| 摘要 |
<p>A data communication sustem (Figure 1) is described that covers a geographic area divided into a plurality of non-overlapping zones (Figure 2) and includes a general communications controller (GCC, 104), a plurality of channel communications modules (CCM 106, 108, 110, 112) and associated transmitters (114, 120, 124) and receivers (116, 118, 122, 126, 128), and a plurality of portable radios (130, 132, 134). Message signals carrying alphanumeric information are communication between the GCC (104) and the portable radios (130, 132, 134) by way of a radio channel. Each CCM (106, 108, 110, 112) takes a signal strength measurement every time it receives a message signal from a portable radio (130, 132, or 134). The GCC (104) gathers the signal strength measurements from the CCM receivers (116, 118, 122, 126, 128) receiving the same message signal and computers an adjusted signal strength for each zone. The GCC (104) then selects the zone having the largest adjusted signal strength for determining the location of the portable radio (130, 132 or 134) that transmitted the message signal. Whenever the GCC (104) transmits a message signal to a portable radio, the CCM transmitter (114, 120, 124) is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio (130, 132, 134). Since the GCC (104). can be simultaneously transmitting message signals to portable radios (130, 132, 134) in other zones using non-interfering CCM transmitters (114, 120, 124), information throughput is greatly enhanced.</p> |
