Fabrication of a Portable ULF Signal Receiver for Monitoring Electromagnetic Earthquake Precursors

A portable Ultra Low Frequency (ULF) signal receiver, which can be made available in Physics laboratory was designed and fabricated for detection and identification of seismo electromagnetic signals that can be considered as precursory phenomena of earthquakes. The receiver circuit has four major sections that function as sophisticated signal processing and amplifier and powered by +5 to -5 V regulated source. A low pass filter circuit, in which a Butterworth filter was the gate of the circuit, was employed to receive Ultra-Low Frequency (ULF) signals of desired frequency. The frequencies of interest are those ranging from 0.001-45 Hz. The desired frequencies then passed through a series of filters to remove transient noise, Electromagnetic Interferences (EMI) and 50 or 60 Hz frequency caused by commercial power, which could cluster the desired signal on the oscilloscope.