The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provide geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It does not require the user to transmit any data, and operates independently of any telephone or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls and maintains the GPS system, it is freely accessible to anyone with a GPS receiver.
Galileo is a global navigation satellite system (GNSS) created by the European Union through the European Space Agency (ESA) and operated by the European Union Agency for the Space Programme (EUSPA). It is headquartered in Prague, Czechia, with two ground operations centres in Oberpfaffenhofen, Germany, and in Fucino, Italy,. The €10 billion project went live in 2016. It is named after the Italian astronomer Galileo Galilei.
GLONASS is a Russian satellite navigation system operating as part of a radionavigation-satellite service. It provides an alternative to Global Positioning System (GPS) and is the second navigational system in operation with global coverage and of comparable precision.
An emergency position-indicating radiobeacon (EPIRB) is a type of emergency locator beacon for commercial and recreational boats, a portable, battery-powered radio transmitter used in emergencies to locate boaters in distress and in need of immediate rescue. In the event of an emergency, such as a ship sinking or medical emergency onboard, the transmitter is activated and begins transmitting a continuous 406 MHz distress radio signal, which is used by search-and-rescue teams to quickly locate the emergency and render aid. The signal is detected by satellites operated by an international consortium of rescue services, COSPAS-SARSAT, which can detect emergency beacons anywhere on Earth transmitting on the distress frequency of 406 MHz. The satellites calculate the position or utilize the GPS coordinates of the beacon and quickly passes the information to the appropriate local first responder organization, which performs the search and rescue. As Search and Rescue approach the search areas, they use Direction Finding (DF) equipment to locate the beacon using the 121.5 MHz homing signal, or in newer EPIRBs, the AIS location signal. The basic purpose of this system is to help rescuers find survivors within the so-called "golden day" during which the majority of survivors can usually be saved. The feature distinguishing a modern EPIRB, often called GPIRB, from other types of emergency beacon is that it contains a GPS receiver and broadcasts its position, usually accurate within 100 m (330 ft), to facilitate location. Previous emergency beacons without a GPS can only be localized to within 2 km (1.2 mi) by the COSPAS satellites and relied heavily upon the 121.5 MHz homing signal to pin-point the beacons location as they arrived on scene.
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications.
The 33-centimeter or 900 MHz band is a portion of the UHF radio spectrum internationally allocated to amateur radio on a secondary basis. It ranges from 902 to 928 MHz and is unique to ITU Region 2 (Americas). It is primarily used for very local communications as opposed to bands lower in frequency. However, very high antennas with high gain have shown 33 centimeters can provide good long-range communications almost equal to systems on lower frequencies such as the 70 centimeter band. The band is also used by industrial, scientific, and medical (ISM) equipment, as well as low-powered unlicensed devices. Amateur stations must accept harmful interference caused by ISM users but may receive protection from unlicensed devices.
Assisted GNSS (A-GNSS) is a GNSS augmentation system that often significantly improves the startup performance—i.e., time-to-first-fix (TTFF)—of a global navigation satellite system (GNSS). A-GNSS works by providing the necessary data to the device via a radio network instead of the slow satellite link, essentially "warming up" the receiver for a fix. When applied to GPS, it is known as assisted GPS or augmented GPS. Other local names include A-GANSS for Galileo and A-Beidou for BeiDou.
Real-time kinematic positioning (RTK) is the application of surveying to correct for common errors in current satellite navigation (GNSS) systems. It uses measurements of the phase of the signal's carrier wave in addition to the information content of the signal and relies on a single reference station or interpolated virtual station to provide real-time corrections, providing up to centimetre-level accuracy. With reference to GPS in particular, the system is commonly referred to as carrier-phase enhancement, or CPGPS. It has applications in land surveying, hydrographic surveying, and in unmanned aerial vehicle navigation.
The International Cospas-Sarsat Programme is a satellite-aided search and rescue (SAR) initiative. It is organized as a treaty-based, nonprofit, intergovernmental, humanitarian cooperative of 45 nations and agencies. It is dedicated to detecting and locating emergency locator radio beacons activated by persons, aircraft or vessels in distress, and forwarding this alert information to authorities that can take action for rescue. Member countries support the distribution of distress alerts using a constellation of around 65 satellites orbiting the Earth which carry transponders and signal processors capable of locating an emergency beacon anywhere on Earth transmitting on the Cospas-Sarsat frequency of 406 MHz.
The local-area augmentation system (LAAS) is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers located around the airport send data to a central location at the airport. This data is used to formulate a correction message, which is then transmitted to users via a VHF Data Link. A receiver on an aircraft uses this information to correct GPS signals, which then provides a standard instrument landing system (ILS)-style display to use while flying a precision approach. The FAA has stopped using the term LAAS and has transitioned to the International Civil Aviation Organization (ICAO) terminology of ground-based augmentation system (GBAS). While the FAA has indefinitely delayed plans for federal GBAS acquisition, the system can be purchased by airports and installed as a Non-Federal navigation aid.
The Quasi-Zenith Satellite System (QZSS), also known as Michibiki (みちびき), is a four-satellite regional satellite navigation system and a satellite-based augmentation system developed by the Japanese government to enhance the United States-operated Global Positioning System (GPS) in the Asia-Oceania regions, with a focus on Japan. The goal of QZSS is to provide highly precise and stable positioning services in the Asia-Oceania region, compatible with GPS. Four-satellite QZSS services were available on a trial basis as of 12 January 2018, and officially started on 1 November 2018. A satellite navigation system independent of GPS is planned for 2023 with seven satellites. In May 2023 it was announced that the system would expand to eleven satellites.
A positioning system is a system for determining the position of an object in space. Positioning system technologies exist ranging from interplanetary coverage with meter accuracy to workspace and laboratory coverage with sub-millimeter accuracy. A major subclass is made of geopositioning systems, used for determining an object's position with respect to Earth, i.e., its geographical position; one of the most well-known and commonly used geopositioning systems is the Global Positioning System (GPS) and similar global navigation satellite systems (GNSS).
Vislink Technologies, Inc. is an American technology company that specializes in the collection, delivery, management and distribution of high quality live video and data. Founded as xG Technology in Sarasota, Florida in 2002, the company had acquired both Vislink and Integrated Microwave Technologies by 2017. In February 2019, xG Technology formally changed its name to Vislink Technologies. The company is headquartered in Hackettstown, New Jersey and has regional offices in Billerica, Massachusetts and Anaheim, California, as well as global offices in the United Kingdom, Dubai and Singapore. Vislink is a publicly traded company listed on the NASDAQ Capital Market.
The GPS-aided GEO augmented navigation (GAGAN) is an implementation of a regional satellite-based augmentation system (SBAS) by the Government of India. It is a system to improve the accuracy of a GNSS receiver by providing reference signals. The Airports Authority of India (AAI)'s efforts towards implementation of operational SBAS can be viewed as the first step towards introduction of modern communication, navigation and surveillance / air traffic management system over the Indian airspace.
The Indian Regional Navigation Satellite System (IRNSS), with an operational name of NavIC, is an autonomous regional satellite navigation system that provides accurate real-time positioning and timing services. It covers India and a region extending 1,500 km (930 mi) around it, with plans for further extension up to 3,000 km (1,900 mi). An extended service area lies between the primary service area and a rectangle area enclosed by the 30th parallel south to the 50th parallel north and the 30th meridian east to the 130th meridian east, 1,500–6,000 km (930–3,730 mi) beyond borders where some of the NavIC satellites are visible but the position is not always computable with assured accuracy. The system currently consists of a constellation of eight satellites, with two additional satellites on ground as stand-by.
Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave. They can be received by other antennas connected to a radio receiver, this is the fundamental principle of radio communication. In addition to communication, radio is used for radar, radio navigation, remote control, remote sensing, and other applications.
A software GNSS receiver is a Global Navigation Satellite System (GNSS) receiver that has been designed and implemented using software-defined radio.
Inside GNSS (IG) is an international controlled circulation trade magazine and website owned by Gibbons Media and Research LLC. It covers space-based positioning, navigation and timing (PNT) technology for engineers, designers, and policy-makers of global navigation satellite systems (GNSS). In the United States, GNSS is identified mainly with the government-operated Navstar Global Positioning System (GPS). InsideGNSS.com is the complimentary website of online news, events, digital newsletters, and webinars, and archived magazine articles.
Metropolitan Beacon System (MBS) is a precise three-dimensional location and timing technology designed to provide services to entire metropolitan areas where GPS or other satellite location signals are blocked or can’t be reliably received.
GPS Block IIIF, or GPS III Follow On (GPS IIIF), is the second set of GPS Block III satellites, consisting of up to 22 space vehicles. The United States Air Force began the GPS Block IIIF acquisition effort in 2016. On 14 September 2018, a manufacturing contract with options worth up to $7.2 billion was awarded to Lockheed Martin. The 22 satellites in Block IIIF are projected to start launching in 2027, with launches estimated to last through at least 2037.
