An efficient and extended range tracking method using a hybrid FSK-FMCW system

Radar systems are considered suitable sensors for detection of moving objects and motion-based tracking. Among various radar types, frequency-shift keying (FSK) radar are attractive for being able to track the absolute range of a moving target with little bandwidth requirement and free from surrounding background clutter interference. However, its maximum unambiguous range is limited due to the periodicity of the phase difference over 2n and it is inversely proportional to the frequency shift between two transmitted frequencies, while its measurement resolution is proportional to this frequency shift. Frequency modulated continuous wave (FMCW) radar has no range limitation on target tracking but occupies a large bandwidth. Therefore, in this paper, a hybrid FSK-FMCW system is proposed by using a short-time operating FMCW system with small bandwidth as reference to increase the FSK system maximum discernable range without losing measurement resolution. Range tracking experiment of a human subject was conducted and results are presented to demonstrate the performance of the proposed hybrid method.