Analysis of receiver sensitivity by the Caple/Huttley method

The aims of the work have been: (i) to escape from the purely observational and mathematical, grouped component analysis of literature from World War 2 to the present, which has not included an understanding of the contributing circuit performance, and has therefore been divorced from accurate circuit measurement, and has often led to considerably inaccurate performance predictions; (ii) to determine a fully integrated circuit to system level method which provides not only an overall value for system sensitivity, but which enables the contribution of each component in the chain to be comprehended and the signal to noise ratio at its input and output to be calculated, and measured for (a) gain limited crystal video receivers, (b) receivers in the gain related region between (a) and (c), (c) bandwidth limited superheterodyne receivers; (iii) to provide an exact method of evaluating “Integration Loss”, by defining the S/N at the interfaces of major components, thereby eliminating errors due to the inexact analysis of the performance of grouped components: primarily the IF bandwidth, the detector diode, and the video bandwidth; (iv) to define the IFM path architecture for EW receivers, and to ensure that the IFM sensitivity and that of the video path can be balanced to be the same value of sensitivity. The key factor in this endeavour has been to determine the contribution of the detector diode to the well known but not quantified “square law loss” of signal to noise ratio, in all non-coherent receivers, whether radar, EW, laser, or communications