Removal of the GLONASS C/A Signal from OH Spectral Line Observations Using a Parametric Modeling Technique

Abstract

Astronomers use the 1612 MHz OH spectral line emission as a unique window on galactic dynamics and the properties of evolved stars. In recent years, experiments using this OH line have become more difficult because of interference from the GLONASS satellite system. In this paper we demonstrate that the C/A component of the GLONASS signal can be removed using a parametric estimation/subtraction technique that exploits known properties of the modulation and requires no additional antennas. Using actual OH line observations, we demonstrate cancellation greater than 20 dB. This technique can be implemented using present-day digital signal processing hardware, and it does not significantly affect the relatively weak astronomy signals or the sensitivity of the measurement.