This paper describes a continuous wave (CW) radar system with body-contact antennas and basic signal processing. The goal is to assess the signals' reproducibility across different subjects as well as a respiration cycle. Radar signals using body-contact antennas with a carrier frequency of 868 MHz are used to acquire the cardiac activity at the sternum. The radar I and Q channel signals are combined to form their magnitude. Signals are collected from six healthy males during paced breathing conditions. The electrocardiogram (ECG) and impedance cardiogram (ICG) signals are acquired simultaneously as reference. The chosen feature in the radar signal is the maximum of its second derivative, which is closest to the ICG B-point. The median and mean absolute errors in pre-ejection period (PEP) in milliseconds between the ICG's B-point and chosen feature in the radar signal range from -6-119.7 ms and 7.8-62.3 ms for all subjects. The results indicate that a reproducible radar signal is obtained from all six subjects. More work is needed on understanding the origin of the radar signals using ultrasound as a comparison.

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Sound is one of the most important medium used for delivering information. With rising crime in today’s society, especially against women, carrying some sort of effective weapon for self-defense purposes has become quite essential. This technology emits sound in a highly controlled, narrow beam, so that audio can be heard only when you are in the field of beam or in a position to hear the reflected sound from a virtual source .Sound wave in the audible range has a characteristic to spread in various directions while moving, but ultrasound is unidirectional. This characteristic of sound finds applications at a lot of different areas. Parametric loudspeakers can be used in the advertisement industry where audio is considered as a key influence but is abstained from use because the sound being multi-directional spreads and bothers even the people not in target.  Usually, in case of a riot, smoke grenades and tear gases are used to control the rioters, which on addition on controlling the target also affect the innocents. This study highlights on using an ultrasonic weapon rather than weapons like hand gun, which can be unsafe and might also initiate legal intrusion.Nowadays MEMS ultrasonic transducers have been put to use which has got very portable design outlet .The study uses the application of ultrasonic beams and sound focusing to build a portable women safety device similar to that of a stun gun.