A non-contact IC card includes a CPU for processing data, a memory for storing a program for controlling the CPU, an antenna for transmitting data and receiving data manner, a plurality of receivers each having a different signal detection level for detecting a signal received by the antenna, a selector...http://www.google.de/patents/US6045042?utm_source=gb-gplus-sharePatent US6045042 - Non-contact IC card having multiple receivers with different signal detection threshholds for minimizing current consumption
