JP2008286722A - Waveform generator and radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveform generator capable of generating a desired waveform such as triangular waveform of high linearity precision, without using a complicated generator. <P>SOLUTION: This waveform generator for generating the waveform rising up gradually from a low level L1, going down therefrom gradually when reaching a high level L2, and rising up gradually therefrom when reaching the low level L1, is equipped with a means for outputting a rising-up wave signal, a means for outputting a going-down wave signal having the waveform going down from a level higher than the high level L2 to the low level L1, and a means for outputting alternate-switchingly the rising-up wave signal and the going-down wave signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a waveform generation device and a radar device that generate a waveform, and more particularly to a waveform generation device and a radar device that generate a triangular wave used in a millimeter wave radar or the like.

FIG. 1 is a block diagram schematically showing a main part of a conventional triangular wave generator. In the figure, reference numeral 1 denotes a microcomputer. The microcomputer 1 includes a CPU 2, ROM 3, RAM 4, DA (digital
An analog) converter 5 and a DA port P are included. The triangular wave generator includes the microcomputer 1, the waveform converter 6, and the integrator 7.
The CPU 2 outputs a rectangular wave from the DA port P via the DA converter 5 according to the control program stored in the ROM 3, and the rectangular wave output from the DA port P is sent to the waveform converter 6. It is designed to be entered.

Further, the CPU 2 controls the waveform converter 6 in accordance with another control program stored in the ROM 3 so that the rectangular wave output from the DA port P is gradually changed from a certain low level as shown in the figure. When it rises and reaches a certain high level, it is converted into a stepped triangular wave that gradually falls from there.

The stepped triangular wave output from the waveform converter 6 is passed through the integrator 7.
The integrator 7 generates a highly linear (continuous) triangular wave by sequentially integrating the stepwise triangular wave input from the waveform converter 6. Therefore, a triangular wave with high linearity is output from the integrator 7.

By the way, in the above-described conventional triangular wave generator, the linearity of the generated triangular wave (
Linearity) accuracy depends on the waveform converter 6, the integrator 7, and the like. Further, the integrator 7 has a relatively large number of parts, and there is a problem that the apparatus becomes complicated. Also, if the device becomes complicated,
The cost is likely to be high.

Further, the waveform conversion of the rectangular wave is performed by the control of the CPU 2, but this waveform conversion is not simple and there is a problem that the waveform conversion control program becomes complicated.
A triangular wave with high linearity accuracy can be seen at the transition from ascending to descending, that is, near the highest point (
A1) in the figure is sharp at the time of transition from descending to rising, that is, near the lowest point (B1 in the figure). In order to generate such a triangular wave, even a stepped triangular wave output from the waveform converter 6
It is necessary to sharpen even when shifting from ascending to descending (A2 in the figure) and when shifting from descending to ascending (B2 in the figure). However, it is not easy to convert a rectangular wave into such a sharp triangular wave. This is one reason why the waveform conversion control program is complicated.

Moreover, as shown in FIG. 2, the following Patent Document 1 discloses a certain sawtooth wave signal (FIG. 2 (a)).
) To generate a triangular wave signal (FIG. 2 (d)) by chaining a non-inverted sawtooth signal (FIG. 2 (b)) that is not inverted and an inverted inverted saw wave signal (FIG. 2 (c)). The technology to do is disclosed. In this technique, the linearity accuracy of a triangular wave depends on a generation circuit that generates a sawtooth wave signal, a non-inverting circuit that does not invert the sawtooth signal, an inversion circuit that inverts the sawtooth signal, a chain circuit, and the like.

In other words, there are many circuits that depend on linearity accuracy. The more dependent circuits, the more difficult it is to ensure high linearity accuracy. For example, if the generation circuit is inaccurate and cannot be lowered immediately from a certain high level to a certain low level and then raised immediately thereafter, a highly accurate sawtooth signal is not generated.

However, it is never easy to generate an accurate sawtooth wave that descends from a certain high level to a certain low level instantaneously and then rises immediately thereafter. If a highly accurate sawtooth wave signal is not generated, a triangular wave with high linearity accuracy cannot be generated.
JP 9-172355 A

Means for solving the problems and their effects

The present invention has been made in view of the above problems, and provides a waveform generation apparatus and a radar apparatus that can generate a desired waveform such as a triangular wave with high linearity accuracy without using a complicated apparatus. It is aimed.

In order to achieve the above object, the waveform generator (1) according to the present invention gradually rises from the low level L1, gradually descends from reaching the high level L2, and gradually falls from there when reaching the low level L1. In a waveform generator for generating a rising waveform, an upstream output control means for outputting an upstream signal from an upstream output means having at least a waveform rising from a low level L1 to a high level L2, and at least from a high level L2 From the downlink output control means for outputting the downlink signal from the downlink output means having a waveform that falls to the low level L1, the uplink signal output from the uplink output means, and the downlink output means Switching control means for alternately switching and outputting the output downstream signal, and the upstream signal from at least the low level L1 It had one of a waveform rising above level L2, a waveform rising from a level lower than low level L1 to high level L2, and a waveform rising from a level lower than low level L1 to above high level L2. A waveform in which the downstream signal descends from at least the high level L2 beyond the low level L1, a waveform that descends from a level higher than the high level L2 to a low level L1, and a level higher than the high level L2 Is characterized by being a signal having any one of the waveforms descending beyond the low level L1.

According to the waveform generator (1), an upstream signal having a waveform that rises from at least a low level L1 to a high level L2, and a downstream signal that has a waveform that descends from at least a high level L2 to a low level L1. Are alternately switched and output, so that it is possible to generate a waveform that gradually rises from the low level L1, gradually falls when reaching the high level L2, and gradually rises therefrom when reaching the low level L1. .

The upstream signal has at least a waveform rising from the low level L1 to the high level L2, at least a waveform rising from a level lower than the low level L1 to a high level L2, and a level higher than the low level L1. The signal has one of the waveforms rising above the level L2.

If the upstream signal is a signal having a waveform that rises at least from the low level L1 to the high level L2, the shape near the high level L2 in the generated waveform can be easily made desired. On the other hand, if the upstream signal is a signal having a waveform that rises from at least a level lower than the low level L1 to a high level L2, the shape near the low level L1 in the generated waveform can be easily formed into a desired shape. be able to.

The downstream signal is a waveform that descends at least from the high level L2 to the low level L1, a waveform that descends from a level higher than the high level L2 to the low level L1, and a level that is higher than the high level L2. It is a signal having any one of the waveforms descending beyond the level L1.

If the downstream signal is a signal having a waveform that falls at least from the high level L2 to the low level L1, the shape near the low level L1 in the generated waveform can be easily made desired. On the other hand, if the downstream signal is a signal having a waveform descending from at least a level higher than the high level L2 to the low level L1, the shape near the high level L2 in the generated waveform can be easily formed into a desired shape. be able to. Therefore, a desired waveform such as a triangular wave with high linearity accuracy can be generated.

Further, it is not necessary to perform complicated control such as waveform conversion control for converting a rectangular wave into a triangular wave as in the conventional case. Also, the upstream signal is at least from the low level L1 to the high level L.
A signal having any one of a waveform rising above 2, a waveform rising at least from a level lower than the low level L1 to a high level L2, and a waveform rising from a level lower than the low level L1 to above the high level L2 Therefore, there is no need to make a signal that when it reaches the level L2 as in the prior art, it immediately falls to the level L1 and then rises immediately thereafter.

The downstream signal also has a waveform that descends from at least the high level L2 beyond the low level L1, a waveform that descends from the level higher than the high level L2 to the low level L1, and a level higher than the high level L2. Since it is sufficient to use a signal having any one of the waveforms that fall below the low level L1, it is necessary to make the signal instantaneously rise to the level L2 when reaching the level L1 and then fall immediately after reaching the level L1 as in the prior art. Absent. Therefore, the control can be simplified.

Further, the radar apparatus (1) according to the present invention gradually rises from the low level L1, and the high level L
In the radar apparatus provided with output means for outputting a transmission signal corresponding to a desired waveform that gradually descends from reaching the low level L1 when reaching the low level L1, at least from the low level L1 to the high level An upstream output control means for outputting an upstream signal from the upstream output means having a waveform rising to L2, and at least from a high level L2 to a low level L1
A down-wave output control means for outputting a down-wave signal from the down-wave output means, the up-wave signal output from the up-wave output means, and output from the down-wave output means. A switching control means for generating the desired waveform by alternately switching and outputting the downstream signal, and a waveform in which the upstream signal rises at least from the low level L1 to the high level L2 A signal having at least one of a waveform rising from a level lower than the low level L1 to a high level L2 and a waveform rising from a level lower than the low level L1 to beyond the high level L2, the downstream signal Is a waveform that descends at least from the high level L2 over the low level L1, at least descends from a level higher than the high level L2 to a low level L1 It is characterized in that it is that waveform, and a signal having one of the waveform that drops beyond the low level L1 from a level higher than the high level L2.

According to the radar apparatus (1), a desired waveform such as a triangular wave with high linearity accuracy can be generated without performing complicated control such as waveform conversion control for converting a rectangular wave into a triangular wave as in the prior art. Can do. Therefore, it is possible to output a transmission signal corresponding to a desired waveform with simple control.

Embodiments of a waveform generation device and a radar device according to the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram schematically showing a main part of the waveform generation device according to the embodiment (1). In the figure, 11 indicates a microcomputer. The microcomputer 11 is a CPU 12, a ROM 13, R
The AM 14, DA converters 15 and 16, DA ports P 1 and P 2, and a switching port P 3 are included, and a waveform generator is configured including the microcomputer 11, the switching unit 17, and the LPF (low-pass filter) 18. ing.

The CPU 12 performs a DA converter 15 in accordance with a control program stored in the ROM 13.
And a sawtooth wave having a waveform that rises from level L1 to level L2 and then to level L3 as shown in FIG. 4A from the DA converter 15 via the DA port P1. The signal W1 is output.

In addition, the CPU 12 performs DA control according to another control program stored in the ROM 13.
An instruction is issued to the converter 16, and the DA converter 16 through the DA port P2 is used as shown in FIG.
The sawtooth wave signal W2 having a waveform descending from the level L3 higher than the level L2 to the level L1 as shown in FIG.

Further, the CPU 12 controls the switching unit 17 by outputting a signal from the switching port P3 according to still another control program stored in the ROM 13, and the DA port P
1 and the sawtooth wave signal W1 output from the DA port P2.
2 are alternately switched at a predetermined timing and output. FIG. 4 (c)
It is the figure which showed the signal output from switching port P3.

When a high level signal is output from the switching port P3, the DA port P1
When the sawtooth wave signal W1 output from the switching port 17 is output from the switching unit 17, while the low level signal is output from the switching port P3, the sawtooth wave signal W2 output from the DA port P2 is output from the switching unit 17. Is output from. FIG. 4D shows the switching unit 17.
It is the figure which showed the signal output from.

The signal output from the switching unit 17 is passed through the LPF 18. LPF1
8 is configured to output the stepped triangular wave input from the switching unit 17 as a continuous (highly linear) triangular wave. The signal output from the switching unit 17 (that is, the signal output from the microcomputer 11) has a stepped shape, but the stepped shape is blunted by the LPF 18 to obtain a linear waveform. FIG. 4E shows a signal output from the LPF 18.
Note that the LPF 18 can remove noise generated when the sawtooth wave signal W1 output from the DA port P1 and the sawtooth wave signal W2 output from the DA port P2 are switched.

In addition, here, the LPF 18 is used to obtain a continuous triangular wave from the stepped triangular wave, but the method of obtaining a continuous triangular wave from the stepped triangular wave is not limited to this, and another implementation is possible. In the form, for example, an arbitrary filter other than the LPF may be used.

According to the waveform generating apparatus of the above embodiment (1), the sawtooth wave signal W1 having a waveform rising from at least level L1 to level L2, and the sawtooth wave having a waveform falling from at least level L2 to level L1. Since the signal W2 and the signal W2 are alternately switched at a predetermined timing, they are gradually increased from the level L1, and when reaching the level L2, gradually descending from there, and when reaching the level L1, a triangular wave gradually increasing from there is generated. can do.

The sawtooth wave signal W1 is a signal having a waveform that rises from the level L1 to the level L3 over the level L2, and the sawtooth wave signal W2 is a level L3 higher than the level L2.
Since it is a signal having a waveform that falls from level to level L1, the vicinity of the highest point (level L2) in the generated triangular wave can be easily pointed. Therefore, a waveform with high linearity accuracy can be generated.

Further, the CPU 12 does not need to perform complicated control such as waveform conversion control for converting a rectangular wave to a triangular wave as in the prior art, and the sawtooth wave signal W1 is instantaneously lowered from the level L2 to the level L1, and immediately thereafter. Since it is not necessary to make a signal such as rising, the control program can be simplified. Also, using LPF18 with relatively few parts,
Since the stepped triangular wave from the switching unit 17 is output as a continuous triangular wave, the apparatus can be simplified and the cost can be reduced.

Here, a signal having a waveform that rises from level L1 over level L2 to level L3 (sawtooth signal W1) and a signal that has a waveform that falls from level L3 higher than level L2 to level L1 ( However, in another embodiment, as shown in FIG. 5, the waveform rises from the level L0 lower than the level L1 to the level L2, as shown in FIG. A signal having a waveform (FIG. 5A) and a signal having a waveform falling from the level L2 over the level L1 to the level L0 (FIG. 5B) are alternately switched and output. good. As a result, a triangular wave (FIG. 5) is generated.
The vicinity of the level L1 in (c)) can be easily sharpened.

In yet another embodiment, as shown in FIG. 6, a signal (FIG. 6A) having a waveform that rises from level L4 lower than level L1 to level L5 over level L2; A signal (FIG. 6B) having a waveform that falls from level L5 higher than level L2 to level L4 over level L1 may be alternately switched and output. Thereby, it is possible to easily form a pointed shape in the vicinity of both the level L1 and the level L2 in the generated triangular wave (FIG. 6C).

Although only the case of generating a triangular wave has been described so far, the waveform generating device according to the present invention is not limited to the generation of a triangular wave, and gradually rises from level L1 and reaches level L2. When the wave gradually falls and reaches level L1, a waveform gradually rising from there, such as a sine wave or a trapezoidal wave, can be generated.

FIG. 7 is a block diagram schematically showing a main part of the waveform generation device according to the embodiment (2). The same components as those of the waveform generation device shown in FIG. 1 in the figure
Reference numeral 1a denotes a microcomputer, and the microcomputer 11a includes a main CPU 12a, ROM 13a, R
The AM 14, DA conversion circuits 21 and 22, DA ports P 1 and P 2, and a switching port P 3 are included, and a waveform generator is configured including the microcomputer 11 a, the switching unit 17, and the LPF 18.
The DA converter circuit 21 includes a DA converter 15 and a sub CPU 21a, and the DA converter circuit 22 includes a DA converter 16 and a sub CPU 22a.

The main CPU 12a determines the DA according to the control program stored in the ROM 13a.
An instruction is given to the sub CPU 21a of the conversion circuit 21, and the DA converter 15 outputs the DA port P.
1 through level L1 from level L1 to level L2 as shown in FIG.
A sawtooth wave signal W1 having a waveform rising to 3 is output.

In addition, the main CPU 12a issues an instruction to the sub CPU 22a of the DA conversion circuit 22 in accordance with another control program stored in the ROM 13a.
Through the A port P2, a sawtooth wave signal W2 having a waveform falling from the level L3 higher than the level L2 to the level L1 as shown in FIG. 4B is output.

Further, the main CPU 12a controls the switching unit 17 by outputting a signal from the switching port P3 according to still another control program stored in the ROM 13a, and D
The sawtooth wave signal W1 output from the A port P1 and the sawtooth wave signal W2 output from the DA port P2 are alternately switched and output at a predetermined timing.

According to the waveform generation apparatus according to the above embodiment (2), the main CPU 12a does not directly control the DA converters 15 and 16, but the DA converter 1 via the sub CPUs 21a and 22a.
Controls 5 and 16 are performed. That is, since the sub CPUs 21a and 22a directly control the DA converters 15 and 16, the processing load on the main CPU 12a can be reduced.

Further, only the case where two DA ports are provided and two types of waveform signals are output from the microcomputers 11 and 11a has been described so far. However, in another embodiment, the number of ports is increased and output from the microcomputer. The number of waveform signals may be increased, and two or more types of waveforms (for example, triangular waves) may be generated.

Triangular waves are sometimes used for millimeter wave radars. Millimeter wave radar can measure relative speed and distance to a target, and is widely used as a monitoring device for the distance between vehicles. If two or more types of triangular waves are used rather than one type, the measurement accuracy of the relative speed and distance to the target can be improved. Therefore, it is useful to increase the types of waveform signals output from the microcomputer.

Further, the case where a desired waveform such as a triangular wave is generated using the stepped waveform signals DA-converted by the DA converters 15 and 16 has been described so far, but is used for generating the desired waveform. Of course, the waveform signal is not limited to the one subjected to DA conversion, and it is needless to say that the desired waveform can be generated from the waveform signal similar to the above even if it is not DA converted.

FIG. 8 is a block diagram schematically showing the main part of the radar apparatus according to Embodiment (3). In the figure, reference numeral 30 denotes a radar apparatus. The radar apparatus 30 includes a microcomputer 31, a transmission / reception unit 41,
The switching unit 17 and the LPF 18 are included. The microcomputer 31 is a CPU 32, RO
M33, RAM 34, DA converters 15, 16, DA ports P1, P2, switching port P3,
An AD (analog-digital) converter 35 and an AD port P4 are included.

The transmitter / receiver 41 includes a voltage controlled oscillator (VCO) 42, an amplifier 43, a directional coupler 44, an amplifier 45, and a mixer 46. The voltage control oscillator 42 performs FM modulation on the modulation signal from the LPF 18 and outputs it as a transmission signal. The transmission signal output from the voltage control oscillator 42 is amplified by the amplifier 43 and sent to the directional coupler 44. Entered,
A part is distributed as a local oscillation signal by the directional coupler 44, and the rest is transmitted toward the target via the transmission antenna 51.
By receiving the reflected wave from the target, the reception signal output from the reception antenna 52 is amplified by the amplifier 45, frequency-converted by the local signal from the mixer 46, and the microcomputer 3.
1 AD converter 35.

The CPU 32 can perform the same control as the CPU 12 (FIG. 3) in accordance with the control program stored in the ROM 33, and can output a signal as shown in FIG. Yes. The signal output from the switching unit 17 is passed through the LPF 18, and a triangular wave with high linearity is output from the LPF 18 (FIG. 4 (
e)).
Further, the CPU 32 executes AD according to another control program stored in the ROM 33.
Based on the signal digitally converted by the converter 35, the distance to the target and the relative speed of the target are calculated.

FIG. 9 is a block diagram schematically showing main parts of the radar apparatus according to Embodiment (4). The same components as those in the radar apparatus shown in FIG. 30a in the figure
Indicates a radar apparatus, and the radar apparatus 30a includes a microcomputer 31a, a transmission / reception unit 41, a switching unit 17, and an LPF 18. The microcomputer 31a has a main CPU 32a,
The ROM 33a, the RAM 34, the DA conversion circuits 21 and 22, DA ports P1 and P2, a switching port P3, an AD converter 35, and an AD port P4 are configured.
The DA converter circuit 21 includes a DA converter 15 and a sub CPU 21a, and the DA converter circuit 32 includes a DA converter 16 and a sub CPU 32a.

The main CPU 32a performs the same control as the main CPU 12a (FIG. 7) according to the control program stored in the ROM 33a so that the switching unit 17 can output a signal as shown in FIG. It has become. The signal output from the switching unit 17 is L
A triangular wave with high linearity is output from the LPF 18 (FIG. 4E).
The main CPU 32a calculates the distance to the target and the relative speed of the target based on the signal digitally converted by the AD converter 35 in accordance with another control program stored in the ROM 33a. Yes.

It is the block diagram which showed schematically the principal part of the conventional triangular wave production | generation apparatus. It is explanatory drawing for demonstrating another conventional triangular wave generator, (a) is a waveform figure of a sawtooth wave signal, (b) is a waveform figure of a non-inverted sawtooth wave signal, (c) is inversion. It is a wave form diagram of a sawtooth wave signal, and (d) is a wave form diagram of a triangular wave signal. It is the block diagram which showed roughly the principal part of the waveform generation apparatus which concerns on embodiment (1) of this invention. It is explanatory drawing for demonstrating the waveform generation apparatus which concerns on embodiment (1), (a) is a waveform diagram of the sawtooth wave signal output from one DA port, (b) is the other DA FIG. 4 is a waveform diagram of a sawtooth wave signal output from a port, (c) is a waveform diagram of a signal output from a switching port, (d) is a waveform diagram of a signal output from a switching unit, (e ) Is a waveform diagram of a triangular wave signal output from the LPF. It is explanatory drawing for demonstrating the waveform generation apparatus which concerns on another embodiment, (a) is a waveform diagram of the sawtooth wave signal output from one DA port, (b) is the other DA port. FIG. 3C is a waveform diagram of a sawtooth wave signal output from FIG. 1, and FIG. 4C is a waveform diagram of a signal output from a switching unit. It is explanatory drawing for demonstrating the waveform generation apparatus which concerns on another embodiment, (a) is a waveform diagram of the sawtooth wave signal output from one DA port, (b) is the other DA It is a wave form diagram of the sawtooth wave signal output from a port, (c) is a wave form diagram of the signal output from a switching part. It is the block diagram which showed roughly the principal part of the waveform generation apparatus which concerns on embodiment (2). It is the block diagram which showed roughly the principal part of the radar apparatus which concerns on embodiment (3). It is the block diagram which showed roughly the principal part of the radar apparatus which concerns on embodiment (4).

Explanation of symbols

Microcomputer 11, 11a, 31, 31a
CPU 12, 32
Main CPU 12a, 32a
ROM 13, 13a, 33, 33a
RAM 14, 34
DA converter 15, 16
Switching unit 17
Low-pass filter 18
DA conversion circuit 21, 22
Sub CPU 21a, 22a
Radar device 30, 30a
DA port P1, P2
Switch port P3
AD port P4

Claims (3)

Ascending gradually from the low level L1, and when reaching the high level L2, gradually descending from there,
In the waveform generation device that generates a waveform that gradually increases from the low level L1,
An upstream output control means for outputting an upstream signal from an upstream output means having a waveform that rises at least from a low level L1 to a high level L2,
A downstream output control means for outputting a downstream signal from the downstream output means having a waveform that falls at least from the high level L2 to the low level L1,
A switching control means for alternately switching and outputting the upstream signal output from the upstream output means and the downstream signal output from the downstream output means;
The upstream signal is
A waveform that rises at least from the low level L1 to the high level L2,
A waveform rising from at least a level lower than the low level L1 to a high level L2,
And a signal having a waveform that rises from a level lower than the low level L1 to a level higher than the high level L2.
The downstream signal is
A waveform descending at least from the high level L2 to the low level L1,
A waveform that falls from a level at least higher than the high level L2 to a low level L1,
And a waveform generation apparatus characterized by being a signal having any one of a waveform that falls from a level higher than the high level L2 and beyond the low level L1. 2. The waveform generation apparatus according to claim 1, further comprising a low-pass filter that outputs the signal output by the switching control means as a continuous signal. Ascending gradually from the low level L1, and when reaching the high level L2, gradually descending from there,
In a radar apparatus comprising output means for outputting a transmission signal corresponding to a desired waveform that gradually rises from the low level L1,
An upstream output control means for outputting an upstream signal from an upstream output means having a waveform that rises at least from a low level L1 to a high level L2,
A downstream output control means for outputting a downstream signal from the downstream output means having a waveform that falls at least from the high level L2 to the low level L1,
Switching control means for generating the desired waveform by alternately switching and outputting the upstream signal output from the upstream output means and the downstream signal output from the downstream output means; With
The upstream signal is
A waveform that rises at least from the low level L1 to the high level L2,
A waveform rising from at least a level lower than the low level L1 to a high level L2,
And a signal having a waveform that rises from a level lower than the low level L1 to a level higher than the high level L2.
The downstream signal is
A waveform descending at least from the high level L2 to the low level L1,
A waveform that falls from a level at least higher than the high level L2 to a low level L1,
And a radar apparatus characterized by being a signal having a waveform that falls from a level higher than the high level L2 to a level that exceeds the low level L1.

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