NorSat-2: Enabling advanced maritime communication with VDES

Abstract

Satellite AIS is well recognized as a system for vessel traffic monitoring and maritime safety. The growing demand for maritime data services has led to the development of a new VHF Data Exchange System (VDES), which will provide two-way communication at higher data rates than possible with current AIS systems. Within the VHF maritime frequency band (156.025-162.025 MHz), VDES integrates AIS with Application Specific Messages (ASM) channels, which have higher capacity and increased reliability. VDES will support the distribution of maritime data, including meteorological and hydrographic data and traffic information. Expanding VDES to a satellite platform will facilitate a global data exchange between ships and shore via satellite. NORSAT-2 is the first satellite to incorporate a VDES payload, in addition to an advanced AIS receiver, both of which are in-orbit reconfigurable software-defined radios developed by Kongsberg Seatex. NORSAT-2 was developed and built by the Space Flight Laboratory (SFL) for Space Norway and the Norwegian Space Centre. With a mass of 16 kg, the satellite design is based on SFL's Next-generation Earth Monitoring and Observation (NEMO) bus, which has proven flight heritage to be a robust and reliable microsatellite platform. To enable directional communication over VHF for the VDES payload, SFL has developed a three-element deployable Yagi-Uda antenna. The antenna is stowed during launch and deployed on-orbit upon command receipt. In addition to NORSAT-2's S-band telemetry and command system, the satellite also has an enhanced S-band feeder uplink which is capable of achieving data rates of up to 1 Mbps. NORSAT-2 is scheduled to launch onboard a Soyuz in Q2 2017 into a 600 km polar sun synchronous orbit. It will be the fourth Norwegian satellite on-orbit and is highly anticipated to be one of the first satellites to supply VDES services, in addition to complementing Norway's existing satellite AIS network. This paper describes the NORSAT-2 mission, with an emphasis on the unique and innovative aspects that are the VDES payload, deployable Yagi antenna, and enhanced S-band uplink.

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

“…The NorSat-1 and -2 satellites, launched simultaneously in July 2017 into ~ 98° inclination, ~ 600-km altitude orbits, are larger than the AISSat satellites, with an approximate 20 × 30 × 40-cm 3 satellite body in addition to fixed solar panel "wings" that extend out from the body, weighing around 16 kg [4,24,25]. Both NorSat satellites have multiple payloads, but the main payload is the ASRx50 AIS payload and the only payload of importance to this paper.…”

“…Furthermore, NorSat-1 is equipped with two low-gain monopole antennas mounted perpendicular to each other for antenna diversity. NorSat-2 is also equipped with two antennas, a monopole and a high-gain Yagi-Uda antenna, the latter primarily for use by the other NorSat-2 payload [24]. An RF switch also connects the Yagi-Uda antenna to the AIS payload, however, but the duty cycle is shared between the two payloads [27].…”

The Impact of Space-Based AIS Antenna Orientation on In-Orbit AIS Detection Performance

“…Smaller antennas lead to smaller power-to-noise ratios, and therefore reduced signal reception. For a nano-sized satellite, the reflector antennas are likely to require too much mass and volume and are therefore mostly ruled out as an option even though there is a nanosatellite using deployable Yagi-Uda type antenna [16]. Still there exists a variety of thin linear antennas suitable for this type of satellite.…”

Research and Development of Mobile Marine Satellite Antenna System in Vietnam

“…Chính vì vậy việc nghiên cứu và chế tạo thiết bị trạm thu tín hiệu vệ tinh trang bị cho tàu biển là cấp thiết hiện nay. Trong khi các trạm thu vệ tinh cố định đã phát triển khá ổn định (chủ yếu chỉ liên quan đến vấn đề thu, phát và xử lý tín hiệu siêu cao tần), việc thu thông tin vệ tinh trên các trạm di động cần giải quyết nhiều vấn đề phức tạp hơn, nhưng cũng đã được áp dụng rất nhiều ở trên thế giới [1][2][3][4][5][6][7].…”

“…Bên cạnh việc phải dò bám vệ tinh do phương tiện mang ăng-ten di chuyển, cần phải quan tâm ứng xử của hệ thống với các thành phần dịch chuyển của tàu. Các nghiên cứu về vấn đề thu thông tin vệ tinh của các trạm di động trên biển đang được nghiên cứu rất có tính thời sự (ví dụ, xem [1,2]). Do đó, việc nghiên cứu, làm chủ công nghệ lõi, sản xuất hệ thống trạm thu thông tin vệ tinh di động thực sự rất cấp bách [7].…”