The navigation application of GPS
Satellite technology for maritime navigation can be traced back to the first generation of satellite navigation system TRANSIT in the 1960s, but this satellite navigation system was originally designed to serve mainly In polar regions, continuous navigation is not possible, and the time interval of its positioning varies with latitude. Above 70 degrees north-south latitude, the average positioning interval does not exceed 30 minutes, but it takes 90 minutes near the equator. The second and third-generation TRANSIT satellites NAVARA and OSCARS launched in the 1980s make up for this shortcoming but still need 10 to 15 minutes. In addition, the Doppler speed measurement technology adopted is also difficult to improve the positioning accuracy (the speed of the ship needs to be accurately known), and it is mainly used for 2D navigation.
The emergence of the GPS system overcomes the limitations of the TRANSIT system. It has not only high precision, continuous navigation, and strong anti-interference ability but also provides seven-dimensional space-time position and velocity information. In the initial test of experimental navigation equipment, GPS demonstrated that it could replace TRANSIT and road-based radio navigation systems and play an epoch-making role in marine navigation. It is difficult to imagine a ship not equipped with GPS navigation systems and equipment today. Navigation applications have truly become the largest user of GPS navigation applications, unmatched by users in any other field.
There are many users of GPS navigation, and their classification standards are also different. According to the type of route, GPS navigation can be divided into five categories: ocean navigation; coastal navigation; port navigation, river navigation; lake navigation.
Different stages or regions have different requirements for navigation safety due to different environments, but they are all to ensure the minimum navigation traffic conflict, the most effective use of the increasingly crowded air routes, ensure navigation safety, and improve transportation. Benefit, save energy. According to the functions of the navigation system, there are roughly the following categories:
1. Autonomous navigation
The autonomous navigation system is suitable for any of the above five routes, which is a simple navigation system; its main feature is that it only provides users with position, speed, heading, and time information and can also include a chart track display without the need for a communication system. Suitable for any ship sailing on the sea, lake, and inland river, from large ocean-going cargo ships to private yachts.
2. Port management and entry guidance
This system is mainly used in port/dock ship scheduling management and entry ship guidance to ensure Safety and order in port/dock navigation. The system requires two-way data/voice communication for the pilot to guide the vessel; port situation/chart display to indicate berthed vessels and available approach routes to avoid collisions. This kind of system has high requirements for the accuracy of the navigation system and uses differential GPS and other enhanced technologies.
3. Route traffic management system
This type of system is similar to 2 but is mainly used for ship navigation and management on offshore and inland river routes; usually needs satellite communication system support, such as INMARSAT.
4. Tracking and monitoring system
This system is mainly used for maritime patrol boats, anti-smuggling boats, and various yachts, especially private yachts, to prevent theft. Depending on the specific object of use, some systems need to provide navigation parameters and two-way data/voice communication, such as anti-smuggling boats. Sometimes it is not necessary to give navigation parameters, such as for private yacht anti-theft; only one-way data communication is required. Once theft occurs, the navigation system on the yacht will continuously send its position and head to the relevant center for easy tracking.
5. Emergency rescue system
The system also includes amphibious aircraft, helicopters, and land vehicles. It is suitable for all five routes and is used for the search and rescue of various seas, lakes, inland rivers, ships, and people in distress. Such systems require two-way data/voice communication, fast response time, and high positioning accuracy.
6. GPS/Sonar combination for underwater robot navigation
This type of combination system can be used for underwater pipeline laying and maintenance (which requires a vision system) ), hydrographic surveys, and other underwater operations, such as underwater surveys at ports/docks, to facilitate the removal of obstructions in the approach channel and ensure the smooth flow of the channel, and can also be used for ocean fishing, fishing boat operation guidance, etc.
7. Other applications
The main navigation technologies used are:
GPS (GNSS) );
sonar technology;
INS;
nautical charts
radio navigation technology;
charts Image matching techniques;
Other techniques.
The main communication technologies used are:
FM and TV sub-carrier one-way data/voice communication;
beacon station network two-way data communication;
trunking communication;
cellular communication;
land-based mobile digital communication;
satellite mobile communication;
Traffic trail communication, etc.
The top 5 communication technologies are mainly used offshore, inland, and in lake areas.
Declare: The above methods are derived from the program system index or shared by netizens. They are for your reference only and do not represent the research views of this website. sex and authority.