JPH0371075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device that converts data in polar coordinate format obtained for each sweep into data in rectangular coordinate format and displays the data on a cathode ray tube.

[Technical Background of the Invention] Generally, in a radar device, a received signal obtained in synchronization with a transmission pulse sent out at regular intervals from a rotating antenna is displayed on a cathode ray tube as it is. However, it is difficult to display sweep data in polar coordinate format directly between Brownian intervals, so in recent years, with the aim of improving general-purpose performance and identification performance, the received signal input from the antenna is displayed at right angles corresponding to each measured position (r, θ). Store the received signal (detection information) in the address (X, Y) of the coordinate system once.
A radar device has been developed that displays images on a cathode ray tube by repeatedly reading them out at high speed.

In a radar device that converts and displays data into rectangular coordinates, for example, the data displayed on the display screen of the cathode ray tube 1 shown in FIG. Each unit area divided by a number of lines is defined as each measured position 2, and when a target object 3 is detected for each measured position 2 [1], when it is not detected. An image memory is provided to store the bit information as [0]. Therefore, for example, when the sweep line 4 exists at an angular position of θ with respect to the Y axis as shown in FIG. The coordinate position is indicated by the black circle ●. When a sweep start trigger signal is input at this point, the bits at each measured position 2 indicated by the black circles are set to [1] or [0] in order from the origin (0, 0). At the same time, this bit information is displayed on the display screen of the cathode ray tube 1.

Then, when the next sweep start trigger signal is input when the sweep line 4 reaches the angular position of (θ + Δθ), the bit of each measured position 2 indicated by the triangle mark Δ corresponding to the sweep line 4 of (θ + Δθ) becomes the origin. From then on, it is sequentially set to [1] or [0]. The bit information set at the same time is displayed on the display screen of the cathode ray tube 1. In this way, when the sweep line 4 rotates 360 degrees in synchronization with the rotational speed (scanning speed) of the antenna, the data image shown in FIG. 4 is completed on the display screen of the cathode ray tube 1.

[Problems with Background Art] However, the radar device configured as described above has the following problems. That is, in order to accurately display a data image on the display screen of the cathode ray tube 1, it is necessary to shorten the sweep period for the sweep line 4 rotating at a constant speed.
If this sweep period is set short, as shown in FIG.
If the angle Δθ between them is small, these two sweep lines 4
This results in a shared measurement position 2. For example, in Figure 5, the black circle ●
The measured position 2 of , and the measured position 2 of the next swept triangular mark Δ are coordinates (0, 0), (1, 0), (3,
1), (4, 1), (5, 1), and (8, 2) overlap.

Generally, when bit information set at each measured position 2 in the image memory is displayed in a corresponding area on the display screen of the cathode ray tube 1, the bit information already displayed in the corresponding area is cleared and new bit information is displayed. Display. Therefore, if there is a measured position 2 shared by adjacent sweep lines 4 as shown in FIG. 5, the black circle obtained by sweeping at the angular position θ
Of the bit information, the bit information corresponding to the shared measured position 2 is the next angular position (θ+Δθ).
It is replaced with the bit information of the triangular mark Δ obtained by sweeping.

Therefore, even if bit information [1] due to a small target object 3 is stored in the corresponding measured position 2 of the image memory at the measured position 2 that is shared during the sweep at the angular position θ, this target object 3 If it is smaller, if the aforementioned target object 3 cannot be confirmed at the same shared measured position 2 when sweeping at the next angular position (θ + Δθ), the bit information corresponding to this measured position 2 indicates that the target object 3 does not exist. Replaced with [0] indicating .

As a result, on the display screen of the cathode ray tube 1, the data image corresponding to the aforementioned small target object 3 appears only momentarily during the sweep period and immediately disappears. In this way, in a conventional radar device that converts to a rectangular coordinate screen and displays it, the smaller the target object 3 becomes at the center of the radar, the smaller the target object 3 is not displayed. There was a problem where the performance decreased.

[Effects of the Invention] The present invention has been made based on the above circumstances, and its purpose is to Even if the target object is not confirmed at the corresponding measured position during the sweep, by displaying the above data as is on the CRT, even a small target object can be reliably displayed on the CRT display screen. The object of the present invention is to provide a radar device capable of improving the data image display function.

[Summary of the Invention] The present invention is capable of detecting a target object in a polar coordinate system (r, θ) by sampling and sweeping a received signal obtained in synchronization with a transmission signal sent out every predetermined period in synchronization with a transmission signal. The number of differential pulse signals (ΔX ₀ , ΔDY ₀ ) that corresponds to the radar device main body that obtains data D ₀ and the polar coordinate system target data obtained by this radar device main body to the rectangular coordinate system (X, Y). A coordinate conversion unit converts target data in a polar coordinate system into a rectangular coordinate system for each sweep by counting, and the target data is transferred to an address corresponding to the rectangular coordinates obtained by the coordinate conversion unit for each sweep. Image memory to store,
In a radar apparatus having a display device that displays the output from the image memory, a first delay memory that delays the differential pulse signal train from the coordinate transformation section by one sweep time, and a display device that displays the output from the coordinate transformation section; The difference pulse signal train of and the difference pulse signal train of the previous sweep (ΔX _-1 , ΔY _-1 ) output from the first delay memory match only during the period in which the number of pulses of each difference pulse signal matches. a determination circuit that outputs a signal; a second delay memory that delays target data output from the radar device main body by one sweep time; D _-1 ) and the coincidence signal output from the determination circuit. An AND circuit outputs AND data of the coincidence signal output from the judgment circuit, and the AND circuit outputs the AND data of this AND circuit and the current target data (D ₀ ) and a logical sum circuit that sends the logical sum data of the image data as corrected target data to the image memory.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the entire radar system of the embodiment, and numeral 11 in the figure is a transmitter/receiver. Connected to this transmitter/receiver 11 is an antenna 13 that is rotated by a drive unit 12 such as a motor at a speed of, for example, 24 rpm. The transmitter/receiver 11 has an antenna 13
The antenna 13 receives the reflected wave from the target object and sends the received signal obtained by the sampling circuit 30 to the display unit ₁₄ as target object data (hereinafter referred to as data signal D0). .
Further, the rotation angle signal θ of the antenna 13 is sent from the drive unit 12 that rotates the antenna 13 to the coordinate conversion unit 15 in the display unit 14 . In addition, trigger circuit 1
For example, frequency 1500Hz to start sweeping from 6
The trigger signal Tr is sent to the transceiver 11, the coordinate conversion section 15 in the display section 14, and the correction circuit 17 to which the data signal _D0 from the transceiver 11 is input. The data signal D corrected by the correction circuit 17 is stored in each corresponding measurement position 2 of the image memory 18 as bit information of [1] or [0].
The bit information stored in the image memory 18 is then displayed on the display screen of the cathode ray tube 1.

Therefore, the antenna 1
3. The drive unit 12, the transceiver 11, the sampling circuit 30, and the trigger circuit 16 constitute the main body of the radar device.

The image memory 18 has the same configuration as the image memory shown in FIG. 5, and divides the data displayed on the display screen of the cathode ray tube 1 shown in FIG. 4 by a number of lines parallel to the X and Y axes. Each unit area divided by each equal line is defined as each measured position 2, and bit information of [1] when the target object 3 is detected and [0] when the target object 3 is not detected is stored for each measured position 2.

As shown in FIG. 3, the coordinate conversion section 15
The input angular position θ of the antenna 13, that is,
Pulse signals ΔX ₀ and ΔY ₀ having a pulse interval corresponding to the angular position θ of the sweep line 4 in FIG. 5 are sent to the correction circuit 17. The pulse intervals of these pulse signals ΔX ₀ and ΔY ₀ are stored in a ROM or the like in correspondence with each angular position θ, and each time a pulse is input, the X coordinate and Y coordinate of the image memory increase by one. Therefore, each pulse signal ΔX ₀ from the trigger signal Tr input time,
Coordinates (X, Y) where the count value of each pulse of ΔY ₀ corresponds to the target data at that time, that is, the data signal D ₀
will be shown.

The correction circuit 17 is constructed as shown in FIG. That is, the data signal D ₀ sent out from the transceiver 11 is input to one input terminal of the OR circuit 19, and is also input to the second delay memory circuit 20b in the delay memory circuit 20. First delay memory circuit 20 in delay memory circuit 20
The pulse signals ΔX ₀ and ΔY ₀ sent out from the coordinate conversion section 15 and the trigger signal Tr from the trigger circuit 16 are input to a. This delay memory circuit 2
0 is the input data signal D ₀ , pulse signal ΔX ₀ ,
ΔY ₀ for one sweep interval, that is, the next trigger signal
This circuit stores information up to the Tr input time. Therefore, data signal D ₀ , pulse signal ΔX ₀ , ΔY ₀
Data signal D- ₁ , pulse signals ΔX- ₁ and ΔY- ₁ stored one sweep ago are output in synchronization with the input time of . The data signal D- ₁ of the previous sweep output from the delay memory circuit 20 is input to one input terminal of the AND circuit 21, and each pulse signal ΔX- ₁ ,
ΔY− ₁ is input to counters 23 and 24 in the determination circuit 22, respectively.

The pulse signals ΔX ₀ and ΔY ₀ sent out from the coordinate conversion section 15 are input to the delay memory circuit 20 and are also input to the counters 25 and 26 of the determination circuit 22 . In addition, each counter 23, 25, 24,
A trigger signal Tr from the trigger circuit 16 is input to the reset terminal 26.

The output signals of counter 23 and counter 25 are input to comparison circuit 27. This comparison circuit 27 stores the image memory 1 counted by each counter 23, 25.
It is determined whether the respective count values X _-1 and X ₀ indicating the X coordinate value of 8 match or not, and if they match, an H level signal is sent to one input terminal of the AND circuit 28 . Similarly, the image memory 18 of the counters 24 and 26
The count values Y _-1 and _Y0 indicating the Y coordinate value of are input to the comparator circuit 29, and from the comparator circuit 29, Y- ₁ = _Y0
At this time, an H level signal is sent to the other input terminal of the AND circuit 28. The output signal C of the AND circuit 28 is input to the other input terminal of the AND circuit 21 to which the data signal D- ₁ is input, and the output signal of the AND circuit 21 is input to the other input terminal of the OR circuit 19. is input to. And this OR circuit 19
The output signal is sent to the image memory 18 as the corrected data signal D.

The operation of the radar device configured in this way is explained in the third section.
This will be explained using the time chart shown in the figure. That is, at the angular position θ of the sweep line 4, the trigger signal Tr
When the data signal D- ₁ and pulse signals ΔX- ₁ and ΔY- ₁ for one sweep are stored in the delay memory circuit 20, the angular position of the sweep line 4 at the next sweep start time _t0 is ( θ+Δθ), the data signal D ₀ , pulse signals ΔX ₀ , ΔY ₀ as shown in the figure are output to the OR circuit 19 of the correction circuit 17, the counter 25,
26. At the same time, the data signal D- ₁ , pulse signals ΔX- ₁ and ΔY- ₁ of the angular position θ of the sweep line 4 one sweep before, outputted from the delay memory circuit 20, are input to the AND circuit 21 and counters 23 and 24. At the same time, each counter 23, 25, 24, 26
starts counting the number of pulses of each input pulse signal.

Each of the comparison circuits 27 and 29 sends an H level signal to the AND circuit 28 when the respective count values X- ₁ , _X0 and Y- ₁ , _Y0 respectively match. Therefore, the output signal C of the AND circuit 28
(coincidence signal) maintains the H level when X- ₁ = _X0 and Y- ₁ = _Y0 , that is, during the period when the measured position 2 due to the sweep of (θ + Δθ) and the sweep of θ match, It changes to L level at time _t1 when X- ₁ ≠ _X0 . Then, at t ₂ when X _-1 =X ₀ , it becomes H level again.

Therefore, the data signal D- ₁ of one sweep ago of the angular position θ outputted from the delay memory circuit 20 passes through the AND circuit 21 only during the period when the output signal C is at the H level, and is input to the OR circuit 19 to calculate the angle. It is logically added to the sweep data signal D ₀ of (θ+Δθ).
As a result, the output data signal D of the OR circuit 19 is a data signal only during the period when the output signal C is at H level.
It becomes a signal of corrected target data obtained by ORing the data signal D- ₁ with _D0 .

With the radar device configured in this way, the presence of a small target object 3 is indicated in the data signal D- ₁ by sweeping θ at the shared measurement position 2 from time t ₀ to time t ₁ [H] level data
Even if P ₁ and P ₂ occur and no data from the same target object 3 is generated in the data signal D ₀ by sweeping (θ + Δθ), the corrected data signal D output from the OR circuit 19 has the following values as shown in the figure. Data shown with diagonal lines
Q ₁ and Q ₂ will occur. Then, the corrected data signal D output from the correction circuit 17 is input to the image memory 18 as a data signal of the angular position (θ + Δθ), and each measured position 2 displayed in rectangular coordinates is set to [1] or [0 ] bit information is stored and displayed on the display screen of the cathode ray tube 1.

As a result, once the data image corresponding to the small target object 3 is displayed on the display screen of the cathode ray tube 1, even if the measured position 2 of this small target object 3 is shared with the measured position 2 of the next sweep. , even if the data of the small target object 3 does not exist in the data signal from the next sweep, the data image will not be erased. Therefore,
The display function of data images displayed on the display screen of the cathode ray tube 1 can be improved.

Note that in this embodiment, descriptions of the sampling circuit and the clocks of each logic circuit are omitted.

[Effects of the Invention] As explained above, according to the present invention, if data indicating the presence of a target object is set at a measured position shared between adjacent sweep lines, even if the data indicating the presence of a target object is Even if the target object is not confirmed at the measurement position, the above data is displayed as is on the cathode ray tube. Therefore, even a small target object can be reliably displayed on the display screen of the cathode ray tube, the display function of the data display image can be improved, and the performance of the entire radar device can be improved.

Furthermore, in the process of writing target object data from the radar device main body to the image memory for each sweep cycle, it is determined whether target object data from one sweep ago exists at the same measurement position, and the current target data is It has been corrected. Therefore, target data can be corrected even with a small storage capacity.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a correction circuit of the display section of a radar device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the entire radar device, and Fig. 3 shows the operation of the radar device. FIG. 4 is a time chart showing the display screen of the cathode ray tube of the rotator device, and FIG. 5 is a diagram showing the image memory. 1... Braun tube (display), 2... Measured position, 3... Target object (target), 4... Sweep line, 1
DESCRIPTION OF SYMBOLS 1... Transmitter/receiver, 12... Drive section, 13... Antenna, 14... Display section, 15... Coordinate conversion section, 1
6...Trigger circuit, 17...Correction circuit, 18...
Image memory, 19... OR circuit, 20... Delay memory circuit, 21, 28... AND circuit, 22...
...determination circuit, 23, 24, 25, 26...counter, 27, 29...comparison circuit, 30...sampling circuit (device for obtaining target data).

Claims (1)

[Claims] 1. A radar device that obtains target object data D ₀ in a polar coordinate system by sampling and sweeping a reception signal obtained in synchronization with a transmission signal sent out every predetermined period in synchronization with the transmission signal. Difference pulse signal (ΔX ₀ , ΔY ₀ ) that corresponds to the polar coordinate system target object data obtained by the main body of the radar device and the rectangular coordinate system
a coordinate conversion section 15 that converts the target data in the polar coordinate system into a rectangular coordinate system for each sweep by counting the number of objects; and an address corresponding to the rectangular coordinates obtained by the coordinate conversion section for each sweep; In a radar device having an image memory 18 for storing the target object data, and a display 1 for displaying the output from the image memory, the differential pulse signal train from the coordinate transformation section is delayed by one sweep time. 1 delay memory 20a,
The current difference pulse (ΔX ₀ , ΔY ₀ ) signal train outputted from the coordinate conversion unit and the difference pulse (ΔX −1 , ΔX −1 , ΔX −1 , ΔX −1 , ΔX ₋₁ ,
A determination circuit 22 that outputs a coincidence signal C only during a period in which the number of pulses of each differential pulse signal of the ΔY _-1 signal train matches each other, and a determination circuit 22 that outputs a coincidence signal C only during a period when the number of pulses of each difference pulse signal of the ΔY -1 signal train matches each other, and a determination circuit 22 that delays target data output from the radar device main body by one sweep time. a second delay memory 20b that outputs logical product data of the target object data (D _-1 ) from one sweep ago outputted from the second delay memory and the coincidence signal outputted from the determination circuit; A logical sum of the logical product data of the logical product circuit 21 and the current target object data (D ₀ ) outputted from the radar device main body is sent to the image memory as modified target data. A radar device comprising a circuit 19.