THE FLUCTUATION SENSITIVITY OF A RADIOMETER WITH IF AMPLIFIER MODULATION

where K 1 and K 2 are the gains for the inputs I and II; ml(t ) and m2(t) are regular periodic functions of the same period as the if amplifier modulation and of unit amplitude, and czi(t) and c~ii(t) are random processes which take into account the fluctuations in the gains at inputs I and II. In the general case o~i(t), aii(t), Ui(t), and Uii(t ) are partially correlated (due, in the first place, to the common if amplifier connected after the electronic switch). Assuming K~fl = 1; ml(t) + m2(t) = 1; Ui(t) , Uii(t) , (~i(t), and aii(t) stationary, and denoting the regular component of the detector current by Id(t___.), we find an expression for the correlation function ZZ T of the nonstationary random process Z(t) = Id(t ) - I"d(t), namely, + 4m,m. [(o~ - b4)2%%: + o~,~,: + b~<,~2%.]. (3) where a t = U~(t), a~i = U~i(t i are the variances of the noise at inputs I and II; RI(T), RII(T ) are the correlation coefficients of the voltages Ui(t), Uii(t ) respectively; b = K~K~ 2 is the ratio of the squares of the gains; a0~0~" is the correlation function of the correlated components of the processes ai(t) and aii(t); and OLIG~ iT, 0/2~2T are the corresponding correlation functions of the noncorrelated components of the same processes (ai(t) = al + a0, aII(t) = a2 - ce0). Since we have assumed that the bandwidth of the if amplifier is very much greater than the modulation frequency, terms which involve the correlation of the noise Ui(t) and Uii(t) do not occur in (3). Using the Wiener-Khintchin e transformation we obtain an expression for the intensity spectrum of the fluctuation process Z(t) in the case when mr(t) is the meander, viz.,