JP2007327814A - Pulse radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse radar system capable of providing an efficient detection method in response to a moving speed of a desired object, by regulating a time difference when finding a time finite difference. <P>SOLUTION: This pulse radar system includes a transmission part 1 for transmitting a pulse-like radio wave toward the object, a pulse control part 2 for controlling a time interval when transmitted intermittently from the transmission part 1, a reception part 4 for receiving a reflected wave from the object by a reception antenna 3, a history accumulation part 5 for accumulating a plurality of waveforms of reception signals from the reception part 4, a difference computing part 6 for finding a difference with respect to the reception signal, using the plurality of history signals from the history accumulation part 5, a detecting part 7 for detecting waveform leading-up timing of the difference signal obtained from the difference computing part 6, and a distance computing part 8 for finding a distance of a moving component, using a control signal from the pulse control part 2 and a detection signal from the detecting part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pulse radar device that efficiently detects a distance according to a moving speed of a desired object.

  In general, a pulse radar system as shown in FIG. 7 is used as a system in which a radar apparatus obtains the distance of an object. In this method, when a pulsed electromagnetic wave, sound wave, light, or other medium is radiated from the radar device and a reflected wave is received from an object, the time difference between the radiated timing and the reflected wave reception timing is used. The distance from the radar to the object was obtained. FIG. 8 shows a schematic diagram of the waveform of this method, and the calculation formula is shown in Equation 1 below.

[Expression 1] R = C / 2 × (ΔT−δTt−δTr)
R is the distance [m] from the radar to the object, C is the propagation speed [m / s] of the medium (electromagnetic wave, sound wave, etc.), and ΔT is the time difference between the timing of pulse driving and the timing of detecting the received signal [S], δTt is the time difference [s] between the pulse-driven timing and the timing at which the transmission wave is emitted, and δTr is the time difference [s] between the timing at which the reflected wave is received and the timing at which the received signal is detected.

  On the other hand, in the pulse radar system, a fixed reflected wave is generated in a time zone equivalent to the vicinity due to insufficient isolation between transmission and reception and unnecessary reflection at the antenna radome, or even an unnecessary reflected wave from a stationary background is detected due to beam spread. Or misdetection.

  In order to avoid this problem, the MTI method disclosed in Japanese Patent Laid-Open No. 2003-222669 (Patent Document 1) has been used. As a result, as shown in Equations 2 to 6, the time difference between the reflected waves acquired by the receiving unit is obtained to extract only the phase fluctuation component due to the Doppler effect of the object, and the false detection due to unnecessary reflection and unnecessary background is removed. The distance of the desired object can be obtained. FIG. 9 shows a schematic diagram of the configuration of the MTI system, and FIG. 10 shows a schematic diagram of the waveform of this system.

[Expression 2] Vt = At × sin [2πFc × t + θt]
[Formula 3] Vr = Ar × sin [{2π (Fc + Fd) × t} − {4π × R / λ} + θt]
[Equation 4] Vif1 = Ad × sin [{2π (Fd) × t} − {4π × R1 / λ}]
[Formula 5] Vif2 = Ad × sin [{2π (Fd) × t} − {4π × R2 / λ}]
[Equation 6] Vdl2 = Vif2-Vif1
= 2 * Ad * cos [{2 [pi] (Fd) * t}-{4 [pi] * (R2 + R1 / [lambda]}] * sin [{2 [pi] (Fd) * t}-{4 [pi] * (R2-R1) / [lambda]}].
= 2 * Ad * cos [{2 [pi] (Fd) * t}-{4 [pi] * (R2 + R1 / [lambda]}] * sin [{2 [pi] (Fd) * t}-{4 [pi] * (V * T) / [lambda]}].
= 2 * Ad * cos [{2 [pi] (Fd) * t}-{4 [pi] * (R2 + R1 / [lambda]}] * sin [{2 [pi] (Fd) * t}-{2 [pi] * Fd * T}].
Vt is a transmission wave, At is an envelope of the transmission wave, Fc is a carrier frequency [■] of the transmission wave, θt is a phase [°] of the transmission wave, Vr is a reflected wave, Ar Is the envelope of the reflected wave, Fd is the Doppler frequency [■] of the reflected wave, R is the distance [m] from the radar to the object, λ is the wavelength [m] of the transmitted wave, and Vif1 Is a received signal acquired at a certain time, Ar is an envelope of the received signal, Vif2 is a received signal acquired at the next timing after acquiring Vif1, Vdl2 is a differential signal, and v is a countermeasure It is a moving speed [m / s], and T is a time difference [s] between detection timings of two received signals to be subjected to a difference calculation.

  Further, in Equation 6, the pulse time width of the control signal in the pulse control unit is sufficiently small with respect to the reciprocal of the Doppler frequency of the object, and the frequency is almost negligible in the pulses detected in each received signal (as shown in FIG. 2). Assuming that the amplitude of the pulse is substantially constant), the first term of Equation 5 can be ignored, so the difference signal is given by Equation 6 from Equation 6.

[Equation 7] Vdl2 = Vif2-Vif1
= Ad × [sin {− (4π × R2 / λ)} − sin {− (4π × R1 / λ)}]
= 2 × Ad × [cos {4π × (R2 + R1) / λ}] × [sin {2π × Fd × T}]
JP 2003-222669 A

  However, in a radar apparatus using a conventional method for obtaining the distance of an object, when a time difference is made between two received signals, the Doppler frequency generated by the movement of the object is the reciprocal of the time difference of the detection timing between the received signals ( When it is an integral multiple of (Fd = 1 / T), the phase variation is rotated by an integral multiple of the period to have the same amplitude value, and the fluctuation component of the object may be removed.

  The present invention has been invented in view of the above-mentioned background art, and its problem is to adjust the time difference when obtaining the time difference, thereby improving the efficiency of the pulse radar device according to the moving speed of the desired object. Is to provide.

  In order to solve the above problems, in the invention according to claim 1 of the present application, a transmission unit that transmits a pulsed radio wave toward an object, and a pulse control unit that controls a time interval when intermittently transmitting the transmission unit A reception unit that receives a reflected wave from an object with a reception antenna, a history storage unit that stores a plurality of waveforms of reception signals from the reception unit, and a reception signal using a plurality of history signals from the history storage unit, The difference calculation unit for obtaining the difference of the difference, the detection unit for detecting the waveform rising timing of the difference signal obtained from the difference calculation unit, the control signal from the pulse control unit and the detection signal from the detection unit to determine the distance of the moving component And a distance calculation unit to be obtained.

  Further, in the invention according to claim 2 of the present application, in the pulse radar device according to claim 1, the difference calculation unit calculates a difference from the received signal by using a difference between the acquisition time differences of a plurality of history signals as a prime number. It is characterized by seeking.

  Further, in the invention according to claim 3 of the present application, in the pulse radar device according to claim 1, the difference calculation unit uses a signal whose ratio of the acquisition time difference of the plurality of history signals changes exponentially. It is characterized by obtaining a difference.

  In the invention according to claim 4 of the present application, the pulse radar device according to claim 1 is characterized in that a transmission / reception unit control unit for controlling the operation of the transmission unit and the reception unit is provided.

  Further, in the invention according to claim 5 of the present application, in the pulse radar device according to claim 1, a speed calculation unit that calculates the speed of the object for which the distance is calculated by the distance calculation unit, and an object that is calculated by the speed calculation unit. A history signal selection unit that selects a plurality of history signals to be provided to the difference calculation unit according to the speed, and the difference calculation unit uses a signal whose ratio of acquisition time difference of the plurality of history signals changes exponentially. After obtaining the difference between the received signal and the received signal, the difference from the received signal is obtained using a prime number.

  Further, in the invention according to claim 6 of the present application, in the pulse radar device according to claim 5, the speed calculation unit uses the phase fluctuation component due to the Doppler effect of the object from the difference signal obtained from the difference calculation unit. It is characterized by obtaining the speed of.

  Further, in the invention according to claim 7 of the present application, in the pulse radar device according to claim 5, the velocity calculation unit uses the time differential component of the distance measurement value of the object obtained from the distance calculation unit to detect the velocity of the object. It is characterized by seeking.

  In the pulse radar device according to the first aspect of the present invention, when the difference calculation unit compares the received waveform, and the Doppler frequency generated by the movement of the object is an integral multiple of the reciprocal of the time difference in detection timing between the received signals, Since the phase rotation due to the Doppler effect is an integral multiple of the cycle and the amplitude level of the moving component is the same, the amplitude level of the differential signal is lost and detection becomes impossible. However, since the phase rotation due to the Doppler effect does not become an integral multiple of the period between different timings, and the amplitude level of the moving component is different, the amplitude level of the differential signal is generated and can be detected. Therefore, when a difference calculation is performed, a plurality of difference signals are obtained using a plurality of history signals, so that detection can be performed regardless of the moving speed of a desired object.

  In the pulse radar device according to the second aspect of the present invention, in particular, since the difference calculation unit obtains the difference from the received signal using the difference between the acquisition time differences of the plurality of history signals as a prime number, Null points where the amplitude level is 0 can be complementarily covered, and a sufficient level can be detected equally according to the moving speed of the desired object.

  In the pulse radar device according to the third aspect of the present invention, in particular, since the difference calculation unit obtains the difference from the received signal by using the one in which the ratio of the acquisition time difference of the plurality of history signals changes exponentially, For example, it is possible to detect a wide range of moving speeds from a person who runs through to a person standing on the spot.

  In the pulse radar device according to the fourth aspect of the present invention, in particular, since a transmission / reception unit control unit for controlling the operation of the transmission unit and the reception unit is provided, the state of the object does not change suddenly. The power consumption can be greatly reduced by performing the difference calculation by intermittently operating the transmission unit and the reception unit and by waiting during the non-operation.

  In the pulse radar device according to the fifth aspect of the present invention, in particular, a speed calculation unit that calculates the speed of the object for which the distance is calculated by the distance calculation unit, and a difference calculation according to the speed of the object that is calculated by the speed calculation unit. And a history signal selection unit for selecting a plurality of history signals to be provided to the unit, and the difference calculation unit obtains a difference from the received signal using an index whose ratio of acquisition time differences of the plurality of history signals varies exponentially. After that, since the difference from the received signal is obtained using a prime number, the moving speed of the object can be detected over a wide range, and the object can be detected with a sufficient response level.

  In the pulse radar device according to the sixth aspect of the present invention, in particular, the velocity calculating unit obtains the velocity of the object using the phase fluctuation component due to the Doppler effect of the object from the difference signal obtained from the difference calculating unit. Therefore, it can be efficiently detected according to the moving speed of the desired object.

  In the pulse radar device according to the seventh aspect of the present invention, in particular, the speed calculation unit obtains the speed of the object using the time differential component of the distance measurement value of the object obtained from the distance calculation unit. It can be efficiently detected according to the moving speed of the object.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

  1 and 2 show a pulse radar device according to a first embodiment corresponding to claim 1 of the present application.

  As shown in FIG. 1, the pulse radar device includes a transmission unit 1 that transmits a pulsed radio wave toward an object, and a pulse control unit 2 that controls a time interval when the transmission unit 1 is intermittently transmitted. The reception unit 4 that receives the reflected wave from the object by the reception antenna 3, the history storage unit 5 that stores the waveform of the reception signal from the reception unit 4, and a plurality of history signals from the history storage unit 5 A difference calculation unit 6 for obtaining a difference from the received signal, a detection unit 7 for detecting the waveform rising timing of the difference signal obtained from the difference calculation unit 6, a control signal from the pulse control unit 2, and a detection signal from the detection unit 7 And a distance calculation unit 8 for determining the distance of the moving component using the.

  Next, the operation of this embodiment will be described based on the waveform of the received signal shown in FIG.

  Of the received signal, the stationary component due to unnecessary reflection and unnecessary background does not change and does not change in phase, but the moving component due to the object changes in the direction of the amplitude axis due to phase rotation due to the Doppler effect, and depends on the acquisition time of the received signal The amplitude level varies (see received signals 1 to 3 in the figure). When the received waveform is differentiated by the difference calculation unit, when the Doppler frequency generated by the movement of the object becomes an integral multiple of the time difference of the detection timing between the received signals (Fd = 1 / T1 in Equation 7), the Doppler effect Since the phase rotation is an integral multiple of the period and the amplitude level of the moving component is the same (see received signals 1 and 2 in the figure), the amplitude level of the differential signal disappears (see the differential signal 12 in the figure), and detection becomes impossible. However, during another timing (when T1 ≠ T2 and Fd ≠ 1 / T2 and T2 is not an integer multiple of T1) in another timing, the phase rotation due to the Doppler effect does not become an integral multiple of the period, and the movement component Since the amplitude levels are different (see the received signals 1 and 3 in the figure), the amplitude level of the differential signal is generated (see the differential signal 13 in the figure) and can be detected.

  Therefore, in the pulse radar device of this embodiment, it is possible to detect regardless of the moving speed of a desired object by obtaining a plurality of difference signals using a plurality of history signals when performing a difference calculation.

  FIG. 3 shows the amplitude level of the differential signal of the pulse radar device according to the second embodiment corresponding to claims 1 and 2 of the present application. Here, only matters different from those in the first embodiment will be described, and other matters are the same as those in the first embodiment, and thus description thereof will be omitted.

  For example, if the Doppler frequency generated by the moving speed (v1) of the object is the reciprocal of the time difference of the detection timing (T1) between the received signals (Fd = 1 / T1 in Equation 7), the phase rotation due to the Doppler effect Is one cycle and the amplitude level of the moving component is the same, the amplitude level of the differential signal is lost and detection becomes impossible. Also, the amplitude level of the differential signal decreases as the moving speed of the object approaches 0 or v1, and if the desired response level is set as a threshold in the system, the response speed range of the object that can satisfy the desired level is limited. End up. However, for example, if the difference is performed every two waveforms (2 × T1) of the received signal detection timing, the amplitude level disappears every half (1/2 × v1) of the moving speed of the object, but the desired response level is reduced. The upper and lower limit values of the response speed range that is satisfied widen, and when the difference calculation is performed for each waveform of the received signal detection timing for every two waveforms, the response speed range becomes wider.

  Therefore, in the pulse radar device of this embodiment, a null point where the other amplitude level is 0 is obtained by obtaining a difference from the received signal by using a signal whose ratio of acquisition time differences of a plurality of history signals is a prime number. Complementary coverage is possible, and a sufficient level can be detected equally according to the desired moving speed of the object.

  FIG. 4 shows the amplitude level of the differential signal of the pulse radar device according to the third embodiment corresponding to claims 1 and 3 of the present application. Here, only matters different from those in the first embodiment will be described, and other matters are the same as those in the first embodiment, and thus description thereof will be omitted.

  When the difference is performed for each waveform, the amplitude level of the difference signal decreases as the moving speed of the object approaches 0 or v1, and when the desired response level is set as a threshold in the system, the object that can satisfy the desired level. The response speed range is limited. However, if the difference is such that the ratio of the acquisition time differences of the plurality of history signals changes exponentially, for example, every waveform (T1), every 5 waveforms (5 × T1), every 25 waveforms (25 When the difference is performed every time difference of 5 times as in (T1), the response level threshold is slightly lower than the previous one, but the limit of the response speed range (for example, the lower limit) is 1/5 × v1, 1/25 × v1 and 1/125 × v1 increase exponentially.

  Therefore, in the pulse radar device of this embodiment, for example, it is possible to detect a wide range of moving speeds from a person who runs through to a person standing on the spot.

  FIG. 5 shows a pulse radar device according to a fourth embodiment corresponding to claims 1 and 4 of the present application. Here, only matters different from those in the first embodiment will be described, and other matters are the same as those in the first embodiment, and thus description thereof will be omitted.

  As shown in FIG. 5, the pulse radar device includes a transmission / reception unit control unit 11 that controls operation / stop of the transmission unit 1 and the reception unit 4 by a plurality of history signals from the history storage unit 5.

  Therefore, in the pulse radar device of this embodiment, when the state of the object does not change so rapidly, every 1 waveform (T1), every 5 waveforms (5 × T1), every 25 waveforms (25 × In T1), the transmission unit 1 and the reception unit 4 are intermittently operated to perform a difference calculation, and when not operating, the power consumption can be significantly reduced.

  FIG. 6 shows a pulse radar device according to a fifth embodiment corresponding to claims 1 and 5 of the present application. Here, only matters different from those in the first embodiment will be described, and other matters are the same as those in the first embodiment, and thus description thereof will be omitted.

  As shown in FIG. 6, the pulse radar device includes a speed calculation unit 9 that calculates the speed of the object obtained by the distance calculation unit 8, and a difference calculation unit 6 according to the speed of the object obtained by the speed calculation unit 9. And a history signal selection unit 10 for selecting a plurality of history signals to be provided.

  Therefore, in the pulse radar device of this embodiment, the difference calculation unit 6 is one in which the ratio of the acquisition time differences of a plurality of history signals changes exponentially, for example, every 1 waveform (T1), every 5 waveforms (5 × T1), the difference calculation is performed on the history signal for every 25 waveforms (25 × T1), and the response level is lowered, but the moving speed of the object can be detected in a wide range. And after that, by obtaining the difference from the received signal using the one whose ratio of the acquisition time difference of the plurality of history signals is a prime number according to the moving speed of the detected object, the object is obtained with a sufficient response level. Can be detected.

  In the pulse radar device according to the sixth embodiment corresponding to claims 1, 5, and 6 of the present application, the Doppler of the object is obtained from the difference signal obtained from the difference calculation unit in the speed calculation unit as shown in Expressions 8 to 10. The speed of the object can be obtained using the phase fluctuation component due to the effect. Therefore, when the receiving unit performs quadrature detection, an IQ quadrature output is obtained as an IF signal, which is given by the following equation from Equation 7.

[Expression 8] Vdil12 = Vifi2-Vifi1
= Ad × [sin {− (4π × R2 / λ)} − sin {− (4π × R1 / λ)}]
= 2 × Ad × [cos {4π × (R2 + R1) / λ}] × [sin {2π × Fd × T}]
[Equation 9] Vdql2 = Vifq2-Vifq1
= Ad × [cos {− (4π × R2 / λ)}-cos {− (4π × R1 / λ)}]
= −2 × Ad × [sin {4π × (R2 + R1) / λ}] × [sin {2π × Fd × T}]
Therefore, if Vdil2 and Vdql2 are obtained, the Doppler frequency Fd of the object can be obtained from Expressions 8 and 9, and can be converted into the moving speed of the object using Expression 10 shown below.

[Equation 10] v = λ / 2 × Fd
Therefore, in the pulse radar device of this embodiment, it is possible to detect efficiently according to the moving speed of the desired object.

  The pulse radar device according to the seventh embodiment corresponding to claims 1, 5, and 7 of the present application uses the time differential component of the distance measurement value of the object obtained from the distance calculation unit as shown in the following Expression 11. The speed of the object can be determined. Therefore, the moving speed of the object is given by the following equation from Equation 11 as the moving distance in the time difference of the received signal detection timing.

[Equation 11] v = (R2-R1) / T
Therefore, in the pulse radar device of this embodiment, it is possible to detect efficiently according to the moving speed of the desired object.

The block diagram which shows the pulse radar apparatus which is 1st embodiment of this invention. The figure which shows the waveform of the pulse radar system of the pulse radar apparatus. The figure which shows the amplitude level of the difference signal of the pulse radar apparatus which is 2nd embodiment of this invention. The figure which shows the amplitude level of the difference signal of the pulse radar apparatus which is 3rd embodiment of this invention. The block diagram which shows the pulse radar apparatus which is 4th embodiment of this invention. The block diagram which shows the pulse radar apparatus which is 5th embodiment of this invention. The block diagram which shows the pulse radar apparatus which is a prior art example. The figure which shows the pulse radar waveform of the pulse radar apparatus. The block diagram of the radar apparatus of the MTI system which is a prior art example. The figure which shows the waveform of the MTI radar system of the radar apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Pulse control part 3 Reception antenna 4 Reception part 5 History storage part 6 Difference calculation part 7 Detection part 8 Distance calculation part 9 Speed calculation part 10 History signal selection part 11 Transmission / reception part control part

Claims (7)

  A transmission unit that transmits a pulsed radio wave toward an object, a pulse control unit that controls a time interval when intermittently transmitting the transmission unit, a reception unit that receives a reflected wave from the object with a reception antenna, A history accumulating unit that accumulates a plurality of waveforms of received signals from the receiving unit, a difference calculating unit that obtains a difference from the received signal using a plurality of history signals from the history accumulating unit, and a difference signal obtained from the difference calculating unit A pulse radar apparatus comprising: a detection unit that detects a waveform rising timing; and a distance calculation unit that obtains a distance of a moving component using a control signal from a pulse control unit and a detection signal from the detection unit.   The pulse radar device according to claim 1, wherein the difference calculation unit obtains a difference from the received signal using a signal whose ratio of acquisition time differences of a plurality of history signals is a prime number.   2. The pulse radar device according to claim 1, wherein the difference calculation unit obtains a difference from the received signal by using a signal whose ratio of acquisition time differences of a plurality of history signals changes exponentially.   2. The pulse radar apparatus according to claim 1, further comprising a transmission / reception unit control unit that controls operations of the transmission unit and the reception unit.   A speed calculation unit that calculates the speed of the object for which the distance was calculated by the distance calculation unit, a history signal selection unit that selects a plurality of history signals to be provided to the difference calculation unit according to the speed of the object determined by the speed calculation unit, The difference calculation unit obtains the difference from the received signal using the one whose ratio of the acquisition time differences of the plurality of history signals changes exponentially, and then obtains the difference from the received signal using the prime number The pulse radar device according to claim 1.   6. The pulse radar device according to claim 5, wherein the velocity calculation unit obtains the velocity of the object using a phase fluctuation component due to the Doppler effect of the object from the difference signal obtained from the difference calculation unit.   6. The pulse radar device according to claim 5, wherein the speed calculation unit obtains the speed of the object using a time differential component of the distance measurement value of the object obtained from the distance calculation unit.

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