How effective can GSM signals, using DCM, be as an aid to coastal navigation?

Abstract

The growth of the Global System for Mobile communications (GSM) network has been considerable in recent years, and coverage can be expected in the majority of larger ports around the world. Additionally, the positioning of base stations means that coverage often extends some distance out to sea. Previous research has established that by using GSM signals a relatively accurate position can be determined when using the Database Correlation Method (DCM) in built-up urban areas (Ahonen and Eskelinen, 2003).

Conducted in the Plymouth Sound area using commercially available software, this project examines the effectiveness of GSM signal positioning using DCM in coastal areas, specifically examining the possibility of using this technology to position vessels.

The results from this research show a clear trend of decreasing accuracy with increasing distance from shore, making vessel positioning impractical beyond 500m of the shore datum. However, the results do show that effective positioning can regularly be achieved to within approximately 200m once on the shore, with errors as low as 25m at times.

Further analysis breaks down these errors, establishing that approximately 13% of the recorded error is likely to be due to fixed errors, most likely caused at the time of database establishment. A major part of this is GPS error at this time, accounting for 10% of the fixed error.