JP3207579B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device capable of correcting a target range movement amount with high accuracy.

[0002]

2. Description of the Related Art Generally, a radar apparatus whose main purpose is to measure a target range shift amount is configured as shown in FIG.

In FIG. 3, an antenna device 11 emits power with a predetermined beam width from an antenna and captures the reflected power. The transmitting / receiving device 12 performs repetitive transmission pulse waveform generation, amplification of received power, frequency conversion, and quadrature detection.

The antenna device 11 and the transmitting / receiving device 1
The reflected pulse reception signal (analog video signal) of the repetition transmission pulse obtained through 2 is sent to the signal processing device 13. The video signal input to the signal processing device 13 is converted into a digital signal by an A / D (analog / digital) conversion circuit 131, the amplitude of which is extracted by an amplitude detection circuit 132, and transmitted to a target detection circuit 133. Can be

The target detection circuit 133 discriminates a target from other echoes based on the magnitude of the input amplitude, and automatically detects a target position in a range cell unit. The target movement amount detection circuit 134 determines the movement amount (speed) of the target by observing the movement between the pulses of the range cell where the target exists from the detection result of the target detection circuit 133.

[0006] Range cell unit target movement amount correction circuit 135
Is information on movement itself between pulses of the target position obtained by the target detection device 133 and the target movement amount detection circuit 13.
Using the speed information obtained in step 4, the target moving amount is corrected in units of range cells so that the moving amount is corrected by one range cell for the first time when the target moves by one range cell. The corrected target position information is sent to the display device 14, and the target position is appropriately displayed in a predetermined format.

However, in the above-described signal processing method, the speed cannot be detected unless the target moves by one or more range cells. Further, since the correction of the target movement amount is also performed only for each range cell, the correction accuracy depends on the range resolution of the radar.

On the other hand, as another signal processing method for detecting the movement amount of the target, as shown in FIG. 4, a received signal from the target (output of the A / D conversion circuit 131) is subjected to FFT (fast Fourier transform) processing. It has been considered that a target Doppler frequency is obtained by performing frequency analysis in a circuit 136, and a movement amount is estimated from the Doppler frequency in a target movement amount detection circuit 137.

However, when estimating the amount of movement by such signal processing, the resolution of the amount of movement is determined by the frequency resolution of the FFT, and the frequency resolution depends on the observation time. Then, it is necessary to take a long measurement time. In particular, when considering a speed detection system used in a high-resolution radar device that requires an extremely high target range movement amount correction accuracy, a satisfactory range movement amount correction accuracy cannot be obtained with such a method.

[0010]

As described above, in the conventional radar device, the target movement amount cannot be detected in a short time and with high accuracy due to the influence of the range resolution.
The measurement of the moving amount of the received signal in the distance direction could not be corrected with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and can detect a target movement amount in a short time and with high accuracy without being affected by the range resolution. It is an object of the present invention to provide a radar device capable of correcting the moving amount of the radar with high accuracy.

[0012]

Means for Solving the Problems] radar according to the present invention in order to achieve the above object apparatus, the repetitive transmission pulses
The reflected pulse received signal is sampled at a sampling frequency equivalent to a range cell.
Digital signal at the end of the
In a radar device that detects a target and determines the amount of movement,
The phase of the received signal due to one of the repeated transmission pulses and its
Another pulse that is more than one repetition period away from the transmission pulse of
A phase difference detection circuit for detecting a difference between a phase of a reception signal and a transmission pulse, and the target moves in a distance direction within a time between two pulses in which the phase difference is detected from phase difference information obtained by the circuit. The target travel distance detection circuit that determines the distance obtained, and the maximum distance included in the target travel distance obtained by this circuit.
In the direction opposite to the moving direction of the target
A first method for shifting a sampled received signal at a dicel interval
Correction circuit and an eye obtained by the target moving distance detection circuit.
The residual difference obtained by subtracting the maximum number of range cells from the target moving distance
The data at the position corresponding to the distance is supported at the range cell interval.
Interpolated from multiple sampled received signals,
By replacing the obtained data with the original data,
In the direction opposite to the moving direction of the target by the residual distance,
Shift received signal sampled at range cell intervals
And a second correction circuit for obtaining the same effect as that, before
Note that the first and second correction circuits perform processing in any order.
Sign.

[0013]

In the radar device having the above structure, the phase difference detection circuit detects the difference between the phase of the received signal due to one transmission pulse and the phase of the received signal due to another transmission pulse separated by at least one distance. The detection circuit converts the amount of phase difference between the pulses into the movement distance in the distance direction between the target pulses, and the conversion is included in the target movement distance by the first correction circuit.
In the direction opposite to the target movement direction for the maximum number of range cells
The received signal sampled at the range cell interval
The correction to be done. Here, since the actual target does not move step by step for each range cell, the second correction cycle is performed.
Correction residual difference in the first correction circuit (target moving distance
Is subtracted by the maximum number of range cells from
From the data points by interpolation calculation, and
By replacing with the data of
The distance is corrected .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. In FIG. 1, the same portions as those in FIG. 3 are denoted by the same reference numerals, and different portions will be mainly described here.

FIG. 1 shows a configuration of a radar apparatus according to the present invention. In a signal processing apparatus 13, a digital video signal output from an A / D conversion circuit 131 is converted into a phase difference detection circuit 13a and a range resampling circuit. The signal is sent to the circuit 13b.

The phase difference detection circuit 13a detects a difference between the phase of a received signal by one transmission pulse and the phase of a received signal by another transmission pulse separated by at least one. The phase difference amount information obtained by the circuit 13a is sent to the target movement amount detection circuit 13c. This target movement amount detection circuit 13c
Converts the input phase difference amount information into target movement amount information.
The converted target movement amount information is stored in the range sampling circuit 13b.
And is sent to the range cell unit target movement amount correction circuit 13d.

The above-mentioned range cell unit target movement amount correction circuit 1
3d, on the basis of the target movement amount information inputted target movement
Maximum range cell included in distance (range cell is sampler
A few minutes, the distance interval corresponding to the
Sampled at the range cell interval in the direction opposite to the movement direction.
The received signal is shifted . The range resampling circuit 13b performs range interpolation (the maximum lens included in the target moving distance) in order to increase the correction accuracy of the correction circuit 13d.
In the direction opposite to the target movement direction, the range cell
Remainder after shifting the received signal sampled at intervals
The received signal at the distance is obtained from the sampled received signal). The operation of the above configuration will be described below with reference to FIG.

The received signal from the target obtained via the antenna device 11 is subjected to frequency conversion and quadrature detection in the transmission / reception device 12, and is sent to the signal processing device 13 as an analog video signal. In the signal processing device 13, the sent video signal is digitally converted by the A / D conversion circuit 131, and then the phase difference amount detection circuit 13a separates the video signal by one or more from the phase of the reception signal by one transmission pulse. The difference between the phase of the received signal and the phase of the received signal due to one transmission pulse is detected. For simplicity of description, a phase difference between received signals due to adjacent transmission pulses will be considered here.

The relationship between the phase difference, the time between the pulses, and the angular velocity of the phase rotation has a relationship as shown in equation (1), and the angular velocity of the phase rotation with respect to the target radar as shown in equation (2). It can be expressed as Doppler frequency caused by motion. Further, the target speed can be obtained from the expression (4) based on the relationship between the Doppler frequency and the target speed shown in the expression (3). Further, the amount of movement of the target in the time between the pulses for which the phase has been obtained can be obtained as in equation (6) from the relationship of equation (5).

[0020]

(Equation 1)

As described above, the target movement amount detection circuit 13c converts the amount of phase difference between pulses into the amount of movement in the distance direction between the target pulses. Based on the target movement amount information, the target movement amount correction circuit 13 for each range cell
In d, the number of cells equal to the maximum number of range cells included in the target moving distance,
Sampling is performed in the direction opposite to the target
The correction for shifting the received signal is performed.

Since the actual target does not move step by step for each range cell, a method called resampling is used here in order to realize the correction of the distance equal to or smaller than the range cell. Received data x at resample point t
(T) is n = ∞ (when no frequency component equal to or higher than fm [Hz] is included : fm is the minimum frequency included in the radar reception signal.
Large value ), received data X at the point of 1/2 fm second
_{The value of P} (P is the sequence number of the sampling point ) is determined by the following equation (the resampling function x (t) is an example, and the resampling point t is obtained from the amount of phase rotation).

[0023]

(Equation 2)

As described above, the correction for the range cell or less is performed by the phase difference detection circuit in the range resampling circuit 13b.
The point of the moving distance equivalent to the phase rotation amount obtained in 13a (Resan
The received data at the (pull point) is
Data obtained by interpolation from the received data
Is replaced with the original data . The received signal corrected in this way is used for radar purpose,
The processing is performed according to the application, and is appropriately displayed on the display device 14.

Therefore, the radar apparatus having the above configuration can detect a target movement amount with high accuracy in a short time by using the phase rotation amount of a reception signal from at least two consecutive transmission pulses. Accurate target movement amount correction can be performed. It should be noted that the present invention is not limited to the above-described embodiment, and can be similarly implemented by various modifications without departing from the gist of the present invention.

[0026]

As described above, according to the present invention, the target movement amount can be detected in a short time and with high accuracy without being affected by the range resolution. Can be provided with high accuracy.

[Brief description of the drawings]

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

FIG. 2 is a waveform chart for explaining resampling processing of the embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional radar device.

FIG. 4 is a block diagram showing a configuration of a radar device using another conventional signal processing method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Antenna device, 12 ... Transmission / reception device, 13 ... Signal processing device, 131 ... A / D conversion circuit, 132 ... Amplitude detection circuit, 133, 133 ... Target detection circuit, 134 ... Target movement amount detection circuit, 135 ... Range cell unit Target moving amount correction circuit, 136: FFT processing circuit, 13a: phase difference amount detecting circuit, 13b: range resampling circuit, 13c: target moving amount detecting circuit, 13d: range cell unit target moving amount correcting circuit, 14: display.

Continuation of the front page (56) References JP-A-5-249237 (JP, A) JP-A-2-6781 (JP, A) JP-A-62-25772 (JP, A) JP-A-62-234087 (JP, A) , A) JP-A-60-205384 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/95

Claims (1)

(57) [Claims] A reflected pulse reception signal of a repeatedly transmitted pulse.
Signal at a sampling cycle equivalent to a range cell
To the target, detect the target by digital signal processing,
In the radar device for obtaining the amount of motion, the phase of the received signal by one of the repetitive transmission pulses and
Another one that is more than one repetition period away from the transmission pulse
A phase difference detection circuit for detecting the difference between the phase of the received signal and the transmission pulse of the target, the target in the distance direction within the time between two pulses that detected the phase difference from the phase difference information obtained by this circuit A target movement distance detection circuit for calculating the distance moved, and the maximum range included in the target movement distance obtained by this circuit
In the direction opposite to the moving direction of the target by the number of cells, the range cell
A first correction circuit that shifts the received signal sampled at the same interval, and a target movement distance obtained by the target movement distance detection circuit.
Equivalent to the residual distance subtracted by the maximum range cell number
The position data is sampled at the range cell interval.
From the number of received signals by interpolation calculation, and the obtained data is
By replacing the original data, it is equivalent to the residual distance
In the direction opposite to the moving direction of the target,
Equivalent to shifting the received signal sampled at
And a second correction circuit for obtaining the result , wherein the first and second correction circuits perform the processing in any order.
Characteristic radar device.