Patent ID: 8149155
Filing Date: 2012-04-03
Classification: G01S

Abstract:
1. A method of measuring a range from a reader unit to a non-contacted IC medium, the method comprising: transmitting an inquiry signal at a first frequency from the reader unit to the non-contacted IC medium; causing the non-contacted IC medium to perform modulation to modulate the first frequency by using a second frequency to obtain a modulated frequency, and causing the non-contacted IC medium to respond to the inquiry signal with a response signal at the modulated frequency, the response signal comprising an upper side band (USB) signal component and a lower side band (LSB) signal component; causing the reader unit to receive the response signal to acquire a plurality of frequency components by extracting I and Q components from the response signal; calculating from the extracted I and Q components a phase difference between the upper side band (USB) signal component and the lower side band (LSB) signal component; and measuring the range by using the calculated phase difference.