The dynamic properties of a digital radiometer system and its operating efficiency

Fluctuation sensitivity models of microwave radiometers

“…If we analyze formula (4), we can conclude that the fluctuation sensitivity in multireceiver radiometers is increasing proportionally to the square root from the number of receiver channels relative to the sensitivity of a single receiver channel, without increasing the duration of measurements. This is in accordance with the theoretical [8] and experimental [9] research. Increased sensitivity is achieved by increasing the time constant of the synchronous filter.…”

“…In papers [6][7][8], a new method of increasing fluctuation sensitivity was described. It is based on the multi-receiver design principle used together with the null method of measurement.…”

Radiometric Receiver for Passive Microwave Imaging System

“…As shown in conducted experiments, the radiometric receiver has a best long time and temperature stability in the zero operating mode, it is fully corresponds to researches conducted earlier [5]. General analysis of Figure2 shows the some down shifting of the noise temperature scale.…”

“…In addition, it increases the requirements to the fiducial source linearity. The modified zero measurement method used in the radiometric receiver, which allows increase in the measurement rate without fluctuation sensitivity loss, is described in [5]. The modification implies the use of two types of synchronous processing pulse modulations, width and amplitude ones.…”

“…According to this modification, the antenna noise temperature is determined by the duration of the pulse-width modulated signal, when zero balance is established, by the following expression [5]:…”