Reduction of multiple harmonics EM noise in helicopter cockpit

A helmet-mounted display (HMD) is a device used to project information on an aircrew´s visor. By using a line-of-sight (LOS) tracker, the HMD allows the pilot to obtain situational awareness and receive flight mission information, and weapon targeting symbology. A common technology for tracking the pilot´s LOS is based on a narrow-band electromagnetic (EM) field transmitted in the cockpit. However, a high energy EM interference which may be emitted within the cockpit, may degrade dramatically the tracker performance. We present a method for reducing noise in HMD tracking system, in which the interfering noise is results from two different harmonic sources with different time-varying basic frequencies. The reduction algorithm is based on Fourier series analysis. Implementing the proposed algorithm in HMD system for combat helicopters shows a significant reduction in noise harmonics and improved LOS performance.