Abstract: A data transmission system comprising a transmitter producing a high-frequency carrier modulated with data and swept in a repetitive time pattern over a wide frequency range. The modulation of the carrier is so controlled that a characteristic of the data signal modulation has a predetermined relationship with respect to the repetitive sweep time pattern. The system receiver comprises a narrow-band IF channel coupled to the output of a mixer arranged to receive the incoming swept-carrier signal and a correspondingly-swept local oscillator signal. The sweep control signal for the local oscillator is developed by a circuit coupled to the mixer output and responsive to the data modulation on the IF signal.

Abstract: An industrial process control system to be used with processes which are geographically spread out over a relatively wide field area, with portions thereof located in respective zones, and wherein the process has associated therewith a large number of instrumentation elements including sensing elements and operating elements for controlling actuators such as process valves. The control system includes a central station with a digital computer which directs signals to a number of primary transmitter/receiver units each producing a swept-carrier wireless signal for transmission to a respective one of the field area zones. Within each zone are a plurality of local transmitter/receiver units similar to the primary units, with each local unit being assigned to one or more sensing elements and/or one or more operating elements.

Abstract: An industrial process control system to be used with processes which are geographically spread out over a relatively wide field area, with portions thereof located in respective zones, and wherein the process has associated therewith a large number of instrumentation elements including sensing elements and operating elements for controlling actuators such as process valves. The control system includes a central station with a digital computer which directs signals to a number of primary transmitter/receiver units each producing a swept-carrier wireless signal for transmission to a respective one of the field area zones. Within each zone are a plurality of local transmitter/receiver units similar to the primary units, with each local unit being assigned to one or more sensing elements and/or one or more operating elements.