Accession Number : AD0686112

Title :   AN OPTIMUM SYSTEM SYNTHESIS FOR OPTICAL RADIOMETRIC MEASUREMENT,

Corporate Author : UTAH STATE UNIV LOGAN ELECTRO-DYNAMICS LABS

Personal Author(s) : Wyatt,Clair L. ; Baker,Doran J. ; Despain,Alvin M.

Report Date : 01 JUN 1968

Pagination or Media Count : 80

Abstract : The minimum detectable signal of an optical radiometer was optimized as a function of modulation and correlation waveforms, and relative amplitudes of source, reference, and noise levels. The mathematical model considers the radiometer as a device to estimate the variance of a Gaussian random process with zero mean. It was found that the optimum system is one which 'looks' at the source for one half of the period and then abruptly switches to the reference for the remainder of the period. The theoretical results for three commonly encountered waveforms were computed and laboratory measurements confirm the results that were interpreted in terms of the detector parameter NEP. These are: (1) The optimum radiometer as described above for which the minimum detectable signal is Pm = 2 NEP. (2) The sine wave radiometer, which utilizes a tuned ac amplifier to select the fundamental sine wave component of the modulated signal for which Pm = 2.46 NEP. (3) The radiometer which produces a triangular wave resulting from the convolution of a chopper blade with an aperture of the same width for which Pm = 4 NEP. (Author)

Descriptors :   (*RADIOMETERS, OPTIMIZATION), MODULATION, STATISTICAL FUNCTIONS, NOISE(RADIO), MATHEMATICAL MODELS, STOCHASTIC PROCESSES, PHOTOMETERS

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE