Possible Sensor Technologies

• Underwater passive acoustic sensors (hydrophones) for biological signals
• Airborne infrared (heat) sensors (passive or active)
• Airborne motion detectors (passive or active)
• Underwater active acoustic sensors (pinging / sonar)
• Bistatic doppler / bistatic sonar
• Ambient Noise Imaging (ANI uses underwater background noise to image objects)
• Underwater capacitance sensors ??
• Airborne capacitance sensors ??
• Synergistic Radar (detect disturbances in commercial FM signals)
• Others??
• Combinations of above sensors to reduce false signals

Some of these sensors or combinations of them might also prevent propeller impacts with floating objects, sunken objects or the ground. They might even assist in reducing Manatee prop strikes?

The Reference Page at the end of this report contains information on many sensors.