Pencil and Paper Calculation of Noise Level in Superheterodyne Radar Receivers

One method
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for determination of noise level in radar receivers involves the use of a calibrated signal generator for input voltage and use of a quadratic detector instead of the second detector of the radar receiver. By a related method, which is described in this paper, the rms noise level may be determined from the second detector output as a function of receiver input for any common type of second detector even though its response is not exactly quadratic. This method is justified mathematically, and in a practical application the noise level of a 600-mc receiver is determined as 11.2 microvolts (referred to input).