Body composition analyzer

DETAILED DESCRIPTION We claim: 1.
A body composition analyzer comprising: a plurality of electrodes attachable to the body of a person, said body forming a network of unknown impedance; a reference network of known impedance coupled in series with said body network; a source of substantially constant peak to peak alternating current coupled to at least one of said electrodes and to said reference network; a voltage sensing circuit coupled to a pair of said body electrodes and to said reference network to provide a signal representative of the sensed voltage across said body network and a signal representative of the sensed voltage across said reference network; digital processing means coupled to said voltage sensing circuit for calculating at least one value representative of said unknown body impedance from said known reference network impedance and a ratio of the sensed voltage across said body network and said sensed voltage across said reference network.
2.
A body composition analyzer as recited in claim 1 further including means for multiplying each of said body voltage signal and said reference voltage signal by an in-phase signal and an out-of-phase signal shifted from said in-phase signal by ninety degrees to provide an in-phase body voltage signal, an out-of-phase body voltage signal, an in-phase reference voltage signal and an out-of-phase reference voltage signal coupled to said digital processing means.
3.
A body composition analyzer as recited in claim 2 wherein said digital processing means includes means for calculating the magnitude of the voltage across said body network from said in-phase and out-of-phase body voltage signals and the magnitude of the voltage across said reference network from said in-phase and out-of-phase reference voltage signals and means for calculating the magnitude of said unknown impedance from the magnitude of the known impedance of said reference network and the ratio of the magnitude of the voltage across said body network and the magnitude of the voltage across said reference network