Low pass filter cutoff frequency analysis and a new centroid method for the rosette scan seeker

Rosette scan seekers transform the infrared radiation of the targets that are in the field of view into modulation signal in the detector by rosette scanning. It obtains the spatial coordinates of the targets by using the time values of the pulses in the modulation signal. It uses a low pass filter in the processor of the seeker in order to filter the noise in the modulation signal. However, low pass filter may cause the loss of some information regarding the targets in the modulated signal depending on its cutoff frequency. To prevent possible information loss, a lower limit analysis of the cutoff frequency of the low pass filter is made using the rosette pattern parameters. Moreover, analysis of the centroid methods used in the clustering algorithms that run after obtaining the spatial locations of the target is made. A novel centroid method is proposed, which has results approximately 2 times better than the methods in the literature.