60 Proceedings Spring 2025 data communications, up to 32 times the capac- ity of AIS, making it more suited for handling the ever-growing volume of marine vessel data and communications. • VDES (VDE-SAT) provides extended coverage, including the Arctic, ensuring seamless commu- nication in remote, hard-to-reach regions. • VDES allows for the integration of cybersecurity measures, safeguarding maritime communications and data exchange from malicious activities. • VDES can provide backup positioning navigation and timing for Global Navigation Satellite System- denied environments by de-spoofing AIS through its ranging mode (R-Mode). • Forward and backward compatibility with legacy AIS. The Four Major Components of VDES To accomplish these additional benefits without consum- ing valuable bandwidth on AIS channels, VDES consists of four individual components/subsystems, each operat- ing in a different frequency range within the VHF mari- time mobile band. These components are: 1. VDES retains original AIS channels primarily for collision avoidance and remains compatible with existing AIS systems. 2. VDES adds two new channels for application- specific messages (ASM), providing additional bandwidth for data exchange between ships, and between ships and shore. 3. VDES introduces a high-speed terrestrial data exchange channel using VDE-TER, which provides faster and more efficient data communications between ships and shore stations. 4. VDES also includes a satellite data exchange component, using VDE-SAT channels for global interoperable two-way communication between ships and satellites and satellites and shore sta- tions. This allows for increased range and coverage, including in remote regions away from land-based coverage such as the Arctic region. The VDES uses a combination of these four compo- nents to provide a robust, high-capacity communication network for maritime communication needs. The fre- quency distribution ensures compatibility with existing AIS systems while providing additional capacity, faster data rates, and extended range for various maritime applications. Coast Guard VDES Use Cases Building on the RDC’s previous investigations on the utility of AIS for other applications, the RDC team What is R-Mode? RMode is the term used for ranging using signals of oppor tunity. The receiver measures the time of arrival of a signal, compares it to the time of transmission to get a travel time, and converts this to the range to the transmitter. If signals from multiple transmitters can be received, then a posi tion can be estimated. RMode ensures that positioning, navigation, and timing are maintained, even when Global Navigation Satellite System is denied due to intentional or unintentional causes. identified multiple operational use cases that may sig- nificantly enhance maritime safety and domain aware- ness for Coast Guard and mariners. 1. VDES can facilitate ship routing and route exchange services, through the ASM channels, allowing for efficient and accurate communication of routes between vessels and shore stations. This can help optimize vessel traffic flow, reduce collision risk, and minimize environmental impacts. 2. VDES can enable the sharing of enhanced Marine Safety Information (MSI) and meteorological infor- mation between ships and shore stations. This can improve situational awareness, enabling mariners to make informed decisions based on the most up- to-date information available. 3. VDES can support SAR operations by providing accurate position, navigation, and communication capabilities. This can help rescue teams locate and extract mariners in distress more efficiently, saving valuable time and increasing the likelihood of suc- cessful rescue operations. 4. Using the Sensitive but Unclassified Tactical Exchange Display System (STEDS), VDES can enable the exchange of sensitive but unclassified tactical information between ships and shore sta- tions which can help improve coordination and support maritime security operations. 5. VDES can enable advanced maritime cybersecurity measures, helping protect maritime communica- tions from malicious activities such as hacking, spoofing, and jamming. This can help ensure the integrity, confidentiality, and availability of mari- time communications, which is essential for main- taining maritime safety and security.
