Real-Time Passive Detection of RF Spark Emission from Gasoline Engines

Recently the proliferation of small gasoline powered unmanned aerial vehicles, ultra light aircraft, and small high speed boats has intensified the threat to the fleet by low observables. The Navy currently relies on infrared systems to detect low radar cross section items. The infrared systems have a period of decreased operation due to the near-grazing angle of solar reflection during sunrise and sunset. This paper presents an algorithm and system that could work in combination with the infrared systems for the close range (within 1km) detection of small gasoline engines in a real-time application. Small gasoline engines produce radio frequency (RF) interference that is the convolution of a pulse train with the impulse response of the spark system. Due to the high sampling rate required to catch the impulse and the low frequency of the pulse train the task of detecting the RF emission of a small engine is not trivial. This paper presents an adaptive algorithm that searches multiple pulse train frequencies to passively detect a small engine.