Patent ID: 7761216

Claim:
A device for determining an internal performance characteristic of an engine during operation of the engine, the device comprising: at least one vibration detector configured to be situated relative to the engine so as to receive and detect vibrations emanating from the engine during operation of the engine, the at least one vibration detector being configured to produce corresponding electrical signals upon receiving and detecting the vibrations; a memory in which data is stored pertaining to frequency of vibrational emanations associated with the internal performance characteristic under various conditions; and a controller coupled to the at least one vibration detector and the memory, the controller being configured (i) to receive the electrical signals from the at least one vibration detector, (ii) to determine, from the received electrical signals, at least one diagnostic frequency of the vibrations, (iii) to compare the determined at least one diagnostic frequency with the data in the memory, and (iv) to produce a measurement of the internal performance characteristic based on the comparison.