Patent ID: 8013716
Filing Date: 2011-09-06
Classification: G06K

Abstract:
1. A method for wireless data transmission, the method comprising the steps of: providing a base station and a backscatter-based transponder, the base station and the backscatter-based transponder transmitting wirelessly between one another; and generating a presence signal by a transmitting portion of the transponder as soon as said transponder enters a transmission range or response range of a carrier signal from said base station independent of data transmitted on said carrier signal by the base station, wherein the data is transmitted by the base station via amplitude modulation including a succession of a plurality of field gaps between amplitude signals, wherein the presence signal is generated by phase modulation and backscattering of said carrier signal that is transmitted by the base station, said presence signal having a substantially constant amplitude, wherein a receiving portion of said transponder detects said data generated by said base station and detects said presence signal generated by said transmitting portion of said transponder, wherein the transponder receives the data while the presence signal is being transmitted, wherein said receiving portion of said transponder is configured to differentiate between the data from the base station and the presence signal generated in said transmitting portion of the transponder, and wherein the transponder stops sending the presence signal when the transponder receives a command signal from said base station.