Microwave Transmitter and Receiver
T h e microwave t r a n s m i t t e r and receiver units constitute t h e basic building blocks for the T D - 3 radio system. T h e y provide the gain necessary to compensate for the transmission loss of the station-tostation air path, and means for changing t h a t gain during periods of radio signal fading. These units also include the selectivity required to keep the radio channels of a route properly separated. As previously pointed out, 1 the Schottky barrier diode modulator is used in microwave receivers now being m a n u f a c t u r e d ; therefore, most of our derivations pertain to this t y p e of receiver. However, our analysis of receiver selectivity requirements pertains to a receiver equipped with a parametric amplifier, whose use was expected when the selectivity requirements were originally established. N. DESIGN FEATURES AND PERFORMANCE OBJECTIVES T h e distinction between a design feature and a performance objective is not always clear because they m a y be related; therefore, somewhat a r b i t r a r y distinctions are made.