Parking meter control unit
Token identifying system
Remote time and charge system
ApplicationNo. 726228 filed on 07/05/1991
US Classes:375/223, Angle modulation375/272, Frequency shift keying375/306, One oscillator455/78With transmitter-receiver switching or interaction prevention
ExaminersPrimary: Kuntz, Curtis
Assistant: Tse, Young T.
Attorney, Agent or Firm
Foreign Patent References
International ClassesH04B 001/44
AbstractAn apparatus and method for communication of data, the apparatus including a transmitter operable to transmit a first signal at a first frequency and a second signal at a second frequency. The second signal is modulated to represent data and the transmitter ends transmission of the second signal when the transmission of data is completed. The apparatus further includes a receiver switchable between a first frequency receive mode and a second frequency receive mode, the first frequency receive mode rendering the receiver operable to receive signals at the first frequency and the second frequency receive mode rendering the receiver operable to receive signals at the second frequency. The first frequency receive mode is a low power mode and the second frequency receive mode is a data communication mode. The apparatus also includes a device for switching the receiver into the low power mode, for switching the receiver into the data communication mode when said first signal is received, and for switching the receiver into the low power mode when transmission of said second signal is ended.