JP2006125947A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the distance and direction to an object by a simple constitution. <P>SOLUTION: This radar system has first and second transmission/reception circuit for transmitting transmission waves and receiving reception waves reflected from the object. The first transmission/reception circuit receives reception waves of transmission waves transmitted by the first transmission/reception circuit and reflected from the object and receives reception waves of transmission waves transmitted by the second transmission/reception circuit and reflected from the object, and the second transmission/reception circuit receives reception waves of transmission waves transmitted by the second transmission/reception circuit and reflected from the object. Through the use of the first and second transmission/reception circuit, the distances from the first and second transmission/reception circuits to the object are computed. By applying the laws of cosines to the computed distances to the object, the angles formed by the straight lines connecting the transmission/reception circuits to the object and the straight line connecting the two transmission/reception circuits to each other are computed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radar apparatus that calculates a distance and a direction to an object based on a propagation delay time from when a transmission wave is transmitted until a reception wave is received.

Several methods have been proposed as a method for detecting not only the distance to an object but also in which direction (angle) the object is in a radar device using electromagnetic waves, lasers, or the like.

For example, the transmission signal is swept left and right, and information on the distance and angle of the object is obtained from the timing of receiving the received wave (see, for example, Patent Document 1). Also, a radar beam is transmitted in a plurality of different directions, There is also one that obtains distance and angle information by measuring the timing at which each radar beam reflected from an object is received (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 3-6473 Japanese Patent Laid-Open No. 3-57429

  However, in the inventions disclosed in Patent Document 1 and Patent Document 2, it is necessary to configure the system by a mechanical or electrical method in order to sweep the transmission signal to the left and right or to transmit a plurality of beams. It has been complicated and expensive. In view of the above problems, an object of the present invention is to detect a distance and a direction to an object with a simple configuration.

  A radar apparatus according to the present invention includes first and second transmission / reception circuits that transmit transmission waves and receive reception waves reflected by an object. The first transmission / reception circuit transmits the first transmission / reception circuit. The transmitted wave received by the object is received and the transmitted wave transmitted by the second transceiver circuit is received by the object, and the second transceiver circuit receives the second wave. The transmission wave transmitted by the transmission / reception circuit is received by the reception wave reflected by the object. The distance from the first and second transmission / reception circuits to the object is calculated using the first and second transmission / reception circuits, and the distance between the calculated object and the distance between the two transmission / reception circuits is formed. By applying a trigonometric function to the triangle, an angle formed by a straight line connecting the transmission / reception circuit and the object and a straight line connecting the two transmission / reception circuits is calculated. Since the direction is calculated using the distance, it is possible to detect the distance and direction to the object with a simple configuration.

  FIG. 1 is a schematic diagram in which a radar apparatus according to the present invention measures the distance and direction of an object. In FIG. 1, two transmission / reception circuits 11 and 12 arranged separately at a distance d transmit a transmission wave radially and receive reception waves reflected by the objects A and B. Show. Transmission waves are transmitted from the transmission / reception circuits 11 and 12 and reflected by the objects A and B, and the transmission / reception circuits 11 and 12 receive the reflected reception waves from the transmission / reception circuits 11 and 12 based on the propagation delay time. Distances a1 and b1 to the objects A and B and distances a2 and b2 from the transmission / reception circuit 12 to the objects A and B are calculated.

但し、∠Ａ１２とは、送受信回路１１及び１２と対象物Ａで形成される三角形の頂点のうち、送受信回路１１を頂点とする角度を表す。∠Ａ２１は送受信回路１１及び１２と対象物Ａで形成される三角形の頂点のうちの送受信回路１２を頂点とする角度、∠Ｂ１２は送受信回路１１及び１２と対象物Ｂで形成される三角形の頂点のうちの送受信回路１１を頂点とする角度、∠Ｂ２１は送受信回路１１及び１２と対象物Ｂで形成される三角形の頂点のうちの送受信回路１２を頂点とする角度である。 At this time, when the transmission / reception circuits 11 and 12 receive all of the reception waves reflected by the objects A and B, the relationship between the distances d, a1, b1, a2, and b2 is expressed as follows using, for example, the cosine theorem. It is expressed as follows.

However, ∠A12 represents an angle having the transmission / reception circuit 11 as a vertex among the vertices of a triangle formed by the transmission / reception circuits 11 and 12 and the object A. ∠A21 is the angle of the vertex of the transmission / reception circuit 12 among the vertices of the triangle formed by the transmission / reception circuits 11 and 12 and the object A, and ∠B12 is the vertex of the triangle formed by the transmission / reception circuits 11 and 12 and the object B Is an angle with the transmission / reception circuit 11 as a vertex, and ∠B21 is an angle with the transmission / reception circuit 12 as a vertex among the vertices of a triangle formed by the transmission / reception circuits 11 and 12 and the object B.

  Further, from the relationship between the distances d, a1, b1, a2, and b2, the point C represented by the equations (5) and (6) and the point D represented by the equations (7) and (8) are also calculated. Is done. That is, points C and D that do not actually exist are also calculated as detection candidates. Therefore, in the radar device according to the present invention, the equations (5), (6), (7), and (8) for the points C and D that do not actually exist are excluded.

  First, the transmission / reception circuit 11 receives a reception wave in which a transmission wave transmitted by itself is reflected by the objects A and B, and the signal processing circuit calculates distances a1 and b1. Next, the transmission / reception circuit 12 receives the reception wave in which the transmission wave transmitted by itself is reflected by the objects A and B, and the signal processing circuit calculates the distances a2 and b2. At this time, the transmission / reception circuit 11 also receives a reception wave in which the transmission wave transmitted from the transmission / reception circuit 12 is reflected by the objects A and B. The transmission / reception circuit 11 recognizes the received wave from the transmission / reception circuit 12, and the signal processing circuit calculates the distance (a2 + a1) and the distance (b2 + b1) from the timing transmitted by the transmission / reception circuit 12. By calculating the distance (a2 + a1), it is possible to identify that the distance a1 calculated by the transmission / reception circuit 11 is reflected by the same object A as the distance a2 calculated by the transmission / reception circuit 12. Similarly, from the distance (b2 + b1), it can be identified that the distance b1 calculated by the transmission / reception circuit 11 is reflected by the same object B as the distance b2 calculated by the transmission / reception circuit 12.

  As described above, the radar apparatus of the present invention calculates the distances a1, b1, a2, b2, a2 + a1, and b2 + b1 in the example of FIG. Thus, by detecting the distance (a2 + a1) and the distance (b2 + b1), the point C and the point D corresponding to the distance (a2 + b1) and the distance (a1 + b2) can be excluded. That is, the candidates for the object can be narrowed down to the points A and B, and the expressions (5), (6), (7), and (8) can be excluded. Accordingly, the angle ∠A12, the angle ∠A21, the angle ∠B12, and the angle ∠B21 are calculated using the equations (1), (2), (3), and (4), and the objects A and B are calculated. Can be calculated. In the above, the example of the cosine theorem has been described, but the angle may be calculated using the sine theorem. In the above description, two examples of the object are shown, but three or more objects may be used. As described above, the direction can be calculated using the distance.

  Specifically, the radar device according to the present invention includes two transmission / reception circuits arranged separately to transmit a transmission wave radially and receive a reception wave reflected by an object, and the transmission A signal processing circuit that calculates a propagation delay time from when a wave is transmitted until a received wave is received, and calculates a distance to the object and a direction of the object based on the calculated propagation delay time. One of the two transmission / reception circuits receives a reception wave in which the transmission wave transmitted by itself is reflected by the object, and the other of the two transmission / reception circuits transmits the two transmission / reception circuits. Each of the transmission waves receives a reception wave reflected by the object, and the signal processing circuit calculates a propagation delay time of the reception wave received by the one transmission / reception circuit, and based on the calculated propagation delay time Sending / receiving one of the above Calculating a distance between a path and the object, calculating a propagation delay time of a received wave received by the other transmission / reception circuit, and calculating the distance between the other transmission / reception circuit and the object based on the calculated propagation delay time. The distance and the distance from the one transmission / reception circuit to the other transmission / reception circuit through the object are calculated, the distance between the two transmission / reception circuits, the calculated distance between the one transmission / reception circuit and the object, From the distance between the other transmission / reception circuit and the object and the calculated distance from the one transmission / reception circuit to the other transmission / reception circuit via the object, the one transmission / reception circuit or the other transmission / reception circuit A radar device that calculates a direction of an object.

  The present invention obtains a distance from the one transmission / reception circuit to the other transmission / reception circuit via the object, so that even when there are a plurality of objects, the configuration is simple using only two transmission / reception circuits. The distance and direction to the object can be calculated.

  In the radar device according to the present invention, it is preferable that the two transmission / reception circuits transmit the transmission waves at different timings in the one transmission / reception circuit and the other transmission / reception circuit.

  The present invention provides a timing difference between a received wave reflected by an object and a received wave reflected by an object transmitted from the one transceiver circuit and a received wave reflected by the object transmitted from the other transceiver circuit. Can be identified. If the one transmission / reception circuit and the other transmission / reception circuit transmit transmission waves at different timings, means such as a reception wave from the one transmission / reception circuit, a reception wave from the other transmission / reception circuit, and a filter in each transmission / reception circuit Therefore, the radar apparatus according to the present invention can be easily configured.

  In the radar device according to the present invention, it is preferable that the two transmission / reception circuits transmit the transmission waves having different modulation frequencies between the one transmission / reception circuit and the other transmission / reception circuit.

  The present invention provides a difference in modulation frequency between a reception wave in which a transmission wave transmitted by the one transmission / reception circuit is reflected by an object and a reception wave in which a transmission wave transmitted by the other transmission / reception circuit is reflected by an object. Can be used to identify. If the reception wave from the transmission wave of the one transmission / reception circuit and the reception wave from the transmission wave of the other transmission / reception circuit are identified by the modulation frequency, the one transmission / reception circuit and the other transmission / reception circuit can transmit simultaneously. Since the two transmitter / receiver circuits transmit the transmission wave at the same time, even when the radar device moves, the relative position between the transmitter / receiver circuits when transmitting the transmission wave is fixed, so the signal processing circuit calculates The accuracy of the distance to the object and the direction can be improved.

  In the radar apparatus according to the present invention, it is preferable that the two transmission / reception circuits transmit transmission waves having different code strings between the one transmission / reception circuit and the other transmission / reception circuit.

  The transmission wave includes a reception wave in which the transmission wave transmitted from the one transmission / reception circuit is reflected by an object and a reception wave in which the transmission wave transmitted from the other transmission / reception circuit is reflected by the object. Can be identified using the difference in the code string. By identifying the reception wave from the one transmission / reception circuit and the reception wave from the other transmission / reception circuit by a code string, two transmission / reception circuits that simultaneously transmit transmission waves of the same modulation frequency can be used.

  The other transmission / reception circuit directly receives a transmission wave transmitted from the one transmission / reception circuit among transmission waves transmitted from the two transmission / reception circuits, and the signal processing circuit directly receives the transmission wave received directly. Based on the timing and the known distance between the two transmission / reception circuits, the transmission timing at which the transmission wave is transmitted from the one transmission / reception circuit is calculated, and the propagation delay time of the reception wave received by the other transmission / reception circuit is calculated. A propagation delay time from the one transmission / reception circuit to the other transmission / reception circuit via the object may be calculated based on the transmission timing.

  According to the present invention, since the signal processing circuit can acquire the timing transmitted from the transmission / reception circuit without correcting the signal processing time in the radar apparatus, more accurate propagation delay time can be calculated.

  The signal processing circuit eliminates an object that does not actually exist among objects whose direction can be calculated based on a distance from the one transmission / reception circuit to the other transmission / reception circuit via the object, Based on the distance between two transmission / reception circuits, the distance between the one transmission / reception circuit and the object, and the distance between the other transmission / reception circuit and the object, the one transmission / reception circuit or the other using the cosine theorem It is preferable to calculate the direction of the object from the transmission / reception circuit.

  In the present invention, the angle formed by the straight line connecting the transmission / reception circuit and the object and the straight line connecting the two transmission / reception circuits can be calculated by applying the cosine theorem to the distance to each object.

  The radar apparatus according to the present invention preferably further includes a conversion circuit that converts the distance and direction calculated by the signal processing circuit into an orthogonal coordinate system.

  According to the present invention, the distance and angle calculated by the signal processing circuit can be converted into XY coordinates.

  According to the present invention, since the direction is calculated using the distance, the distance and direction to the object can be detected with a simple configuration.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 2 is a circuit diagram showing an example of the radar apparatus according to the present embodiment. The radar apparatus according to the present embodiment transmits the transmission waves 104 and 204 radially, and the transmission waves 104 and 204 are separately disposed so as to receive the reception waves 105 and 205 reflected by the objects A and B. The transmission / reception circuits 11 and 12 and the transmission delay time until the transmission waves 104 and 204 are transmitted and the reception waves 105 and 205 are received are calculated, and the objects A and B are calculated based on the calculated propagation delay time. And a signal processing circuit 13 for calculating the direction of the objects A and B from the distance, and one of the two transmission / reception circuits 11 and 12 has transmitted by itself. The transmission wave 204 receives the reception wave 205 reflected by the objects A and B, and the other transmission / reception circuit 11 of the two transmission / reception circuits 11 and 12 has two transmission / reception circuits 11. 12 and 12 receive the received waves 105 and 205 reflected by the objects A and B, respectively, and the signal processing circuit 13 propagates the propagation delay of the received wave 205 received by one of the transmitting and receiving circuits 12. The time is calculated, the distance between one transmission / reception circuit 12 and the objects A and B is calculated based on the calculated propagation delay time, and the propagation delay times of the received waves 105 and 205 received by the other transmission / reception circuit 11 are calculated. Based on the calculated propagation delay time, the distance between the other transmission / reception circuit 11 and the objects A and B and the distance from the one transmission / reception circuit 12 to the other transmission / reception circuit 11 via the objects A and B are calculated. The distance between the two transmission / reception circuits 11 and 12, the calculated distance between one transmission / reception circuit 12 and the objects A and B, and the calculated distance between the other transmission / reception circuit 11 and the objects A and B. From a distance of from one transceiver circuit 12 which is calculated each time to the other transceiver circuit 11 via the object A and B, to calculate the direction of the object A and B from one transceiver circuit 12 or the other of the transmitting and receiving circuit 11.

  The transmission / reception circuit 12 includes a pulse generation circuit 41 that outputs a pulse signal 202, an oscillator 42 that outputs an oscillation wave 209, a distributor 43 that distributes the oscillation wave 209, and the presence / absence of the pulse signal 202 from the pulse generation circuit 41. A pulse modulator 44 that outputs a modulated pulse signal 203 by switching between passing and blocking of the oscillation wave 209 from the distributor 43, an amplifier 45 that amplifies the modulated pulse signal 203 output from the pulse modulator 44, and a modulated pulse A transmission antenna 46 that transmits the signal 203 radially as a transmission wave 204; a reception antenna 47 that receives the reception wave 205 of the transmission wave 204 reflected by the objects A and B; and outputs a modulated pulse signal 206; 47. The amplifier 48 amplifies the modulation pulse signal 206 output from the signal 47 and the oscillation wave 209 distributed by the distributor 42. Demodulator 49 that demodulates 206 and outputs pulse signal 207, amplifier 50 that amplifies pulse signal 207 output from demodulator 49, and comparator 51 that detects pulse signal 207 and outputs it to signal processing circuit 13. And including.

  The transmission / reception circuit 11 includes a pulse generation circuit 21 that outputs a pulse signal 102, an oscillator 22 that outputs an oscillation wave 109, a distributor 23 that distributes the oscillation wave 109 of the oscillator 22, and a pulse signal 102 from the pulse generation circuit 21. A pulse modulator 24 that outputs and outputs a modulated pulse signal 103 by switching between passing and blocking of the oscillation wave 109 from the distributor 23, and an amplifier 25 that amplifies the modulated pulse signal 103 output from the pulse modulator 24. A transmission antenna 26 that transmits the modulated pulse signal 103 radially as a transmission wave 104; and a reception that receives the reception wave 105 and the reception wave 205 reflected from the object by the transmission wave 104 and outputs the modulation pulse signals 106 and 206. An antenna 27, an amplifier 28 for amplifying the modulated pulse signals 106 and 206 output from the receiving antenna 27, and a distributor A demodulator 29 that demodulates the modulated pulse signals 106 and 206 with the oscillation wave 109 distributed at 3 and outputs pulse signals 107 and 207; and an amplifier 30 that amplifies the pulse signals 107 and 207 output from the demodulator 29; And a comparator 31 that detects the pulse signals 107 and 207 and outputs them to the signal processing circuit 13.

但し、Ｌは距離（ｍ）、Ｔｏはレーダー装置が送信波を送信してから受信波を受信するまでの時間（ｓｅｃ）、ｃは光速（ｍ／ｓｅｃ）である。なお、予めレーダー装置内の各回路での伝搬遅延時間を測定しておき、検出した時間をレーダー装置が送信波を送信してから、受信波を受信するまでの時間に換算することで、対象物までの伝搬遅延時間を算出することが好ましい。 The signal processing circuit 13 determines the distance to the objects A and B based on the propagation delay time from when the transmission waves 104 and 204 are transmitted to when the reception waves 105 and 205 are received, and from the distance to the objects A and B. The direction is calculated. There is a time difference To between the pulse signal 102 or 202 output from the pulse generation circuit 21 or 41 and the pulse signal 107 or 207 input to the signal processing circuit 13. This indicates that the object is present at a distance corresponding to the time difference To. The round-trip distance to the object can be calculated from equation (9).

Where L is the distance (m), To is the time (sec) from when the radar device transmits the transmission wave to receiving the reception wave, and c is the speed of light (m / sec). In addition, the propagation delay time in each circuit in the radar device is measured in advance, and the detected time is converted into the time from when the radar device transmits the transmission wave to when the reception wave is received. It is preferable to calculate the propagation delay time to the object.

  A pulse count method, a flip-flop circuit method, or the like can be applied to the circuit that calculates the time included in the signal processing circuit 13. In the pulse counting method, when the pulse signal 102 or 202 is output by the pulse generation circuit 21 or 41, the start timing is set, and when the pulse signal 107 or 207 is input to the signal processing circuit 13, the stop timing is counted. Time is calculated from the number of pulses.

  FIG. 3 is a circuit diagram showing an example of a circuit for calculating the time included in the signal processing circuit. The circuit shown in FIG. 3 uses a set-reset type flip-flop system. The pulse signals 107 and 207 of the comparators 31 and 51 shown in FIG. 2 are input to the input terminal 61, amplified by the amplifier 62, and then shaped by the waveform shaping circuit 63. A signal from an RZ code conversion circuit (not shown) is input from the input terminal 64 to the set terminal of the flip-flop circuit 65. A signal from the waveform shaping circuit 63 is input to the reset terminal of the flip-flop circuit 65. If the time from when the transmission wave is transmitted until the reception wave is received is short, the time from setting to reset of the flip-flop circuit 65 is short, and the time from when the transmission wave is transmitted until reception is received is long. When the output from the flip-flop circuit 65 is smoothed by the low-pass filter 66, the output terminal 67 corresponds to the propagation delay time to the object. DC level is output.

  Here, when there are two objects, two pulse signals 107 or 207 are input to the signal processing circuit 13 shown in FIG. 2 in one frame. In the case of the flip-flop circuit system, the signal is input twice to the reset terminal of the flip-flop circuit 65, but the flip-flop circuit 65 does not operate at the second reset input. For this reason, a plurality of reset terminals are prepared for one set terminal, and a branch circuit that is input to a different reset terminal every time the pulse signal 107 or 207 is newly input is provided on the input side of the reset terminal. Is preferred. A plurality of flip-flop circuits may be prepared. With such a configuration, it is possible to calculate propagation delay times of received waves from a plurality of objects received by two transmission / reception circuits. Even in the pulse count method, there are two stop timings. However, it is preferable that a plurality of received waves be received by providing a plurality of stop timings as in the flip-flop circuit.

  The clock period of the transmission waves 104 and 204 is desirably 10 MHz or less. If the maximum detection distance from the radar device to the object is 16 m, when the next transmission wave is transmitted before one transmission wave is transmitted and reflected by the object at a distance of 16 m, it returns. The object at the maximum detection distance cannot be detected. When an object is present at a maximum detection distance of 16 m, the round-trip time of a transmission wave to the object is 106 nsec. The clock frequency with one cycle of 106 nsec is 9.4 MHz. Therefore, if the clock period of the transmission wave is 10 MHz or less, the maximum detection distance can be ensured to be 16 m or more.

  The pulse width of the transmission wave, that is, the pulse signal 102 or 202 is desirably 2 nsec or less. If the minimum detection distance from the radar device to the object is 30 cm, transmission of one transmission wave is not completed until one transmission wave is transmitted and reflected back from the object at a distance of 30 cm. The object at the minimum detection distance cannot be detected. At a minimum detection distance of 30 cm, the round trip time of the transmission wave is 2 nsec. Therefore, if the pulse width of the pulse signal 102 or 202 is 2 nsec or less, the minimum detection distance can be ensured to be 30 cm or less.

  Next, a method for calculating the distance from the objects A and B from the propagation delay time until the transmission waves 104 and 204 are transmitted and the reception waves 105 and 205 are received will be described with reference to FIGS. I will explain. FIG. 4 is a first example of signals transmitted and received by the radar apparatus according to the present embodiment, (a) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, (e) and (F) shows the received pulse signal. In the radar apparatus shown in FIG. 4, two transmission / reception circuits 11 and 12 transmit transmission waves 104 and 204 having different timings in one transmission / reception circuit 12 and the other transmission / reception circuit 11. In (a), the trigger signal 101 is shown and is output at time t1. In (b), a trigger signal 201 is shown and is output at time t5. In (c), the pulse signal 102 is output at time t2 after time difference Tt from time t1. In (d), the pulse signal 202 is output at time t6 after the time difference Tt from time t5. Note that a time difference Tt is required until the pulse signals 102 and 202 are output. This is because the transmission / reception circuits 11 and 12 receive the trigger signal and output the pulse signal, which causes a delay in processing. is there. The time difference Tt caused by this delay is fixed and is grasped by the signal processing circuit 13 as will be described later.

In (e), the pulse signal 107 in which the pulse signal 102 shown in (c) is reflected by the object A is received at time t3, and the pulse signal 102 shown in (c) is reflected by the object B. The pulse signal 107 received at time t4. At this time, a time difference Ta11 from time t2 to time t3 is a propagation delay time until the transmission / reception circuit 11 receives the reception wave 105 in which the transmission wave 104 is reflected by the object A. Since the signal processing circuit 13 knows the timing of the trigger signal 101 and the timing of the pulse signal 107 and grasps the time difference Tt in advance, the signal processing circuit 13 can calculate the time difference Ta11 and based on the calculated time difference Ta11. Thus, a distance (2 × a1) that is a round trip of the distance a1 can be calculated. The time difference Tb11 from time t2 to time t4 is a propagation delay time until the transmission wave 104 is received by the transmission / reception circuit 11 when the transmission wave 104 is reflected by the object B, and the signal processing circuit 13 is similarly configured. Thus, the time difference Tb11 is obtained, and the distance (2 × b1) that is the round trip of the distance b1 can be calculated based on the time difference Tb11.

  Further, in (e), a pulse signal 207 obtained by reflecting the pulse signal 202 shown in (d) on the object A is a time t9, and a pulse signal obtained by reflecting the pulse signal 202 shown in (d) on the object B at time t9. 207 is received at time t10. At this time, a time difference Ta21 from time t6 to time t9 is a propagation delay time until the transmission / reception circuit 11 receives the reception wave 205 in which the transmission wave 204 is reflected by the object A. Since the signal processing circuit 13 knows the timing of the trigger signal 201 and the timing of the pulse signal 207 and grasps the above-described time difference Tt, the signal processing circuit 13 can calculate the time difference Ta21, and based on the calculated time difference Ta21. 1 can be calculated (a2 + a1). A time difference Tb21 from time t6 to time t10 is a propagation delay time until the transmission / reception circuit 11 receives the reception wave 205 in which the transmission wave 204 is reflected by the object B. Similarly, the signal processing circuit 13 obtains the time difference Tb21 and can calculate the distance (b2 + b1) shown in FIG. 1 based on the time difference Tb21.

  In (f), a pulse signal 207 in which the pulse signal 202 shown in (d) is reflected by the object A is received at time t7, and the pulse signal 202 shown in (d) is reflected by the object B. The pulse signal 207 received at time t8. At this time, a time difference Ta22 from time t6 to time t7 is a propagation delay time until the transmission / reception circuit 12 receives the reception wave 205 in which the transmission wave 204 is reflected by the object A. Since the signal processing circuit 13 knows the timing of the trigger signal 201 and the timing of the pulse signal 207 and grasps the above-described time difference Tt, the signal processing circuit 13 can calculate the time difference Ta22, and based on the calculated time difference Ta22, FIG. The distance (2 × a2) that is the round trip of the distance a2 shown in FIG. A time difference Tb22 from time t6 to time t8 is a propagation delay time until the transmission wave 204 is received by the transmission / reception circuit 12 when the transmission wave 204 is reflected by the object B, and the signal processing circuit 13 similarly Thus, the time difference Tb22 is obtained, and the distance (2 × b2) that is the round trip of the distance b2 shown in FIG. 1 can be calculated based on the time difference Tb22.

  As shown in FIG. 4, the time t5 is later than the time t4, and the times t7, t8, t9, and t10 are trigger signals (not shown) of the transmission / reception circuit 11 for the transmission wave to be transmitted next. Faster than). That is, after each transmission / reception circuit receives a reception wave, the next transmission wave is transmitted. As described above, the two transmission / reception circuits 11 and 12 transmit the transmission waves having different timings in the one transmission / reception circuit 12 and the other transmission / reception circuit 11, and thus the pulse signals 107 and 207 received by the transmission / reception circuit 11 are signaled. It can be identified by the processing circuit 13. Since transmission waves at different timings can be controlled at the timing of outputting the trigger signals 101 and 201, the pulse signals 107 and 207 can be identified only by the signal processing circuit 13 without using other circuits.

  Further, FIG. 5, FIG. 1 and FIG. 2 show a method for calculating the relationship between the distances from the propagation delay time until the transmission waves 104 and 204 are transmitted and the reception waves 105 and 205 are received to the objects A and B. It explains using. FIG. 5 is a second example of signals transmitted and received by the radar apparatus according to the present embodiment, (a) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, (e) and (F) shows the received pulse signal. In the radar apparatus shown in FIG. 5, two transmission / reception circuits 11 and 12 transmit transmission waves 104 and 204 having different modulation frequencies in one transmission / reception circuit 12 and the other transmission / reception circuit 11. The radar apparatus shown in FIG. 5 is almost the same as FIG. 4 described above, but in FIG. 5B, the trigger signal 201 is output at the same time t1 as the trigger signal 101, and in FIG. The pulse signal 202 is output at time t2 at the same time as the pulse signal 102. Further, in FIG. 5E, the time difference Ta11 from time t2 to time t3, the time difference Tb11 from time t2 to time t4, the time difference Ta21 from time t2 to time t9, and the time difference Tb21 from time t2 to time t10. Yes. In FIG. 5F, the time difference Ta22 from time t2 to time t7 is the time difference Tb22 from time t2 to time t8. As described with reference to FIG. 4, each distance can be calculated based on the time difference.

  If the modulation frequencies of the transmission waves 104 and 204 are different, the pulse signal 107 and the pulse signal 207 can be identified by separating the modulation pulse signals 106 and 206 for each modulation frequency. For example, a frequency separation filter can be used to separate the modulated pulse signals 106 and 206. In this case, the demodulator 29 and the oscillator 22 for demodulating the modulated pulse signals 106 and 206 are required. Further, a demodulator 29 that demodulates each of the modulated pulse signals 106 and 206 and separates and outputs the pulse signal 107 and the pulse signal 207 may be used. Also in this case, an oscillator capable of demodulating the modulated pulse signal 106 is required. In this manner, the pulse signals 107 and 207 can be separately input to the signal processing circuit 13 by being separated for each modulation frequency.

  As described above, the transmission / reception circuits 11 and 12 that simultaneously transmit transmission waves are identified by identifying the reception wave 205 from the one transmission / reception circuit 12 and the reception wave 105 from the other transmission / reception circuit 11 by the modulation frequency. Can be used. By transmitting the transmission wave at the same time, even when the radar apparatus moves, the relative position between the transmission / reception circuits when transmitting the transmission waves 104 and 204 is fixed, so that the object calculated by the signal processing circuit 13 The accuracy of the distance and direction can be improved.

  Note that the transmission timings of the transmission waves from the transmission / reception circuits 11 and 12 may be different. Since the modulation frequency and timing are different, if the timing of outputting the transmission wave of the oscillator 22 is changed in accordance with the timing of transmission of the transmission wave from the transmission / reception circuits 11 and 12, a reception wave having a different modulation frequency is converted into one oscillator 22, One demodulator 29 and one comparator 31 can perform processing.

  Further, in the radar apparatus shown in FIG. 5, the two transmission / reception circuits 11 and 12 may transmit transmission waves of different code strings in one transmission / reception circuit 12 and the other transmission / reception circuit 11. For example, the trigger signal 101 output from the signal processing circuit 13 may be “11010100” and the trigger signal 201 may be “11010101”. Further, the pulse signal 102 or 202 output from the pulse generation circuits 21 and 41 can be a code string. The signal processing circuit 13 can identify the pulse signal 107 and the pulse signal 207 by identifying whether the signal following the code string “1101010” is 0 or 1. The identification may be performed by the comparator 31. In this case, the pulse signal 107 and the pulse signal 207 may be separated and input to the signal processing circuit 13. The code strings “11010101” and “11010100” may be arbitrary digits, and may be identified by any of the code strings. However, it is preferable to use a code string for identification after a specific code string such as “1101010” indicating that it is a code string for identifying a transmission / reception circuit in preparation for receiving another radio signal. . Further, it may be a pseudo-random sequence having periodicity such as an M sequence or a Gold sequence, and demodulation is facilitated by using the pseudo-random sequence.

  Thus, if the code strings of the transmission waves 104 and 204 are different, the signal processing circuit 13 can identify the pulse signal 107 and the pulse signal 207 regardless of the transmission / reception timing and the modulation frequency. Since the same transmission / reception circuit can be used for the transmission / reception circuits 11 and 12, the circuit configuration can be simplified by sharing components.

  Note that the time t2 at which the pulse signal shown in FIGS. 4 and 5 is output may be the timing at which the transmission antennas 26 and 46 transmit. Moreover, the timing which outputs the trigger signals 101 and 201 may be sufficient. Further, each time at which the pulse signals 107 and 207 are received may be a timing at which the reception antenna 27 or 47 receives a reception wave. Alternatively, the timing at which the comparator 31 or 51 detects the pulse signal 107 or 207 may be used.

  Further, the signal processing circuit 13 includes a distance between the one transmission / reception circuit 12 and the other transmission / reception circuit 11, a distance between the one transmission / reception circuit 12 and the object, a distance between the other transmission / reception circuit 11 and the object, From the distance from one transmission / reception circuit 12 to the other transmission / reception circuit 11 through the object, the direction of the objects A and B from one transmission / reception circuit 12 or the other transmission / reception circuit 11 is calculated using the cosine theorem. Is preferred. As shown in FIG. 1, the signal processing circuit 13 has a distance from the transmission / reception circuit 12 to the other transmission / reception circuit 11 through the object is a distance (a2 + a1) and a distance (b2 + b1). Of the objects that can be calculated, objects that do not actually exist are excluded, candidate objects are narrowed down to points A and B, and the calculated distance (2 × a1), distance (2 × b1), distance (2 × a2), distance (2 × b2), distance (a2 + a1), and distance (b2 + b1), the distances d, a1, b1, a2, and b2 are expressed by the above-described equations (1) to (4) (ie, point A). , The angle ∠A12, the angle ∠A21, the angle １２B12, and the angle ∠B21 are calculated, and the directions of the objects A and B can be calculated.

  In the radar device according to the present invention, the signal processing circuit includes a distance between the one transmission / reception circuit and the target that is substantially equal to a distance from the one transmission / reception circuit to the other transmission / reception circuit through the target. The combination of the distance between the other transmission / reception circuit and the object is specified, the object that does not actually exist among the objects whose directions can be calculated is excluded, the distance between the two transmission / reception circuits, From the distance between one transmission / reception circuit and the object, and the distance between the other transmission / reception circuit and the object, the object from the one transmission / reception circuit or the other transmission / reception circuit using the cosine theorem The direction is calculated.

  As shown in FIG. 1, the signal processing circuit 13 is calculated because the distance from the transmission / reception circuit 12 to the other transmission / reception circuit 11 through the object is a distance (a2 + a1) and a distance (b2 + b1), respectively. A combination of the distance a1 and the distance a2 that is substantially equal to the distance (a2 + a1) is specified, a combination of the distance b1 and the distance b2 that is substantially equal to the calculated distance (b2 + b1) is specified, and the candidate of the object is designated as points A and B. Based on the calculated distance (2 × a1), distance (2 × b1), distance (2 × a2), distance (2 × b2), distance (a2 + a1), and distance (b2 + b1), the distances d and a1 , B1, a2 and b2 are applied to the above-mentioned formulas (1) to (4) (that is, cosine theorem formulas for points A and B), and angle ∠A12, angle ∠A21, angle ∠B12 and angle ∠ B 1 is calculated, it is possible to calculate the direction of the object A and B.

  Furthermore, the signal processing circuit 13 may further include a coordinate conversion circuit that converts the calculated distance and direction into an orthogonal coordinate system. By providing the coordinate conversion circuit, the distances a1, b1, a2, and b2, the angle ∠A12, the angle ∠A21, the angle ∠B12, and the angle ∠B21 calculated as in the above example are converted into XY coordinates. be able to.

(Embodiment 2)
FIG. 6 is a circuit diagram illustrating an example of a radar apparatus according to the second embodiment. The radar apparatus according to this embodiment differs from the radar apparatus shown in FIG. First, instead of the signal processing circuit 13 shown in FIG. 2, a signal processing circuit 15 including signal conversion circuits 300 and 301 and a distance calculation circuit 302 is provided. In the radar apparatus of FIG. 2, the signal processing circuit 13 outputs the trigger signals 101 and 201. However, in this embodiment, an independent timing generation circuit 14 that outputs the trigger signals 101 and 201 is provided.

  The timing generation circuit 14 generates and outputs trigger signals 101 and 201 for the pulse generation circuits 21 and 41 as in the case of FIG. In this case, the timing generation circuit 14 is provided in the vicinity of the transmission / reception circuit 11 or the transmission / reception circuit 12, and is provided at a position away from the distance calculation circuit 302.

  The signal conversion circuits 300 and 301 are arranged in the vicinity of the transmission / reception circuits 11 and 12 as input / output interfaces with the transmission / reception circuits 11 and 12, respectively. The signal conversion circuits 300 and 301 calculate distances to calculate the distance to the object and the direction of the object based on the propagation delay time until the transmission waves 104 and 204 are transmitted and the reception waves 105 and 205 are received, respectively. The circuit 302 is connected. The distance calculation circuit 302 is provided at a position away from the transmission / reception circuits 11 and 12, and is provided, for example, in the vicinity of a display device that indicates the detected distance and direction of the object.

  When the transmission / reception circuit 11 receives the trigger signal 101 via the signal conversion circuit 300, the transmission / reception circuit 11 generates the pulse signal 102 and transmits the transmission wave 104, and also receives the reception wave reflected from the object, as in FIG. 105 is received. The received wave 105 received is demodulated by the demodulator 29 and then output from the comparator 31 as a pulse signal 107. As will be described later, the transmission / reception circuit 11 directly receives the transmission wave 204 transmitted from the transmission / reception circuit 12 as a direct wave 210 and also receives a reception wave 205 in which the transmission wave 204 is reflected by an object. Similarly, these received signals 210 and 205 are demodulated by the demodulator 29 and then output from the comparator 31 as a pulse signal 207.

  Based on the trigger signal 101 and the pulse signal 107, the signal conversion circuit 300 obtains the propagation delay time from when the transmission wave 104 is transmitted until the reception wave 105 is received, and the obtained propagation delay time is converted into the digital signal 310. The data is converted and sent to the distance calculation circuit 302. Similarly, in the signal conversion circuit 300, the transmission / reception circuit 12 transmits the transmission wave 204 based on the pulse signal 207 of the direct wave 210 directly received from the transmission / reception circuit 12 and the pulse signal 207 of the reception wave 205 with respect to the transmission wave 204 of the transmission / reception circuit 12. The propagation delay time from when the signal is sent to when the received wave 205 is received is obtained, and the obtained propagation delay time is converted into a digital signal 311 and sent to the distance calculation circuit 302.

  When the transmission / reception circuit 12 receives the trigger signal 201 via the signal conversion circuit 301, the transmission / reception circuit 12 generates the pulse wave 202 and transmits the transmission wave 204 and receives the reception wave reflected from the object, as in FIG. 205 is received. The received wave 205 received is demodulated by the demodulator 49 and then output from the comparator 51 as a pulse signal 207.

  Based on the trigger signal 201 and the pulse signal 207, the signal conversion circuit 301 obtains a propagation delay time from when the transmission wave 204 is transmitted until the reception wave 205 is received, and the obtained propagation delay time is converted into the digital signal 312. The data is converted and sent to the distance calculation circuit 302.

  In this way, in the present embodiment, the propagation delay time is obtained by the signal conversion circuits 300 and 301 provided in the vicinity of the transmission / reception circuits 11 and 12, and the propagation delay time is calculated as the digital signals 310, 311, and 312 to calculate the distance. By outputting to the circuit 302, even when the distance between the distance calculation circuit 302 and the transmission / reception circuits 11 and 12 is large, it is possible to realize a radar device with high noise durability.

  Next, the procedure for calculating the propagation delay time in the signal conversion circuits 300 and 301 will be described in detail with reference to FIGS. FIG. 7 is an example of signals transmitted and received by the radar apparatus according to the second embodiment. (A) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, and (e) and (f). ) Indicates a received pulse signal. Also in this example, similarly to the case of FIG. 4, the radar apparatus transmits the transmission waves 104 and 204 at different timings in one transmission / reception circuit 12 and the other transmission / reception circuit 11.

  As shown in FIGS. 7A, 7 </ b> C, and 7 </ b> E, the transmission wave 104 is transmitted from the transmission / reception circuit 11 at time t <b> 2 delayed by the time difference Tt with respect to the trigger signal 101, and the reception wave of the transmission wave 104 is received. 105 is received by the signal conversion circuit 300 as the pulse signal 107 at times t3 and t4. Since the signal conversion circuit 300 knows the timing of the trigger signal 101 and knows the time difference Tt in advance, it can calculate the time differences Ta11 and Tb11 between the transmitted pulse signal 102 and the received pulse signal 107. The calculated time differences Ta11 and Tb11 are converted into digital signals 310 as propagation delay times and output to the distance calculation circuit 302.

  As shown in FIGS. 7B, 7 </ b> D, and 7 </ b> F, the transmission wave 204 is transmitted from the transmission / reception circuit 12 at time t <b> 6 delayed by the time difference Tt with respect to the trigger signal 201, and the reception wave of the transmission wave 204 is received. 205 is received by the signal conversion circuit 301 as a pulse signal 207 at times t7 and t8. Since the signal conversion circuit 301 grasps the timing of the trigger signal 201 and grasps the time difference Tt in advance, it can calculate the time differences Ta22 and Tb22 between the transmitted pulse signal 202 and the received pulse signal 207. The calculated time differences Ta22 and Tb22 are converted into digital signals 312 as propagation delay times and output to the distance calculation circuit 302.

  As shown in FIG. 7 (e), the pulse signal 202 transmitted from the transmission / reception circuit 12 at time t6 is the direct signal 210 received as the pulse signal 207 at time t11, and the pulse signal 202 transmitted from the transmission / reception circuit 12 is received. The received waves 205 by the objects A and B are received as a pulse signal 207 by the signal conversion circuit 300 at times t9 and t10. Since the signal conversion circuit 300 has not received the trigger signal 201 for the transmission / reception circuit 12, the transmission timing t6 that is the time when the transmission wave 204 of the transmission / reception circuit 12 is transmitted cannot be grasped as it is. However, the signal conversion circuit 300 knows in advance the distance d between the transmission / reception circuits 11 and 12, and knows the time difference Td required for the direct wave 210 to propagate the distance d. As can be seen from FIG. 7E, the time difference Td is a time difference between the transmission timing t6 and the direct reception timing t11 that is the time when the direct wave 210 is directly received. Accordingly, the transmission timing t6 at which the pulse signal of the transmission / reception circuit 12 is transmitted can be calculated by subtracting this time difference Td from the direct reception timing t11 of the directly received pulse signal.

  The signal conversion circuit 300 obtains the time difference between the transmission timing t6 of the transmission / reception circuit 12 thus obtained and the reception timings t9 and t10 of the reception wave 205, whereby the transmission wave 204 transmitted from one transmission / reception circuit 12 is obtained. Propagation delay times Ta21 and Tb21 that are reflected by the object and received by the other transmission / reception circuit 11 are calculated. The signal conversion circuit 300 converts the propagation delay times Ta21 and Tb21 into a digital signal 311 and outputs the digital signal 311 to the distance calculation circuit 302.

  In this way, by calculating the transmission timing (time t6) of one transmission / reception circuit 12 using the timing of the direct wave 210 directly received (that is, the direct reception timing t11), as shown in FIG. The circuit 15 and the timing generation circuit 14 can be separated. Furthermore, since the signal processing circuit 15 can acquire the timing transmitted from the transmission antenna 46 without correcting the signal processing time in the radar apparatus, a more accurate propagation delay time can be calculated.

  In the first embodiment and the second embodiment, only the transmission / reception circuit 11 receives the reception wave in which the transmission wave transmitted from the transmission / reception circuit 12 is reflected by the object. You may receive the received wave in which the transmitted transmission wave was reflected by the target object.

  The radar device according to the present invention can be applied to a vehicle-mounted device for the purpose of vehicle collision prevention and auto cruise, and can also be used as a fixed radar device.

It is a schematic diagram in which the radar apparatus according to the present invention measures the distance and direction of an object. 1 is a circuit diagram illustrating an example of a radar device according to Embodiment 1. FIG. It is a circuit diagram which shows an example of the circuit which calculates the time contained in a signal processing circuit. It is a 1st example of the signal which the radar apparatus based on Embodiment 1 transmits / receives, (a) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, (e) and (f) are Indicates the received pulse signal. It is a 2nd example of the signal which the radar apparatus based on Embodiment 1 transmits / receives, (a) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, (e) and (f) are Indicates the received pulse signal. FIG. 6 is a circuit diagram illustrating an example of a radar device according to a second embodiment. It is an example of the signal which the radar apparatus which concerns on Embodiment 2 transmits / receives, (a) and (b) are trigger signals, (c) and (d) are transmitted pulse signals, (e) and (f) are received A pulse signal is shown.

Explanation of symbols

11, 12: Transmission / reception circuit, 13, 15: Signal processing circuit, 14: Timing generation circuit, 21, 41: Pulse generation circuit, 22, 42: Oscillator, 23, 43: Branch, 24, 44: Modulator, 25 45, 28, 48, 30, 50: amplifier, 27, 47: receiving antenna, 29, 49: demodulator, 31, 51: comparator, 61: input terminal, 62: amplifier, 63: waveform shaping circuit, 64 : Input terminal, 65: flip-flop circuit, 66: low-pass filter, 67: output terminal, 101, 201: trigger signal, 102, 202, 107, 207: pulse signal, 103, 203, 106, 206: modulation pulse Signal, 105, 204: Transmission wave, 105, 205: Reception wave, 300, 301: Signal conversion circuit, 302: Distance calculation circuit, 310, 311, 312: Digital signal , T1~t11: Time, To, Tt, Td, Ta11, Tb11, Ta21, Tb21, Ta22, Tb22: the time difference

Claims (7)

Two transmission / reception circuits arranged separately to transmit a transmission wave radially and receive the reception wave reflected by the object;
A signal processing circuit for calculating a propagation delay time from when the transmission wave is transmitted until a reception wave is received, and calculating a distance to the object and a direction of the object based on the calculated propagation delay time; A radar device comprising:
One of the two transmission / reception circuits receives a reception wave in which a transmission wave transmitted by itself is reflected by the object,
The other of the two transmission / reception circuits receives a reception wave in which a transmission wave transmitted by the two transmission / reception circuits is reflected by the object,
The signal processing circuit calculates a propagation delay time of a received wave received by the one transmission / reception circuit, calculates a distance between the one transmission / reception circuit and the object based on the calculated propagation delay time, The propagation delay time of the received wave received by the other transmission / reception circuit is calculated, and the distance between the other transmission / reception circuit and the object and the one transmission / reception circuit pass through the object based on the calculated propagation delay time. Calculating a distance to the other transmission / reception circuit; a distance between the two transmission / reception circuits; a calculated distance between the one transmission / reception circuit and the object; a calculated distance between the other transmission / reception circuit and the object; The direction of the object from the one transmission / reception circuit or the other transmission / reception circuit is calculated from the calculated distance from the one transmission / reception circuit to the other transmission / reception circuit via the object. Radar apparatus, characterized by.   2. The radar device according to claim 1, wherein the two transmission / reception circuits transmit the transmission waves at different timings in the one transmission / reception circuit and the other transmission / reception circuit.   2. The radar device according to claim 1, wherein the two transmission / reception circuits transmit the transmission waves having different modulation frequencies between the one transmission / reception circuit and the other transmission / reception circuit.   2. The radar device according to claim 1, wherein the two transmission / reception circuits transmit transmission waves having different code strings between the one transmission / reception circuit and the other transmission / reception circuit. The other transmission / reception circuit directly receives the transmission wave transmitted by the one transmission / reception circuit among the transmission waves transmitted by the two transmission / reception circuits,
The signal processing circuit calculates a transmission timing at which a transmission wave is transmitted from the one transmission / reception circuit based on a direct reception timing of the transmission wave received directly and a known distance between the two transmission / reception circuits, The propagation delay time from the one transmission / reception circuit to the other transmission / reception circuit via the object is calculated based on the transmission timing among the propagation delay times of the received wave received by the other transmission / reception circuit. The radar device according to any one of claims 1 to 4.   The signal processing circuit eliminates an object that does not actually exist among objects whose direction can be calculated based on a distance from the one transmission / reception circuit to the other transmission / reception circuit via the object, Based on the distance between two transmission / reception circuits, the distance between the one transmission / reception circuit and the object, and the distance between the other transmission / reception circuit and the object, the one transmission / reception circuit or the other using the cosine theorem The radar device according to claim 1, wherein the direction of the object from the transmission / reception circuit is calculated. The radar apparatus according to claim 1, further comprising a conversion circuit that converts the distance and direction calculated by the signal processing circuit into an orthogonal coordinate system.

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