• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    PURPOSE: To detect and correct frequency modulation characteristic using a simple configuration and at a low cost in a radar apparatus. CONSTITUTION: A modulated-signal generation circuit 29 frequency-modulates a VOC 24 by triangular waves indicated in Fig. (b), so as to operate as an FM-CW type radar 21. A signal processing circuit 30 generates a detection modulating signal, indicated in Fig. (c) from the circuit 29 so as to be given to the VOC 24. A high-frequency signal, which is frequency-modulated by the VOC 24, is transmitted as radio waves from a transmitting antenna 22, and it is reflected by a target, so as to be received by a receiving antenna 24. On the basis of the received signal and the high-frequency signal, a beat signal is obtained by a mixer 26, and a frequency shift with reference to a voltage V1 is detected on the basis of the frequency of the beat signal. When the voltage V1 of the detected modulating signal is changed over, a frequency shift corresponding to a different voltage V1 is obtained, and the frequency modulation characteristics can be detected.
    公开号:KR20030007099A
    申请号:KR1020020039965
    申请日:2002-07-10
    公开日:2003-01-23
    发明作者:이사지오사무
    申请人:후지쓰 텐 가부시키가이샤；
    IPC主号:
    专利说明:

    Radar Device {RADAR APPARATUS}
    [31] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus using frequency modulation (FM), such as the FM-CW system, and particularly to the detection and correction of its frequency modulation characteristics.
    [32] Conventionally, the FM-CW system radar 1 having a basic configuration as shown in Fig. 16 is mainly mounted on an automobile and used for collision warning, collision prevention and reduction, intervehicle control of automatic cruise control, automatic driving, and the like. 16A shows a schematic electrical configuration, and FIG. 16B shows a modulated signal waveform. Prior arts relating to FM-CW radars are disclosed in, for example, Japanese Patent Application Laid-Open No. 5-40169, Japanese Patent Application Laid-Open No. 7-55942, Japanese Patent Application Laid-Open No. 8-327728, and the like. Japanese Patent Laid-Open No. 5-40169 discloses a technique for improving the reception S / N ratio by using a second frequency modulation.
    [33] In the basic configuration of the FM-CW system radar 1, as shown in FIG. The transmission antenna 2 is given a high-frequency signal of the millimeter wave generated from the VCO 4 which is a voltage controlled oscillator. A part of the high frequency signal which excites the transmission antenna 2 from the VCO 4 is offset from the coupler 5 and mixed with the reception signal from the reception antenna 3 in the mixer 6. The output signal from the mixer 6 is selected from B.P.F.7, which is a bandpass filter, and amplified by the amplifier 8. The high frequency signal generated from the VCO 4 is frequency modulated in accordance with the voltage level of the modulated signal given from the modulated signal generating circuit 9.
    [34] For example, in the FM-CW system radar 1 of the millimeter wave, an FM modulated wave having a maximum frequency shift amount of about tens to hundreds of MHz by using a modulation signal having a triangular waveform of several hundred Hz as shown in Fig. 16A. Occurs. As the modulated signal, a top wave (chirp wave) is sometimes used. If the frequency modulation characteristic of VCO4 is good in linearity with respect to the change in the voltage level of the modulated signal, the frequency of the high frequency signal generated from VCO4 also changes linearly in correspondence with Fig. 16 (b). The frequency of the reflected radio wave received by the reception antenna 3 is delayed from the frequency of the high frequency signal given to the transmission antenna 2 by the time when the radio waves round the distance to the target. When a high frequency signal whose frequency changes from VCO4 to a triangular waveform corresponding to Fig. 16 (b) is generated, and the distance to the target is constant, the signal output from the mixer 6 at the time when the radio wave reciprocates the distance. Corresponding constant frequency bit signal components are included. This bit signal component is selected by B.P.F.7, amplified by the amplifier 8, and input to the signal processing circuit 10 to calculate the distance to the target object. In addition, when the distance to the target changes, the influence of the Doppler shift appears on the frequency of the bit signal, and the relative speed can be calculated in the signal processing. If the frequency of the bit signal is fb, the frequency depending on the distance is fx, and the frequency depending on the relative speed is fd,
    [35] fb = fx ± fd
    [36] to be.
    [37] In the FM-CW system radar 1, the frequency modulation characteristic in the VCO 4 has an important influence on the measurement accuracy. Japanese Patent Application Laid-Open No. 7-55924 describes a technique for measuring the frequency modulation characteristics of a voltage controlled oscillator generating a high frequency signal of an FM-CW system radar in advance, correcting them with an inverse function of the measured characteristics, and improving linearity. Is disclosed. Japanese Unexamined Patent Application Publication No. 8-327728 discloses a technique for correcting a modulated signal such that the frequency of the high frequency signal generated by the FM-CW radar device changes to a triangular waveform. Further, Japanese Patent Laid-Open No. 6-34756 discloses a linearity of a voltage controlled oscillator that generates a high frequency signal serving as a transmission source in a radar transponder that transmits and responds by transmitting a frequency modulated radio wave when receiving a radio wave from a radar. The technique of correcting the correction by data previously stored in the memory is disclosed. However, these prior arts do not directly describe how to measure the frequency modulation characteristics.
    [38] Fig. 17 shows a schematic configuration for measuring modulation frequency characteristics in the conventional FM-CW system radar 1 shown in Fig. 16A and detecting whether or not linearity is maintained. A separate signal source 11 is prepared, the high frequency signal from VCO4 is branched at the coupler 12, mixed at the mixer 13 and down-converted, and at the counter 14, the frequency of the signal source 11 is adjusted. Counts the difference. In addition to the downlink frequency conversion, there is also a method of counting the frequency of the high frequency signal from the VCO4.
    [39] The FM-CW system radar 1 mounted on an automobile is used in a harsh environment regarding vibration, temperature, and the like. For this reason, even if the linearity of the frequency modulation characteristic is satisfactory initially, there is a possibility of deterioration during use. Even if the FM-CW system radar 1 itself is equipped with a configuration for detecting the linearity of the frequency characteristic, if the configuration of the down-frequency converter as shown in Fig. 17 is employed, the signal source 11 or mixer 13 can be used. Expensive millimeter wave high frequency use is required. When counting the frequency of the high frequency signal from VCO4, it is not possible to directly count the millimeter wave band, so it is necessary to use a divider. However, if the divider operating in the millimeter wave band is expensive and the division ratio becomes large, Measurement accuracy falls.
    [40] That is, when the frequency modulation characteristic is detected or corrected in the conventional system as shown in Fig. 17, there are the following problems.
    [41] (1) The higher the transmission frequency, the higher the role of components such as detectors and dividers.
    [42] (2) The higher the transmission frequency, the greater the division ratio and the worse the measurement accuracy.
    [43] SUMMARY OF THE INVENTION An object of the present invention is to provide a radar apparatus capable of inexpensively realizing detection and correction of frequency modulation characteristics with a simple configuration.
    [1] Fig. 1 is a block diagram showing a schematic electrical configuration of an FM-CW system radar 21, which is a first embodiment of the present invention, and a waveform diagram of a modulation signal and a detection modulation signal.
    [2] FIG. 2 is a time chart showing a principle in which frequency shift can be obtained based on a detection modulated signal in the embodiment of FIG. 1.
    [3] 3 is a graph showing an example of frequency modulation characteristics of the VCO 24 of FIG.
    [4] FIG. 4 is a waveform diagram of the detection modulated signal generated by the modulation signal generation circuit 29 of FIG. 1 and a time chart of the obtained bit signal.
    [5] FIG. 5 is a waveform diagram of the detection modulated signal generated by the modulation signal generation circuit 29 of FIG. 1 and a time chart of the obtained bit signal.
    [6] Fig. 6 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 31 according to the second embodiment of the present invention.
    [7] Fig. 7 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 41 according to the third embodiment of the present invention.
    [8] Fig. 8 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 61 which is the fourth embodiment of the present invention.
    [9] 9 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 71 according to the fifth embodiment of the present invention.
    [10] FIG. 10 is a flowchart showing a processing procedure in the embodiment of FIGS. 8 and 9.
    [11] Fig. 11 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 81 as the sixth embodiment of the present invention.
    [12] Fig. 12 is a block diagram showing the electrical configuration of the signal processing circuit 100 of the FM-CW system radar which is the seventh embodiment of the present invention.
    [13] Fig. 13 is a block diagram showing the schematic electrical configuration of the FM-CW system radar 111 as the eighth embodiment of the present invention.
    [14] FIG. 14 is a block diagram showing a configuration example of the signal source 12 of the embodiment of FIG. 13.
    [15] Fig. 15 is a block diagram showing a schematic electrical configuration of the FM-CW system radar 121 as the ninth embodiment of the present invention.
    [16] Fig. 16 is a block diagram showing a schematic electrical configuration of a conventional FM-CW system radar 1 and a waveform diagram of a modulation signal.
    [17] FIG. 17 is a block diagram showing an electrical configuration for detecting frequency modulation characteristics in the FM-CW system radar of FIG.
    [18] (Explanation of symbols for the main parts of the drawing)
    [19] 21, 31, 41, 61, 71, 81, 111, 121... FM-CW radar
    [20] 22. Transmit antenna 23. Receiving antenna
    [21] 24. VCO 26, 113, 127... Mixer
    [22] 29, 49... Modulation signal generation circuit
    [23] 30, 40, 50, 70, 80, 90, 100, 120, 130... Signal processing circuit
    [24] 32. Modulated signal correction circuit 42. D / A Converter
    [25] 51. Memory 62, 72, 102, 122... A / D Converter
    [26] 63, 124. Microcomputer 74. Detection circuit
    [27] 75... Transducer 82. temperature Senser
    [28] 104. Frequency counters 112, 125. Signal
    [29] 114. Changeover switch 116, 117, 118, 119... oscillator
    [30] 126. Gate switch
    [44] The present invention provides a radar device for frequency-modulating and transmitting a high frequency signal, and receiving a reflected wave to detect a target.
    [45] Modulated signal generating means for generating and applying a modulated signal to the high frequency generating means for generating a high frequency signal to modulate the high frequency signal;
    [46] Mixing means for mixing the high frequency signal generated from the high frequency generating means and the received signal of the reflected radio wave; And
    [47] The modulation signal generating means is controlled so as to give the high frequency generating means a detection modulated signal that changes between a plurality of predetermined signal levels and maintains a predetermined time for each signal level, and the high frequency signal and the received signal input from the mixing means. And signal processing means for detecting the frequency of the differential signal and detecting the frequency modulation characteristic of the high frequency generating means based on the relationship between the signal level of the detection modulated signal and the frequency of the differential signal.
    [48] According to the present invention, a radar device for frequency-modulating and transmitting a high frequency signal, and receiving a reflected wave to detect a target includes a modulation signal generating means, a mixing means, and a signal processing means. The modulated signal means generates a modulated signal capable of controlling the change state to the high frequency generating means. The mixing means mixes the high frequency signal generated from the high frequency generating means and the received signal of the reflected radio wave. The signal processing means controls the modulation signal generating means so as to give the high frequency generating means a detection modulated signal which varies between a plurality of predetermined signal levels, and the predetermined time is maintained for each signal level, and the high frequency signal from the mixing means. And a frequency is detected by inputting a signal of a component of the difference between the received signal and the frequency modulation characteristic of the high frequency generating means based on the relationship between the signal level and the frequency of the detection modulated signal. The detection modulated signal generated from the modulated signal generating means is changed between a plurality of predetermined signal levels, mixed with the received signal from the target and mixed in the mixing means to detect the frequency of the signal of the difference component, and the detection modulated signal. The relationship between the signal level and the frequency can be obtained to detect the frequency modulation characteristic of the high frequency generating means. Since the reception signal is used as the signal source of the high frequency for frequency characteristic detection, and the mixing means can also share the reception, the frequency modulation characteristic can be detected simply with an inexpensive configuration.
    [49] The present invention further includes modulation characteristic correction means for correcting the modulated signal based on the frequency modulation characteristic detected by the signal processing means so that the frequency modulation characteristic does not deviate from a predetermined normal range. It is done.
    [50] According to the present invention, since the modulated signal is corrected so that the modulated frequency characteristic, which can be easily detected with a cheap structure, does not deviate from a predetermined normal range, the correction of the frequency modulated characteristic can be performed simply with a cheap structure.
    [51] Further, the present invention is based on the frequency modulation characteristic detected by the signal processing means, the width calculation that calculates the frequency modulation width which is the difference between the frequency when the signal level of the modulation signal is the maximum value and the frequency when the minimum value It further comprises a means.
    [52] According to the present invention, the frequency modulation width, which is the difference between the frequencies when the signal level of the modulation signal is the maximum value and the minimum value, can be calculated based on the frequency modulation characteristic detected as a change in frequency between the plurality of signal levels. have.
    [53] Further, in the present invention, the explosion calculation means is provided with a counter for counting the frequency of the difference.
    [54] According to the present invention, since the change in frequency between a plurality of signal levels is counted by a counter, the change in frequency can be easily measured.
    [55] Further, the present invention is characterized by further comprising width correction means for correcting the modulated signal such that the frequency modulation width is a predetermined value based on the frequency modulation width calculated by the width calculation means.
    [56] According to the present invention, the frequency modulation width of the frequency modulation characteristic can also be corrected to a predetermined value. In addition, it is also possible to correct | amend on a calculation at the time of distance calculation in a signal processing part.
    [57] Further, in the present invention, the modulation characteristic correction means or the width correction means is characterized in that the correction is performed when the level of the received signal of the reflected radio wave is more than a predetermined level.
    [58] According to the present invention, when the level of the received signal is higher than or equal to the predetermined level, correction can be performed and the correction can be performed stably.
    [59] In addition, the present invention further includes a temperature detecting means,
    [60] The modulation characteristic correcting means or the width correcting means performs correction when the temperature detected by the temperature detecting means becomes a predetermined temperature.
    [61] According to the present invention, even when the frequency of the high frequency signal generated from the high frequency generating means changes in accordance with the temperature, correction is performed when the temperature detecting means reaches a predetermined temperature, thereby reducing the influence of the temperature and precision of the frequency modulation characteristics. Can improve.
    [62] In the present invention, the modulation characteristic correction means or the width correction means is characterized in that the correction is performed when the distance of the target is a predetermined distance range.
    [63] According to the present invention, since the distance range or the like where the signal level of the received signal is likely to be lowered out of the predetermined distance range does not enter the correction process, it is possible to avoid the degradation of the accuracy of correction.
    [64] In the present invention, the modulation characteristic correction means or the width correction means is characterized in that the correction is performed when the relative speed of the target is a predetermined speed range.
    [65] According to the present invention, correction is performed when the speed is within a predetermined speed range in consideration of the relative speed of the target, so that the accuracy of the correction can be improved.
    [66] In the present invention, the signal processing means detects the frequency characteristic when the input level for receiving the reflected radio wave from the target is higher than or equal to a predetermined reference level during normal radar operation.
    [67] According to the present invention, since the frequency modulation characteristic is detected when the input level of the received signal is equal to or greater than a predetermined reference level, it is possible to concentrate on the normal target detection process.
    [68] In the present invention, the signal processing means is characterized in that the detection of the frequency characteristic when the distance of the target is a predetermined distance range.
    [69] According to the present invention, since the frequency modulation characteristic is detected when the distance to the target is out of the predetermined distance range, it is possible to concentrate on the normal target detection processing.
    [70] Further, in the present invention, the signal processing means detects the frequency characteristic immediately after the first detection of the target after the start of the radar operation, and determines whether the normal modulation operation for the high frequency generating means is performed. It is characterized by determining.
    [71] According to the present invention, when the target is initially detected and the reflected wave can be received, it is determined whether or not the frequency modulation characteristic of the high frequency generating means is normal, so that an abnormality can be detected early.
    [72] The present invention further includes a reference signal source for generating a reference signal for reducing a frequency with respect to the difference signal between the high frequency signal and the received signal input from the mixing means to the signal processing means,
    [73] The signal processing means inputs a difference signal whose frequency is reduced by the reference signal, and detects the frequency characteristic.
    [74] According to the present invention, since the reference signal generated from the reference signal source is heterodyned and the frequency is reduced with respect to the component of the difference between the high frequency signal and the received signal obtained by the mixing means, frequency measurement can be easily performed.
    [75] In the present invention, the reference signal source,
    [76] Basic signal generating means for generating a basic signal that is the basis of the mood signal; And
    [77] And dividing means for dividing the frequency of the basic signal generated from the basic signal generating means into a plurality of switchable division ratios to convert the frequency into a reference signal.
    [78] According to the present invention, it is possible to switch the frequency division ratio of the division means, switch the frequency of the reference signal obtained by dividing the basic signal generated from the basic signal generation means, and lower the frequency to improve the accuracy of frequency measurement.
    [79] In the present invention, the reference signal source,
    [80] Having a plurality of reference signal generating means,
    [81] By selecting any one of the reference signal generating means,
    [82] The reference signal is generated from the selected reference signal generating means.
    [83] According to the present invention, it is possible to determine the frequency to be measured by switching a plurality of reference signal generating means, generating a reference signal, and comparing the signal components obtained by switching, thereby improving accuracy.
    [84] In the present invention, the reference signal source is characterized in that it comprises signal calculation means for generating the reference signal by arithmetic processing according to a preset program.
    [85] According to the present invention, a reference signal of a frequency suitable for measuring a frequency can be generated to improve measurement accuracy.
    [86] In the present invention, the reference signal source is characterized in that for supplying a signal operation processing clock signal to the signal processing means.
    [87] According to the present invention, since the generation of the reference signal and the supply of the clock signal to the signal processing means can be performed from a common reference signal source, space saving and cost reduction can be achieved.
    [88] In the present invention, the frequency of the reference signal is set so that the difference from the frequency of the received signal from the target is within the bit signal band during the radar operation.
    [89] According to the present invention, since the reference signal set in the bit signal band is used, it is possible to lower the band of the difference frequency obtained by heterodyning and to improve the measurement accuracy.
    [90] In the present invention, the signal processing means performs at least a part of the processing of the bit signal.
    [91] According to the present invention, since the processing of the bit signal and the processing of the detection of the frequency characteristic are carried out at least partly in common, the overall configuration can be simplified and can be realized at low cost.
    [92] In the present invention, the signal processing means is characterized in that a predetermined time for maintaining the signal level of the detection modulated signal is changed in accordance with the distance to the target.
    [93] According to the present invention, it is possible to optimize the detection of the frequency modulation characteristics with respect to the distance to the target, and to improve the detection accuracy.
    [94] In the present invention, the signal processing means is characterized in that a predetermined time for maintaining the signal level of the detection modulated signal is changed in accordance with the relative speed of the target.
    [95] According to the present invention, it is possible to increase the detection accuracy of the frequency characteristic in consideration of the relative speed with the target.
    [96] In the present invention, the signal processing means is characterized in that it detects the frequency of the difference signal between the high frequency signal and the received signal in consideration of the Doppler shift based on the relative speed of the target.
    [97] According to the present invention, even when it is difficult to see a relatively stationary target in the case of being mounted on an automobile, the frequency modulation characteristic can be detected with high precision in consideration of the Doppler shift.
    [98] EMBODIMENT OF THE INVENTION Hereinafter, each form of embodiment of this invention is described based on drawing. In each embodiment, the part corresponding to embodiment mentioned above is attached | subjected with the same code | symbol, and the overlapping description is abbreviate | omitted. Moreover, you may combine several embodiment in the range which does not overlap with each other. In addition, a description may be abbreviate | omitted in the common part with previous embodiment.
    [99] Fig. 1 shows a schematic electrical configuration of the FM-CW system radar 21 according to the first embodiment of the present invention, and the waveforms of the modulation signal and the detection modulation signal. The basic structure of the FM-CW system radar 21 of this embodiment is the same as that of the conventional FM-CW system radar 1 shown to Fig.16 (a). That is, the transmission antenna 22, the reception antenna 23, the VCO 24, the coupler 25, the mixer 26, the BPF 27, the amplifier 28, the modulated signal fish circuit 29 and the signal processing circuit (30). Radio waves are transmitted from the transmission antenna 22, and the reflected radio waves from the target and the like are received by the reception antenna 23. The transmission antenna 22 is given a high-frequency signal of the millimeter wave generated from the VC0 24 which is a voltage controlled oscillator. A part of the high frequency signal which excites the transmission antenna 22 from the VCO 24 branches from the Doppler 25 and is mixed with the reception signal from the reception antenna 23 in the mixer 26. The bit signal in the output signal from the mixer 26 is selected by B.P.F.27, which is a bandpass filter, and amplified by the amplifier 28. The high frequency signal generated from the VCO 24 is frequency modulated in accordance with the voltage level of the modulated signal given from the modulated signal generating circuit 29. The bit signal is processed by the signal processing circuit 30, and the distance and relative speed of the target are calculated.
    [100] For example, the millimeter-band FM-CW radar 21 uses a modulated signal of several hundred Hz triangular waveform as shown in FIG. Occurs. A sawtooth wave (chirp wave) may be used as the modulated signal. Normal operation of the FM-CW system radar 21 is similar to that of the conventional FM-CW system radar 1 shown in FIG. In this embodiment, the voltage as shown in Fig. 1 (c) from the modulation signal generation circuit 29 indicates whether the frequency modulation characteristics of the VCO 24 are good in linearity with respect to the change in the voltage level of the modulation signal. A rectangular waveform detection modulated signal that changes in V1) is supplied to the VCO 24 to enable detection.
    [101] FIG. 2 shows a theory in which a single shift component of frequency modulation corresponding to the modulation signal for detection of the rectangular waveform shown in FIG. 1C is obtained. With respect to the change in the voltage V1 as shown in Fig. 1C, the frequency shifting component ΔF is obtained from the VC24. This frequency shifting component ΔF is obtained at a point A in Fig. 1A, as shown in Fig. 2A, and is substantially the same as the waveform transmitted from the transmission antenna 22. Figs. At point B of FIG. 1 (a) received by the reception antenna 23 after being reflected on the target, the phase is delayed as shown in FIG. 2 (b) based on the propagation delay of the radio wave. At point C on the output side of the mixer 26 shown in Fig. 1A, as shown in Fig. 2C, a bit signal having a frequency of ΔF is obtained for the propagation delay period. If the relative velocity between the target and the target is not zero, the Doppler shift component is also included, but it is about several kHz. Since the frequency ΔF of the bit signal is several MHz to several 10 MHz, the influence of the Doppler shift component is small.
    [102] 3 shows an example of frequency modulation characteristics in the VCO 24 of FIG. The frequency shift amount between the minimum value V1 which is the lower limit voltage of the modulation signal and the maximum value V2 which is the upper limit voltage is obtained by multiplying the frequency shift value Fn corresponding to the section voltage Vn. As a modulation signal for detection, a method of changing the voltage level between V1 and V2 is to change the step shape as shown in FIG. 4 and to change the peak value of the pulse shape as shown in FIG. Is considered.
    [103] Fig. 4 shows the waveform of the detection modulated signal changing in step shape in (a), and shows the frequency shift of the bit signal in (b). Fig. 5 shows waveforms of a detection modulation signal that changes in a pulse shape in (a), and shows frequency shift of a bit signal in (b). In the frequency shift of FIG. 4 (b) corresponding to the stepped voltage change in FIG. 4 (a), the modulation width is obtained by multiplying each frequency shift component by the following equation (1). As for the voltage change in the pulse shape as shown in Fig. 5A, the last frequency shifting component shown in Fig. 5B is a multiplication value.
    [104] (Wed 1)
    [105] ...(One)
    [106] In this embodiment, a triangular waveform modulated signal is given to the VCO 24, which is a high frequency generating means, to generate a high frequency signal whose frequency changes, and to transmit radio waves from the transmission antenna 22 based on the generated high frequency signal. The FM-CW system radar 21 which receives the reflected radio wave and detects a target object includes a modulated signal generating circuit 29 which is a modulation signal generating means, a mixer 26 which is a mixing means and a signal processing circuit which is a signal processing means ( 30). The modulated signal generation circuit 29 generates a detection modulated signal capable of controlling the state of defense in the VCO 24. The mixer 26 mixes the high frequency signal generated from the VCO 24 and the received signal of the reflected radio wave. As shown in Fig. 4 (a) or 5 (a), the signal processing circuit 30 changes the detection modulation signal between the predetermined plurality of signal levels and maintains a predetermined time for each signal level. The modulation signal generation circuit 29 is controlled to give to (24). The signal processing circuit 30 inputs a signal of a component of the difference between the high frequency signal and the received signal from the mixer 26 to detect the frequency, and based on the relationship between the signal level and the frequency of the detection modulated signal, the VCO 24 Detect the frequency modulation characteristic of. Since the reception signal is used as the signal source of the high frequency for frequency characteristic detection, and the mixer 26 can also share the reception, the frequency modulation characteristic can be detected simply with an inexpensive configuration.
    [107] Fig. 6 shows a schematic electrical configuration of the FM-CW system radar 31 according to the second embodiment of the present invention. In the present embodiment, a modulated signal of the triangular wave generated by the modulated signal generating circuit 29 is corrected by the modulated signal correcting circuit 32 and given to the VCO 24. The modulated signal correction circuit 32 corrects the modulated signal in accordance with the correction signal given by the new processing circuit 40. As in the first embodiment, the signal processing circuit 30 generates a correction signal so that the frequency modulation characteristic to be detected does not deviate from a predetermined normal range. The frequency modulation characteristic corrects the linearity indicating the linearity range and the modulation width indicating the upper and lower limits. As the linearity correction, a line circuit or the like can be used. A gain control amplifier, a variable attenuator, or the like can be used to correct the modulation width. The modulation signal correction circuit 32 functions as a range correction means if the linearity correction is to be performed, and as a modulation characteristic correction means if the modulation width is corrected.
    [108] Fig. 7 shows a schematic electrical configuration of the FM-CW system radar 41 according to the third embodiment of the present invention. In this embodiment, the D / A converter 42 is included in the modulation signal generating circuit 49, and a digital signal representing modulation data given from the signal processing circuit 50 is converted into an analog signal to generate a modulation signal. do. The signal processing circuit 50 detects the frequency modulation characteristic and corrects the characteristic as in the first embodiment. The modulation data is stored in the internal memory 51. In this embodiment, the memory 51 functions as range correction means and width correction means.
    [109] In the embodiment shown in Figs. 6 and 7, since the modulated signal is corrected so that the modulated frequency characteristic that can be easily detected with the cheaper configuration does not deviate from the predetermined normal range, the correction of the frequency modulated characteristic can also be easily performed with the cheaper configuration. have.
    [110] Fig. 8 shows a partial electrical configuration of the FM-CW system radar 61 which is the fourth embodiment of the present invention. In the present embodiment, the bit signal output from the amplifier 28 is converted into a digital signal by the A / D converter 62, and the signal level is obtained by the DSP 64, which is a digital signal processor, or the FFT processing 63 by a microcomputer. Obtain The FFT process 63 is a fast Fourier transform process and is realized by program operation such as the DSP 64. The signal processing circuit 70 of this embodiment includes an A / D converter 62 and a DSP 64. The signal level of the bit signal can be determined with respect to any reference level.
    [111] 9 shows a partial electrical configuration of the FM-CW system radar 71 according to the fifth embodiment of the present invention. In this embodiment, the bit signal is detected by the detection circuit 74, and the converter 75 compares with the reference signal to determine the signal level. The reference signal given to the converter 75 converts the bit signal into a digital signal by the A / D converter 72 and sets it as arithmetic processing in the microcomputer 73, the DSP 73, the DSP, or the like. The signal processing circuit 80 of this embodiment includes an A / D converter 72 and a microcomputer 73.
    [112] FIG. 10 shows the processing procedure for detecting the frequency modulation characteristic in accordance with the embodiment of FIGS. 8 and 9 in accordance with the signal level of the received signal. The procedure starts from step a0. In step a1, the bit signal level is calculated as a normal FM-CW radar. In step a2, it is determined whether the bit signal level is larger than the set reference level. If it is determined that the bit signal level is larger than the set level, it is determined at step a3 whether or not to detect the frequency modulation characteristic. The detection of the frequency characteristic may be performed for the target to be detected initially after the power is turned on, for example, but it is not always necessary. When it is determined that the modulation characteristic is detected in step a3, the detection processing of the frequency modulation characteristic is performed similarly to the first embodiment of the embodiment in step a4. In step a5, it is determined whether there is a problem in the detection result. If there is a problem, in step a6, correction processing is performed as in the second or third embodiment of the embodiment, or alarm processing is performed in an alarm or the like. When it is determined in step a2 that it is not larger than the set level, when it is determined in step a3 that detection of the modulation characteristic is not performed, when it is determined that there is no problem in step a5, in step a7 Normal FM-CW radar processing is performed. Since correction is performed when the input level of the received signal is equal to or greater than a predetermined reference level, the correction can be performed stably.
    [113] In addition, in step a3, when the target is first detected and the reflected wave can be received, it is possible to detect an abnormality early by determining whether the frequency modulation characteristic of the VCO 24 is normal.
    [114] Fig. 11 shows a schematic electrical configuration of an FM-CW system radar 81 as a sixth embodiment of the present invention. In the present embodiment, when a temperature sensor 82 such as a thermistor detects a temperature near the VCO 24 or the like and the frequency modulation characteristic of the VCO 24 changes with temperature, correction for each arbitrary temperature is also possible. The accuracy of the modulation characteristics can be improved. The temperature detected by the temperature sensor 82 can be given to the signal processing circuit 90 to perform correction similarly to the embodiment of FIG. 6 or FIG. 7. Further, correction can be made when the temperature detected by the temperature sensor 82 as the temperature detection means becomes a predetermined temperature. Even when the frequency of the high frequency signal generated from the VCO 24 changes with temperature, correction is performed when the temperature reaches a predetermined temperature, thereby reducing the influence of temperature and improving the accuracy of the frequency modulation characteristic.
    [115] Further, in each embodiment of the present invention, the frequency modulation characteristic is detected or corrected when the distance of the target is a predetermined distance range, so that the frequency modulation characteristic is detected or detected when the relative speed of the target is a predetermined speed range. It is preferable to perform correction. By deviating from the predetermined distance range such as a range where the signal level of the received signal is likely to be low, such detection does not enter the detection process or correction process at such a distance, so that the accuracy of detection or correction can be avoided. Regarding the relative speed, detection and correction are performed when the target speed range is set in consideration of the relative speed of the target, so that the accuracy can be improved.
    [116] Fig. 12 shows a partial electrical configuration of the signal processing circuit 100 of the FM-CW system radar which is the seventh embodiment of the present invention. In the present embodiment, similar to the embodiment of FIG. 9, the bit signal is converted into a digital signal by the A / D converter 102, input to the microcomputer 103, and the frequency is counted by the frequency counter 104. The result is entered into the microcomputer 104. Since the frequency counter 104 is used, frequency measurement of the bit signal can be easily performed.
    [117] Fig. 13 shows a schematic electrical configuration of an FM-CW system radar 111 that is an eighth embodiment of the present invention. In the present embodiment, the bit signal of the FM-CW system radar can be heterodyned by mixing the reference signal generated from the signal source 112 with the mixer 113, and further reducing the frequency so that frequency measurement can be easily performed. . The output of the mixer 113 is selected by B.P.F.114, amplified by the amplifier 115 and given to the signal processing circuit 120. The signal processing circuit 120 detects and corrects the frequency modulation characteristic in the same manner as in the above embodiments.
    [118] FIG. 14 shows an example of realizing the signal source 112 in the embodiment of FIG. 13. Fig. 14A includes a changeover switch 114, a divider 115 'and an oscillator 116. Figs. The oscillator 116 is a basic signal generating means for generating a basic signal that is the basis of the mood signal. The divider 115 'serves as a divider for dividing the frequency of the basic signal into a plurality of dividing ratios switchable by the changeover switch 114 to convert the frequency into a reference signal. In FIG. 14B, the outputs of the plurality of oscillators 117, 118, and 119 are switched by the changeover switch 114. In Fig. 14 (c), the reference signal can be generated directly from the signal processing circuit 120 by program processing to improve the measurement accuracy. In addition, when the reference signal and the clock signal of the signal processing circuit 120 are shared, there is no need to prepare a new signal source 113, and space saving and cost reduction can be achieved.
    [119] In the embodiment of Fig. 13, the frequency of the reference signal is set so that the difference in frequency of the received signal from the target is within the bit signal band during the radar operation. Since the reference signal set in the bit signal band is used, the band of the difference frequency obtained by heterodyning can be lowered and the measurement accuracy can be improved. In Fig. 13, the signal processing circuit 120 performs at least a part of the processing of the bit signal in the FM-CW system radar. At least a part of the processing of the bit signal and the detection of the frequency modulation characteristics are performed in common, so that the whole configuration can be simplified and can be realized at low cost.
    [120] Fig. 15 shows a schematic electrical configuration of the FM-CW system radar 121 as the ninth embodiment of the present invention. In this embodiment, the one disclosed as the second embodiment in JP-A-5-40169 can be applied to improve the S / N of the received signal. The bit signal is digitally converted by the A / D converter 122, and the FFT processing 123 is performed by the DSP 124 or the like. The bit signal is obtained from the mixer 26 after giving a modulation signal from the signal source 125 to the gate switch 126 to frequency modulate the received signal, and then the bit signal is mixed with the modulation signal in the mixer 127. It is detected. The signal processing circuit 130 of this embodiment includes an A / D converter 122 and a DSP 124.
    [121] In each of the embodiments described above, in the detection modulated signal shown in Fig. 4 (a) or Fig. 5 (b), the time (t 1 , t 2 ,) for maintaining the voltage level at a plurality of values in the range of V1 to V2 is shown . t 3 , ... t n ) is preferably changed in accordance with the distance to the target and the relative speed. As a result, the frequency modulation characteristic detection can be optimized in accordance with the distance to the target and the relative speed, and the detection accuracy can be improved.
    [122] In addition, it is preferable that the signal processing circuit of each embodiment detects the frequency of the bit signal component of the difference between the high frequency signal and the received signal in consideration of the Doppler shift based on the relative speed of the target. This is because the frequency modulation characteristic can be accurately detected in consideration of the Doppler shift even when it is difficult to see a relatively stationary target in the case of being mounted on an automobile.
    [123] In each of the above embodiments, the FM-CW system radar has been described, but the present invention can be similarly applied as long as the radar uses frequency modulation.
    [124] As described above, according to the present invention, the frequency modulation characteristic of the high frequency generating means can be detected using the received signal from the target. Since the reception signal is used as a signal source of high frequency for frequency characteristic detection, and the mixing means can also be shared for reception, the frequency modulation characteristic can be detected simply with an inexpensive configuration.
    [125] Further, according to the present invention, since the modulation signal is corrected so that the modulation frequency characteristic does not deviate from the predetermined normal range, the correction of the frequency modulation characteristic can be performed simply with an inexpensive configuration.
    [126] Further, according to the present invention, the frequency modulation width can be calculated from the change of frequency between the plurality of signal levels.
    [127] According to the present invention, since the counter is counted, the change in frequency can be easily measured.
    [128] According to the present invention, the frequency modulation width of the frequency modulation characteristic can be corrected to a predetermined value.
    [129] Further, according to the present invention, stable correction can be performed when the level of the received signal is higher than or equal to a predetermined level.
    [130] Further, according to the present invention, the influence of temperature can be reduced, and the accuracy of the frequency modulation characteristic can be improved.
    [131] According to the present invention, if the distance of the target object is out of an appropriate range, the correction process is not entered, so that the deterioration of the accuracy of correction can be avoided.
    [132] Further, according to the present invention, the accuracy of the correction can be improved in consideration of the relative speed of the target. For example, accuracy can be improved by turning off targets that generate high relative velocity components, such as roadsides and opposing differences.
    [133] According to the present invention, when the input level of the received signal is not equal to or higher than a predetermined reference level, it is possible to concentrate on the normal target detection process. Since it is determined at the signal level during normal radar operation whether or not the detection processing of the frequency modulation characteristic is performed, the number of detection processing can be reduced.
    [134] According to the present invention, when the distance to the target deviates from the predetermined distance range, it is possible to concentrate on the normal target detection process.
    [135] According to the present invention, if an abnormality occurs in the frequency modulation characteristics of the high frequency generating means, it can be detected early.
    [136] According to the present invention, since the frequency is reduced by heterodyning the reference signal generated from the reference signal source to the bit signal which is a component of the difference between the high frequency signal and the received signal obtained by the mixing means, it is easy to measure the frequency of the bit signal. I can do it.
    [137] Further, according to the present invention, a plurality of frequency division ratios can be switched to lower the frequency, thereby improving the accuracy of frequency measurement.
    [138] Further, according to the present invention, since the plurality of reference signals are switched and the signal components obtained by switching are compared, the frequency to be measured can be determined, and the accuracy can be improved.
    [139] Further, according to the present invention, a reference signal of a frequency suitable for measuring the frequency can be generated to improve the measurement accuracy.
    [140] Further, according to the present invention, the generation of the reference signal and the supply of the clock signal to the signal processing means can be performed in common, and space saving and cost reduction can be achieved.
    [141] According to the present invention, measurement accuracy can be improved by using a reference signal set in the bit signal band.
    [142] According to the present invention, at least a part of the processing of the bit signal and the detection of the frequency characteristic are performed in common, and the whole structure can be simplified, the cost can be reduced, and the like.
    [143] Further, according to the present invention, it is possible to optimize the detection of the frequency modulation characteristics in accordance with the distance to the target and to improve the detection accuracy.
    [144] Further, according to the present invention, it is possible to improve the detection accuracy of the frequency characteristic in consideration of the relative speed with the target.
    [145] According to the present invention, even when it is difficult to see a relatively stationary target, the frequency modulation characteristic can be detected with high precision in consideration of the Doppler shift.
    权利要求:
    Claims (22)
    [1" claim-type="Currently amended] A radar apparatus for frequency-modulating and transmitting a high frequency signal, and receiving a reflected wave to detect a target.
    Modulated signal generating means for generating and applying a modulated signal to the high frequency generating means for generating a high frequency signal to modulate the high frequency signal;
    Mixing means for mixing the high frequency signal generated from the high frequency generating means and the received signal of the reflected radio wave; And
    The modulation signal generating means is controlled so as to give the high frequency generating means a detection modulated signal which is changed between a plurality of predetermined signal levels and maintained for each signal level, and the high frequency signal and the received signal input from the mixing means. And signal processing means for detecting a frequency of the differential signal of the signal and detecting a frequency modulation characteristic of the high frequency generating means based on the relationship between the signal level of the detection modulated signal and the frequency of the differential signal.
    [2" claim-type="Currently amended] 2. The apparatus according to claim 1, further comprising modulation characteristic correction means for correcting the modulation signal so that the frequency modulation characteristic does not deviate from a predetermined normal range based on the frequency modulation characteristic detected by the signal processing means. Radar device characterized in that.
    [3" claim-type="Currently amended] The frequency modulation width as claimed in claim 1 or 2, wherein a frequency modulation width which is a difference between a frequency when the signal level of the modulated signal is the maximum value and a frequency when the minimum value is the minimum value is based on the frequency modulation characteristic detected by the signal processing means. And a radar calculating means for calculating.
    [4" claim-type="Currently amended] 4. The radar apparatus according to claim 3, wherein the explosion calculation means includes a counter for counting a frequency of the difference.
    [5" claim-type="Currently amended] 5. The apparatus according to claim 3 or 4, further comprising width correction means for correcting the modulated signal such that the frequency modulation width is a predetermined value based on the frequency modulation width calculated by the width calculation means. Radar device characterized in that.
    [6" claim-type="Currently amended] The radar apparatus according to claim 2 or 5, wherein the modulation characteristic correction means or the width correction means corrects when the level of the received signal of the reflected radio wave is equal to or higher than a predetermined level.
    [7" claim-type="Currently amended] The method of claim 2 or 5, further comprising a temperature detecting means,
    And the modulation characteristic correction means or the width correction means corrects when the temperature detected by the temperature detection means becomes a predetermined temperature.
    [8" claim-type="Currently amended] The radar apparatus according to claim 2 or 5, wherein the modulation characteristic correction means or the width correction means corrects when the distance of the target is a predetermined distance range.
    [9" claim-type="Currently amended] The radar apparatus according to claim 2 or 5, wherein the modulation characteristic correction means or the width correction means corrects when the relative speed of the target is within a predetermined speed range.
    [10" claim-type="Currently amended] 10. The signal processing apparatus according to any one of claims 1 to 9, wherein said signal processing means is characterized in that, in a normal radar operation, when the input level for receiving the reflected radio wave from the target is equal to or greater than a predetermined reference level, A radar device, characterized in that for detecting the.
    [11" claim-type="Currently amended] 10. The radar apparatus according to any one of claims 1 to 9, wherein said signal processing means detects said frequency characteristic when the distance of said target is within a predetermined distance range.
    [12" claim-type="Currently amended] 12. The signal processing means according to any one of claims 1 to 11, wherein the signal processing means detects the frequency characteristic immediately after the first detection of the target after the start of the radar operation, and the normality with respect to the high frequency generating means. And determining whether or not the modulation operation is performed.
    [13" claim-type="Currently amended] The reference signal source according to any one of claims 1 to 12, wherein a reference signal source for generating a reference signal for reducing a frequency is used for the difference signal between the high frequency signal and the received signal input from the mixing means to the signal processing means. Additionally,
    And the signal processing means inputs a differential signal whose frequency is reduced by a reference signal to detect the frequency characteristic.
    [14" claim-type="Currently amended] The method of claim 13, wherein the reference signal source,
    Basic signal generating means for generating a basic signal that is the basis of the mood signal; And
    And a dividing means for dividing the frequency of the basic signal generated from the basic signal generating means into a plurality of switchable division ratios to convert the frequency into a reference signal.
    [15" claim-type="Currently amended] The method of claim 13, wherein the reference signal source,
    Having a plurality of reference signal generating means,
    By selecting any one of the reference signal generating means,
    And generating the reference signal from the selected reference signal generating means.
    [16" claim-type="Currently amended] The radar apparatus according to claim 13, wherein the reference signal source includes signal calculating means for generating the reference signal by arithmetic processing in accordance with a preset program.
    [17" claim-type="Currently amended] The radar apparatus according to any one of claims 13 to 16, wherein said reference signal source supplies a signal calculation processing clock signal to said signal processing means.
    [18" claim-type="Currently amended] 18. The radar apparatus according to any one of claims 13 to 17, wherein the frequency of the reference signal is set so that a difference from the frequency of the received signal from the target is within a bit signal band during the radar operation.
    [19" claim-type="Currently amended] 19. The radar apparatus according to claim 18, wherein said signal processing means performs at least a part of processing of said bit signal.
    [20" claim-type="Currently amended] 20. The radar according to any one of claims 1 to 19, wherein the signal processing means changes a predetermined time for maintaining a signal level of the detection modulated signal according to the distance to the target. Device.
    [21" claim-type="Currently amended] 21. The radar according to any one of claims 1 to 20, wherein the signal processing means changes a predetermined time for maintaining a signal level of the detection modulated signal according to the relative speed of the target. Device.
    [22" claim-type="Currently amended] The signal processing means according to any one of claims 1 to 21, wherein the signal processing means detects a frequency of the difference signal between the high frequency signal and the received signal in consideration of the Doppler shift based on the relative speed of the target. Radar device.
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    同族专利:
    公开号 | 公开日
    DE60215078T2|2007-05-03|
    EP1275979B1|2006-10-04|
    US6597308B2|2003-07-22|
    JP2003028951A|2003-01-29|
    CN1252491C|2006-04-19|
    EP1275979A2|2003-01-15|
    KR100487756B1|2005-05-06|
    CN1396464A|2003-02-12|
    DE60215078D1|2006-11-16|
    US20030016163A1|2003-01-23|
    US20050007271A1|2005-01-13|
    EP1275979A3|2003-08-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-07-11|Priority to JP2001211314A
    2001-07-11|Priority to JPJP-P-2001-00211314
    2002-07-10|Application filed by 후지쓰 텐 가부시키가이샤
    2003-01-23|Publication of KR20030007099A
    2005-05-06|Application granted
    2005-05-06|Publication of KR100487756B1
    优先权:
    申请号 | 申请日 | 专利标题
    JP2001211314A|JP2003028951A|2001-07-11|2001-07-11|Radar apparatus|
    JPJP-P-2001-00211314|2001-07-11|
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