Abstract: Calls entered into a paging system are processed by a controller which identifies the call source from which the call originates, and from a table of predetermined call sources the controller generates a source tag identifying the call source. The source tag is transmitted together with any caller generated message to a paging receiver. The paging receiver, upon receiving the source tag, selects a predetermined message from a table of predetermined messages, and displays the predetermined message stored within and displays the predetermined message together with the caller generated message. The tables of predetermined call sources and predetermined messages are definable by the paging receiver user.

Abstract: A selective call system is provided in which string searching or text matching operations are performed on data from data generating devices such as condition sensors in a security system. When a predetermined string is identified, an address of a selective call receiver such as a pager is generated and that receiver is called. The invention is applicable to other applications where data is generated which includes predetermined character strings.

Abstract: A selective call control center is provided for transmission of calls to selective call receivers, such as paging receivers. In a first aspect, priorities are assigned to call sources and to call receivers and the order of transmission of calls is determined by the control center as a function of the priorities of the source and the receiver for each call. In a second aspect, at least one call receiver is provided having at least two addresses and the address to be selected from the at least two addresses for calling that receiver is determined dependent on the priority of the source of the call.

Abstract: An improved synchronization system for use with simulcast transmission systems is described. The invention provides a method and means for keeping the information signals for adjacent transmitters in the system in synchronization. This invention utilizes a centrally located master transmitter and control unit and a plurality of secondary transmitters disposed in an annular fashion around the master transmitter. In operation, the innermost annular band is synchronized to the master transmitter, while the remainder of the system is disabled. The next adjacent annular band is then synchronized to the innermost annular ring. The process is repeated until every annular band in the system is synchronized.

Abstract: A simulcast transmitter apparatus having automatic synchronization capability is disclosed which utilizes a signal readily available from any one of a number of available master timing sources to maintain a constant, uniform time delay to the transmitter via its interconnect link, even though the time delay corresponding to this interconnect link is susceptible to variation. Each interconnect link may consist of a phone line or other radio link which exhibits a relatively fixed, but unstable, delay. Each base station includes at least a transmitter and an adaptive-delay device which operates as a remotely-adjustable delay network upon receipt of a resync signal from a central controller to readjust and automatically maintain a uniform amount of time delay to each transmitter in the base stations.

Abstract: An improved simulcast transmission system having automatic synchronization is disclosed which utilizes a signal from any one of a number of readily available master timing sources to maintain a constant, uniform time delay to a multiplicity of transmitters even though the time delay corresponding to an included individual interconnect link is susceptible to variation. This simulcast system includes a central controller for controlling, via an interconnect link, the operation of each transmitter located at a plurality of base station sites. This central controller includes a master timing signal receiver and periodically outputs a resynchronization command via the interconnect link to the base stations. Each interconnect link may consist of a phone line or other radio link which exhibits a relatively fixed, but unstable, delay.

Abstract: In certain situations it is necessary to detect a slight change in a continuous wave signal and to be able to specifically determine the exact position of the change. This is especially necessary in situations where a continuously changing signal (with respect to time) is generated and where it is necessary to determine, at a particular instant of time, any change in the signal from a previous corresponding instant of time. Where the signal is periodic in nature and substantially repeatable between cycles it is possible to establish a memory data base of signal levels as a function of time. Comparisons can then be made on successive cycle against the known, or precalculated data base. Changes between the data base and the new signal result give a positive signal change indication.