Abstract: A method and apparatus for preventing harmful foreign voltage from being applied to a fixed wireless terminal. Upon the detection of a harmful voltage, the fixed wireless terminal is prevented from being connected to the tip-and-ring lines of a premises' land-line. The voltage is detected by a voltage-detector. The invention may also be used to disconnect the normally-closed connection of the fixed wireless terminal with the tip-and-ring lines of the premises' land-line upon the detection of a harmful voltage on the tip-and-ring lines.

Abstract: A wireless communication system allow two-full two-way communication among a net or loop of stations. Each station is in direct communication with another member of the net such that a logical communication loop is created about the net. Each station combines its received signal with its own audio signal for retransmission to the next member of the loop whereby audio from said station is passed in turn to each of the other loop members. Transmission frequency hopping is utilized to insure system privacy and minimize interference with or from other loops operating in the same area. The system dynamically reconfigures itself to allow for the addition or dropping of a station without breakdown of the loop.

Abstract: A universal input-output apparatus has: a controllable source of electrical energy including at least one drive source having an output terminal and a return terminal; an electrical energy measuring device including at least one energy sensor having an input terminal connected to the output terminal of the controllable source of electrical energy; a twin leaded line having the first ends thereof connected to the output and return terminals of the drive source, respectively; and an integrity tester in the form of a zener diode connected across the second ends of the first and second leads, respectively, a first terminal connected to one of the second ends, a second terminal connected via a unidirectional conductor to the one second end and a third terminal connected via a resistive device to the one second end.