Method and apparatus for making high-precision measurements

Apparatus for measuring a predetermined parameter, comprising:

• a displaceable sensor carried by a mounting member such that the displaceable sensor changes in location, form or length with respect to the mounting member in accordance with said predetermined parameter;
• a transmitter for transmitting a cyclically-repeating energy wave through a transmission channel to or in said displaceable sensor;
• a receiver for receiving said cyclically-repeating energy wave transmitted through said transmission channel to or in said displaceable sensor;
• and a data processor for continuously changing the frequency of transmission of the cyclically-repeating energy wave in accordance with changes in said predetermined parameter such that the number of waves received is a whole integer and for utilizing the change in frequency to produce a measurement of said predetermined parameter.

Apparatus for monitoring the condition of lubricating oil in an automotive vehicle, comprising:

• a transmitter at a first location with respect to a body of said lubricating oil for transmitting a cyclically-repeating energy wave through said body of lubricating oil;
• a receiver at a second location with respect to said body of lubricating oil for receiving said cyclically-repeating energy waves after traversing said body of lubricating oil;
• and a data processor for continuously changing the frequency of transmission of the cyclically-repeating energy wave in accordance with changes in said condition of the lubricating oil such that the number of waves received is a whole integer;
• and utilizing the change in frequency to produce an indication of the composition, and thereby of the cleanliness, of said lubricating oil.