Pager with reverse paging facility

Abstract

Position determining apparatus including at least one base station including a base transmitter which periodically transmits timing signals and a plurality of mobile remote units. Each remote unit includes a mobile receiver operative to receive timing signals transmitted by at least one base transmitter; synchronization circuitry receiving the timing signals and providing a spread-spectrum frequency-hopping sequence characteristic of the particular remote unit; a mobile transmitter producing a radiated frequency-hopped signal responsive to the frequency-hopping sequence and the timing signal; and a message generator operative to modify the radiated frequency-hopped signal to transmit a message to the at least one base station. least one base station.

Dependencies are inferred from the claim text.