A turn-key Concept for active cancellation of Global Positioning System L3 Signal

TL;DR

This paper introduces a turnkey active cancellation system for GPS signals, specifically targeting the L3 frequency, to prevent interference in radio telescope observations without requiring additional antennas.

Contribution

The paper presents a novel, easily integrable active cancellation concept for GPS signals in radio telescopes, capable of detecting and adapting to dynamic modulation changes.

Findings

Effective detection and cancellation of GPS L3 signal demonstrated

System can adapt to changing modulation modes

Potential for integration with existing radio telescope systems

Abstract

We present a concept, developed at the National Astronomy and Ionosphere Center (NAIC) at Arecibo, Puerto Rico, for active suppression of Global Positioning System (GPS) signals in the 305 m dish radio receiver path prior to backend processing. The subsystem does not require an auxiliary antenna and is intended for easy integration with radio telescope systems with a goal of being a turnkey addition to virtually any facility. Working with actual sampled signal data, we have focused on the detection and cancellation of the GPS L3 signal at 1381.05 MHz which, during periodic test modes and particularly during system-wide tests, interfere with observations of objects in a range of redshifts that includes the Coma supercluster, for example. This signal can dynamically change modulation modes and our scheme is capable of detecting these changes and applying cancellation or sending a blanking signal, as appropriate. The subsystem can also be adapted to GPS L1 (1575.42 MHz), L2C (1227.6 MHz), and others. A follow-up is underway to develop a prototype to deploy and evaluate at NAIC.