Ship tracking results from state-of-the-art space-based AIS receiver systems for maritime surveillance

Abstract

Norway currently operates four satellites with Automatic Identification System (AIS) receivers. The first-generation satellites, AISSat-1 and AISSat-2, are equipped with a two-channel, single-antenna AIS receiver, while NorSat-1 and NorSat-2 are equipped with an improved AIS receiver capable of decoding on all four AIS channels and using the two antennas installed on the NorSat satellites. This paper aims to investigate the ship tracking performance enhancement realised by the technology improvements of antenna diversification, frequency diversification, and advanced algorithms. The ship tracking capability of the NorSat satellites is presented and shown to yield a significant improvement, up to a 20% point increase, over the first AISSat generation ship tracking capability. A further 20% point increase is achieved in select areas using frequency diversity introduced in the AIS system since the development of the AISSat satellites. In addition, NorSat-1 detected 34% more vessels than AISSat-2 over the same timeframe. The contribution to the performance improvement from the incremental improvements in decoding algorithms, antenna diversity, and frequency diversity is indicated in the results. The results indicate that, in the short term, upgrading to the latest algorithms, low noise electronics, and taking advantage of antenna diversity is the greatest performance enhancer. In the medium and long term, the frequency diversity likely yields the greatest performance enhancement.

In-orbit AIS performance of the Norwegian microsatellites NorSat-1 and NorSat-2

“…The median number of ships detected daily is 497.5 for NorSat-1, which is only 3% higher than for AISSat-1. The improvement can be seen as an increased detection probability during an overpass [13]. The average daily number of observations per ship is 2.4 for AISSat-1 and 3.7 for NorSat-1, which improve the temporal resolution and the tracking capability.…”

“…Other methods for quantifying the tracking capability of satellite-AIS systems, defined as the probability of re-detecting ships as they move around the globe, are presented with examples from AISSat-1 and -2 in [12]; an update including NorSat-1 and -2 is made in [13].…”

Battery Current and Temperature Mission Profiles for CubeSats at Low Earth Orbit

“…Furthermore, tracking of ships (automatic identification system (AIS)) and aircraft (automatic-dependent surveillancebroadcast (ADS-B)) can be considered as remote sensing activities. AIS tracking is performed for example by a Norwegian constellation of AISSat-1,2 and NorSat-1,2 [28]. Historically, nearly 50% of nano/micro-satellites were dedicated to earth observation/remote sensing [1].…”

Monitoring global fishing activity in proximity to seamounts using automatic identification systems

“…Furthermore, several new AIS satellites have been launched by multiple major service providers since late 2013 onwards, which has increased spatial and temporal coverage year on year (Fournier et al, 2018;Šakan et al, 2018;Skauen, 2019).…”