Fixed and Mobile Interference Cancellation for Syrian National Earthquake Monitoring Network

Abstract

The performance of radio communication system can be severely degraded by the presence of radio interference (RI) signals. Indeed, this degradation may be overcome to some good extent by using various modern coding and modulation techniques. However, the effectiveness of these techniques depends highly on the power level of RI signals. Better still if the RI signal can be suppressed at the output of the antenna prior to entering the receiver. In this paper we propose a viable scheme for RI suppression using phase array antenna by means of adjusting the phase of the array element only (i.e. phase perturbation) so that a null or more in the overall antenna pattern in directions of RI sources are synthesized. The system is otherwise known as phase only null-steering (PHONS). The optimum phase perturbation is evaluated using constrained optimization procedure which is based on Lagrange multiplier. The performance of the proposed PHONS is evaluated using computer simulation for a number of different conditions. The proposed PHONS scheme is compared with side lobe canceller using minimum mean square error (MMSE) criterion in terms of complexity and convenience. An earthquake monitoring network was deployed nation wide in Syria back in 1987.The network is intended to sense, register, and monitor the seismic signals, and, subsequently locate the center of the earthquake event by means of time of arrival (TOA). However, being an analogue system, the network inherently suffers from a number of drawbacks such as the constant drift of operating points. These are usually remedied by sustained efforts of calibration and maintenance. However, the network at the radio segments is most venerable to the RI interference. This interference enters the receivers and causing a burst false alarm and thus degrading the network performance beyond any acceptable level. In this paper we propose the PHONS scheme as a candidate solution to solve the problem of RI interference that the network is suffering from