METHOD OF TRANSMITTING AND RECEIVING DATA, SYSTEM AND RECEIVER THEREFOR

摘要

A data signal is transmitted by a transceiver unit at an unknown frequency within a known range of frequencies. The data signal is received at a receiver (1) within the known range of frequencies. At the receiver (1), the range of frequencies is divided into plural frequency bands each of width less than the uncertainty in the transmission frequency of the data signal. The presence of the data signal in at least one of the frequency bands is detected and the detected data signals are demodulated. A very low cost transmitter can thereby be used in the transceiver unit, allowing two-way communication between the receiver (1) and the transceiver unit.