Binary phase shift key modulator with programmable level control

A BPSK modulator for modulating a binary data signal onto a carrier signal for transmission comprising

• a center tap transformer having first and second windings,
• first and second transistors, each having a collector, an emitter and a base, the first and second transistors connected together in a mirror configuration, the bases of the first and second transistors for receiving the binary data signal, the collectors of the first and second transistors being coupled to the first winding of the center tap transformer, the center tap of the transformer being DC biased, and the second winding providing the BPSK modulated carrier output signal,
• a third transistor having a collector, an emitter and a base, the collector being coupled to the emitters of the first and second transistors, the base being coupled to the carrier signal, and
• programmable gain control means also coupled to the base of the third transistor for providing step-wise level control of the BPSK modulated carrier output signal.