System for determining the immittance vector which is the difference between an unknown immittance and a known immittance

Claim 1

ASYSTEM FOR DETERMINING THE VALUE OF AN UNKNOWN ADMITTANCE COMPRISING: A SOURCE OF CONTROLLED A.-C. SIGNAL; AN UNKNOWN ADMITTANVE, A KNOWN ADMITTANCE, AND A PAIR OF RESISTORS OF EQUAL VALUE CONNECTED IN A FOUR TERMINAL, FOUR LEGGED BRIDGE WHEREIN THE KNOWN ADMITTANCE IS CONNECTED IN THE FIRST LEG, THE UNKNWON ADMITTANCE IS CONNECTED IN THE SECOND LEG, ONE OF THE PAIR OF RESISTORS IS CONNECTED INTHE THIRD LEG, AND THE OTHER OF THE PAIR OF RESISTOR IS CONNECTED IN THE FOURTH LEG; EACH OF THE RESISTORS HAVING A CONDUCTANCE MUCH GREATER THAN THE ADMITTANCE OF EACH OF THE KNOWN ADMITTANCE AND THE UNKNOWN ADMITTANCE; THE CONTROLLED A.-C. SIGNAL BEING FED TO THE BRIDGE ACROSS TWO OPPOSITE TERMINALS, ONE OF SUCH TERMINALS BEING THE COMMON JUNCTION OF THE TWO RESISTORS, THE OTHER OF SUCH TERMINALS BEING THE COMMON JUNCTION OF THE KNOWN ADMITTANCE AND THE UNKNOWN ADMITTANCE; AN A.-C. OUTPUT SIGNAL BEING PRODUCED ACROSS THE OTHER TWO OPPOSITE TERMINALS OF THE BRIDGE; A PAIR OF RESOLVERS, EACH HAVING TWO INPUTS; MEANS CONNECTING THE TERMINALS OF THE BRIDGE ACROSS WHICH THE A.-C. OUTPUT SIGNAL IS PRODUCED TO ONE OF THE INPUTS OF EACH OF THE PAIR OF RESOLVERS; MEANS CONNECTING THE TERMINALS OF THE BRIDGE ACROSS WHICH THE SOURCE OF CONTROLLED A.-C. SIGNAL IS CONNECTED TO THE OTHER INPUT OF THE FIRST OF THE PAIR OLF RESOLVERS SUCH THAT THE OUTPUT OF THE FIRST RESOLVER IS PROPORTIONAL TO THE DIFFERENCE BETWEEN THE CONDUCTANCES OF THE UNKNOWN ADMITTANCE AND THE KNOWN ADMITTANCE; A 90* PHASE SHIFT NETWORK HAVING AN INPUT AND AN OUTPUT; MEANS CONNECTING THE SOURCE OF CONTROLLED A.-C. SIGNAL TO THE INPUT OF THE 80* PHASE SHIFT NETWORK AND MEANS CONNECTING THE OUTPUT OF THE 90* PHASE SHIFT NETWORK TO THE OTHER INPUT OF THE SECOND OF THE PAIR OF RESOLVERS SUCH THAT THE OUTPUT OF THE SECOND RESOLVER IS PROPORTIONAL TO THE DIFFERENCE BETWEEN THE SUSCEPTANCES OF THE UNKNOWN ADMITTANCE AND THE KNOWN ADMITTANCE.