DUAL CHANNEL DUAL SPEED FM SUBCARRIER PAGING SYSTEM

摘要

The effective transmission range of awireless paging system is varied bychang-ing the transmission data rate. Signal (31)is transmitted at a fast data rate to receivers(26) in a small transmission range (18) fromtransmitter (28). Signal (30) is transmittedat a slower data rate so that a receiver (26)can reliably receive messages over a largertransmission range (32) from the transmitter(28) for sparse transmitter coverage. Thedual transmission data rates are transmittedeither on separate subcarriers on the sameFM channel, on the same subcarrier ofdifferent FM channels or alternatively ondifferent subcarriers of different FM channels.In a region with dense transmissioncoverage, the receiver decodes transmissionmessages at the faster transmission data rate. Inregions with sparse transmission coverage,the receiver decodes messages at the slowerdata rate.