A radio wave is an electromagnetic wave or electrical oscillation. Frequency is the number of times (cycles) a radio wave oscillates per second. One cycle per second is referred to as hertz (Hz). Radio waves are part of the electromagnetic spectrum with frequencies lower than infrared waves.

Radio wave sensing works first by transmitting a high-frequency wave to the person or object of interest. A higher frequency means a greater number of cycles per second, which in turn requires sufficiently fast processing that matches the wave's frequency after the wave is received. This means more power has to be consumed. To cope with this situation and process waves that reflect off the target (pulse echoes) with less power, OMRON has adopted a technique of converting pulse echoes into a low-frequency or digital signal so that it is processed as a small wave. When the transmitted wave is compared with the received wave, a difference will be noticed in waveforms. The farther away the target of interest is situated, the longer time it takes for the pulse echo to return, thus resulting in a pulse-echo delay. This delay in the received wave causes a difference in the transmitted and received waveforms, from which you can estimate the return time of the pulse echo. This is how the distance to the target is determined.

OMRON's key strength is in its proprietary signal processing technology for handling the pulse echo. The pulse echo contains a variety of information, and the length and speed of the return wave and the time it takes to return all vary depending on the type of target and the distance between it and the sensor. To correctly assess the target based on various information carried by the pulse echo, numerous processing steps are carried out to detect the position and motion of a person or object so as to offer information of value for people and machines.

Detecting Motion, Intention Under Unfavorable Conditions

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