tau=sza_calc_tau(nu,za) Calculate system temperature Tsys at given freq (Hz) and opacity tau
0001 function tsys=sza_calc_tsys(nu,tau) 0002 % tau=sza_calc_tau(nu,za) 0003 % 0004 % Calculate system temperature Tsys at given freq (Hz) and opacity tau 0005 0006 tatm=300; % Assume atmosphere 300K 0007 tscope=0; % % extra noise from non-ideal telescope structure 0008 % Set extra noise to zero based on reasoning that Trx from DASI 0009 % includes warm lense and throat. In SZA primary is warm but throat is 0010 % cold - overall certainly should not be worse. 0011 0012 % Numbers from a DASI loadcal session in Nov 2001 0013 % Should be replaced with proper numbers from measurements of SZA 0014 % receivers 0015 ref_nu=(26.5:35.5)*1e9; 0016 ref_trx=[34.5015,26.1011,21.8966,22.3953,22.1318,23.6529,26.1444,27.2927,31.0079,36.2607]; 0017 0018 trx=interp1(ref_nu,ref_trx,nu); 0019 0020 Tcmbrj=2; % RJ temp of CMB 0021 tsys=(trx+tscope).*exp(tau)+tatm*(exp(tau)-1)+Tcmbrj; 0022 0023 return