The X-band transmitter consists of two fully cross-redundant units, each containing an X-band oscillator, a QPSK modulator, and a final power amplifier with 4W RF output power. The two oscillator modules operate at center frequencies 130MHz apart to reduce ACI (adjacent channel interference). The operating frequencies of the two oscillator modules are 8120 MHz and 8250 MHz, respectively. The QPSK modulator accepts a digital video signal consisting of two I, Q data streams differentially coded at a data rate of 75 Mbps each, totaling 150 Mbps per channel. Each unit consists of one oscillator, a QPSK modulator, and a final power amplifier that can be turned on and off independently of the others. When both units are powered on, the device can process the entire data stream up to 300 Mbps.
