Occupant detection system

An electric field sensor, comprising:

• a. at least one electrode;
• b. a first reference capacitor;
• c. a second reference capacitor;
• and
• d. a sensing circuit comprising a plurality of states, wherein in a first state said sensing circuit is operatively coupled to at least one said electrode so as to provide for generating a first signal responsive to the capacitance of said at least one said electrode, in a second state said sensing circuit is operatively coupled to said first reference capacitor so as to provide for generating a second signal responsive to the capacitance of said first reference capacitor, in a third state said sensing circuit is operatively coupled to said second reference capacitor so as to provide for generating a third signal responsive to the capacitance of said second reference capacitor, and said sensing circuit is adapted to provide for generating a measure responsive to the capacitance of said at least one said electrode responsive to said first signal, said second signal and said third signal.

A method of generating a response from an electric field sensor, comprising:

• a. operatively coupling an oscillatory voltage signal across a voltage divider, wherein said voltage divider comprises a first impedance operatively coupled to a switched impedance at a node;
• b. switching said switched impedance in accordance with a plurality of states, wherein in a first state said switched impedance comprises at least one electrode of an electric field sensor, in a second state said switched impedance comprises a first reference capacitor, and in a third state said switched impedance comprises a second reference capacitor;
• c. generating a plurality of corresponding response signals from said node corresponding to each of said first state, said second state and said third state;
• and
• d. generating the response from the electric field sensor responsive to said plurality of corresponding response signals.