The masked subsystem block ILStest, from the ILS sublibrary of the block-library NAVLIB, is called from within the masked Simulink block ILS, in order to check whether or not the localizer and glideslope signals are valid at the current aircraft position. The block ILStest is called from within the block ILS (Nominal ILS values). See the references for more information about ILStest.
utst = [Gamma_loc Gamma_gs Rloc Rgs]' Gamma_loc: 2D-angle between line from c.g. of aircraft to lo- calizer antenna and runway center-line (as seen from above), [rad] Gamma_gs : 2D-angle between line from c.g. of aircraft to glideslope antenna and runway center-line (as seen from above), [rad] Rloc : 2D-distance from aircraft's c.g. to localizer antenna (as seen from above), [m] Rgs : 2D-distance from aircraft's c.g. to glideslope anten- na (as seen from above), [m]
yils4 = [LOCflag GSflag]'.
Note: GSflag = 0 if aircraft is in area where glideslope signals can be received with appropriate accuracy; LOCflag = 0 if the aircraft flies in area where the localizer signals are receivable. If the aircraft is too far away, GSflag and/or LOCflag are set to 1.
Apart from the FDC user-manual, the following reference contains more information about the ILS signals: