A unit controlling the measurement range in a microwave radiometer

A control unit for a switched radiometer with pulse-length modulation of th e reference signal is described. The measurement range is varied by changin g the type of modulation of the high-frequency antenna signal and two refer ence signals generated by the reference generators, which produce a constan t noise power. To do this, the control unit forms two types of additional m odulating pulses, The number of periods of these additional pulses determin es the radiometer resolution, and their type determines the shift of the co nversion scale. The unit uses a single-chip microcontroller, and time inter vals of modulation are set by a 10-bit binary counter. In a range of 60-316 K, the introduction of additional pulses in the modulation increased the i nstrument resolution from 0.25 to 0.03125 K.