Patent ID: 7479921
Filing Date: 2009-01-20
Classification: G01S

Abstract:
1. A distance measuring device measuring a distance to an object of measurement, comprising: a sending source outputting a transmission signal having a variable frequency; a transmission unit generating and emitting to said object of measurement an electromagnetic wave of the same frequency as said transmission signal; a detecting unit detecting a reflected wave of said electromagnetic wave; and a signal processing unit calculating a distance to said object of measurement by an operation of a relation between said detected reflected wave and the frequency of said transmission signal; wherein said detecting unit includes wave-detecting means for performing synchronous detection of said detected reflected wave with said transmission signal, to extract a phase change component of said reflected wave; and said signal processing unit includes frequency converting means for changing variable frequency of said extracted phase change component by a frequency corresponding to a prescribed distance, analysis signal generating means for taking, as an analysis signal, one of upper and lower side bands obtained by said frequency converting means, and Fourier transform means for performing Fourier transform on said analysis signal to calculate a profile, and for finding distance to said object of measurement based on a local maximum of said profile and said prescribed distance.