ELECTROMAGNETIC ENVIRONMENTAL MEASUREMENT SYSTEM EMPLOYING FREQUENCY LEVEL SELECTIVE PROCESS

This paper describes a method of measuring quasistationary electromagn etic waves, whose level, generation time, radiation points, and rates of the incidents are not always constant. Those quasi-stationary waves radiated from the amateur radio, the land mobile station, and so on, sometimes cause electromagnetic interference (EMI) and are rather diff icult to detect. The frequency and the electromagnetic field level of those waves can be detected effectively by frequency domain measuremen ts using a high-resolution spectrum analyzer. This measurement system detects EMI waves whose peak level is above a threshold line set in th e specific frequency range. Measurements were also carried out in urba n areas to investigate the environment for citizen-band. Results indic ate that there is a close relationship between the occurrence rates an d the human activities. This system is useful for detecting the cause of EMI and establishing countermeasures against electromagnetic waves.