Abstract: A frequency hopping synthesizer is constructed from two FET-based multiplier circuits each responsive to a carrier input signal and a modulation signal to produce respective output signals which are in-phase combined to provide a frequency-shifted signal. The multiplier circuits each comprise two dual-gate field effect transistor (FET) amplifiers which are electrically balanced to suppress unmodulated carrier components so that only the modulated carrier signal appears. The respective carrier input signals and modulation signals are in quadrature phase relationship. A direct digital synthesizer controllably generates signal components which serve as the modulation signals for the multiplier circuits.

Abstract: A secure wireless party line system that can be used by a group of mobile users to communicate with each other like a wired party line but without the cumbersome inconvenience of long wired tether. The party line function is achieved by the use of a fixed wireless repeater. The fixed wireless repeater receives spread spectrum transmissions from all N mobile users at a frequency f1, and passes the received signals through an RF amplifier and upconverter, and then to an IF amplifier and power divider, which converts the received signals down to a convenient intermediate frequency (IF), and feeds N receive spread spectrum processors, each dedicated to receive a coded spread spectrum transmission from one user. The received voice outputs from the N users are then combined in a N-channel voice data multiplexer, and broadcast at a frequency f2 to all users with a common spread spectrum code word added by a transmit spread spectrum processor.

Abstract: A base station in a cellular communications system is connected to a plurality of remote cellular sites by a communications link having a base terminal coupled to a remote terminal by two optical fibers. The base terminal receives RF downlink channels from the base station and optically transmits the RF channels as a non-overlapping composite signal to the remote terminal on a first fiber. The RF downlink channels are individually recovered at the remote terminal and distributed to disignated cell sites. The remote terminal also functions to receive RF uplink channels from the cell sites and optically transmit the RF channels as a non-overlapping composite signal to the base terminal on a second fiber. The RF uplink channels are indivicually recovered at the base terminal and forwarded to the base station.

Abstract: A method for generating a large number of stable microwave frequency components for wideband lightwave distribution networks is shown. A single oscillator is used at a transmitter to provide all of the required subcarriers. The subcarriers are modulated by high data rate channels and then multiplexed for transmission over a fiber optic line. At a receiver, all of the tuning frequencies required for channel selection are generated by a single oscillator.

Abstract: An adjustable waveguide short circuit using a thin partition or rectangular pin parallel to the E-field in the waveguide and movable along longitudinal slots centrally located on the two broad walls of the waveguide.