Target Object Detection System

• US 20080042895A1
• Filed: 02/08/2005
• Published: 02/21/2008
• Est. Priority Date: 02/08/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Inaba, Takayuki
• Granted Patent: US 7,652,616 B2
• Time in Patent Office: Days
• US Class Current: 342/112
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/536 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
• CPC Class Codes: G01S 13/931 of land vehicles

Abstract

A time needed until measurement values are obtained in a two-frequency continuous wave radar systems is reduced.

A target object detection system (1) that emits to target objects transmission signals (22), as transmission waves (23), whose frequencies have been modulated successively into a plurality of stepped frequencies, and receives echoes (24) of the transmission waves (23) reflected from the target objects, thereby to calculate relative velocities of the target objects by frequency-analyzing reception signals (25) obtained from the received echoes (24). The target object detection system (1) includes: a frequency modulation means (2) that executes a plurality of times frequency-modulation processes to successively modulate the transmission signals (22) into those of the stepped frequencies, within a minimum measurement time in which a desired velocity resolution is achieved; and a frequency-analysis means (6) that frequency-analyzes throughout the plurality of frequency-modulation processes the reception signals (25) obtained by receiving the echoes (24) of the transmission signals (22) modulated into those of an identical stepped frequency in the plurality of frequency-modulation processes iterated by the frequency-modulation means (2).

Claims

1. A target object detection system for emitting, toward a target object, transmission signals as transmission waves, whose frequencies have been modulated successively into a plurality of stepped frequencies, and for receiving echoes of the transmission waves reflected from the target object, thereby to calculate a relative velocity of the target object by frequency-analyzing reception signals obtained from the echoes,

the target object detection system comprising:

a frequency-modulation means for executing a plurality of times frequency-modulation processes to successively modulate the transmission signals into those of the stepped frequencies, within a minimum measurement time in which a desired velocity resolution is achieved; and

a frequency-analysis means for frequency-analyzing throughout the plurality of frequency-modulation processes those signals, among the reception signals, corresponding to an identical stepped frequency in the frequency-modulation processes.

2. The target object detection system as recited in claim 1, wherein

the frequency-analysis means, by executing the frequency-analyzing throughout the plurality of frequency-modulation processes, generates a first frequency-analysis-result signal from reception signals corresponding to a first stepped frequency in the frequency-modulation processes, and, by executing the frequency-analyzing throughout the plurality of frequency-modulation processes, generates a second frequency-analysis-result signal from reception signals corresponding to a second stepped frequency different from the first stepped frequency,

the target object detection system further comprising

a distance-calculation means for detecting frequency components as a first peak frequency and a second peak frequency at which respective amplitude values of the first and the second frequency-analysis-result signals peak, to calculate a distance to the target object from the difference in signal phase between the detected first and second peak frequencies.

3. The target object detection system as recited in claim 1, wherein

the frequency-analysis means, by frequency-analyzing, throughout the plurality of frequency-modulation processes, reception signals corresponding to each of those stepped frequencies chosen from the plurality of stepped frequencies of the transmission signals modulated by the frequency-modulation means, generates frequency-analysis-result signals from the reception signals,

the target object detection system further comprising:

a velocity-calculation means for detecting frequency components that give peak amplitude values of the frequency-analysis-result signals obtained from the reception signals corresponding to those stepped frequencies, to calculate from the frequency components a relative velocity of the target object; and

a distance-calculation means for calculating phase component shifts with respect to those stepped frequencies by frequency-analyzing throughout the plurality of stepped frequencies the frequency components detected by the velocity-calculation means, to calculate a distance to the target object based on the phase component shifts.

4. The target object detection system as recited in claim 3, wherein

the distance-calculation means, by frequency-analyzing throughout the plurality of frequency-modulation processes by mean of a super-resolution method, the frequency components detected by the velocity-calculation means, calculates phase component shifts with respect to those stepped frequencies chosen from the plurality of stepped frequencies.