Coherent noise filtering for vehicle collision avoidance systems

The system generates a phase shifted radar signal based on information from received coherent noise

Electronics Sensors

Navy researchers have invented a way to ensure that driver-assist technologies are not inadvertently impaired by other vehicles with the same technology or environmental interference. The invention has been patented and licenses are available to businesses for commercial use. After reviewing the opportunity, contact TechLink for more information.

Coherent, electromagnetic noise is all around us, like radar systems, mobile phones, and power supplies. The noise can interfere with driver-assistive technology like anti-collision sensors in passenger vehicles.

To lessen the interference of coherent noise on vehicle systems, Navy scientists have developed a real-time process to test varying transmitted signals against incoming noise using a matched filter and then selecting the best signal for transmission.

In one instance of this technology, the width of transmitted pulses can be varied prior to transmission, but a constant midpoint-to-midpoint time is maintained. After receiving a signal with coherent noise interference, the midpoints of the pulses are aligned causing the coherent noise to become non-coherent. Similarly, the transmitter can generate phase shift sequences that are applied to outgoing emissions.

The system will have direct application in collision avoidance and lane change assistance modules in cars and trucks. For example, two vehicles with collision avoidance or navigation radar can be operating with the same equipment, same radar, same or similar waveforms, and same frequency. One vehicle can apply calculated phase shifts to its generated signals or create outbound signals which are reflected off an object and returned as received reflected signals.

Sources of coherent noise in this example can include emissions from the second vehicle as well as reflected emissions off of the second vehicle. Vehicle one receives the reflected signals as well as emissions from vehicle two (as coherent noise). The system onboard vehicle one applies a complement of respective previously applied calculated phase shifts to each pulse in the received reflected signal to remove the phase shifts from a sequence of pulses and then applies the matched filter to eliminate all signals in the modified version of reflected signal that do not match the first waveforms of the initial signals.

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