Infrasound Recording Equipment at Kiruna Geophysical Observatory

摘要

A technical description of equipment for detection and recording of infrasound at 2 Hz is given and some examples of recordings are shown. Two small tripartite arrays with three microphones each are used with a spacing of 2 km between the arrays. A correlator with two microphones spaced 60 m apart on a rotating boom is also used. Each of the tripartite arrays is operated with two phase comparators which use zero crossing comparison apart on a rotating boom is also used. Each of the tripartite arrays is operated with two phase comparators which use zero crossing comparison technique, while the correlator uses the one-bit correlation technique and has the features of an gate. A direction discriminator compares the phase at two sets of NS microphones and two sets of EW microphones and the amplitude of the signal. When the signals are close in phase, i.e. come from the same direction at both arrays and have sufficient amplitude, a digital pen-recording is given. (Author)