Abstract: A subharmonic carrier-canceling baseband/K upconverter system uses a first splitter to separate an incoming RF signal into two equal components: in-phase (1) and quadrature (Q, 180 degrees delayed). A second splitter is used to separate a local oscillator signal into two equal components: in-phase (I) and quadrature (Q, 90 degrees delayed). A first subharmonic mixer is used to mix both I components, while a second subharmonic mixer is used to mix both Q components. The outputs of both mixers are then combined to produce an output RF signal having reduced second order harmonics close to said local oscillator frequency.

Abstract: A method of measuring input-backoff to an amplifier in a time-division multiple access (TDMA) communication system having a carrier recovery segment and a clock recovery segment prior to a data segment in a traffic burst. A monitoring station transmits a CW pilot signal within the amplifier's bandwidth. In the guard time between bursts, the monitoring station measures the unsuppressed pilot level output by the amplifier. While a ground station is transmitting an unmodulated carrier during carrier recovery or a carrier modulated at the clock frequency during clock recovery, the monitoring station measures the suppressed pilot level, suppressed by the non-linear interaction of pilot and carrier. The amount of pilot suppression is related to the input power back-off of the carrier by a previously measured or a theoretically derived relationship.