Peter M Vansloun

US Patent:

43228283, Mar 30, 1982

Filed:

Jan 9, 1981

Appl. No.:

6/223627

Inventors:

Dave Hoff - Brooklyn Park MN
Peter H. Vansloun - Hopkins MN

Assignee:

Honeywell Inc. - Minneapolis MN

International Classification:

G01S 1100

US Classification:

367118

Abstract:

Apparatus for classifying the activity of an aircraft including the geophone proximate an airfield used by jet airplanes for generating a signal indicative of the existence of the jet aircraft. Amplifier means are provided for enhancing the signal. The signal is then passed through a low pass filter means for receiving the signal and passing only that portion having a frequency less than about 30 Hz. A high band pass filter also receives the signal and passes only that portion having a frequency ranging from about 90 Hz to about 120 Hz. Two demodulator means are provided which receive the low pass signal to provide a low pass envelope and receive the high band pass signal to produce a high band pass envelope. Threshold signal generating means are provided to receive the low pass envelope and the high band pass envelope, and generate a signal when either or both envelopes reach a predetermined threshold. Finally, comparator means are provided for comparing the time sequence of the signals generated by said threshold signal generating means to determine the activity of the jet aircraft.