JPH04274786A - Pulsed radar apparatus - Google Patents

Abstract

PURPOSE:To make it possible to separately design the range ambiguity and the Doppler ambiguity. CONSTITUTION:A code modulator 10 subjecting a sine wave signal to code modulation, a phase detector 4 which radiates a pulse signal obtained by this code modulation to a target through an antenna 1 for transmission and reception and subjects a reflection pulse from this target to phase detection, and a demodulator 6 demodulating a digitized signal of the signal subjected to the phase detection, are provided. A target detector 7 is made to distinguish the modulated pulse on the basis of the demodulated signal and to detect a distance to the target therefrom. Meanwhile, it is made not to distinguish the modulated pulse and to detect the velocity of the target therefrom.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse radar device that uses code-modulated pulse signals to detect the speed and distance of a target.

0002

[Prior Art] FIG. 5 is a block diagram showing a conventional pulse radar device shown in, for example, "Radar Technology" published by the Institute of Electronics and Communication Engineers, published on August 10, 1985, page 5. In the figure, 1 is Transmission/reception antenna, 2 is transmission/reception switch, 3
is a low noise amplifier that amplifies the received signal, 4 is a phase detector,
5 is an analog/digital converter (hereinafter referred to as an A/D converter), 7 is a target detector, 8 is a local oscillator that generates a sine wave signal, 9 is a power amplifier, and 12 is a modulator that modulates the sine wave signal into a pulse signal. It is a modulator that

Next, the operation will be explained. Local oscillator 8
The generated sinusoidal signal is modulated into a pulse signal by a modulator 12. This pulse signal is amplified by a power amplifier 9, passes through a transmitting/receiving switch 2, and is radiated into the air from a transmitting/receiving antenna 1. On the other hand, this radiated pulse signal hits the target, and the signal reflected from the target is received by the transmitting/receiving antenna 1, passes through the transmitting/receiving switch 2, and is amplified by the low noise amplifier 3. The amplified signal is phase-detected by a phase detector 4 and converted into a digital signal by an A/D converter 5. Furthermore, this digital signal is input to the target detector 7, which detects the target and calculates the distance and speed.

0004

[Problem to be Solved by the Invention] Since the conventional pulse radar device is configured as described above, the pulse repetition period is set to Tprt (S), and the range ambiguity is set to R.
max, the Doppler ambiguity as Fmax, and the speed of light as C, the relationships of Equations 1 and 2 hold true.

[0005]

[Math 1]

[0006]

[Math 2]

For this reason, the range ambiguity Rma
Both x and Doppler ambiguity Fmax are functions of Tprt, and there is a problem that they cannot be designed independently.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a pulse radar device in which range ambiguity and Doppler ambiguity can be designed independently.

[0009]

[Means for Solving the Problems] A pulse radar device according to the present invention includes a code modulator that code-modulates a sine wave signal;
A phase detector that radiates the code-modulated pulse signal toward a target through a transmitting/receiving antenna and detects the phase of the reflected pulse from the target, and a demodulator that demodulates the digitalized signal of this phase-detected signal. and causes the target detector to differentiate the modulated pulses based on the demodulated signal to detect the range of the target, while not distinguishing the modulated pulses to detect the target velocity. It is designed to detect.

0010

[Operation] The target detector of the present invention handles received pulses differently for distance measurement and velocity measurement, thereby making it possible to increase range ambiguity by several times the number of code types than in conventional pulse radar equipment. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a transmitting/receiving antenna, 2 is a transmitting/receiving switch, 3 is a low noise amplifier that amplifies the received signal, 4 is a phase detector, 5 is an A/D converter, 6 is a demodulator, and 7 is a target detection 8 is a local oscillator as a signal generating means for generating a sine wave signal, 9 is a power amplifier, 10 is a code modulator, 11
is a code generator.

FIG. 2 shows details of the demodulator 6. In the figure, 13 is a shift register, 14 is a multiplier, and 15 is an adder, and here three sets of these are provided.

FIG. 3 shows details of the target detector 7 in an embodiment of the present invention, in which 17 is a detector for detecting a demodulated signal, and 18 is a range finder for measuring distance based on the output of the detector 17. , 19 is a Doppler classifier, 20 is a detector 1
This is a speedometer that measures the speed of a target based on the output of 7.

Furthermore, FIG. 4 is a timing chart showing a transmission signal in an embodiment of the present invention, where 16 is a transmission signal.

Next, the operation will be explained. First, a sine wave signal generated by the local oscillator 8 is modulated by a special code generated by a code generator 11 in a code modulator 10 . This modulated signal becomes, for example, the transmission signal 16 in FIG.

This transmission signal 16 has a pulse repetition period (p
rt) and subpulse width (τ) are always constant, and a
Multiple ways expressed by l, bm, cn (for example, N
), and the pulse width is T
1 (=lτ), T2 (=mτ), T3 (=nτ)
It becomes a signal. As a result, the dot-tra ambiguity does not change, and the range ambiguity increases by multiple times (N
times).

The signal modulated by the code modulation 10 in this manner is amplified by the power amplifier 9, passes through the transmitter/receiver switch 2, and is radiated into the air from the transmitter/receiver antenna 1. On the other hand, the reflected signal reflected from the target is received by the transmitting/receiving antenna 1,
The signal passes through the transmitter/receiver switch 2 and is amplified by the low noise amplifier 3. Further, the thus amplified signal is subjected to phase detection by a phase detector 4, and converted into a digital signal by an A/D converter 5.

The converted digital signal having a plurality of codes is input to a demodulator 6. In this demodulator 6, the input digital signal is distributed to, for example, three systems as shown in the figure, code al for processing, code bm for processing, code c
n is input to each shift register 13 for processing. The number of stages of these shift registers 13 matches the number of codes of each code. The output of each stage of each shift register 13 is multiplied by the complex conjugate of the code in a multiplier 14,
An adder 15 calculates the sum of each multiplication value.

The output signals of these adders 15 are input to the target detector 7. In this target detector 7, in which adder 15 the reflected signal from the target is detected.
If there is an output signal, the range finder 18 measures the distance for each output from each adder 15. Furthermore, in speed measurement, the outputs of each adder in the demodulator 6 are combined, a Doppler frequency is determined by a Doppler separator 19, and a speed meter 20 determines the target speed based on this.

[0020] In this way, the distance and velocity of the target are determined by discriminating and discriminating pulses, respectively. As a result, each can be independently designed so that the range ambiguity Rmax of this pulse radar device becomes as shown in Equation 1, and the Doppler ambiguity Fmax becomes Equation 2.

[0021]

[Effects of the Invention] As described above, the present invention includes a code modulator that code modulates a sine wave signal, and a pulse signal obtained by code modulation that is radiated toward a target through a transmitting/receiving antenna. and a demodulator that demodulates the digitized signal of the phase-detected signal. The range ambiguity and Doppler ambiguity can each be designed independently. There is an effect that you can get what you can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a pulse radar device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a demodulator in the present invention.

FIG. 3 is a block diagram showing details of a target detector in the present invention.

FIG. 4 is a timing chart diagram showing transmission signals in the present invention.

FIG. 5 is a block diagram showing a conventional pulse radar device.

[Explanation of symbols]

1 Transmitting/receiving antenna 4 Phase detector, 5 Analog/digital converter (A/D converter) 6
Demodulator 7 Target detector 8 Signal generating means (local oscillator) 10 Code modulator 11 Code generator

Claims (1)

[Claims] 1. A signal generating means for generating a sine wave signal, a code generator for generating a code for code modulating the sine wave signal, and a code generator for code modulating the sine wave signal with the code to generate a pulse signal. a code modulator that performs code modulation; a transmitting/receiving antenna that radiates a pulse signal code-modulated by the code modulator into the air and receives the pulse signal reflected at a target;
a phase detector that phase-detects the received signal obtained by the transmitting and receiving antenna; an analog/digital converter that converts the phase-detected signal by the phase detector into a digital signal; A demodulator demodulates a code-modulated digital signal, a target distance is determined based on the signal demodulated by the demodulator, and each modulated pulse is differentiated and the target velocity is determined based on each modulated pulse. A pulse radar device that includes a target detector that processes and detects each target without distinguishing between the two.