HIGH-PRECISION MEASURING METHOD AND APPARATUS PARTICULARLY USEFUL FOR NON-INVASIVELY MONITORING GLUCOSE LEVELS

摘要

A method and apparatus for monitoring a condition having a known relation to, or influence on, the transit time of a cyclically-repeating energy wave moving through a transmission channel (100), by: (a) transmitting a cyclically-repeating energy wave through the transmission channel from a transmitter (101) at one end to a receiver (102) at the opposite end; (b) continuously changing the frequency of the transmitter according to changes in the monitored condition while maintaining the number of waves in the transmission channel as a whole integer; and (c) utilizing the changes in frequency of the transmitter to provide a continuous indication of the monitored condition. Operation (b) is preferably performed by detecting a predetermined fiducial point in each cyclically-repeating energy wave received by the receiver, but may also be performed by the use of a phase-locked loop circuit (103), to maintain the number of energy waves in the loop of the transmission channel as a whole integer.