초록 ▼

The invention provides a radar that transmits a radio wave and receives an echo of the radio wave, which is characterized by possessing (1) a reception means that detects a beat signal of the echo and the radio wave, (2) a first frequency analysis means that analyzes the beat signal into frequency c

The invention provides a radar that transmits a radio wave and receives an echo of the radio wave, which is characterized by possessing (1) a reception means that detects a beat signal of the echo and the radio wave, (2) a first frequency analysis means that analyzes the beat signal into frequency components, and detects a peak signal of frequency spectra obtained thereby, and (3) a second frequency analysis means that analyzes the beat signal into frequency components with a frequency resolution different from that of the first frequency analysis means, and detects a peak signal of frequency spectra obtained thereby.

대표청구항 ▼

What is claimed is: 1. A radar that transmits a signal and receives a reflection signal of the signal, comprising: a reception means for detecting a beat signal of the reception signal and the transmission signal; a first frequency analysis means for analyzing the beat signal into frequency compon

What is claimed is: 1. A radar that transmits a signal and receives a reflection signal of the signal, comprising: a reception means for detecting a beat signal of the reception signal and the transmission signal; a first frequency analysis means for analyzing the beat signal into frequency components with a first frequency resolution, and detecting a peak signal of frequency spectra obtained thereby; and a second frequency analysis means for analyzing the beat signal into frequency components with a second frequency resolution finer than the first frequency resolution, said second frequency analysis means analyzing the peak signal detected with a threshold value based on the peak signal detected by the first frequency analysis means, and detecting a peak signal of frequency spectra obtained thereby. 2. A radar according to claim 1, comprising a transmission means for emitting a continuous wave subjected to a repetitive frequency modulation, as the radio wave. 3. A radar according to claim 1, wherein the second frequency analysis means analyzes the beat signal into frequency components with second frequency resolution, when the peak signal detected by the first frequency analysis means belongs to a frequency band determined according to a speed of a movable body loaded with the radar. 4. A radar according to claim 3, comprising a transmission means for emitting a plurality of continuous waves of different transmission frequencies as the radio wave. 5. A radar according to claim 1, wherein the second frequency analysis means analyzes the beat signal into frequency components with the second frequency resolution, when the peak signal detected by the first frequency analysis means belongs to a variable frequency band set in advance. 6. A radar according to claim 5, comprising a transmission means for emitting a plurality of continuous waves of different transmission frequencies as the radio wave. 7. A radar according to claim 1, comprising a transmission means for emitting a plurality of continuous waves of different transmission frequencies as the radio wave. 8. A radar according to claim 1, comprising a measurement means for, when the second frequency analysis means detects the peak signal, calculating at least one of a distance from the radar to the object and a relative velocity of the radar and the object, on the basis of the beat signal. 9. A radar according to claim 8, wherein when the first frequency analysis means detects the peak signal, and when the frequency analysis by the second frequency analysis means is not executed, the measurement means calculates at least one of a distance from the radar to the object and a relative velocity of the radar and the object, on the basis of the peak signal detected by the first frequency analysis means. 10. An alarm device, comprising: a determination means for determining whether or not a calculation result of the measurement means of the radar according to claim 9 satisfies a predetermined information condition; and a means that informs a determination result of the determination means to a driver. 11. An alarm device, comprising: a determination means for determining whether or not a calculation result of the measurement means of the radar according to claim 8, satisfies a predetermined information condition; and a means that informs a determination result of the determination means to a driver. 12. A radar according to claim 1, wherein: the reception means samples the beat signal, and gives sampled signals generated thereby to the first frequency analysis means and the second frequency analysis means; the first frequency analysis means analyzes the a plurality of sampled signals from the sampling means into frequency components by the Fast Fourier Transform; and the second frequency analysis means down samples the plurality of sampled signals from the sampling means, and analyzes the plurality of sampled signals generated thereby into frequency components by the Fast Fourier Transform. 13. A radar according to claim 12, wherein the radar is loaded into a vehicle, and when the vehicle is traveling at a speed of 60 km/h or more, the reception means samples the beat signal at sampling intervals whereby the first frequency analysis means is capable of detecting a first stopping vehicle being ahead of 50 m or less from the vehicle, and the second frequency analysis means down samples the beat signal at sampling intervals that allows the detection of both the first stopping vehicle and a second stopping vehicle existing on a lane adjacent to a lane on which the first stopping vehicle exists. 14. A radar according to claim 1, comprising a transmission means for emitting a continuous wave subjected to a repetitive frequency modulation, as the radio wave. 15. A radar according to claim 1, comprising a transmission means for emitting a plurality of continuous waves of different transmission frequencies as the radio wave. 16. A radar as defined in claim 1, wherein said second frequency analysis means comprises: a low pass filter for removing higher frequency component of an input signal, a down sampler for sampling an output of said low pass filter, and a fast Fourier transform part for fast-Fourier-transforming an output from said down sampler. 17. The radar according to claim 1, wherein the second frequency analyzing means analysis only the peak signal detected by the first frequency analysis means. 18. A program being executed in a radar, the program allowing the radar to execute the processing of: detecting a beat signal of a transmission signal from the radar and a reflection signal of the transmission signal from the radar; a first frequency analysis that analyzes the beat signal into frequency components with a first frequency resolution, and detects a peak signal of frequency spectra obtained thereby; and a second frequency analysis that analyzes the beat signal into frequency components with a frequency resolution different from that of the first frequency analysis, said second frequency analysis analyzing the peak signal detected with a threshold value based on the peak signal detected by the first frequency analysis, and detects a peak signal of frequency spectra obtained thereby. 19. The program according to claim 18, wherein the second frequency analysis analyzes only the peak signal detected by the first frequency analysis. 20. A program being executed in a radar, the program making the radar execute the processing of: detecting a beat signal of a transmission signal from the radar and a reflection signal of the transmission signal from the radar; a first frequency analysis that analyzes the beat signal into frequency components by a first frequency resolution, and detects a peak signal of frequency spectra obtained thereby; and a second frequency analysis that analyzes the beat signal into frequency components by a second frequency resolution finer than the first frequency resolution, said second frequency analysis analyzing the peak signal detected with a threshold value based on the peak signal detected by the first frequency analysis, and detects a peak signal of frequency spectra obtained thereby. 21. The program according to claim 20, wherein the second frequency analysis analyzer only the peak signal detected by the first frequency analysis.