Self-checking supervision circuit

Claim 1

A SELF-CHECKING SUPERVISION CIRCUIT COMPRISING A SOURCE OF CODED SIGNALS TO BE CHECKED, A CHECKING CIRCUIT FOR CHECKING SAID CODED SIGNALS AND PROVIDING A FIRST PULSE OUTPUT WHEN THE CODED SIGNALS BEING CHECKED ARE CORRECT, BISTABLE ELEMENT MEANS HAVING FIRST AND SECOND STABLE CONDITIONS, FIRST AND SECOND INPUT TERMINAL MEANS, AND OUTPUT TERMINAL MEANS, SAID FIRST INPUT TERMINAL MEANS BEING ARRANGED TO SET SAID BISTABLE ELEMENT MEANS TO SAID FIRST CONDITION UPON APPLICATION OF A PULSE THERETO, SAID SECOND INPUT TERMINAL MEANS BEING ARRANGED TO SET SAID BISTABLE ELEMENT MEANS TO SAID SECOND CONDITION UPON THE APPLICATION OF A PULSE THERETO, SAID OUTPUT TERMINAL BEING ARRANGED TO PRIVIDED AN OUTPUT WHEN SAID BISTABLE ELEMENTS ARE SHIFTED FROM SAID FIRST CONDITION TO SAID SECOND CONDITION, MEANS FOR ENERGIZING SAID CHECKING CIRCUIT AND BISTABLE ELEMENT IN CYCLES OF A PLURALITY OF A SEQUENTAL INSTANTS COMPRISING MEANS FOR APPLYING A PULSE OF SAID FIRST INPUT TERMINAL MEANS AT A FIRST INSTANT, MEANS FOR APPLYING A PULSE TO SAID SECOND INPUT TERMINAL MEANS AT A SECOND INSTANT ONLY IF A CODED SIGNAL TO BE CHECKED IS PRESENT, MEANS FOR APPLYING SAID CODED SIGNAL TO SAID CHECKING CIRCUIT AT A THIRD INSTANT WHEREBY SAID FIRST PULSE IS APPLIED TO SAID FIRST INPUT TERMINAL MEANS AT SAID THIRD INSTANT IF SAID CODED SIGNALS ARE PRESENT, MEANS FOR APPLYING A PULSE TO SAID SECOND INPUT TERMINAL MEANS AT A FOURTH INSTANT, MEANS INHIBITING OUTPUT PULSES FROM SAID OUTPUT CIRCUIT EXCEPT DURING SAID FOURTH INSTANT, ALARM MEANS, AND MEANS CONNECTING SAID ALARM MEANS TO SAID BISTABLE ELEMENT MEANS WHEREBY THE ABSENCE OF A PULSE AT SAID OUTPUT TERMINAL MEANS DURING SAID FOURTH INSTANT IS INDICATED.