Self-calibratable phase sensitive measuring apparatus

Claim 1

A SELF-CALIBRATABLE SENSITIVE MEASURING APPARATUS COMPRISING MEANS DEFINING AN INPUT SIGNAL CHANNEL, MEANS DEFINING A REFERENCE SIGNAL CHANNEL, EACH CHANNEL HAVING INPUT AND OUTPUT CONNECTIONS, PHASE SENSITIVE DETECTOR MEANS ELECTRICALLY COUPLED TO THE OUTPUTS OF THE CHANNELS TO PROVIDE AN ELECTRICAL OUTPUT IN ACCORDANCE WITH A PHASE RELATIONSHIP OF THE SIGNALS IN THE REFERENCE AND INPUT SIGNAL CHANNELS AND PROVIDING A NULL OUTPUT WHEN THE SIGNALS BEAR A SPECIFIC PHASE RELATIONSHIP TO ONE ANOTHER, A PAIR OF PRECISION PHASE REFERENCE NETWORKS AFFORDING TWO PREDETERMINED, DIFFERENT DISCRETE PHASE SHIFTS FOR A GIVEN SIGNAL PASSED THERE-THROUGH, SAID INPUT CONNECTIONS INTRODUCING A REFERENCE INPUT SIGNAL INTO THE REFERENCE CHANNEL, MEANS TO CONNECT THE REFERENCE INPUT SIGNAL TO THE PHASE REFERENCE NETWORKS AND MEANS TO CONNECT THE OUTPUTS OF EITHER OF THE TWO PHASE REFERENCE NETWORKS TO THE INPUT END OF THE INPUT SIGNAL CHANNEL, ATR LEAST TWO PHASE ADJUSTING MEANS, MEANS TO CONNECT THE TWO PHASE ADJUSTING MEANS IN AT LEAST ONE CHANNEL TO SHIFT THE PHASE OF THE SIGNAL IN ONE CHANNEL RELATIVE TO THE SIGNAL IN THE OTHER CHANNEL, MEANS WHEREBY WITH ONE OF THE PRECISION PHASE ADJUSTING MEANS, WHEREBY WITH ONE OF THE PRECISION PHASE REFERENCE NETWORKS CONNECTED TO THE INPUT SIGNAL CHANNEL THE SIGNAL IN ONE OF THE TWO CHANNELS CAN BE ADJUSTED BY ONE PHASE ADJUSTING MEANS TO PRODUCE A NULL OUTPUT FROM