Power line harmonic radiation: A systematic study using DEMETER spacecraft

We present results of a systematic survey of Power line harmonic radiation (PLHR) observed by the DEMETER spacecraft. DEMETER is a French micro-satellite launched in June, 2004 with an altitude of orbit of about 700 km. It is designed specifically to study electromagnetic effects connected with seismic and man-made activity. All available high-resolution burst-mode electromagnetic data measured since the beginning of the mission till July 2006 (altogether about 1650 h of data) have been analyzed using an automatic identification procedure. This procedure was specially developed to search for emissions of PLHR type. It is running in DEMETER control center in Orléans, France. 49 PLHR events with frequency spacing of 50/100 or 60/120 Hz have been found, allowing us to perform a statistical study of properties of PLHR. It is shown that for all the events, the observed frequency spacing corresponds well to the power system frequency at anticipated source locations. Moreover, the frequency of the observed lines often (80%) corresponds to the exact harmonics of the power system base frequency. Finally, the most intense events are observed at lower frequencies and no weak events are observed under geomagnetically disturbed conditions.