JP2985104B2 - Test equipment for radar evaluation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for radar evaluation. This is used when simulating a shift injection.

[0002]

2. Description of the Related Art Generally, in a radar evaluation test system, as shown in FIG. 2, a modulator 22 in a radar test apparatus 21 reflects a Doppler shift signal DS generated at a relative speed with respect to a radar transmission radio wave from a target. Give to the received radio waves. Here, the conventional radar evaluation test system shown in FIG. 2 includes a radar under test 25 having a transmitting antenna 23 and a receiving antenna 24, and a radar testing device having a receiving antenna 26, a modulator 22, and a transmitting antenna 27. 21 combinations.

The modulator 22 is for injecting the Doppler shift signal DS into the target reflected radio wave, and is constituted by a single sideband balanced modulator. The characteristics of the modulator 22 of the radar test apparatus 21 in the system of FIG. 2 will be described below with reference to the block diagram of FIG. 3 and the circuit diagram of FIG. 3 and 4, 31 is a two divider, 32 is a 90 ° phase shifter, 33 and 34 are balanced modulators, 35 is a combiner, and 41 and 4
2 is a transformer and 43, 44, 45 and 46 are diodes.

In such a configuration, when the transmission wave of the radar transmission wave is modulated with a Doppler frequency signal using the single sideband balanced modulators 33 and 34, a Doppler shifted target reflected signal is output. You. The phase difference between the two Doppler frequency signals is set to 90 °, and is converted into a signal whose frequency is shifted upward or downward depending on the sign of the phase difference.

The output signal of the modulator 22 is a Doppler shifted spectrum signal as shown in FIG. At this time, as shown in the figure, a signal having a large number of spectra is included in addition to the Doppler shift signal, which is not the same as the actual radar target reflection signal.

[0006]

The conventional test apparatus for radar evaluation uses a Doppler shift signal to simulate the relative speed as a function as shown in FIG. This is a method of injecting a Doppler shift signal generated corresponding to the relative speed with respect to a target into a radar transmission radio wave as a reflection signal, and modulating it into a reflection radio wave using a single sideband balanced modulator. . This modulation method has a problem that, unlike a real radar reflection signal, it cannot be accurately evaluated as a radar reflection signal in a test frequency region because a lot of spurious components are generated in the Doppler shift output signal.

An object of the present invention is to provide a radar evaluation test apparatus in which Doppler-shifted radio waves which do not include spurious signals when a target is reflected are radiated toward a radar under test in view of the above-mentioned problems in the conventional type. , So that it can be simulated and measured in the same way as when the radar is actually used.

[0008]

In order to solve the above-mentioned problems, a radar evaluation test apparatus according to the present invention receives a radio wave transmitted from a radar under test, detects a radar, and reflects a radio wave reflected from an object to be tracked. In the radar test equipment that returns a signal that simulates the Doppler
A single sideband modulator that injects the shift signal into the carrier,
A high-frequency signal processing unit that includes a voltage-controlled oscillator that sends out a simulation signal and outputs a difference signal between the modulator output and the voltage-controlled oscillator output; and a control voltage of the voltage-controlled oscillator based on the difference signal from the high-frequency signal processing unit. And a control unit for following and controlling a spectrum having a large modulator output.

[0009]

According to the above construction, the radar transmission radio wave emitted from the radar under test is received, and the carrier of the reception radio wave is Doppler
By modulating with a shift signal and following the largest spectrum of the modulated signal, unnecessary spectrum is reduced as Doppler-shifted reflected radio waves from the target object, and it becomes a simulation signal similar to the actual radar reflected wave. It becomes possible.

[0010]

FIG. 1 shows an embodiment of a radar evaluation test apparatus according to the present invention. The radar evaluation test apparatus 11 includes a receiving antenna 12, a transmitting antenna 13, a modulator 14,
It has a high-frequency signal processing unit 15 and a control unit 16. The radar under test 17 is an object to be tested by the radar evaluation test apparatus 11, and includes a transmitter 18, a transmitting antenna 19,
It has a receiving antenna 110 and a receiver 111.

The radio wave emitted from the transmitting antenna 13 of the radar evaluation test apparatus 11 is received by the receiving antenna 110 of the radar 17 under test, and the radio wave emitted from the transmitting antenna 19 of the radar 17 under test is It is received by the receiving antenna 12 of the radar evaluation test device 11. Instead of such transmission by radio waves, it is also possible to connect the radar under test and the test apparatus for radar evaluation 11 with a cable and transmit a signal via the cable.

In FIG. 1, a transmitter 18 oscillates a carrier wave, emits it as a radar wave from a transmitting antenna 19 of a radar under test, and receives it by a receiving antenna 12 of a radar evaluation test apparatus 11. The received radio wave is modulated by an external Doppler shift signal by the modulator 14 in the same manner as in the above-described conventional technique, and then output to the high-frequency signal processing unit 15. This modulated signal is shifted in frequency to the upper side or the lower side of the carrier wave and contains many spurious components.

As shown in FIG. 6, the high-frequency signal processing section 15 includes a first two-way splitter 61, a second two-way splitter 62, and a 90 ° splitter.
It comprises a phase shifter 63, a first balanced modulator 64, a second balanced modulator 65, a voltage controlled oscillator 66, and a directional coupler 67.

Output signal from modulator 14 (RF IN)
Is input to the first two divider 61 and after being divided into two,
One is to the 90 ° phase shifter 63 and the other is to the second balanced modulator 6.
5 is output. The 90 ° phase shifter 63 sets the phase of the signal to 90 °.
The phase-shifted signal is output to the first balanced modulator 64 by 90 °.

The high-frequency signal processing section 15 has a voltage-controlled oscillator 66 for controlling the oscillation frequency in accordance with a voltage signal from a control section 16 which will be described later. Via the second two-way distributor 6
2 is input. The second splitter 62 converts the input signal into two.
And is output to the first and second balanced modulators 64 and 65, respectively. The first and second balanced modulators 64 and 65 are constituted by a transformer and a diode as shown in FIG. 4 and output a difference signal between two input signals in principle. It can be considered that a sine wave signal having a frequency difference of the output signal of the voltage controlled oscillator 66 as a component is output. As a result, the high-frequency signal processing unit 15
4 and the difference signal between the output of the voltage controlled oscillator 66 controlled by the control unit 16 are output from the first and second balanced modulators 6.
A signal having a phase difference of 90 ° is output from 4,65. FIG. 7 shows, as an example, output waveforms of the first and second balanced modulators 64 and 65, and the same waveform having a 90 ° phase difference is output. This phase difference becomes + 90 ° or −90 ° depending on whether the input signal to the high-frequency signal processing unit 15 is higher or lower than the output signal of the voltage controlled oscillator 66.

The control unit 16 operates so as to make the frequency difference between the two signals close to zero using the polarity of the phase difference.

The control section 16 includes a first amplifier 68 and a second amplifier 69 for amplifying the output signals of the first and second balanced modulators 64 and 65 of the high-frequency signal processing section 15, and the amplified output signal. A first pulse shaper 610 and a second pulse shaper 611 for forming a pulse signal, and a polarity determiner 6 for determining the polarity of the phase difference between the pulse-shaped output pulses.
12, a frequency difference unit 613 whose pulse duty ratio changes according to the pulse period, and a frequency difference unit 613
614 that outputs an output signal of the same according to an instruction of the polarity determiner 612; a switching unit 615 that switches between a positive voltage signal and a negative voltage signal according to the instruction of the gate unit 614; The integrator 616 is configured to integrate the output signal.
Output signal of the high frequency signal processing unit 15 of the voltage controlled oscillator 6
6 is used as the control voltage.

Next, the operation will be described in detail. The first and second amplifiers 68 and 69 convert weak signals from the high-frequency signal processing unit 15 to first and second amplifiers using a commonly used operational amplifier or the like.
The signals are amplified so that the signals can be pulse-shaped by the second pulse shapers 610 and 611. In this case, the gain is set to such an extent that the spurious is not pulse-shaped.

The pulse shapers 610 and 611 set the threshold voltage so that the duty ratio of the output pulse becomes approximately 50%.

The frequency differentiator 613 is constituted by a one-shot multivibrator, and generates one pulse by triggering the rise of an input pulse signal. Even when the frequency differencer 613 is outputting a pulse, when the next input pulse signal is input, the input pulse is regarded as a new trigger and a pulse signal is output. That is, since the trigger is retriggerable, if the input pulse period is shorter than the time constant of the one-shot multivibrator, a positive value is maintained.

As shown in FIG. 7, the polarity determiner 612
When the output signal (A) ′ of the first pulse shaper 610 rises, it is determined whether the output signal (B) ′ of the second pulse shaper 611 is positive or negative. The input signal of the high-frequency signal processing unit 15 is compared with the output signal of the voltage controlled oscillator 66. If the frequency is high, the phase of the signal (B) 'is delayed by 90 ° with respect to the signal (A)', so that the output of the polarity determiner 612 is Becomes negative. When the input signal of the high-frequency signal processing unit 15 is lower in frequency than the output signal of the voltage controlled oscillator 66, the signal (B) is compared with the signal (A) ′.
Since the phase of 'advances by 90 °, the output of the polarity determiner 612 becomes positive.

The gate unit 614 is composed of two AND gates, and one of two AND gates is provided in accordance with the output of the polarity judgment unit 612.
By turning on one gate and turning off one gate, a pulse corresponding to the frequency difference between the input signal of the high-frequency signal processing unit 15 from the frequency differentiator 613 and the output signal of the voltage controlled oscillator 66 is output alternately. Will be.

The switching section 615 is composed of a positive / negative constant voltage source and an analog switch, and switches a DC current from a positive voltage source or a negative voltage source to be applied to the integrator 616 by an analog switch according to the output of the gate section 614. ,
Output to the integrator 616.

The integrator 616 includes a commonly used operational amplifier, a resistor, and a capacitor, and integrates the voltage of the switching unit 615. The output signal of the integrator 616 is used for voltage control of the output frequency of the voltage controlled oscillator 66 of the high frequency signal processing unit 15. Thus, the modulator 1
The tracking control is performed only for the signal having the large spectrum of the output of No. 4.

For example, in the case of a target object having a rotating portion other than the relative speed of the airframe, such as a helicopter or a propeller aircraft, a signal having a spectrum corresponding to the reflected signal from the rotating portion is added to the output signal of the apparatus. Thus, a detailed reflected wave of the target object can be easily obtained, and the radar under test can be evaluated in more detail.

[0026]

As described above, according to the present invention,
Various reflected waves from an actual target object can be generated, and Doppler-shifted radio waves that do not include spurious waves are radiated toward the radar under test, and can be simulated as in the case of actual use of the radar.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a radar evaluation test apparatus as one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a conventional radar evaluation test apparatus.

FIG. 3 is a block diagram illustrating a configuration of a modulator.

FIG. 4 is a circuit diagram of a balanced modulator.

FIG. 5 is a spectrum diagram of an output waveform of a modulator.

FIG. 6 is a block diagram illustrating a configuration of a high-frequency signal processing unit and a control unit.

FIG. 7 is a timing chart of the control unit.

[Explanation of symbols]

 Reference Signs List 11 Test apparatus for radar evaluation 12 Receiving antenna 13 Transmitting antenna 14 Modulator 15 High-frequency signal processing unit 16 Control unit 17 Radar under test 18 Transmitter 19 Transmitting antenna 110 Receiving antenna 111 Receiver 61 First two divider 62 second splitter 63 90 ° phase shifter 64 first balanced modulator 65 second balanced modulator 66 voltage controlled oscillator 67 directional coupler 68 first amplifier 69 second amplifier 610 first Pulse shaper 611 Second pulse shaper 612 Polarity determiner 613 Frequency differencer 614 Gate unit 615 Switching unit 616 Integrator

Continuation of the front page (56) References JP-A-61-65179 (JP, A) JP-A-58-200178 (JP, A) JP-A-61-45606 (JP, A) JP-A-59-208478 (JP) , A) Fully open 63-48175 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (1)

(57) [Claims] 1. A radio wave transmitted from a radar under test is received,
A radar evaluation test device for transmitting a signal simulating a reflected radio wave from an object of radar detection and tracking, and a single sideband modulator for injecting a Doppler shift signal generated by a relative speed into a carrier wave. A high-frequency signal processing unit that includes a voltage-controlled oscillator that sends out a simulation signal and outputs a difference signal between the modulator output and the voltage-controlled oscillator output; and controls the voltage-controlled oscillator based on the difference signal from the high-frequency signal processing unit. A control unit for obtaining a voltage and controlling to follow a spectrum having a large output from the modulator.