Time-of-occurrence markers

Claim 1

AN EVENT MARKER COMPRISING IN COMBINATION; A CAPACITOR HAVING A FIRST AND SECOND TERMINAL FOR PRODUCING A VOLTAGE RAMP THEREACROSS IN RESPONSE TO A TRIGGER PULSE INDICATIVE OF THE OCCURRENCE OF AN EVENT, A SUBSTANTIALLY CONSTANT CURRENT GENERATOR COUPLED TO SAID CAPACITOR FOR CHARGING SAID CAPACITOR, A FIRST AND A SECOND SEMICONDUCTOR DIODES, A REFERENCE DIRECT CURRENT VOLTAGE SOURCE; MEANS CONNECTING SAID SOURCE, SAID FIRST, AND SAID SECOND SEMICONDUCTOR DIODES ACROSS SAID CAPACITOR TO MAINTAIN A FIXED POTENTIAL THEREON BEFORE THE OCCURRENCE OF AN EVENT; A BISTABLE IMPEDANCE DEVICE HAVING A HIGH-IMPEDANCE STATE WHEN THE POTENTIAL ON SAID CAPACITOR IS BELOW A PREDETERMINED LEVEL AND A LOW-IMPEDANCE STATE WHEN SAID POTENTIAL IS ABOVE SAID PREDETERMINED LEVEL; MEANS COUPLING SAID DEVICE BETWEEN THE JUNCTION OF SAID FIRST AND SECOND DIODES AND SAID SECOND TERMINAL FOR CARRYING THE OUTPUT CURRENT OF SAID CURRENT GENERATOR AND OF SAID REFERENCE SOURCE; AND MEANS COUPLED SAID TRIGGER PULSE TO SAID DEVICE FOR SWITCHING SAID DEVICE FROM SAID LOW- TO SAID HIGH IMPEDANCE STATE THEREBY MARKING THE ORIGIN OF SAID RAMP WHICH RISES TO AN AMPLITUDE DEPENDENT ON SAID PREDETERMINED LEVEL.