Star tracking system

Claim 1

A MONITORING DEVICE FOR DETERMINING THE POSITION OF A TARGET OBJECT IN THE FIELD OF VIEW OF THE MONITORING DEVICE COMPRISING: MEANS FOR NUTATING SAID FIELD OF VIEW INCLUDING SAID TARGET OBJECT ABOUT A NUTATION AXIS AT A CERTAIN FUNDAMENTAL ROTATION FREQUENCY; A RETICLE POSITIONED IN THE RADIANT ENERGY OF SAID NUTATING FIELD VIEW WITH ITS CENTER ON SAID NUTATION AXIS, SAID RETICLE HAVING A PATTERN WHICH IS SYMMETRICAL ABOUT ITS CENTER AND INCLUDES AT LEAST ONE OBSCURING AND AT LEAST TWO TRANSMITTING SECTORS; SAID RETICLE THEREFORE MODULATING LIGHT FROM SAID TARGET OBJECT, WHEN IT IS IN THE CENTER OF SAID FIELD OF VIEW SO AS TO FORM A CIRCLE CENTERED WITH RESPECT TO SAID NUTATION AXIS AND THEREFOR THE CENTER OF SAID RETICLE, AT A FULLY MODULATED FREQUENCY EQUAL TO THE NUMBER OF TRANSMITTINNG SECTORS TIMES SAID FUNDAMENTAL NUTATION FREQUENCY; LIGHT FROM SAID TARGET OBJECT, WHEN NOT SO CENTERED, BEING PASSED BY SAID RETICLE AT LEAST PARTIALLY AT A LESSER FREQUENCY THAN SAID FULL MODULATED FREQUENCY; DETECTOR MEANS, POSITIONED BEHIND SAID MODULATING MEANS THEREBY RECEIVING SAID MODULATED RADIANT ENERGY, SAID DETECTOR THEREFORE PRODUCING A SIGNAL CONTAINING COMPONENTS AT BOTH SAID FULLY MODULATED FREQUENCY AND SAID LESSER FREQUENCY WHEN SAID TARGET OBJECT IS AT A DISTANCE FROM SAID CENTER OF SAID FIELD OF VIEW; AND MEANS FOR DERIVING SOLELY FROM SAID LESSER FREQUENCY COMPONENT OF SAID DETECTOR SIGNAL AN OUTPUT CONTAINING INFORMATION AS TO THE MAGNITUDE AND DIRECTION OF THE MONITORED POSITION OF SAID OBJECT FROM SAID CENTERED POSITION.