Abstract: A liquid level measurement system including a vertical linear member and a float. The linear member includes a plurality of electrical conductors, each representing one bit of a multiple bit Gray code and each including alternate portions which interact with the float to produce a signal in the conductor indicative of a logical "1" or "0". The "1" portions and the "0" of the conductors form a unique binary code word at each position of the float. A phase comparator in a readout device attached to the conductors compares the signals from each conductor with a reference and constructs a unique address code word indicative of the position of the float. An inductor extending the length of the linear member powers the system, without electrical leads to the float.

Abstract: A linear position measurement system including a linear member and a relatively movable member. The linear member includes a plurality of serpentine electrical conductors, each representing one bit of a multiple bit Gray code. At any longitudinal position of the movable member, an inductor in the movable member induces oppositely phased signals in those conductors which lie along a first long edge of the linear member and in those which lie along an opposite edge. A phase comparator in a readout device attached to the conductors compares the signals from each conductor with a reference and constructs a unique address code word indicative of the position of the movable member. The inductor in the movable member is activated through a special circuit which is powered by inductive coupling with a coil carried by the linear member.