JPH04363682A - Converter for directional pulse signal resolution in radar - Google Patents

Abstract

PURPOSE:To convert at an arbitrary multiplying ratio with a simple circuit in the case to convert the resolution of a directional pulse signal generated from an aerial wire element into the resolution of a bearing direction used on the indicating element side. CONSTITUTION:A pulse period measuring element 11 measures the time Tb of one period of the first directional pulse signal generated at every rotation of a constant angle of an antenna, and a pulse number counting element 12 counts the number N of the first directional pulses generated in one period of the antenna. An operating element 13 finds (t) by the operation of Tb*N/D, letting necessary resolution as D, and sets this to a timer 14. The timer 14 generates the second directional pulse signal at the period of (t). A PLL circuit and a frequency divider become useless, and furthermore a multiplying ratio of the second directional pulse signal to the first directional pulse signal can be changed by setting the necessary resolution D.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for converting the resolution of an azimuth pulse signal generated as an antenna rotates in a radar.

0002

[Prior Art] By rotating the antenna, the pointing direction of the antenna is sequentially changed, pulsed radio waves are emitted, and the distance to the target is detected based on the time difference until the reflected waves from the target return. Radar devices are used on ships and the like.

[0003] Such a radar device is composed of an antenna unit installed outside the ship and an indicator unit installed inside the ship. It consists of a pulse signal generator, etc. This pulse signal generator generates a reference pulse signal (heading signal) when the antenna points in a reference direction such as the bow of the ship, and also generates a direction pulse signal (bearing signal, azimuth signal) every time the antenna rotates by a certain angle.
occurs. The instruction section side detects the direction of the antenna based on the reference pulse signal and the azimuth pulse signal, and sequentially writes the radar echo signals onto the memory. However, since the number of pulse signals per one round of the antenna of the azimuth pulse signal sent from the antenna section is small compared to the resolution of the azimuth direction during detection and display, the number of pulses of the azimuth pulse signal per one round of the antenna is The azimuth pulse signal with the required resolution is generated by multiplying the

FIG. 5 shows an example of a conventional circuit for multiplying the azimuth pulse signal. In FIG. 5, 1 is a PLL circuit, which is composed of a comparator 2 that compares frequencies and phases, a low-pass filter 3, and a voltage-controlled oscillation circuit 4. Also 5
, 6 are frequency dividing circuits. When the azimuth pulse signal (first azimuth pulse signal) sent from the antenna section is input to the input of the PLL circuit 1, the PLL circuit 1 divides the frequency of the output signal by the frequency dividing circuit 5. is the first
The frequency is controlled to be equal to the frequency of the azimuth pulse signal. The frequency dividing circuit 6 divides the frequency of the signal at a constant frequency division ratio and generates a second azimuth pulse signal. In the example of FIG. 5, if the number of pulses per antenna cycle of the first direction pulse signal is 450, the number of pulses per antenna cycle of the second direction pulse signal is 450 x 2048/225 = 4096 pulse signals. .

[0005]

[Problems to be Solved by the Invention] However, in conventional radars in which the resolution of the azimuth pulse signal is converted by such a multiplier circuit, a PLL circuit and two frequency divider circuits are required, making it relatively complicated. The circuit scale was large, which caused the cost to increase. Furthermore, since the resolution of the azimuth pulse signal sent from the antenna section and the resolution of the azimuth direction for detection and display are constant, the magnification ratio is also fixed. Therefore, it is not possible to use another antenna section with a different resolution of the azimuth pulse signal, and if you are forced to use it,
A circuit must be added to convert the resolution of the azimuth pulse signal output from the antenna section to the detection/display resolution.

An object of the present invention is to reduce costs by making it possible to convert the resolution of an azimuth pulse signal with a reduced circuit scale.

Another object of the present invention is to make variable the multiplication ratio when converting the azimuth pulse signal resolution, thereby making it possible to use any antenna section having a different azimuth pulse signal resolution.

[0008]

[Means for Solving the Problems] The azimuth pulse signal resolution conversion device in the radar of the present invention is a means for measuring the time (Tb) of one cycle of the first azimuth pulse signal generated every time the antenna rotates by a certain angle. and means for counting the number (N) of the first azimuth pulses generated during one period of the reference pulse signal generated each time the antenna points in the reference direction, and generating a second azimuth pulse signal at a set time period. and means for setting the timer to a time of Tb*N/D, where the required resolution is D.

[0009]

[Operation] In the azimuth pulse signal resolution conversion device in a radar of the present invention, first, the time Tb of one cycle of the first azimuth pulse signal generated every time the antenna rotates by a certain angle is measured, and the antenna is oriented in the reference direction. The number N of first azimuth pulses that occur during one period of the reference pulse signal that is generated every time
is counted. Then, if the resolution of the azimuth pulse signal required for detection, display, etc. is D, then Tb*N/D
The time is set on the timer. The timer means generates a second azimuth pulse signal at a set time period. Therefore, the first azimuth pulse signal with the resolution N is converted into the second azimuth pulse signal with the set resolution D. The time Tb of one period of the first azimuth pulse signal and the number N of first azimuth pulses occurring during one period of the reference pulse signal are each actually measured, and by giving the required resolution D, the second azimuth pulse with an arbitrary resolution is determined. A pulse signal is obtained.

As described above, according to the present invention, a PLL circuit and two frequency dividing circuits are not required, and each means can be constructed with a relatively small-scale circuit, thereby reducing costs. Furthermore, by simply changing the required resolution D, the resolution of the azimuth pulse signal can be converted at any magnification ratio, so any antenna section with a different azimuth pulse signal resolution can be used.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of the configuration of an azimuth pulse signal resolution conversion apparatus which is a first embodiment of the present invention. In FIG. 1, the pulse signal period measuring section 11 measures the time Tb of one period of the first azimuth pulse signal sent from the antenna section.
Measure. For example, by waiting for the rise of the first azimuth pulse signal, starting the clock count after detecting the rise, and stopping the count at the next rise, the counter can count the time of one cycle of the first azimuth pulse signal. It is calculated as a number and the result is given to the arithmetic unit 13. The pulse number counting section 12 counts the number N of first azimuth pulses generated during one period of the reference pulse signal sent from the antenna section. For example, it consists of a counter and a latch circuit, and the counter is reset at the rising edge of the reference pulse signal, and the counter is reset from the falling edge of the reference pulse signal.
The number of rises of the azimuth pulse signal is counted, and the contents of the counter are latched by the latch circuit at the next rise of the reference pulse signal, and then the counter is reset. Then, the contents of the latch circuit are provided to the arithmetic unit 13. The calculation unit 13 reads Tb from the pulse period measuring unit 11, reads the value N from the pulse number counting unit 12, and further calculates the required resolution D.
is read from the input section, etc., the calculation of Tb*N/D is performed, and the result is set in the timer 14. The timer 14 provides an interrupt signal to the arithmetic unit 13 at a set time period. The arithmetic unit 13 responds to an interrupt signal given from the timer 14 and performs processing in the XY converter 15 by interrupt processing. The interrupt signal given from the timer 14 to the arithmetic unit 13 at approximately constant intervals is the second azimuth pulse signal. The X-Y converter 15 performs a process of writing the radar echo signal into the memory of the XY coordinate system according to the direction of the antenna.

[0012] Current one-chip microcomputers are equipped with all functions such as a function to measure the period of a rectangular wave signal, a pulse signal count function, and a timer function (timer interrupt function). The signal period measuring section 11, the pulse number counting section 12, the calculating section 13, and the timer 14 can all be configured as a one-chip microcomputer 10.

FIG. 2 shows the timing of each part shown in FIG. 1 as a waveform diagram. In FIG. 2, the reference pulse signal is generated every time the antenna rotates once, and the first azimuth pulse signal is generated every time the antenna rotates by a certain angle, and the first azimuth pulse signal is generated at Th during one rotation of the antenna. Number of pulses N(
For example, 450) is the pulse number counting section 12 shown in FIG.
The time Tb of one period of the first azimuth pulse signal is measured by the pulse period measuring section 11 shown in FIG. Then, a second azimuth pulse signal is generated at a period of time t set in the timer 14. Although the rotational speed of the antenna is approximately constant, there is some variation, one period Th of the reference pulse signal varies slightly, and the first azimuth pulse signal includes jitter. Therefore, the time Tb of one cycle of the first azimuth pulse signal also fluctuates, but this one cycle Tb
Immediately after the measurement of , the period t of the second azimuth pulse signal is corrected. In FIG. 2, the period t1 of the second azimuth pulse signal is determined from the period Tb1 of the first azimuth pulse signal, and the period t2 of the second azimuth pulse signal is determined from the period Tb2 of the first azimuth pulse signal.

Further, the pulse signal generator for generating the first azimuth pulse signal usually uses a slit disk, and a photointerrupter detects rotation of the antenna at a fixed angle. Since this slit disk is attached to a motor shaft or the like, the slit may become clogged with dust, grease, etc., resulting in omissions in pulse signal generation. For example, if one slit becomes clogged, one pulse signal disappears during the generation of the first direction pulse signal, as shown in FIG. As a result, the time Tb of one cycle of the first azimuth pulse signal is doubled. However, when the measurement result of the pulse period measuring section 11 is significantly different from the previous measurement value or the average value up to that point, the calculation section 13 shown in FIG. It can be determined that there is some type of malfunction in the system, and an alarm can be issued to call for attention. Alternatively, if the time of one cycle of the first azimuth pulse signal is approximately twice the average value, it is assumed that the slit is clogged in that section, and
As long as the set value t for the timer 14 is not updated during that period, the radar can operate without any problems.

Next, FIG. 4 shows a block diagram of the main part of the azimuth pulse signal resolution conversion device in a radar according to a second embodiment. The difference from the first embodiment shown in FIG. 1 is that the calculation unit 13 only sets the time t to the timer 14, and directly performs coordinate transformation based on the output signal of the timer 14. That is, the functions of the pulse period measuring section 11 and the pulse number counting section 12 are the same as those shown in FIG. The period t of the second azimuth pulse signal is determined based on the setting value D of the detection/display resolution setting section 21 and is set in the timer 14. The timer 14 counts up the θ counter 16 at a period of t. This θ counter 16 is reset by the reference pulse signal, counts up by the output signal of the timer 14, and specifies the upper address of the ROM 18. The R counter 17 counts up based on the clock when reading out one sweep's worth of radar echo data written in the primary memory 20, and is reset each time reading of one sweep's worth is completed.
Specify the lower address of 8. The ROM 18 uses the θ counter 16 and R counter 17 as addresses to store the secondary memory 19.
generates an address signal. This ROM 18 stores the values of the R counter 17 and θ counter 16 as R and θ coordinate values.
Data to be converted into corresponding X and Y coordinate values is written in advance. The secondary memory 19 writes the output data of the primary memory 20 using the output of the ROM 18 as an address. The primary memory 20 stores one sweep of the digital data of the radar echo signal in synchronization with the write clock signal, and stores the contents in synchronization with the read clock until the next transmission trigger pulse signal is generated. Secondary memory 1
Output to 9. In this way, a value corresponding to the direction of the antenna is determined for the θ counter 16, and radar echo data in that direction is written into the secondary memory 19.

[0016]

[Effects of the Invention] According to the present invention, the following effects can be achieved.

(2) The PLL circuit and two frequency divider circuits that were conventionally required are no longer necessary, and the resolution of the azimuth pulse signal can be converted with a small-scale circuit configuration, resulting in lower costs.

■The multiplication ratio of the azimuth pulse signal generated from the antenna section for the necessary detection and display can be arbitrarily set, and there is no need to change the circuit or program for this purpose. be.

(2) There is no need to adjust the resolution of the azimuth pulse signal generator in the antenna section to the number of pulses required by the indicating section, and any optimal azimuth pulse signal generator can be designed.

(2) Furthermore, when combining different antenna sections and indicating sections, the azimuth pulse signal conversion circuit used in the past becomes unnecessary.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of an azimuth pulse signal resolution conversion device according to a first embodiment.

FIG. 2 is a waveform diagram of each part in FIG. 1;

FIG. 3 is a waveform diagram of a first azimuth pulse signal due to a failure of the azimuth pulse signal generator.

FIG. 4 is a block diagram of main parts of an azimuth pulse signal resolution conversion device according to a second embodiment.

FIG. 5 is a block diagram of a conventional azimuth pulse signal resolution conversion device.

Claims (1)

[Claims] 1. A means for measuring the time (Tb) of one cycle of a first azimuth pulse signal generated each time the antenna rotates by a certain angle; means for counting the number (N) of the first azimuth pulses occurring during one period; timer means for generating the second azimuth pulse signal at a set time period; An azimuth pulse signal resolution conversion device for a radar, comprising means for setting a time in the timer.