Abstract: An improved simulcast transmission in which a signal transmitted by a master station provides a reference frequency signal, as well as a voice and data path, is described. The system can be configured such that a master station can transmit AFSK data and voice or FSK data and voice. In either case, the remote transmitter will retransmit FSK and voice.

Abstract: The invention is a microphonics suppression means for a high frequency resonant cavity. The resonant cavity is used in a RF oscillator to generate UHF/VHF frequencies. The resonant cavity comprises an outer wall portion, a center conductor portion, a tuning slug and a plurality of coupling probes. The coupling probes, tuning slug and center conductor are held in a fixed relationship by a microphonics suppression means made of a low dielectric material which fits over and around the center conductor and encapsulates the coupling probes and collars the tuning slug. The microphonics suppression means reduces the effect of microphonics on the output signal of the RF oscillator, thus allowing a clean output signal suitable for high power applications.

Abstract: A frequency modulator for radio frequency (RF) signals is described that symmetrically modulates the RF signal with either binary signals or voice signals without distorting the amplitude of the binary signal near bit edges. The inventive frequency modulator includes a reference signal generator, a phase comparator for comparing the reference signal and a feedback signal to provide an error signal, a filter for filtering the error signal, a voltage-controlled oscillator (VCO) responsive to the filtered error signal for generating an output signal, a divider for dividing the VCO output signal by a predetermined number to provide the feedback signal, circuitry coupled to the VCO for modulating the VCO output signal with the binary signal, and circuitry coupled to the divider for varying the predetermined number of the divider between a first predetermined number and a second predetermined number in response to the binary signal.