JP3906869B2 - FM-CW radar equipment - Google Patents

Description

  In order to prevent collision accidents during traveling of passenger cars, buses, trucks, etc. that occur due to poor visibility in bad weather such as rain, fog, snow, etc. The present invention relates to an FM-CW radar apparatus that detects an object or the like, obtains a relative distance and a relative speed, notifies the driver of the danger, and applies it to safe driving of the vehicle.

  FIG. 12 schematically shows a conventionally known FM-CW radar apparatus, and FIG. 13 is a configuration diagram of the conventional FM-CW radar apparatus.

  In FIG. 12, reference numeral 1 denotes a host vehicle equipped with an FM-CW radar device, 2 denotes a front vehicle running in the forward direction, and 3 denotes an oncoming vehicle running in the oncoming lane.

  The transmission wave transmitted from the FM-CW radar device attached near the front of the host vehicle 1 is reflected, for example, when the vehicle 2 ahead exists, and returns to the FM-CW radar device as a reception wave (reflected wave). Come. The FM-CW radar device calculates the frequency difference between the transmitted radio wave and the received radio wave, and calculates the relative distance and relative speed between the host vehicle 1 and the vehicle 2 ahead. The same detection can be performed for the oncoming vehicle 3 and obstacles (not shown) in the oncoming lane other than the vehicle 2 ahead by directing the transmission wave.

  13, 4 is a modulation means, 5 is an oscillator, 6 is a directional coupler, 7 is a transmission antenna, 8 is a reception antenna, 9 is a mixer, 10 is an amplifier, 11 is an A / D (Analog to Digital) converter, 12 Is a frequency analyzing means, 13 is a target detecting means, 14 is a distance speed calculating means, 15 is a transceiver comprising a modulating means 4, an oscillator 5, a directional coupler 6, a mixer 9 and an amplifier 10.

First, the modulation means 4 generates a frequency modulation (FM) signal and sends it to the oscillator 5. The oscillator 5 generates a high-frequency signal modulated by the FM signal, and sends it to the transmission antenna 7 and the mixer 9 via a directional coupler. The transmission antenna 7 emits the transmitted high-frequency signal to a target such as a vehicle ahead as a transmission wave. If the target exists, the received wave (reflected wave) with a time delay is received by the receiving antenna 8 and sent to the mixer 9. The mixer 9 generates a frequency difference signal between the reflected wave and the transmission wave distributed by the directional coupler 6 (hereinafter referred to as a beat signal) and sends it to the amplifier 10. The amplifier 10 amplifies the beat signal and comes to the A / D converter 11. The A / D converter 11 converts the beat signal from an analog signal format to a digital signal format and sends the beat signal to the frequency analysis means 12. The frequency analysis means 12 takes a digitized beat signal and obtains a frequency distribution by processing such as FFT (Fast Fourier Transform). The target detection means 13 compares the frequency distribution with the threshold value, and determines the target that is the maximum among those exceeding the threshold value. The distance / velocity calculation means 14 calculates the relative distance and relative speed of the target based on the frequency picked up by the target detection means 13.

  14 and 15 are diagrams for explaining a method of calculating the relative distance and the relative speed of the target. FIG. 14 shows a change in frequency, and FIG. 15 shows a frequency distribution. The basic principle is S.I. A. Hovanesian's book “Radar System Design & Analysis” (published by Artech House). 78-P. 81. In FIG. 14, 16 indicates the transmission frequency of the FM-CW radar apparatus, and 17 indicates the reception frequency.

  First, the radio frequency is transmitted by changing the transmission frequency 16 to be constant in the a section, rising in the b section, and falling in the c section. When the vehicle 2 in front of FIG. 12 exists at a relative speed v and a relative distance R, a light speed C [m / s], a transmission wavelength λ [m], and a frequency gradient K1 [Hz / s] The beat frequency fd of the section is expressed by the formula 1, the beat frequency fr1 of the b section is expressed by the formula 2, and the beat frequency fr2 of the c section is expressed by the formula 3.

  Therefore, fd, fr1, fr2 are obtained from the frequency analysis, and the target relative speed and relative distance can be obtained by solving the combination of the relative speed V and the relative distance R satisfying the expressions 1, 2, and 3.

For fd, fr1, and fr2, beat signals in the a section, the b section, and the c section can be obtained by frequency analysis such as FET (Fast Fourier Transform), respectively. FIG. 15 shows a case where the beat signal in the case where there is only one target is subjected to frequency analysis. (A) is the a section, (b) is the b section, and (c) is the c section FET results, and the respective peak frequencies correspond to fd, fr1, and fr2. When there are two or more targets that reflect radio waves, such as the vehicle ahead, the spectrum waveform on the frequency axis is also synthesized when frequency analysis is performed, and there are a plurality of peak frequencies. By searching for a combination of frequencies that satisfies Equation 3, the relative speed and relative distance of each target can be obtained.

The conventional FM-CW radar apparatus can easily determine the threshold value after the frequency analysis when the beat signal includes only the signal from the target, and can determine the frequency of the target. Thermal noise (receiver noise) is also amplified and mixed in the output of, and the frequency distribution becomes complicated as shown in FIG. If the threshold is set too high, such as the threshold 19, the first target 20 can be detected, but the second target 21 cannot be detected. If the threshold is set too low, such as the threshold 22, the receiver noise 23 is detected. FIGS. 16B and 16C are diagrams illustrating a detection method in which the target frequency is compared with the average value of the surroundings and the target value is detected when the frequency exceeds the average value of the surroundings. , 25 is a threshold value obtained by multiplying the average value 24 by a coefficient determined from the false alarm probability, and 26 indicates a range for selecting the average value. The threshold value 25 in FIG. 16B is a threshold value when attention is paid to the second target object 21, and the amplitude of the second target object 21 exceeds the threshold value 25, so that it is detected as a target object. However, in the case where the first target 20 is adjacent to the second target 21 as shown in FIG. 16C, the average value increases and the second target 21 cannot be detected.

  The FM-CW radar apparatus according to the present invention is made to solve the above-described problems. The target detection threshold is easily set, and even if a plurality of targets are adjacent to each other, they interfere with each other. It suppresses each so that it can detect each.

  The FM-CW radar apparatus according to the present invention is mounted on a vehicle, transmits FM-CW waves in front of the vehicle, receives reflected waves from the vehicle ahead or obstacles, and generates beat signals of the transmitted waves and received waves. In an FM-CW radar apparatus for determining the distance and speed to the vehicle or obstacle ahead, the gain control means for controlling the gain of the amplifier that amplifies the beat signal, and the beat signal received in the absence of the target Noise average value storage means for storing in advance an average value of noise components on the frequency axis generated by the transceiver of the FM-CW radar apparatus according to the gain, and detecting the inclination angle of the vehicle body with respect to the vehicle running surface A threshold value for determining the target of the beat signal by multiplying the vehicle body inclination detection means by the average value of the noise component corresponding to the gain and an exponential coefficient corresponding to the information of the inclination angle. A threshold value calculating means for, those having comparison means for comparing the output waveform and the threshold value of the beat signal, and the maximum value detecting means for detecting a maximum value of the frequency analysis result.

  The FM-CW radar apparatus according to the present invention measures the relationship between the gain of the transceiver and the average value of the receiver noise and the relationship between the inclination of the vehicle body and the spectrum of the receiver noise in advance, and the gain and the inclination state of the vehicle body. The threshold value for target detection is set according to the above.

  Further, the FM-CW radar apparatus according to the present invention measures the relationship between the gain of the transceiver and the average value of the receiver noise and the relationship between the spectrum of the rainfall and the receiver noise in advance, and matches the gain and the state of the rain. A threshold value for target detection is set.

  Further, the FM-CW radar apparatus according to the present invention measures the relationship between the gain of the transceiver and the average value of the receiver noise and the relationship between the temperature of the transceiver and the receiver noise in advance, and determines the gain and the temperature of the transceiver. In addition, a threshold value for target detection is set.

  Furthermore, the FM-CW radar apparatus according to the present invention is mounted on a vehicle, transmits FM-CW waves in front of the vehicle, receives reflected waves from the vehicle in front of the vehicle or obstacles, and transmits transmitted waves and received waves. In an FM-CW radar apparatus that obtains the distance and speed to the vehicle or obstacle ahead based on the beat signal, vehicle body inclination detection means for detecting the inclination angle of the vehicle body with respect to the vehicle running surface, and an index corresponding to the inclination angle information Threshold calculation means for determining a target judgment threshold for the beat signal based on a coefficient, comparison means for comparing the output waveform of the beat signal with the threshold, and a maximum value detection means for detecting the maximum value of the frequency analysis result And.

  According to the present invention, the relationship between the gain of the transceiver and the amplitude value of the noise component is measured in advance, and the threshold setting is facilitated by setting the threshold value of the target detection in conjunction with the gain. There is an effect that target detection can be performed while suppressing interference between the two.

  Further, according to the present invention, the frequency distribution of the noise component with respect to the gain is measured in advance as a pattern, the threshold value is accurately set by setting the threshold value of the target detection in conjunction with the gain, and a plurality of target signals There is an effect that target detection can be performed while suppressing interference between the two.

  According to the present invention, the relationship between the antenna direction and the reflection level of the radio wave from the ground is measured in advance, and the target detection threshold is set in conjunction with the vehicle direction and the gain of the transceiver. There is an effect that the setting can be performed accurately and target detection can be performed while suppressing interference between a plurality of target signals.

  Further, according to the present invention, the relationship between the rainfall and the reflection level of the radio wave from the ground is measured in advance, and the threshold value is accurately set by setting it in conjunction with the rainfall information and the gain of the transceiver, and a plurality of There is an effect that target detection can be performed while suppressing interference between target signals.

  In addition, according to the present invention, the relationship between the temperature of the transceiver and the noise amplitude value is measured in advance, and the threshold value is accurately set by setting in conjunction with the temperature and gain of the transceiver, and a plurality of targets There is an effect that target detection can be performed while suppressing interference between signals.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of an FM-CW radar apparatus showing Embodiment 1 of the present invention. In the figure, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are the same as those in FIG. 27 is a gain control means, 28 is a noise average value storage means, 29 is a threshold value calculation means, 30 is a comparison means, and 31 is a maximum value detection means.

The beat signal converted into the digital signal format in the A / D converter 11 is sent to the frequency analysis means 12 and the gain control means 27. The gain control means 27 checks the magnitude of the beat signal, checks whether the A / D converter 11 is not saturated or the input is too small, and adjusts the gain of the amplifier 10 so that the beat signal becomes an optimum level. To do. Further, the gain control means 27 sends an argument corresponding to the value set in the amplifier 10 to the threshold value calculation means 29. The threshold calculation means 29 takes in a set value (average value of noise components) corresponding to the gain from the noise average value storage means 28 using the argument passed from the gain control means 27. The average value of the noise component is a value obtained by receiving a beat signal in the absence of a target in advance and performing frequency analysis, and then calculating the average value in the frequency axis direction and evaluating the noise component generated from the transceiver 15 It is. FIG. 6 is a diagram showing the relationship between the frequency distribution of noise components and the average value when the gain changes. Reference numerals 36a, 36b, 36c, and 36d denote frequency distributions of noise components. Reference numerals 37a, 37b, 37c, and 37d denote average values of noise components. Normally, the noise component rises proportionally or monotonically as the gain increases. FIG. 7 is a diagram showing the relationship between the gain and the average value of the noise components. Reference numeral 38 denotes a characteristic curve representing a change in the noise component, which is data stored in the noise average value storage means 28. The threshold value calculation means 29 takes in the noise average value corresponding to the gain from the noise average value storage means 28, obtains the threshold value for distinguishing the noise from the target by Equation 4, and gives it to the comparison means 30. Equation 4 is a threshold value a, a coefficient k, and an average noise value b, and the coefficient k is set so that the probability of occurrence of erroneous detection is sufficiently low.

  Next, the comparison means 30 determines that the target is the target if the output of the frequency analysis means 12 exceeds the threshold value a. FIG. 8 shows an example in which the receiver noise 23 is not selected by the threshold a (threshold 25), and only the first target 20 and the second target 21 are selected. The amplitude value of the target selected by the comparison means 30 is sent to the maximum value detection means 31. If the amplitude value is continuous on the frequency axis, the maximum value detecting unit 31 detects the maximum point and sends the frequency value of the maximum point to the distance speed calculating unit 14. The distance speed calculation means 14 can obtain the relative speed and relative distance of the target as in the conventional case.

Embodiment 2. FIG.
FIG. 2 is a block diagram of an FM-CW radar apparatus showing Embodiment 2 of the present invention. In the figure, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are the same as those in FIG. 27 is a gain control means, 29 is a threshold value calculation means, 30 is a comparison means, 31 is a maximum value detection means, and 32 is a noise pattern storage means.

The beat signal converted into the digital signal format in the A / D converter 11 is sent to the frequency analysis means 12 and the gain control means 27. The gain control means 27 checks the magnitude of the beat signal, checks whether the A / D converter 11 is not saturated or the input is too small, and adjusts the gain of the amplifier 10 so that the beat signal becomes an optimum level. To do. Further, the gain control means 27 sends an argument corresponding to the value set in the amplifier 10 to the threshold value calculation means 29. The threshold value calculation unit 29 takes in a noise pattern corresponding to the gain from the noise pattern storage unit 32 by the argument passed from the gain control unit 27. The noise pattern is obtained by receiving a beat signal in the absence of a target in advance and averaging the frequency-analyzed spectrum, that is, the noise spectrum, a plurality of times. FIG. 9A is a diagram showing the relationship between the noise spectrum when the gain changes and the noise pattern subjected to the averaging process. Reference numerals 39a, 39b, and 39c denote noise spectra. Reference numerals 40a, 40b, and 40c denote noise patterns. Usually, the amplitude of the noise component increases almost in proportion to the gain. In addition, due to the low-pass characteristics until the beat signal is output from the transceiver 15, the amplitude value tends to decrease as the frequency increases, as shown in FIG. 9A. The threshold value calculation means 29 takes in a noise pattern corresponding to the gain from the noise pattern storage means 32, obtains a threshold value for distinguishing the noise from the target by Equation 5, and gives it to the comparison means 30. Equation 5 is a threshold value a, a coefficient k, a gain G of the transceiver, and an nth noise level N (n) on the frequency axis, and the coefficient k is set so that the probability of erroneous detection is sufficiently low.

  The comparison unit 30 determines that the target is the target if the output of the frequency analysis unit 12 exceeds the threshold value a. FIG. 8 shows an example in which the receiver noise 32 is not selected by the threshold value a (threshold value 34), and only the first target 29 and the second target 30 are selected. The amplitude value of the target selected by the comparison means 30 is sent to the maximum value detection means 31. If the amplitude value is continuous on the frequency axis, the maximum value detecting unit 31 detects the maximum point and sends the frequency value of the maximum point to the distance speed calculating unit 11. The distance speed calculation means 14 can obtain the relative speed and relative distance of the target as in the conventional case.

Embodiment 3 FIG.
FIG. 3 is a block diagram of an FM-CW radar apparatus showing Embodiment 3 of the present invention. In the figure, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are the same as those in FIG. Reference numeral 27 denotes gain control means, 28 denotes noise average value storage means, 29 denotes threshold value calculation means, 30 denotes comparison means, 31 denotes maximum value detection means, and 33 denotes vehicle body inclination detection means.

The beat signal converted into the digital signal format in the A / D converter 11 is sent to the frequency analysis means 12 and the gain control means 27. The gain control means 27 checks the magnitude of the beat signal, checks whether the A / D converter 11 is not saturated or the input is too small, and adjusts the gain of the amplifier 10 so that the beat signal becomes an optimum level. To do. Further, the gain control means 27 sends an argument corresponding to the value set in the amplifier 10 to the threshold value calculation means 29. The threshold value calculation means 29 takes in the noise average value corresponding to the gain from the noise average value storage means 28 by the argument passed from the gain control means 27. The threshold value calculation means 29 also fetches an angle indicating how much the vehicle body is inclined from the horizontal direction from the vehicle body inclination detection means 33. The vehicle body inclination detection means 33 calculates the change in the positional relationship of the vehicle body with respect to the ground by detecting the expansion and contraction of the suspension supporting the wheels. The threshold value calculation means 29 obtains a threshold value for distinguishing the target from the average noise value and the vehicle body inclination angle.

FIG. 10 is a diagram illustrating the relationship between the vehicle and the transmission radio wave. Reference numeral 41 denotes a vehicle 41 equipped with this apparatus, and reference numeral 42 denotes a transmission / reception beam indicating the directivity of the antenna. (A) is a case where the vehicle 41 faces upward from the horizontal, (b) is a case where the vehicle 41 is horizontal to the ground, and (c) is a case where the vehicle 41 faces downward from the horizontal. is there. Since radio waves are generally reflected from the ground, the more the vehicle 41 faces the ground, the greater the reflection from the ground. FIG. 11 is a diagram showing the relationship between the noise component frequency distribution and the noise pattern subjected to the averaging process when the pitch angle of the vehicle 41 is changed in a situation where there is no target and the gain of the transceiver 15 is constant. . Reference numerals 43a, 43b, and 43c denote frequency distributions of noise components. Reference numerals 44a, 44b, and 44c denote noise patterns. When the transmission / reception beam 42a is upward as shown in FIG. 10 (a), the noise component is the noise pattern 44a. When the transmission / reception beam 42b is horizontal as shown in FIG. 10 (b), the noise component is the noise pattern 44b. ), When the transmission / reception beam 42c is horizontal, the noise component is different from the noise pattern 44c. The threshold for distinguishing the target is obtained by an approximate expression such as Equation 6 and given to the comparison means 30. Equation 6 is a threshold value a, a coefficient k, an average noise value b, a frequency f, and an nth noise level N (n) on the slope Δθ axis, and the coefficient k is set so that the probability of occurrence of erroneous detection is sufficiently low. .

  The comparison unit 30 determines that the target is the target if the output of the frequency analysis unit 12 exceeds the threshold value a. FIG. 11B shows an example in which the amplitude of the first target 20 exceeds the threshold value a (threshold value 25) and is selected as the target, and the amplitude value is sent to the maximum value detecting means 31. If the amplitude value is continuous on the frequency axis, the maximum value detecting unit 31 detects the maximum point and sends the frequency value of the maximum point to the distance speed calculating unit 14. The distance speed calculation means 14 can obtain the relative speed and relative distance of the target as in the conventional case.

Embodiment 4 FIG.
FIG. 4 is a block diagram of an FM-CW radar apparatus showing Embodiment 4 of the present invention. In the figure, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are the same as those in FIG. 27 is a gain control means, 28 is a noise average value storage means, 29 is a threshold value calculation means, 30 is a comparison means, 31 is a maximum value detection means, and 34 is a rain detection means.

The beat signal converted into the digital signal format in the A / D converter 11 is sent to the frequency analysis means 12 and the gain control means 27. The gain control means 27 checks the magnitude of the beat signal, checks whether the A / D converter 11 is not saturated or the input is too small, and adjusts the gain of the amplifier 10 so that the beat signal becomes an optimum level. To do. Further, the gain control means 27 sends an argument corresponding to the value set in the amplifier 10 to the threshold value calculation means 29. The threshold value calculation means 29 takes in the noise average value corresponding to the gain from the noise average value storage means 28 by the argument passed from the gain control means 27. The threshold calculation means 29 also fetches rainfall information from the rain detection means 34. The rain detection means 34 obtains information by attaching a sensor for detecting moisture to, for example, a hood of a vehicle or a groove for rain water. The threshold value calculation means 29 obtains a threshold value for distinguishing the target from the average noise value and the rainfall information, and sends it to the comparison means 30. Usually, when there is rain, the reflection of radio waves from the ground becomes strong, so the amplitude of the noise component is increased. It shows the same tendency as the elevated state. Therefore, the threshold value can be calculated more accurately by measuring the average noise value at the time of rainfall and the average noise value at the time of restriction in advance and having the difference as a correction value. The comparison means 30 is the frequency analysis means 12.
If the output exceeds the threshold value, it is determined that the target is the target, and the amplitude value is sent to the maximum value detecting means 31. If the amplitude value is continuous on the frequency axis, the maximum value detecting unit 31 detects the maximum point and sends the frequency value of the maximum point to the distance speed calculating unit 14. The distance speed calculation means 14 can obtain the relative speed and relative distance of the target as in the conventional case.

Embodiment 5 FIG.
FIG. 5 is a block diagram of an FM-CW radar apparatus showing Embodiment 5 of the present invention. In the figure, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are the same as those in FIG. Reference numeral 27 denotes a gain control means, 28 denotes a noise average value storage means, 29 denotes a threshold value calculation means, 30 denotes a comparison means, 31 denotes a maximum value detection means, and 35 denotes a temperature detection means.

The beat signal converted into the digital signal format in the A / D converter 11 is sent to the frequency analysis means 12 and the gain control means 27. The gain control means 27 checks the magnitude of the beat signal, checks whether the A / D converter 11 is not saturated or the input is too small, and adjusts the gain of the amplifier 10 so that the beat signal becomes an optimum level. To do. Further, the gain control means 27 sends an argument corresponding to the value set in the amplifier 10 to the threshold value calculation means 29. The threshold calculation means 29 takes in the noise average value corresponding to the gain from the noise average value storage means 28 by the argument passed from the gain control means 27. The threshold calculation means 29 also fetches temperature information of the transceiver 15 from the temperature detection means 35. The temperature detection means 35 obtains information by attaching a temperature sensor such as a thermistor to the transceiver 15, for example. The threshold value calculation means 29 obtains a threshold value for distinguishing the target from the noise average value and the temperature information and sends it to the comparison means 30. Usually, the transmitter / receiver 15 changes the transmission output and gain depending on the temperature, and the amplitude of the noise component changes. . Therefore, the noise average value at each temperature is measured in a state where the output of the gain control means 27 is fixed in advance, and the threshold value can be calculated more accurately by having the noise component difference between the temperatures as a correction value. it can. If the output of the frequency analysis unit 12 exceeds the threshold value, the comparison unit 30 determines that the target is a target, and sends the amplitude value to the maximum value detection unit 31. If the amplitude value is continuous on the frequency axis, the maximum value detecting unit 31 detects the maximum point and sends the frequency value of the maximum point to the distance speed calculating unit 14. The distance speed calculation means 14 can obtain the relative speed and relative distance of the target as in the conventional case.

It is a figure for demonstrating Embodiment 1 of this invention. It is a figure for demonstrating Embodiment 2 of this invention. It is a figure for demonstrating Embodiment 3 of this invention. It is a figure for demonstrating Embodiment 4 of this invention. It is a figure for demonstrating Embodiment 5 of this invention. It is a figure for demonstrating Embodiment 1 of this invention. It is a figure for demonstrating Embodiment 1 of this invention. It is a figure for demonstrating Embodiment 1 of this invention. It is a figure for demonstrating Embodiment 2 of this invention. It is a figure for demonstrating Embodiment 3 of this invention. It is a figure for demonstrating Embodiment 3 of this invention. It is a figure for demonstrating the outline | summary of an FM-CW radar apparatus. It is a figure for demonstrating the structure of the conventional FM-CW radar apparatus. It is a figure for demonstrating the principle of the conventional FM-CW radar apparatus. It is a figure for demonstrating the principle of the conventional FM-CW radar apparatus. It is a figure for demonstrating the subject of the conventional FM-CW radar apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Own vehicle, 2 vehicle ahead, 3 oncoming vehicle, 4 modulation means, 5 oscillator, 6 directional coupler, 7 transmitting antenna, 8 receiving antenna, 9 mixer, 10 amplifier, 11 A / D converter, 12 frequency analysis Means, 13 target detection means, 14 distance speed calculation means, 15 transceiver, 16 transmission frequency, 17 reception frequency, 18a, 18b, 18c frequency spectrum of the target, 19 threshold, 20 first target, 21 second target , 22 threshold value, 23 receiver noise, 24 noise average value, 25 threshold value, 26 target range of average value calculation, 27 gain control means, 28 noise average value storage means, 29 threshold value calculation means, 30 comparison means, 31 maximum value detection Means 32 noise pattern storage means 33 vehicle body tilt detection means 34 rain detection means 35 temperature detection means 36 noise components Frequency distribution, the average value of the 37 noise component, the noise mean for the 38 gain, the frequency distribution of the 39 noise component, 40 noise pattern, 41 a vehicle, 42 transmitting and receiving beams, the frequency distribution of the 43 noise component, 44 noise pattern.

Claims (3)

Installed in the vehicle, transmits FM-CW wave in front of the vehicle, receives the reflected wave from the vehicle or obstacle ahead, and reaches the vehicle or obstacle ahead based on the beat signal of the transmission wave and reception wave In FM-CW radar equipment that calculates distance and speed,
Gain control means for controlling the gain of an amplifier for amplifying the beat signal;
Noise average value storage means for storing in advance an average value of noise components on the frequency axis generated by the transceiver of the FM-CW radar device according to the gain for the beat signal received in the absence of a target; ,
Vehicle body inclination detection means for detecting the inclination angle of the vehicle body relative to the vehicle running surface;
A threshold value calculation means for determining a threshold value for target determination of the beat signal by multiplying an average value of the noise component according to the gain and an exponential coefficient according to the information of the inclination angle;
Comparison means for comparing the frequency distribution of the beat signal with the threshold value;
Local maximum detection means for detecting the local maximum of the frequency distribution based on the output of the comparison means;
An FM-CW radar apparatus comprising:   The FM-CW radar apparatus according to claim 1, further comprising a rain detection unit that detects a rain state, wherein the threshold value calculation unit determines a threshold value for target determination using at least the rain state information.   The temperature detection means for detecting the temperature of the transceiver is further provided, and the threshold value calculation means determines a threshold value for target determination using at least the detected temperature information. FM-CW radar equipment.

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