JP3288489B2 - 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 detection device which emits radio waves, ultrasonic waves, etc. from a device main body, processes reflected waves and displays the processed waves on a display, and more particularly to gain control of a radar reception signal in a radar device. About the improvement of the part.

[0002]

2. Description of the Related Art In order for an observer to use a ship radar in an optimal image state, it is necessary to appropriately adjust reception sensitivity. Usually, the adjustment of the receiving sensitivity is performed by a gain circuit in the radar device receiving unit. FIG. 9 shows a block diagram of a reception sensitivity adjustment unit of a conventional radar device.

[0003] A gain circuit arranged in a receiving unit receives a video signal (image signal) obtained by processing a radar reception signal,
The gain-adjusted video signal is output to the signal processing unit of the instruction unit. A gain voltage is input to the gain circuit, and the gain (gain) of the video signal, that is, the strength of the receiving sensitivity is changed by adjusting the gain voltage. This gain voltage is usually generated by a voltage generator in the indicating unit.
The control of the voltage generated by the voltage generation unit is performed by rotating a knob provided in the operation unit. Therefore, the reception sensitivity is adjusted by rotating the knob of the operation unit. The observer judges the image by manually operating the knob while looking at the display of the indicating section, and adjusts the image so as to obtain the optimum receiving sensitivity.

FIG. 10 shows a STC (Sensitive) as a gain control unit for controlling the gain of a radar reception signal.
2 shows an STC adjustment unit of a conventional radar device when an (Time Time Control) circuit is used. ST
The C circuit has a function of reducing the sea surface reflection component from a signal in which the reflection (echo) from the target and the reflected wave from the sea surface waves are mixed, that is, the function of suppressing the gain as the distance becomes shorter. The STC voltage that determines the effectiveness is generated by a voltage generation unit provided in the instruction unit. Observers
The STC voltage generated by the voltage generation unit is adjusted by operating a knob provided on the operation unit so that the image displayed on the display is in an optimal display state.

[0005]

However, in the conventional radar devices shown in FIGS. 9 and 10, it is necessary for an observer who looks at the display to manually adjust the image so that the subject is in the best image state. In addition, even with the same model, it is difficult to adjust all devices to uniform reception sensitivity due to variations in the elements that make up the circuit, etc.Changes in sea conditions due to changes in the weather, and how sea surface reflection varies depending on the wind direction. It was difficult to adjust and maintain the optimal video in real time for the difference.

An object of the present invention is to provide a radar apparatus that automatically performs gain adjustment and STC adjustment based on a predetermined signal component in a received signal. Further, there is provided a radar apparatus which quantifies and evaluates video information effective for the adjustment, and automatically adjusts the reception sensitivity and STC so that the video on the display is in an optimum state according to the result. It is in.

[0007]

SUMMARY OF THE INVENTION The present invention provides a radar receiving signal.
STC circuit that suppresses the signal gain as the distance decreases,
Signal component exceeding a certain threshold from the output signal of C circuit
Effective signal component separating means for separating a signal as an effective signal component
And a signal component within a predetermined distance range from the separated effective signal component.
Gate means to extract the minute and count the extracted signal components
Counting means, comparing the counted value with the reference value, and as a result
Gain control signal for adjusting the gain of the STC circuit according to
Adjusting means for controlling the echo from the effective signal component so that the
Land component removal unit that removes what follows above as land component
And The present invention also provides for the
A GAIN circuit for controlling the gain, and an output of the GAIN circuit.
Signal component exceeding a certain threshold from the force signal is an effective signal
Effective signal component separating means for separating as a component,
From the effective signal component, an antenna with little effect of echo
Noise component in a section at a position more than a predetermined distance from the
Gate means for extracting the noise and counting the extracted noise components
Counting means, comparing the counted value with the reference value, and as a result
Gain control signal for adjusting the gain of the GAIN circuit in accordance with
Signal adjustment means.

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

The effective signal component for gain control is separated from the output signal of the gain control section. The effective signal component is a noise component when the gain control unit is a gain circuit for sensitivity adjustment, and is an echo component when the gain control unit is an STC circuit. Then, a signal component within a predetermined distance range is extracted from the separated effective signal component by the gate means. The reason why the predetermined distance range is extracted is to remove signal components in a distance range unnecessary for sensitivity adjustment or STC adjustment.
That is, when performing sensitivity adjustment, the predetermined distance range is set to a range of a position separated by a predetermined distance or more where there is almost no reflected signal from the target, that is, almost no echo, and in the case of STC adjustment, it is an STC adjustment target. The range is set to a range, that is, a range from the antenna position to a position separated by a predetermined distance. Next, the extracted signal components are counted and quantified. Then, the count value is compared with a preset reference value, and the level of the gain control signal is adjusted according to the result. Performing this operation for each sweep enables very fine adjustment.

[0015] Also, by removing, from the effective signal component, an echo that continues for a predetermined length or more as a land component, S
It is possible to prevent TC from working too much to make a nearby target invisible.

In addition, it is possible to automate the gain adjustment by separating the echo component and the noise component from the output signal of the gain control unit, comparing the signal with a reference value, and controlling the gain in the gain control unit in accordance with the result. Become. At this time, if the separated components are counted and quantified, the accuracy of gain adjustment is improved.

[0017]

FIG. 1 is a block diagram showing a reception sensitivity automatic adjustment unit of a radar apparatus according to a first embodiment of the present invention. A radar reception signal received by an antenna (not shown) passes through various circuits such as an amplification and detection circuit, is converted into a video signal projected on a display, and is input to the gain circuit 1. In the gain circuit 1, the receiving sensitivity changes depending on the level of the voltage applied to the circuit. The output of the gain circuit 1 is input to an instruction unit (not shown) and displayed on a display as an image.

The video signal after passing through the gain circuit 1 is
It is input to the receiving sensitivity automatic adjustment unit in addition to the instruction unit. The video signal input to the automatic adjustment unit is output to the effective signal separation unit 2
to go into. The effective signal separation unit 2 separates only a voltage component equal to or higher than a certain threshold, that is, a voltage component effective for sensitivity adjustment from a received signal. Further, this active ingredient is binarized with respect to the time axis. The binarized effective component is input to the effective noise extraction unit 4 and reflected from the target (echo).
The echo component is removed from the binarized received signal in which the noise component and the white noise are mixed. Gate means is used to remove this echo component. The gate means passes a signal in a section in a distance range where the influence of the echo component is considered to be almost insignificant, that is, in a section in a distance range apart from the antenna position by a predetermined distance or more. In this manner, the reception sensitivity can be uniformly adjusted only for white noise irrespective of the distance, without being affected by the surrounding ships and the terrain.

The effective noise component extracted by the effective noise extraction unit 4 is input to a noise amount quantification unit 5, where the effective noise component is integrated and converted so that it can be represented by a numerical value. The comparator 7 compares the digitized integrated value of the effective noise component with an optimum value 6 which is a reference value for sensitivity adjustment which is set in advance, and outputs a signal indicating the magnitude relationship between the two. . The voltage controller 8 controls a voltage generator 9 that outputs a gain voltage (gain control signal) to the gain circuit 1 according to an output signal of the comparator 7. This part corresponds to the knob of the conventional device. If the optimum value 6 indicates a state in which the optimum value 6 is larger than the digitized noise amount, that is, a state in which the sensitivity is insufficient, the voltage control unit 8
And outputs a signal that changes the voltage in a direction in which the sensitivity increases.

In the reverse state, a signal for changing the voltage in a direction in which the sensitivity is lowered is output.

The voltage generator 9 outputs a gain voltage to the gain circuit 1, and changes the gain voltage according to a control signal from the voltage controller 8.

As described above, in the apparatus shown in FIG. 1, only a component effective for gain adjustment is extracted from the video signal which has passed through the gain circuit 1 once.

This active ingredient is quantified.

The quantified active ingredient is compared with the optimal value of the same parameter.

The gain voltage is changed based on the result of the comparison and fed back to the gain circuit.

The reception sensitivity is adjusted by a series of operations described above.

The above operation is executed every time one radar pulse is output, that is, every one sweep.

Next, FIG. 2 shows a detailed configuration diagram of the above-described automatic reception sensitivity adjustment section.

The video signal output from the gain circuit 1 of the radar receiver is input to the voltage comparator 10. The output of the reference voltage generator 11 is also input to the voltage comparator 10, where the two are compared. Reference voltage generator 1
The reference voltage generated at 1 is a threshold value for extracting a voltage component of a certain level or more. The output of the voltage comparator 10 is at the "H" level when the video signal is higher than the reference voltage, and is at the "L" level otherwise, thereby separating the effective signal component and binarizing it as shown in FIG. Realize.

The oscillator 12 outputs a generation timing of a gate pulse in the gate generation unit 13 and a basic clock for quantifying a noise amount. The TX trigger 14 is a pulse signal indicating a radar transmission start timing, and serves as a basic signal for calculating the distance from the radar to the target. The gate generator 13 removes a reflection component (echo component) from the target from the separated and binarized video signal, and generates a gate signal for passing only an effective noise component. Here, it is considered that there is almost no influence of reflection (echo) from the target, that is, a gate signal is formed to pass a signal in a section at a position apart from the antenna position by a predetermined distance or more. This signal is generated based on the clock pulse of the oscillator 12 and the TX trigger 14. The gate signal and the binarized video signal are combined (logical product) to extract a noise signal in a specific distance range. The gate generating section 13 and the synthesizing section 15 constitute the effective noise extracting section 4 of FIG.

The counter section 16 counts the section of the extracted effective noise component using the clock from the oscillator 12.
That is, of the signals input to the counter section 16, "H"
Section is counted up by the clock, and the section of "L" is not counted. Therefore, the count value of the counter unit 16 corresponds to the digitized noise amount.

The optimum value data storage section 17 stores, as an optimum value, a numerical value obtained when the noise is counted by the above-described method of digitizing the amount of noise while being adjusted to the optimum sensitivity. The numerical value represented here is an 8-bit binary number, and the data of the counter section 16 and the optimum value data are input to the numerical comparator 18. Numerical comparator 18 is 8
It is composed of a bit comparator and outputs a magnitude relationship between two numerical values as a voltage signal. The MPU 19 is an 8-bit microprocessor, receives the output signal of the numerical comparator 18 and determines whether the noise amount is optimal or insufficient with respect to the optimum value, and converts the voltage to the gain voltage currently stored therein which is currently being output. On the other hand, the voltage to be output next is determined and DA
A control signal is output to C20. DAC 20 is an 8-bit D
The A converter outputs a gain voltage according to the control data from the MPU 19 and feeds it back to the gain circuit 1.

FIG. 3 is a time chart of the automatic reception sensitivity adjusting section shown in FIG. The gate signal A output from the gate generator 13 rises when the time T has elapsed from the transmission pulse P. The time T is set to a length at which the transmission pulse P is emitted and the echo is considered to be almost nonexistent. As a result, a signal obtained by binarizing white noise in the section of the gate signal A is input to the counter unit 16. The counter section 16 receives a clock from the oscillator 12 and the binary signal B in the section of the gate signal, and counts the clock when the signal B is "H". That is,
The clock indicated by D is counted. Therefore, the count value increases when the white noise is large, and decreases when the white noise is small.

Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram of an STC automatic adjustment unit of a radar device according to another embodiment of the present invention.

The STC circuit 30 adjusts a gain of a video signal based on an STC voltage input from an STC voltage generator described later. The STC voltage has a sawtooth waveform, and functions as a gain suppression voltage that sets the gain to almost 0 at a distance of 0 and gradually recovers the gain as the distance increases. The STC circuit 30 uses this S
The gain of the video signal is controlled based on the TC voltage, and is output to an instruction unit (not shown) and output to the STC automatic adjustment unit shown in FIG.

In the STC automatic adjustment section, the STC circuit 3
The output of 0 is received by the echo component separation unit 31. The echo component separation unit 31 separates a signal component having a magnitude corresponding to an echo component from a video signal including a sea surface reflection component, a reflection component from a target (echo component), and white noise. The separated signal is binarized in the binarization unit 32 based on the presence or absence of an echo with respect to the time axis, and among the binarized echo signals, only a signal within a distance range to be subjected to STC adjustment is extracted. Is done. By adjusting only echoes in this range to be adjusted, S
Adjustment of TC becomes possible.

The land component removing unit 34 further removes a component reflected from the land from the echo signal to be adjusted. In the control method of this embodiment in which the amount of echo is quantified and the STC voltage is brought close to the optimum value, when the land component is counted as an echo, the STC is too effective and even small targets near the land are removed as sea surface reflection. I will. Therefore,
The land component removing unit 34 is provided to perform an operation of removing a reflected component from the land. The echo amount digitizing section 35 integrates the extracted echo signals and converts the echo amount so that the echo amount can be represented by a numerical value. The optimum value 36 stores a numerical value when the echo amount at the time of obtaining the optimum image is quantified by the echo amount quantifying unit 35. The comparator 37 compares the output magnitude relation between the echo quantity quantifying unit 35 and the optimum value 36, and outputs a signal indicating the magnitude relation between the actual echo quantity and the optimum value. The voltage control unit 38 controls the adjustment of the STC voltage, and operates as follows according to the magnitude relationship between the actual echo amount output from the comparator 37 and the optimum value.

That is, when the echo amount is smaller than the optimum value, the voltage is changed in a direction to loosen the STC, and when the echo amount is larger than the optimum value, the voltage is changed in a direction to increase the STC.

In the voltage generator 39, the voltage controller 3
8 outputs the STC voltage to the STC circuit 30 in accordance with the instruction from 8.

The above control is performed for each sweep.
By performing this series of operations continuously, the STC adjustment of the video on the display is always kept in an optimal state.

FIG. 5 is a detailed block diagram of the STC movement adjusting section.

The STC circuit 30 is a circuit that performs an STC adjustment operation, and the effect of removing sea surface reflection can be adjusted by changing the STC voltage applied to the circuit. STC circuit 30
, And the video signal subjected to the STC adjustment is output from the comparator 4
At 1, it is compared with the reference voltage 40. The reference voltage 40 is used by the comparator 41 to separate only a component corresponding to an echo whose voltage is higher than others among reflection (echo) from the target, sea surface reflection, and white noise included in the video signal. Is the reference voltage. After separating the echo components, the comparator 41 binarizes the presence / absence of the echo into “H” and “L” with respect to the time axis and outputs the result. The TX trigger 42 is a transmission start timing signal, and is a pulse signal serving as a reference for calculating the distance from the radar to the target. The oscillator 43 outputs a generation timing of a gate pulse and a basic clock for quantifying an echo amount. The gate generation unit 44 generates a gate pulse that allows only an echo in a distance range to be subjected to STC adjustment to pass, by counting the clocks from the TX trigger 42 and the oscillator 43. Normally, the distance range targeted for STC adjustment is set to a range from distance 0 to a predetermined fixed distance. The echo signal separated and binarized by the comparator 41 is combined with the gate pulse by the combining unit 45 (logical product) and converted into an echo signal within a predetermined distance range. The gate generating unit 44 and the synthesizing unit 45 correspond to the effective component extracting unit 33 shown in FIG.

The digital one-shot 46 includes the oscillator 4
3 is a one-shot time counting pulse, and operates using an echo signal input from the synthesizing unit 45 as a trigger, and corresponds to the land component removing unit 34 in FIG. The digital one-shot 46 does not output when the length of the input echo signal is shorter than the length determined by the predetermined time constant, and outputs the digital one-shot 46 when the input echo signal continues for a certain time or more, that is, for a certain length or more. , The output is set to “H” for a time exceeding the portion corresponding to the time constant. Counter 47
Is an 8-bit counter that operates using a clock from the oscillator 43 as a counting pulse. The counter 47 receives both an echo component and a signal determined as land from the digital one-shot 46. Here, when only an echo component is input, a 100% counting operation is performed assuming that an echo other than the land is input, but both the echo component and the output of the digital one-shot 46 (land component) are input. If this is the case, this period is counted as a part of the land area by decimating the number of clocks. Thus, the number of clocks counted by the counter 47 is represented as an echo amount. This counter 47 corresponds to the echo amount quantifying unit 35 in FIG.

The optimum value data latch 48 is constituted by an 8-bit latch, and stores an echo amount expressed when the echo amount is quantified by the above-described method when the STC adjustment is in an optimum state. The comparator 49 is an 8-bit data comparator, compares the actual echo converted into a numerical value with the optimum value, and outputs a signal indicating the magnitude relation. MPU50
Is an 8-bit microprocessor, which reads a magnitude-related signal output from the comparator 49 every time the above-described series of digitization and comparison operations performed at a constant cycle is completed, and performs STC adjustment according to the magnitude. A program for outputting a DAC control signal for increasing or decreasing the STC voltage in a direction approaching the optimum type is stored. The DAC 51 is a DA converter corresponding to an STC voltage generator, and adjusts and outputs the STC voltage according to a control signal from the MPU 50. DAC5
The STC voltage output from 1 is input to the STC circuit 30 and fed back to the STC adjustment.

The above-described series of operations are repeatedly performed at regular intervals (every 1 sweep to 30 sweeps). Therefore, the STC adjustment is always kept in the optimum state.

FIG. 6 is a time chart of the STC automatic adjusting section shown in FIG. The gate signal A generated by the gate generation unit 44 is set to the on state for a certain period of time from the antenna position at the distance 0, and when an echo component is input from the comparator 41 during this time, it passes through the synthesis unit 45 and passes through the effective echo. It becomes component B. If the effective echo component B includes a continuous echo that continues for a certain period of time or more, the continuous echo is regarded as being due to the land component, and the digital one-shot 46 outputs the signal E. The counter 47 reduces the frequency of the effective echo component B by 1 / during the period when the signal E is output.
The number of clocks (thinned out clocks) dropped to 4/3/4 is counted. As a result, the clock C of the oscillator 43 is counted for an echo portion other than the land as shown in FIG. The clock C 'dropped to 4 is counted. That is, for the land area, the clock C is thinned out and counted.

The function of the digital one-shot 46 will be described with reference to FIG. FIG. 7 is a diagram showing the effect of the STC on the display when there is land. If there is no digital one shot 46,
Because the land exists as shown by S
The effect of TC becomes excessive. That is, the STC voltage increases. Therefore, if there is a small target p near the land,
This p may be removed as sea surface reflection. However, if the digital one-shot 46 is provided, the count of the land area is reduced as described above.
Of the small target p can be prevented from being removed as STC as shown in FIG. Note that “a” in the figure shows a manual STC in the conventional device (in the manual STC, the effect of the STC is uniform in all directions).

FIG. 8 is a diagram showing the operation of this embodiment when there is a strong wind. When there is a strong wind, as shown in FIG. 8A, the sea surface reflection of the radar wave in the case of a head wind becomes strong. However, if the effect of the STC is automated as in this embodiment,
As shown in FIG. 8B, the effect of the STC becomes stronger in the direction of the head wind. FIG. 3A shows a manual STC in the conventional apparatus. However, if the STC is set to the size of FIG. 4A in order to eliminate sea surface reflection b by the manual STC, the small target p is removed. However, when the effect of the STC is automated as in the present embodiment, the STC is changed to c, and the influence of the wind is removed, and the optimum STC adjustment is performed.

Since the above operation is performed every one to thirty sweeps, extremely fine STC adjustment can be expected. Also, by changing the optimum values 6 and 36 shown in FIGS. 1 and 4 to appropriate values in accordance with the setting of the radar transmission pulse width, the display distance range, and the like, automatic adjustment suitable for each operation situation becomes possible. .

[0050]

According to the present invention, since the video information effective for gain control, such as noise components and echo components, is quantified and the gain control of the radar reception signal is automatically performed, manual adjustment by the observer is performed. This makes it possible to always adjust and maintain the optimum video image in real time without being affected by the variation of each device and without being affected by changes in the weather or sea conditions.

Further, by performing the above-described control for each sweep, extremely fine control for each direction can be performed. Further, in the case of performing the STC automatic adjustment, since the land component removing unit for removing the land component from the effective signal component is provided, it is possible to prevent a small target near the land from being removed as sea surface reflection. .

Also, the automatic gain adjustment can be achieved simply by separating the echo component and the noise component from the output signal of the gain control unit, comparing the result with a reference value, and controlling the gain in the gain control unit in accordance with the result. At this time, by counting and quantifying the separated components, the accuracy of gain adjustment can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a receiving sensitivity automatic adjustment unit in a radar apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed block diagram of the reception sensitivity automatic adjustment unit.

FIG. 3 shows a timing chart of the reception sensitivity automatic adjustment unit.

FIG. 4 is a diagram illustrating a radar apparatus according to a second embodiment of the present invention;
FIG. 2 shows a block diagram of a TC automatic adjustment unit.

FIG. 5 is a detailed block diagram of the STC automatic adjustment unit.

FIG. 6 shows a timing chart of the STC automatic adjustment unit.

FIG. 7 is a diagram illustrating a function of a digital one-shot.

FIG. 8A is a diagram showing a reflection state of a radar wave by a wave in a strong wind, and FIG. 8B shows a digital one-shot function in a strong wind.

FIG. 9 shows a block diagram of a reception sensitivity adjustment unit of a conventional radar device.

FIG. 10 is a block diagram of a conventional radar apparatus when an STC circuit is used as a gain control unit for controlling the gain of a radar reception signal.
4 shows a TC adjustment unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-69286 (JP, A) JP-A-51-142291 (JP, A) JP-A-51-28792 (JP, A) 157385 (JP, A) JP-A-60-195470 (JP, A) JP-A-5-72319 (JP, A) JP-A-56-148676 (JP, U) JP-A-2-41183 (JP, U) Japanese Utility Model Application Hei 4-85184 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/95

Claims (3)

(57) [Claims] 1. The gain of a radar reception signal is suppressed as the distance becomes shorter.
That extraction and STC circuit, this and the effective signal component separating means for separating the effective signal component constant signal components exceeding the threshold from the output signal of the STC circuit, a signal component in a predetermined distance range from the effective signal component separated a gate means for, counting means for counting the extracted signal component is compared with the count value and the reference value, the ST according to the result
A gain control signal adjusting means for adjusting the gain of the C circuit, what the echo from the effective signal component continues for more than a predetermined length
A radar apparatus comprising: a land component removing unit that removes the land component . 2. The gain of a radar reception signal is suppressed as the distance decreases.
An effective signal component extracting means for extracting an effective signal component from the output signal of the STC circuit , comparing the extracted effective signal component with a reference value, and adjusting the gain of the STC circuit according to the result. Gain control signal adjusting means, and a means for controlling the effective signal component so that the echo continues for a certain length or more.
A radar apparatus comprising: a land component removing unit that removes the land component . 3. A GAIN for controlling a gain of a radar reception signal.
Circuit and the output signal of this GAIN circuit
Signal component that separates the signal component
From the separation means and the separated effective signal component,
Of a section that is at least a predetermined distance from the antenna position
Gate means for extracting the noise component; counting means for counting the extracted noise component; comparing the counted value with a reference value;
A radar device comprising: a gain control signal adjusting unit that adjusts a gain of an IN circuit .