JPH0436679A - Azimuth angle measuring instrument by beam scanning - Google Patents

Abstract

PURPOSE:To perform measurement in real time and with high resolution by finding the difference of neighboring reception information stored corresponding to a distance from a transmitter/receiver at every azimuth angle at the same distance. CONSTITUTION:The transmitter/receiver 10 is controlled by a scan control circuit 14 synchronized with a synchronous circuit 16, and scans a main beam at prescribed cycle in a direction of azimuth angle. The signal of a received reflection wave is switched by a switch 18 at every micro scan, and is allocated to reception circuits 50, 60, and is stored in memory 56, 66. Those signals are read out sequentially by the read instruction of a readout circuit 20 synchronizing with the circuit 16, and the difference of two signals is outputted from an OP amplifier 72. As or an output signal, the differentiated value of a reception signal of increment or decrement when the edge of the output signal traverses a material P to be measured is found when the main beam is located at theta1. In such a way, the azimuth angle of the material P to be measured can be found, and the resolution of the direction of azimuth angle can be improved, and an accurate azimuth angle and accurate shape can be found.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention relates to a positioning device, particularly a beam that measures the position, shape, etc. of an object by transmitting and receiving ultrasonic or radio waves with a known beam pattern while scanning them. This invention relates to a scanning positioning device.

[Prior Art] Positioning devices that transmit and receive ultrasonic waves or radio waves to obtain physical information about an object to be measured are known. In order to improve the azimuth resolution of such a positioning device, the following methods are used.

The first method is to narrow the beam width of the transmitted wave, and to narrow this beam width, the scale of the transducer and antenna is increased, or the transmission frequency is increased. .

Second, the reflected waves reflected from the object to be measured are received by multiple transducers and antennas arranged in a straight line, and the received signals are combined to achieve positioning with relatively high resolution. One example is a synthetic aperture method that performs this.

[Problems to be Solved by the Invention] However, in the first conventional method described above, there is a problem in that the transducer and antenna are large, so there are severe restrictions, and it is difficult to increase the transmission frequency. There is an upper limit on propagation loss, and for this reason, the first method described above is very difficult.

Furthermore, the second method has the disadvantage of being relatively susceptible to noise, which makes it difficult to reliably detect weak reflected signals. In order to improve the signal-to-noise ratio, it has conventionally been necessary to increase the output of the transmitted wave or to reduce the noise in the first stage of the receiver, but both of these methods lead to larger and more complex equipment. ,
Furthermore, the processing time associated with the synthetic aperture calculation cannot be ignored, making it difficult to measure in real time.

Therefore, without changing the size of the transducer or antenna,
In addition, there has been a need for an apparatus that can improve the azimuth resolution for positioning an object without changing the transmitting and receiving frequencies.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide a beam scanning positioning device that can measure the position, shape, etc. of a measured object in real time and with high resolution without changing the size or frequency of the transducer or antenna.

[Means for Solving the Problems] Measurement Principle Below, the measurement principle of the present invention will be explained first with reference to FIGS. 2 and 3.

FIG. 2 shows a beam pattern of ultrasonic waves or radio waves transmitted and received from a transducer or an antenna. In the figure, the vertical axis indicates transmission strength or reception sensitivity, and the horizontal axis indicates azimuth angle.

As is clear from the figure, a plurality of side lobes are bundled to the left and right around the main beam, and the ultrasonic waves or radio waves here have directivity in the direction of the main beam. Here, D indicates the spread of the main beam in the azimuth and angle direction, and W indicates the power half width, that is, the beam width.

In conventional equipment using such a beam pattern, it is difficult to determine the position and shape of the object to be measured within the area of the main beam, and for this reason, the resolution in the azimuth and angle direction depends on the beam width. was.

However, in the present invention, it is possible to improve the resolution in the azimuth and angle direction using such a beam pattern. That is, it is characterized in that the object to be measured is measured using a steeply sloped part of the main beam, in other words, the side surface of the beam. In other words, the present invention scans the main beam in the azimuth and angle direction, detects fluctuations in the received signal (rapid rise in the received signal level) that occur when the object to be measured crosses the side surface Lm or Rm of the main beam, and based on this detection. It is used to find the position of the object to be measured. In addition, the present invention is characterized in that information about the object to be measured obtained through the above measurements is displayed superimposed on a conventional display image, thereby making it possible to provide an image with improved azimuth resolution.

This will be further explained using FIG. FIG. 3 shows the concept of scanning the object P to be measured with the main beam.

When the edge of the main beam θ1 crosses the object P to be measured, the received signal level increases due to the reflected wave from the object P to be measured. When the main beam is further scanned, the level of the received signal gradually increases according to the characteristics shown in FIG. 2, and gradually decreases after passing the center of the main beam. Then, when the main beam is scanned to θ3, the reflected wave from the object to be measured P becomes unreceivable. Therefore, it is possible to determine the azimuth angle of the object to be measured P by monitoring the fluctuation in the received signal level when the edge of the main beam crosses the object to be measured P for the first or last time. Note that here, the distance between the object to be measured P, the transducer, and the antenna can be easily calculated based on the time difference between wave transmission and reception.

As described above, according to the principle of the present invention, it is possible to detect the object to be measured at the edge of the main beam, and the trajectory of the object to be measured within the area of the main beam can be detected at an azimuth angle. This can eliminate problems such as spreading in different directions or obscuring the location.

Measuring means In order to achieve the above-mentioned object using the above-mentioned principle, the present invention transmits ultrasonic waves or radio waves with a known beam pattern, receives reflected waves from the object to be measured, and converts the transmitted and received waves into This is a positioning device that sequentially scans in each predetermined direction to determine the position, shape, etc. of an object to be measured, and includes a storage section that stores received wave information for each direction, and information on each adjacent direction that is read from the storage section. A difference calculator that inputs received wave information and calculates the difference of each received wave information at points having the same distance from the transducer among the received wave information; and an azimuth correction means for correcting the azimuth angle based on the beam pattern, and the object to be measured is measured at the edge of the scanned beam pattern.

Further, the present invention includes a combining circuit that combines a signal modulated in brightness in proportion to the received signal strength and an output signal from the direction correcting means, and a combining circuit that combines the signal modulated in brightness in proportion to the received signal strength and the output signal from the direction correcting means. It is characterized by displaying the output signal in a different color.

[Operation] According to the above configuration, the reflected wave from the object to be measured is received and stored as received wave information in the storage section according to the distance from the transducer for each azimuth angle. Then, received wave information at adjacent azimuth angles is read out from the storage section, and a difference between the two at the same distance is determined by a difference calculator. This difference indicates the variation in the received signal level when the edge portion of the main beam mentioned above crosses the object to be measured.

Then, the difference calculated by the difference calculator is corrected by the azimuth correction circuit based on the beam pattern.

That is, by adding the azimuth angle that is half the spread of the main beam to the azimuth angle at which the reception level fluctuation occurs, the normal azimuth angle of the object to be measured can be determined.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a preferred embodiment of a beam scanning positioning device according to the present invention. Here, a characteristic configuration is shown and a simple amplifier circuit and the like are omitted.

In the figure, 10 is a transducer that transmits and receives ultrasonic waves or radio waves, and receives a transmission signal from a transmission circuit 12. Furthermore, scanning of the transducer 10 in the azimuth and angle direction is controlled by a scan control circuit 14, and its main beam is scanned in the azimuth and angle direction at a predetermined period.

In the figure, reference numeral 16 denotes a synchronization circuit, which supplies the transmission circuit 12 and the scanning control circuit 14 with a synchronization signal T related to wave transmission and reception. Furthermore, synchronization signals are also supplied to circuits to be described later.

The signal of the reflected wave received by the transducer 10 is then input to the switch 18, switched for each micro-scan, and distributed to the next-stage receiving circuits 50 and 60.

The receiving circuit 50.60 includes a pulse compression analog circuit 52,
62, A/D converter 54.64 and frame memory 56
．． It consists of 66.

Here, the pulse compression analog circuits 52 and 62 perform pulse compression for performing analog deconvolution related to the distance to the object to be measured Q. The signals output from the pulse compression analog circuits 52.62 are each then sent to an A/D converter 54.64, where they are digitized and sent to a memory 56.66 for storage.

Therefore, the received signals are stored in the memories 56 and 66 for each minute angle scan related to beam scanning.

When the received signals are stored in the two frame memories 56 and 66, the read circuit 20 that receives the synchronization signal T3 from the synchronization circuit 6 sends a read command to each memory, and each memory 56 and 66 The received signals stored from the receiver are sequentially read out in correspondence with the distances determined by the respective receiving times. Each read signal is then sent to the switch 70. This switch 70 is provided to alternately invert two inputs of a difference calculator (OP amplifier) 72, which will be described later, and receives a synchronization signal T4 from the synchronization circuit 16 to perform the switching operation.

The OP amplifier 72 has a child terminal and one terminal as input terminals, and outputs the difference between two input signals. Here, the child terminal is a non-inverting terminal, and one terminal is an inverting terminal.

That is, if the switch 70 does not perform the switching operation, the received signal read out from the memory 56 will be OP.
On the other hand, the received signal read out from the memory 66 is input to one terminal of the OP amplifier 72. Then, the difference between these two signals will be output.

Note that this output signal indicates that the main beam shown in Fig. 3 is θ1.
This shows the increase in the received signal when the edge of the beam crosses the object to be measured P. In other words,
The OP amplifier 72 determines a variation in the amount of increase or decrease in the received signal, in other words, a differential value.

The signal output from the OP amplifier 72 is then input to a selection circuit 74, where a positive level signal among the received signals is selected and output.

In other words, this selection circuit 74 selects the one with a positive differential value, and this determines whether the scanning of the main beam in FIG. 3 is, for example, in the +θ force direction θ1 or in the −θ force direction θ3. .

The signal output from the selection circuit 74 is then input to a color calculation circuit 76, where it is converted into a color image signal and sent to the next image memory 78 where it is temporarily stored.

The output signal is branched from one of the output terminals of the switch 70 and sent to an image calculation circuit 82, where it is converted into a color image signal.

In the figure, 80 is a readout circuit that gives a readout command to the image memory 78, which receives a synchronization signal T1 from the synchronization circuit 16 and a scanning angle signal θ from the scan control circuit 14, and issues a readout command based on these information. It is outputting. The readout timing is such that the main beam center direction matches the azimuth angle of the object to be measured, and the signal read out from the image memory 78 is sent from the image calculation circuit 82. It is combined with the output signal in a combining circuit 84. As a result, the color information read from the image memory 78 that measures the object to be measured at the edge of the beam is combined with the received color information as amplitude information outputted from the image calculation circuit 82 as in the past. become.

The combined signal from the combining circuit 84 is displayed on a display 86.
Here, the signal from the image processing circuit 82 and the signal from the image memory 78 are displayed in different colors.

Then, the above operations are performed sequentially for each minute azimuth angle,
Furthermore, scanning is performed in the opposite direction (-θ direction) to observe the shape of the object to be measured.

As described above, in the present embodiment, in the case of a rotary scanning antenna of a radar, the correction of the azimuth angle at which the object to be measured is located is delayed by a predetermined time of the readout command sent from the readout circuit 80 to the image memory 78. However, in beam scanning by switching delay lines, as in the case of multi-element transducer arrays, the shape of the beam pattern changes, so it is necessary to provide a correction calculation circuit for the azimuth angle based on the azimuths of the peak and slope. is suitable. In addition, the selection circuit 7
By providing a gate circuit having a predetermined threshold level in 4, it is possible to eliminate noise contained in the received signal. Furthermore, a counter or the like synchronized with scanning control may be connected to the readout circuit 80, and a readout command to the image memory 78 may be sent out based on this counter. In either case, accurate positioning is achieved by measuring the object to be measured at the edge of the main beam, and then correcting the pointing direction of the peak of the beam pattern of this main beam to the azimuth angle of the object to be measured. It is possible to provide clear images with improved resolution.

[Effects of the Invention] As explained above, according to the beam scanning positioning device according to the present invention, the azimuth angle of the object to be measured, which could not be determined within the main beam range conventionally, can be determined. It is possible to significantly improve resolution. Therefore, it is possible to determine the accurate azimuth angle, accurate shape, etc. of the object to be measured.

Furthermore, since the resolution in the azimuthal and angular directions has been improved, the images provided are also clear, making it possible to provide clear images that are extremely easy to recognize.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a beam scanning positioning device according to the present invention, FIG. 2 is an explanatory diagram showing a beam pattern, and FIG. 3 is an explanatory diagram showing beam scanning. 18゜20゜Scan control circuit Synchronous circuit...Switcher...Memory...Readout circuit Difference calculator selection circuit Image memory synthesis circuit

Claims (2)

[Claims] (1) Transmit ultrasonic waves or radio waves with a known beam pattern and receive reflected waves from the object to be measured, and scan the transmitted and received waves sequentially in each predetermined direction to determine the position, shape, etc. of the object to be measured. A positioning device is provided, which includes a storage unit that stores received wave information for each direction, and inputs the received wave information read from the storage unit in each adjacent direction, and selects a transmitter/receiver among the received wave information. a difference calculator that calculates the difference in each received wave information at the same distance from the difference calculator; and an azimuth correction means that corrects the azimuth angle based on the beam pattern with respect to the difference information from the difference calculator. A beam scanning positioning device comprising: and Measures an object to be measured at the edge of a beam pattern being scanned. (2) The beam scanning positioning device according to claim (1), further comprising a synthesizing means for synthesizing a brightness-modulated signal in proportion to the received signal strength and an output signal from the azimuth correction means, the brightness modulation A beam scanning positioning device characterized in that the signal output from the direction correction means and the output signal from the direction correction means are displayed in different colors.