Respiration monitoring for apnea diagnosis and movement tracking for physical activity analysis are essential and valuable indicators of underlying medical conditions in senior health care. Compared with other health sensing technologies, radar has shown its advantages in terms of non-contact implementation, immunity to ambient light and temperature changes, hardware simplicity, and long range coverage. Among various radar types, frequency-shift keying (FSK) radar inherits the ability to measure respiration from Doppler radar, while also having the ability to track the absolute range of a moving target with much less bandwidth requirement than frequency modulated continuous wave (FMCW) radar and ultra-wideband (UWB) radar. Therefore, in this paper, an FSK radar system is employed for both remote respiration monitoring and absolute range tracking. Fundamental theory and operating principle of FSK system are detailed. Respiration monitoring and range tracking experiments of a human subject were performed in an indoor environment. Results are presented to demonstrate the practical feasibility of the FSK sensing technology being applied to single senior home care applications.