JP2857681B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a radar apparatus, and more particularly, to a means for performing timing adjustment so that a received signal can be taken from a point whose distance from an antenna is equal to zero as a base point. Regarding improvement.

<Conventional Technology> In general, a radar apparatus emits a microwave detection radio wave from an antenna and receives a reflected wave from a target again by the antenna. Then, the received signal from the antenna is digitized and stored in a memory as image data.
By outputting to a display such as T, image information on the target is obtained.

In such a radar apparatus, in order to obtain an image having no distortion in the distance direction, it is necessary to capture and display a received signal with a base point where the distance from the antenna is equal to zero as a base point.

Here, if the reception signal is started immediately in response to the transmission trigger pulse that simply determines the timing of launching the detection radio wave, the reception signal must be received starting from a point where the distance from the antenna is equal to zero. do not become. This is because there is a certain delay from the output of the transmission trigger pulse to the reception of a reception signal starting from a point where the distance from the antenna is equivalent to zero. The causes include a propagation delay of a cable connecting the transmission trigger pulse generation unit and the transmission / reception unit, a delay in a circuit of the transmission / reception unit, and the like.

As described above, the amount of delay from the output of the transmission trigger pulse to the reception of a received signal based on the position where the distance from the antenna is equal to zero differs depending on the length of the cable, the characteristics of the transmission / reception unit, and the like. It will be. If the received signal obtained by the antenna is displayed as it is while ignoring such a delay, the image is distorted in the distance direction, and the distance recognition based on the radar information is erroneously recognized, which is dangerous.

Therefore, in the related art, when the radar device is mounted on a ship or the like, the timing is adjusted so that the received signal data can be taken from a position where the distance from the antenna is equal to zero as a base point.

As shown in FIG. 6, a delay adjustment circuit c is provided between a transmission trigger pulse generator a for generating a transmission trigger pulse and a sampling circuit b for digitizing a received signal at a predetermined sampling period. So that the transmission trigger pulse is supplied as a start pulse for starting sampling to the sampling circuit b via the delay amount adjusting circuit c.
The above-described transmission trigger pulse is transmitted by the delay amount adjusting circuit c so that the detection radio wave is emitted to the test target placed at a fixed distance from the antenna and the image based on the detection radio wave is not generated. The amount of delay for is manually adjusted.

<Problems to be Solved by the Invention> As described above, in the conventional radar device, when the radar device is newly installed on a ship or the like, when the cable length is changed, or when the circuit component of the transmission / reception unit is replaced. Each time
It was necessary to adjust the timing so that the received signal could be taken starting from a location where the distance from the antenna was equal to zero. For this reason, the adjustment operation has become extremely complicated.

<Means for Solving the Problems> The present invention has been made in view of such circumstances, and has an automatic timing so that a received signal can be taken in from a position where a distance from an antenna is equal to zero as a base point. This is to make adjustments.

Since an antenna used for a radar device usually shares transmission and reception, a circulator that changes a signal flow between transmission and reception is provided between the transmission / reception unit and the antenna. In this circulator, a part of the transmission radio wave goes directly to the receiving circuit side before being emitted from the antenna. Since this signal (so-called main bank) does not go out of the antenna, it is a signal whose distance from the antenna is equivalent to zero.

Therefore, if the main bank is detected and the received signal from the antenna is taken in with this signal as a base point, there will always be no error in the timing of taking in the received signal.

The present invention has been made in view of such a fact, and in order to solve the above-described problem, a transmission trigger pulse generation unit 1 that generates a transmission trigger pulse that determines a timing of emitting a detection radio wave from an antenna, A sampling circuit 2 which digitizes a reception signal obtained by receiving a reflected wave from a target of a detection radio wave by an antenna at a predetermined sampling period and captures the signal, and a plurality of beams of reception signal data sampled by the sampling circuit 2 A buffer memory 8 for temporarily storing, an image memory 10 for storing received signal data transferred from the buffer memory 8 as image data, and an address for generating an address signal for writing / reading image data to / from the image memory 10 A generating circuit 12 and a CR for displaying an image of the image data read from the image memory 10; The following configuration is adopted in a radar apparatus provided with a display 16 such as T.

That is, in the first invention, the transmission trigger pulse generator 1 is configured such that the output cycle of the transmission trigger pulse is different for each transmission trigger pulse.
An A / D converter 20 for digitizing a reception signal obtained by an antenna in a predetermined sampling period in response to a transmission trigger pulse from the transmission trigger pulse generator 1, and an A / D converter
A main bank detection memory 22 for storing a plurality of beams of received signal data digitized in 20, and a sweep correlation relating to the plurality of beams stored in the main bank detection memory 22 is included in the received signal data. A main bank detecting circuit 24 for detecting a main bank, and a start pulse generating unit 26 for outputting a start pulse for starting sampling to the sampling circuit 2 in response to the main bank detected by the main bank detecting circuit 24. Have.

In the second invention, the transmission trigger pulse generator 1
Is configured such that the output cycle of the transmission trigger pulse is different for each transmission trigger pulse, and
The transmission trigger pulse from the transmission trigger pulse generating unit 1 is given to the sampling circuit 2 as a start pulse for starting sampling, and a sweep correlation is performed on the reception signal data for a plurality of beams stored in the buffer memory 8. A main bank detection circuit 24 for detecting a main bank included in the received signal data, and a start pulse for generating a write address to the address generation circuit 12 in response to the main bank detected by the main bank detection circuit 24 Start pulse generator 26
And

<Operation> In the configuration according to the first aspect of the invention, the transmission trigger pulse is output from the transmission trigger pulse generation unit 1, and at the same time, the reception signal is digitized in response to the transmission trigger pulse, and the main bank detection memory 22 is output. Is stored in The main bank detection circuit 24 detects a main bank included in the received signal data by performing a sweep correlation on the received signal data for a plurality of beams. Here, since the output cycle of the transmission trigger pulse output from the transmission trigger pulse generation unit 1 is set to be different for each transmission trigger pulse, a so-called secondary echo of the detection radio wave reflected by the same target is used. Are different from each other in time, and the correlation of the secondary echo is removed. On the other hand, the time from the output timing of the transmission trigger pulse until the main bank is obtained is constant irrespective of the change in the output cycle of the transmission trigger pulse, so that the main banks are correlated. When the main bank is detected in this way, the start pulse generator 26 outputs a start pulse for starting sampling to the sampling circuit 2 in response to this, so that the sampling circuit 2 Start sampling data.

On the other hand, in the configuration according to the second invention, the transmission trigger pulse is output from the transmission trigger pulse
In response to the transmission trigger pulse, the received signal is sampled by the sampling circuit 2 and stored in the buffer memory 8. The main bank is a strong signal included in the received signal immediately after the transmission trigger pulse is output,
It can be clearly distinguished from other strong signals. Therefore, the main bank detection circuit 24 detects a main bank included in the received signal data by performing a sweep correlation on the received signal data for a plurality of beams. And
If the main bank is detected, the start pulse generator 26
Outputs a start pulse for generating a write address to the address generating circuit 12 in response to this, so that the received signal data stored in the buffer memory 8 is written to the image memory 10 from that point.

Thus, in both the first and second inventions,
Since the main bank is detected and the received signal data from the antenna is stored in the image memory 10 using the signal of the main bank as a base point, an image based on the received signal data from a location where the distance from the antenna is equal to zero is always obtained. Can be displayed. For this reason, since no image distortion occurs in the distance direction, erroneous distance recognition based on the radar information is avoided.

Embodiment 1 Embodiment 1 FIG. 1 is a block diagram of a radar apparatus according to an embodiment of the first invention.

In FIG. 1, reference numeral 1 denotes a transmission trigger pulse generator that generates a transmission trigger pulse that determines the timing of emitting a detection radio wave from an antenna (not shown). Are different for each transmission trigger pulse, that is, the transmission trigger pulse has jitter. Reference numeral 2 denotes a sampling circuit which digitizes a reception signal obtained by receiving a reflected wave from the target of the detection radio wave by the antenna at a predetermined sampling period and takes in the signal. In this example, the A / D converter 4 and the coding circuit are used. 6 The encoding circuit 6 compresses, for example, 8-bit received signal data into 3-bit data in order to reduce the data storage capacity of the image memory 10 described later. Reference numeral 8 denotes a buffer memory for temporarily storing a plurality of beams (for example, three beams) of the received signal data sampled by the sampling circuit 2, and is provided for adjusting a writing speed of the received signal data to the image memory 10. I have. The buffer memory 8 transfers the already stored latest received signal data for one beam to the image memory 10 at the next stage until the received signal data for one beam is newly stored. It has become so. Reference numeral 10 denotes an image memory that stores received signal data transferred from the buffer memory 8 as image data, 12 denotes an address generation circuit that generates an address signal for writing / reading image data to / from the image memory 10, and 14 denotes a read signal from the image memory 10. A D / A converter 16 converts the output image data into an analog signal. Reference numeral 16 denotes a display such as a CRT for displaying an image signal passing through the D / A converter 14.

Reference numeral 20 denotes an A / D converter that digitizes a received signal at a predetermined sampling period in response to a transmission trigger pulse from the transmission trigger pulse generator 1. Reference numeral 22 denotes a plurality of beams that have been digitized by the A / D converter 20. A main bank detection memory for storing (for example, three beams) reception signal data,
Each time the received signal data for the beam is newly stored,
The oldest received signal data already stored is rewritten by this data. Reference numeral 24 denotes a main bank detection circuit for detecting a main bank included in the received signal data by performing a sweep correlation for a plurality of beams stored in the main bank detection memory 22. Reference numeral 26 denotes a main bank detected by the main bank detection circuit 24. And outputs a start pulse for starting sampling to the sampling circuit 2 in response to the start pulse.

Next, the operation of the radar device having the above configuration will be described with reference to a timing chart shown in FIG.

An antenna (not shown) is swivel-scanned at a constant period, and a transmission trigger pulse that determines the timing of the detection radio wave emission is repeatedly output from the transmission trigger pulse generator 1 during each swivel scan (see FIG. 2 (a)). ). In this case, the output cycle Ti of the transmission trigger pulse is different for each transmission trigger pulse. And this transmission trigger pulse is A / D
Since the signal is applied to the converter 20 as a start pulse for starting A / D conversion, the A / D converter 20 digitizes the received signal over a certain period in response to this signal (see FIG. 2 (b)). . Then, the received signal is stored in the main bank detection memory 22.

When the reception signal data for a plurality of beams (for example, three beams) is stored in the main bank detection memory 22 (the second beam).
(See (c) to (e) of FIG.), The main bank detection circuit 24
The main bank included in the received signal data is detected by performing a sweep correlation on the received signal data for a plurality of beams. That is, since the output cycle of the transmission trigger pulse output from the transmission trigger pulse generator 1 is set to be different for each transmission trigger pulse, a so-called secondary echo of the detection radio wave reflected on the same target ( (Indicated by symbols x _{1 to} x ₃ in the figure), the temporal arrival positions are different from each other, and the correlation of the secondary echo is excluded. On the other hand, the output timing of the transmission trigger pulse is used as a base point. Main bank (reference symbols y _{1 to} y _{3 in the} figure)
The time t ₀ until the edge (indicated by) is obtained is constant regardless of the change in the output cycle Ti of each transmission trigger pulse.
y _{1 to} y ₃ are correlated. Therefore, by taking the sweep correlation, the main bank included in the received signal data can be detected (see FIG. 2 (f)). However, the first edge after the transmission trigger pulse shown in FIG.

When the main bank is detected in this manner, the start pulse generator 26 outputs a start pulse for starting sampling to the sampling circuit 2 in response to the detection (see FIG. 2 (g)). In response to this start pulse, the A / D converter 4 starts A / D conversion on the received signal (see FIG. 2 (h)). Therefore, the start timing of the A / D conversion is a point where the distance of the detection radio wave from the antenna is equivalent to zero. The A / D-converted received signal data (see FIG. 2 (i)) is coded by a coding circuit 6 in the next stage and stored in the buffer memory 8. The latest reception signal data for one beam stored in the buffer memory 8 is transferred to the image memory 10 as image data until reception signal data corresponding to the next one beam is newly input. You. The image data stored in the image memory 10 is read out in synchronization with the TV scan, converted into an analog signal by the D / A converter 14, and then output to the display 16 for image display.

The received signal may include a swept false image.
A swept false image is a phenomenon in which a reflected wave for a certain transmitted wave appears not in its sampling period but in the next sampling period.It is a kind of false image, and this may cause the detection of the main bank to be erroneous. Consider that. That is, in the main bank detection circuit 24, the reception signal data for a plurality of beams (FIGS.
See (c)), simply examine the sweep correlation by taking these and, if they have a temporal width of the extent to which the second sweep artifact x ₁ ~x ₃ included in each received signal data is present May not sufficiently remove the second swept false image, as shown in FIG. 3 (d). To avoid this inconvenience, the edge position of the received signal data (falling edge in this example)
Is preferably detected. In this case, since the edge position of the second swept false image is different, the second swept false image can be more reliably removed as shown in FIG.

Second Embodiment FIG. 4 is a block diagram of a radar apparatus according to a second embodiment of the present invention, and portions corresponding to the first embodiment are denoted by the same reference numerals.

In this embodiment, the transmission trigger pulse generator 1 is configured such that the output cycle of the transmission trigger pulse is different for each transmission trigger pulse, and the transmission trigger pulse is supplied to the sampling circuit 2 to start sampling. It is provided as a pulse. Further, the main bank detection circuit 24 is configured to take a sweep correlation with respect to a plurality of beams of received signal data stored in the buffer memory 8.
The start pulse generation unit 26 responds to the main bank detected by the main bank detection circuit 24 to
Is different from that of the first embodiment in that a start pulse for generating a write address is output to the first embodiment. Other configurations are the same as those in the first embodiment.

According to the above configuration, compared with the first embodiment, the A / D converter 2
0 and the main bank detection memory 22 can be omitted, and there is an advantage that the circuit configuration can be further simplified.

Next, the operation of the radar apparatus shown in FIG. 4 will be described with reference to a timing chart shown in FIG.

In this embodiment, when a transmission trigger pulse is output from the transmission trigger pulse generator 1 (see FIG. 5A), this transmission trigger pulse is transmitted to the A / D converter 4 of the sampling circuit 2 by an A / D converter. The A / D converter 4 digitizes the received signal for a certain period in response to the signal as a start pulse for starting the D conversion (see FIG. 5B). That is, sampling of the received signal data is started simultaneously with the output timing of the transmission trigger pulse (see FIG. 5 (c)).

The received signal data captured by the sampling circuit 2 is stored in the buffer memory 8. The received signal data for a plurality of beams (for example, three beams) stored in the buffer memory 8 is sent to the main bank detection circuit 24. The main bank detection circuit 24 detects a main bank included in the received signal data by taking a sweep correlation with respect to the received signal data for a plurality of beams (see FIG. 5 (d)). When the main bank is detected, the start pulse generator 26 responds to this by
, A start pulse for generating a write address is output (see FIG. 5E).

On the other hand, the latest received signal data for one beam is read out from the buffer memory 8 until the next received signal data for one beam is newly stored, and is stored in the image memory 10.
Although the transfer is started, since the read initial write address from the address generating circuit 12 in the period t ₀ of the received signal data is not generated for (FIG. 5 (f)
See), of the received signal data read from the buffer memory 8, the data contained in the time period t ₀ from the output timing of the transmission trigger pulse until the main bank is detected is discarded and the distance from the antenna is zero Only the received signal data starting from the corresponding point is stored in the image memory 10 as image data (see FIG. 5 (g)).

As described above, in any of the inventions described in the first and second embodiments, the main bank is detected, and the received signal data from the antenna is stored in the image memory 10 based on the signal of the main bank. Therefore, it is possible to always display, as image information, received signal data from a location where the distance from the antenna is equal to zero.

In each of the above embodiments, when the main bank cannot be detected, a transmission failure has occurred in the magnetron, so that the reception signal data is not taken in at this time. That is, in the conventional radar apparatus, even when the transmission fails, the data fetch operation is performed regardless of the presence or absence of the transmission. If the transmission fails, there is no transmitted signal from the antenna, so there is no reflected signal from the target, so even if the device starts data sampling of the received signal, there is no signal, so No display appears on the CRT screen. That is, since data “0” is written in the image memory, the data already written in the image memory is thereby erased. As a result, if transmission fails when the antenna is located at an angle, data “0” is written in a straight line at a location corresponding to the angle in the image memory. If it is clearly displayed above, a dark straight line will be drawn for the target. In the present invention, such a problem can be effectively prevented, and the image quality can be improved.

<Effects of the Invention> According to the present invention, by detecting the main bank, the timing is automatically adjusted so that the received signal is displayed starting from a position where the distance from the antenna is equal to zero. Therefore, even when a radar device is newly installed on a ship or the like, or when a cable or a circuit component of a transmission / reception unit is replaced, timing adjustment as in the related art becomes unnecessary. As a result, excellent effects such as elimination of complicated timing adjustment operations are exhibited.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a block diagram of a radar apparatus according to the first embodiment, and FIGS. 2 and 3 are used to explain the operation of the apparatus shown in FIG. FIG. 4 is a block diagram of the radar apparatus according to the second embodiment, and FIG. 5 is a timing chart for explaining the operation of the apparatus shown in FIG. FIG. 6 is a block diagram including a circuit portion for timing adjustment of a conventional radar device. 1 ... a transmission trigger pulse generator, 2 ... a sampling circuit, 8 ... a buffer memory, 10 ... an image memory, 12 ...
Address generation circuit, 16 display unit, 20 A / D converter, 2
2 Main bank detection memory 24 Main bank detection circuit 26 Start pulse generator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (2)

(57) [Claims] A transmission trigger pulse generator for generating a transmission trigger pulse for determining a timing of emitting a detection radio wave from an antenna; and a reception obtained by receiving a reflection wave of the detection radio wave from a target by an antenna. A sampling circuit (2) for digitizing and capturing a signal at a predetermined sampling period, a buffer memory (8) for temporarily storing a plurality of beams of reception signal data sampled by the sampling circuit (2), and a buffer Memory (8)
An image memory (10) for storing received signal data transferred from the memory as image data, an address generation circuit (12) for generating an address signal for writing / reading image data to / from the image memory (10), (1
And a display (16) such as a CRT for displaying the image data read from (0) in the form of a CRT. While being configured so as to be different for each trigger pulse, a received signal obtained by the antenna is digitized at a predetermined sampling period in response to a transmission trigger pulse from the transmission trigger pulse generator (1). A / D converter (20)
And a main bank detection memory (22) for storing received signal data for a plurality of beams digitized by the A / D converter (20); and a plurality of data stored in the main bank detection memory (22). A main bank detection circuit (24) for detecting a main bank included in the received signal data by taking a sweep correlation with respect to the received signal data for the beam; and responding to the main bank detected by the main bank detection circuit (24). A start pulse generator (26) for outputting a start pulse for starting sampling to the sampling circuit (2). 2. A transmission trigger pulse generator (1) for generating a transmission trigger pulse for determining a timing of emitting a detection radio wave from an antenna, and a reception obtained by receiving a reflection wave of the detection radio wave from a target by an antenna. A sampling circuit (2) for digitizing and capturing a signal at a predetermined sampling period, a buffer memory (8) for temporarily storing a plurality of beams of reception signal data sampled by the sampling circuit (2), and a buffer Memory (8)
An image memory (10) for storing received signal data transferred from the memory as image data, an address generation circuit (12) for generating an address signal for writing / reading image data to / from the image memory (10), (1
And a display (16) such as a CRT for displaying the image data read from (0) in the form of a CRT. Each of the trigger pulses is configured to be different from each other, and the transmission trigger pulse from the transmission trigger pulse generator (1) is supplied to the sampling circuit (2) as a start pulse for starting sampling. A main bank detecting circuit (24) for detecting a main bank included in the received signal data by performing a sweep correlation with respect to the received signal data for a plurality of beams stored in the buffer memory (8); ) In response to the main bank detected in step (b), the start pulse of the write address generation to the address generation circuit (12). Radar apparatus, comprising a, a start pulse generator (26) for outputting.