseudo target signal, and 3 is the signal power of the pseudo target signal. Distributor for branching into two systems, 4 a phase shifter for controlling the phase of the pseudo target signal, 5 a switch for selecting the radiation position of the pseudo target signal on the array antenna, 6 a pseudo target signal Array antenna for radiating a space into the space, 7 is an attenuator control unit that generates an attenuator control signal, 8 is a distributor control unit that generates a distributor control signal, and 9 is a phase shifter control signal. , A switch controller 10 for generating a control signal for the switch,
Is a radio wave radiation position calculation unit that sends control data from the pseudo target position to each of the control units 7 to 10, 12 is a calibration antenna that receives a pseudo target signal radiated into space, and 13 is a pseudo antenna that the calibration antenna receives. It is a receiver that measures the reception level of the target signal. Next, the operation of the conventional pseudo target signal generator will be described. The characteristic of the pseudo target signal generation method by this device is that the direction of arrival of the pseudo target signal is changed by changing the ratio of radiated power from a plurality of element antennas on the array antenna that radiates radio waves and keeping each radiation phase constant. To control. Therefore, the pseudo target signal generated by the radio wave source passes through the output port of the switch corresponding to the target position set by the radio wave radiation position calculation unit and is radiated from the array antenna connected thereto. Furthermore, when the pseudo target position exists between the element antennas, the pseudo target signal power is branched into two systems with a distribution ratio according to the angle internal division ratio between the elements,
The signals of each system are adjusted in the phase shifter # 1 and the phase shifter # 2 so as to have the same phase at the aperture of the array antenna. The mechanism of power distribution by the distributor and position control on the array antenna will be described later. As a result, the pseudo target signal can be smoothly position-controlled on the array antenna at the resolution level of the power distribution ratio. On the other hand, the radio wave source that generates the pseudo target signal generates the reflected wave of the radar according to the distance, speed, the transmission frequency of the radar, and the modulation method of the pseudo target. Especially for the radar transmission frequency and modulation method, the signal processing time order (tens of ms
Since it is necessary to follow c), the radio wave source directly refers to the radar internal signal.

A method of power distribution by a distributor will be described with reference to FIG. The pseudo target signal is input from the attenuator to the distributor. Power divider inside the distributor 1:
The signals evenly distributed to 1 are input to two phase shifters inside the distributor. The phase control of the phase shifter is executed by the control data of the distributor control unit. At this time, the control of the two phase shifters is set so that the sum of the two values becomes 90 °. As a result, the outputs of the two systems that have passed through the hybrid circuit are distributed at a distribution ratio of 0 to ∞ between 0 and 90 ° as shown in FIG. 4, and the arrival angle of the pseudo target signal by combining the two outputs is 2 elements. It can be controlled so that the spaces are connected almost linearly. In this system, the radiation level varies due to the deviation from the linearity of the attenuator and the difference in the individual characteristics of the distributor. Next, a method of radiating the above two systems of signals from the array antenna will be described with reference to FIG. FIG. 5 shows a case where the position of the pseudo target coincides with the element of the array antenna.
FIG. 5B shows a case where the position of the pseudo target is a point where the two elements of the array antenna are internally divided 1: 2. At this time, a difference in radiation level occurs due to the antenna combining gain between (a) and (b). This antenna gain distribution is shown in FIG. 5C, and there is a maximum difference of 3 dB. That is, the radiation level periodically changes due to the movement of the pseudo target. In addition, variations in the loss of the feed cable to each element antenna also cause an error.

[0004]

Since the conventional pseudo target signal generator is constructed as described above, a change in the position of the pseudo target on the array antenna causes a fluctuation in the signal level on the order of several dB. Factors of variation include individual characteristics of the distributor described in FIG. 4, deviation from linearity of the attenuator, combined gain of the array antenna described in FIG. 5, transmission loss, and the like. Also, if the frequency band used by the radar is wide, each device in the transmission system,
The signal level also fluctuated due to the frequency characteristics of the power supply cable. Such a signal level variation also affects the S / N of the pseudo target signal and causes a factor of amplitude fracturing and a false target, which is not preferable as a device for simulating a reflected wave of a radar. Further, in the long term, it takes a long time to adjust the control data system in which the characteristics and loss caused by the hardware of the transmission system are fixed over time. The present invention has been made to solve the above problems, and suppresses the fluctuation of the pseudo target signal level caused by the change of the position of the pseudo target and the change of the transmission frequency of the radar, and makes it possible to achieve a uniform level on the array antenna. The purpose is to obtain a signal distribution and to obtain a device whose correction value can be easily changed in response to a change in system characteristics.

[0005]

In the pseudo target signal generator according to the present invention, a correction table is added to the attenuator and the distributor for controlling the amplitude of the pseudo target signal by providing a control table that can be updated sequentially. A system that enables an adjustment sequence using feedback from the calibration receiving system is constructed. In addition, a method of selecting a correction control table for each subband is adopted for the transmission frequency switching operation of the radar, which requires a high-speed response during operation.

[0006]

In the pseudo target signal generator according to the present invention, the attenuator and the distributor for controlling the amplitude of the pseudo target signal are provided with updatable control tables, so that the radiation due to the characteristics of each device, the combined gain at the time of radiation, etc. Suppress fluctuations in level. This control table can be sequentially updated by using the feedback from the calibration receiving system, and adjustment can be performed at any time during long-term operation. Further, by dividing the transmission frequency of the radar into some sub-bands and having a correction control table, it is possible to carry out an optimum correction process for the radar operation.

[0007]

【Example】

Example 1. As an embodiment of the present invention, an adjustment method using the correction function of the pseudo target signal generator will be described with reference to FIGS.
Will be explained. FIG. 1 is a block diagram of a pseudo target signal generator according to the present embodiment, and FIG. 6 is a diagram for explaining the operation of the device having the above configuration, and is a conceptual diagram of correction data of a control table. 1, 1 to 12 are the same as or equivalent to those in FIG. 3, 16 is an attenuator correction unit, 17 is a distributor correction unit, 18 is an attenuator table, 19 is a distributor table, and 20 is a table correction unit. 1 to 12 in FIG.
For, the same operation as the conventional device is performed. A correction table corresponding to the transmission frequency of the radar is held in the attenuator table and the distributor table, and is fixed to the target frequency band during adjustment. The correction data corresponding to the pseudo target position is sent from the target table to the attenuator correction unit and the distributor correction unit, where the conventional correction process for the control data is performed. Since the correction data works to compensate the linearity or flatness of the level control characteristics of the attenuator and the distributor as shown in FIG. 6, the level finally radiated from the array antenna also changes to the pseudo target position and transmission frequency. It approaches a certain value regardless. Next, the calibration receiving system will be described. The reception level of the pseudo target signal measured by the calibration antenna and the receiver shown in FIG. 1 is fed back to the table correction unit on the signal control side.
In accordance with this, the above-mentioned correction data is changed and re-measurement is performed to obtain the optimum correction value. By carrying out this adjustment sequence, it is possible to adjust to an optimum state at any time even if the transmission system characteristics change over time due to long-term use of the device.

Example 2. As another embodiment of the present invention, the operation of the pseudo target signal generator is shown in FIGS.
Will be explained. Example 1. The relationship between Adjustment of the present apparatus was carried out in Example 2, and then Example 2. Therefore, the maximum effect of the present invention can be achieved by actually operating. FIG. 2 is a block diagram of the pseudo target signal generator in the present embodiment, and FIG. 7 is a diagram for explaining the operation of the device in the above configuration, which is a conceptual diagram of control table selection by transmission frequency. 1 to 11, 1 in FIG.
6 to 19 are the same as those in FIG. 1, 14 is a counter, 15
Is a selector. For 1 to 11 and 16 to 19 in FIG. 2, the same operation as that at the time of adjustment in FIG. 1 is performed. The frequency of the pseudo target signal generated by the radio wave source is measured by the counter, and the selector selects the corresponding subband correction table according to the result. The sub-band bandwidth is set so that level fluctuations within that band will not cause operational problems. The attenuator table and the distributor table are the same as those in Example 1. As described above, the correction value for each subband of the transmission frequency is held, and the correction data selected by the selector is sent to the correction units of the attenuator and the distributor. The above series of operations needs to follow the operation of the radar in several tens of msec, but even if the subband width is 10 MHz, the sampling time of the counter that recognizes this is 0.
It becomes 1 msec and there is no problem in measurement.

[0009]

As described above, according to the present invention, it is possible to suppress the fluctuation of the pseudo target signal radiation level that has conventionally occurred in the pseudo target signal generator and to update the correction value used there at any time. Become. As a result, it is possible to suppress the occurrence of false target signal level fractures or false targets that should not exist originally, and improve the S / N evaluation accuracy of the radar. Further, even when the alignment in the pseudo target signal generator is broken due to some factor, the readjustment can be easily performed by preparing the calibration receiving system. Since the correction is performed by software, it is possible to compare the old and new data tables and use it for pursuing a defective portion.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a pseudo target signal generator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a pseudo target signal generator according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional pseudo target signal generator.

FIG. 4 is a diagram for explaining the operation of a conventional pseudo target signal generator.

FIG. 5 is a diagram for explaining the operation of a conventional pseudo target signal generator.

FIG. 6 is a diagram for explaining the operation of the pseudo target signal generator according to the embodiment of the present invention.

FIG. 7 is a diagram for explaining the operation of the pseudo target signal generator according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radio wave source 2 Attenuator 3 Divider 4 Phase shifter 5 Switch 6 Array antenna 7 Attenuator control unit 8 Distributor control unit 9 Phase shifter control unit 10 Switch control unit 11 Radio wave radiation position calculation unit 12 Calibration antenna 13 Receiver 14 Counter 15 Selector 16 Attenuator correction unit 17 Distributor correction unit 18 Attenuator table 19 Distributor table 20 Table correction unit

Claims (2)

[Claims] 1. A reflected wave of a radio wave transmitted from a radar is generated as a pseudo target signal, and the amplitude and amplitude of the pseudo target signal are
In a device that controls the direction of arrival of the pseudo target signal by controlling the phase and radiating the same phase from the array antenna, compensates for fluctuations in the signal level on the feed path to the array antenna when the target position changes. for,
A radio wave radiation position calculation unit that generates the amplitude / phase control data of the pseudo target signal and the switch control data, an attenuator and a power distributor that control the amplitude of the pseudo target signal on the power supply path, and a shift that controls the phase of the pseudo target signal. Phaser, switch for selecting the radiation position of the pseudo target signal, array antenna that radiates the output of the switch into space, calibration antenna for receiving the pseudo target signal from the array antenna, received signal of the calibration antenna Enter the receiver,
Pseudo target signal comprising a correction table unit for feeding back the reception level of the receiver to update the correction value, and a radio wave source for generating a pseudo target signal corresponding to the distance and speed of the pseudo target. Generator. 2. A reflected wave of a radio wave transmitted from a radar is generated as a pseudo target signal, and the amplitude and amplitude of the pseudo target signal are
In a device that controls the direction of arrival of the pseudo target signal by controlling the phase and radiating from the array antenna in the same phase, the signal level on the feed path to the array antenna changes the target position and changes the transmission frequency of the radio wave source. In order to compensate for the occasional fluctuation, a radio wave radiation position calculation unit that generates the amplitude / phase control data and switch control data of the pseudo target signal, an attenuator and a power distributor that control the amplitude of the pseudo target signal on the power supply path. , A phase shifter that controls the phase of the pseudo target signal, a switch that selects the radiation position of the pseudo target signal, an array antenna that radiates the output of the above switch into space, a counter that measures the frequency of the pseudo target signal, the distance of the pseudo target , And a pseudo target signal generator that generates a pseudo target signal corresponding to a speed.