ABSTRACT
Wireless sensors that have more advantages relative to wired sensors are playing an important role in improving the quality of life in daily indoor space. Ultrawideband (UWB) impulse-radio uses nanosecond pulses spreading out all over a continuous wide bandwidth. It offers many advantages such as low-cost implementation, low transmission power, ranging, multipath immunity, and low interference. A different approach of UWB, which solves the previous problems, is the use of stepped-FM pulse sequences instead of transmitting a nanosecond short pulse. The stepped-FM UWB sensor can detect radio interference by monitoring the phase detector output in passive mode and is then designed to have some spectrum hole at the transmitter in order to prevent any conflict and to coexist with the other narrowband wireless systems. The requirement for monitoring the state of the elderly person in care facilities and hospitals is increasing year by year since the increase in accidents involving the elderly persons is of great concern.
