Appendix: Glossary

The Basics

Control Segment

The control segment of a navigation satellite system includes a ground-based network of master control stations, monitor stations, and data uploading stations. The master control stations adjust the satellites’ orbit parameters and onboard high-precision clocks when necessary to maintain accuracy. Monitor stations, usually installed over a broad geographic area, monitor the satellites’ signals and status, and relay this information to the master control stations. The master control stations analyze these signals, and then transmit orbit and time corrections to the satellites via data uploading stations.¹

GNSS Receiver

A GNSS receiver—or a satellite receiver—processes the signals transmitted by satellites, and is the user interface to any global navigation satellite system (GNSS). A GNSS receiver displays a navigation solution after computing user position, velocity, and time (PVT).²

PNT (Positioning, Navigation, and Timing)

“Positioning [is] the ability to accurately and precisely determine one’s location and orientation two-dimensionally (or three-dimensionally when required) referenced to a standard geodetic system…Navigation [is] the ability to determine current and desired position (relative or absolute) and apply corrections to the course, orientation, and speed to attain a desired position…Timing [is] the ability to acquire and maintain accurate and precise time from a standard…anywhere in the world and within user-defined timeliness parameters. When PNT is used in combination with map data and other information (weather or traffic data, for instance) the result is…the modern navigation system better known as [a global navigation satellite system].”³

Space Segment

The space segment of a navigation satellite system consists of satellites orbiting about 20,000 kilometers above Earth. Each system has its own constellation of satellites, arranged in orbits necessary to provide the desired coverage. Each satellite in a constellation broadcasts a signal that identifies it and provides its time, orbit, and status. Satellites receive orbit and time corrections from master control stations via data uploading stations.⁴

User Segment

The user segment of a navigation satellite system “consists of equipment that processes the received signals from…satellites and uses them to derive and apply location and time information. The equipment ranges from smartphones and handheld receivers used by hikers, to sophisticated, specialized receivers used for [high-end] survey and mapping applications.”⁵

Performance

Accuracy

Accuracy is a statistical measure of performance for navigation satellite systems. It is the degree of conformance of an estimated or measured receiver position, velocity, and/or time with the true receiver position, velocity, and/or time. Because accuracy is a statistical measurement of performance, navigation satellite system accuracy is meaningless unless it includes a statement of uncertainty regarding the relevant position, velocity, and/or time.⁶

Availability

Availability is a statistical measure of performance for navigation satellite systems. It is the percentage of time that system services are usable by a receiver within a specified coverage area. Availability is a function of the physical environment, the technical capabilities of the transmitting satellites, and constellation figuration.⁷

Integrity

Integrity is a statistical measure of performance for navigation satellite systems. It “is the measure of trust that can be placed in the correctness of information supplied by a navigation [satellite] system. Integrity includes the ability of [a] system to provide timely warnings to users [if and] when the system should not be used for navigation.”⁸

Precision

Precision is a statistical measure of performance for navigation satellite systems. It is an expression of how closely a measurement is repeated over time. Importantly, precision has no relation to any given value or benchmark.⁹

Time to First Fix

“Time to First Fix (TTFF) is a measure of performance of a GNSS receiver.”¹⁰ TTFF is the measure of the time required for a GNSS receiver to acquire satellite signals and navigation data, and to subsequently calculate a position solution.^{11 12}

Various Global Navigation Satellite Systems

BeiDou

BeiDou is a space-based global navigation satellite system (GNSS). It is a Chinese system, and will soon be capable of providing positioning, navigation, and timing (PNT) services to users on a continuous worldwide basis. It began offering services to the public in the Asia-Pacific region in late 2012. BeiDou is expected to provide global navigation services, similar to GPS, GLONASS, and Galileo, by 2020.¹³

Galileo

Galileo is a space-based global navigation satellite system (GNSS) that provides a highly accurate, guaranteed global positioning service. It is an independent European system under civilian control, unlike GPS, GLONASS, and BeiDou, which are technically military systems, under military control, providing a civil service. Galileo initiated services in late 2016 and it is interoperable with GPS and GLONASS.¹⁴

GLONASS (Global Navigation Satellite System)

The Global Navigation Satellite System (GLONASS) is a space-based global navigation satellite system (GNSS). It provides reliable positioning, navigation, and timing (PNT) services to users on a continuous worldwide basis. GLONASS is operated by the Government of Russia and is freely available to civilians. It is an alternative and complementary to other GNSSs, such as the American GPS, the Chinese BeiDou system, and the European Galileo system.¹⁵

GNSS (Global Navigation Satellite System)

A global navigation satellite system (GNSS) “is a constellation of satellites providing signals from space that transmit positioning and timing data to GNSS receivers. These receivers then use this data to determine their location [globally].”¹⁶

GPS (Global Positioning System)

The Global Positioning System (GPS) is a space-based global navigation satellite system (GNSS). It provides reliable positioning, navigation, and timing (PNT) services to civilian and military users on a continuous worldwide basis. GPS is operated by the United States Government and is freely accessible to anyone with a GPS receiver.¹⁷

IRNSS (Indian Regional Navigation Satellite System)

The Indian Regional Navigation Satellite System (IRNSS) is a space-based regional navigation satellite system (RNSS). It is owned by the Government of India with coverage area including India and the surrounding region. It is an independent and autonomous system and includes seven satellites in its constellation. IRNSS was expected to be operational by early 2018, but was delayed by the failures of a satellite and its replacement. Of note, IRNSS was renamed the Navigation Indian Constellation (NavIC) in April 2016.¹⁸

QZSS (Quasi-Zenith Satellite System)

The Quasi-Zenith Satellite System (QZSS) is a space-based regional navigation satellite system (RNSS). It is the Japanese system, providing coverage of the Asia-Oceania region, while maintaining compatibility with GPS. The system, which includes a constellation of four satellites, began to provide services in late 2018. Enabled by the reception of signals from satellites such as GPS satellites, QZSS provides highly precise data and stable positioning services that cannot be obtained merely by GPS.¹⁹

RNSS (Regional Navigation Satellite System)

A regional navigation satellite system (RNSS) “is a constellation of satellites providing signals from space that transmit positioning and timing data” to receivers within a specified region.²⁰ These receivers then use this data to determine their location regionally.

GPS Blocks

GPS Block IIF

GPS Block IIF is a generation, or block, of GPS satellites that is part of the GPS modernization program. The block notably includes “the addition of a third civil signal in a frequency protected for safety-of-life transportation…Compared to previous generations, [GPS Block IIF] satellites have a longer life expectancy and a higher accuracy requirement.”²¹ The block includes a total of twelve satellites; the first was launched in May 2010 and the last was launched in February 2016.²²

GPS Block III

GPS Block III is a planned generation, or block, of satellites that is part of the GPS modernization program. GPS Block III “will provide more powerful signals in addition to enhanced signal reliability, accuracy, and integrity, all of which will support precision, navigation, and timing services.”²³ Other key advances for GPS Block III include a fourth civilian GPS signal (LC1) and a 15-year life expectancy.²⁴ Launch of the first satellite is planned for December 2018.²⁵

Augmentation Systems

Augmentation

Augmentation is a method of improving—or “augmenting”—the performances of a global navigation satellite system (GNSS), such as precision, accuracy, integrity, and availability, through use of external information.²⁶

Differential Correction

“Differential correction is a class of techniques [used to improve] the accuracy of [GNSS] positioning by comparing measurements taken by two or more receivers.”²⁷

EGNOS (European Geostationary Navigation Overlay Service)

The European Geostationary Navigation Overlay Service (EGNOS) is the European satellite-based augmentation system (SBAS). “EGNOS was the first pan-European navigation satellite system—a precursor to the Galileo system—and augments various GNSS for safety-critical tasks such as guiding aircraft and navigating ships.”²⁸ The system is mainly operational over Continental Europe and its surrounding islands.²⁹

GBAS (Ground-Based Augmentation System)

A ground-based augmentation system (GBAS) “aims to enhance global navigation satellite system (GNSS) services for aviation during departure, approach, and landing, as well as during surface operations. It has local coverage—the surroundings of an airport—and helps to ensure aviation requirements in terms of integrity, accuracy, and safety…A GBAS includes two or more satellite receivers, which collect pseudoranges for all primary satellites in view, then computes and broadcasts differential corrections and integrity-related information…Any aircraft may use these corrections to compute its position.”³⁰

Safety-of-Life

Safety-of-Life (SoL) “applications augment GNSS services intended for safety-critical transportation systems. Target domains include aviation, maritime navigation, rail travel, and automobile travel, where degradation in navigation system performance without a timely alert would endanger lives.”³¹ Different jurisdictions enforce different standards, adhere to different regulations, and use different technology. Nonetheless, “the key performance parameter for Safety-of-Life applications is integrity, or the trust that a user can have in the functioning of a navigation satellite system.”³²

Signal Authentication

Signal authentication is a concept related to navigation satellite systems. “The basic idea is that a GNSS receiver would like to ensure that a received signal is identical to the originally transmitted signal, and that it was transmitted by a trusted source.”³³ Signal authentication signatures can be generated through cryptographic techniques. The concept can help to mitigate deliberate signal interference. Signal authentication has been proposed for both GPS and the Galileo system.³⁴

SBAS (Satellite-Based Augmentation System)

A satellite-based augmentation system (SBAS) is used “for the safety-critical task of guiding aircraft—vertically and horizontally—during different operations, such as approach and landing…It supports wide-area and/or regional augmentation through the use of geostationary satellites, which broadcast augmentation information related to integrity and differential corrections…An SBAS can help to mitigate satellite position errors, satellite clock—or time—errors, and errors caused by the delay of a signal passing through the ionosphere…While the main goal of an SBAS is to provide integrity assurance, a system can also increase accuracy.”³⁵

WAAS (Wide Area Augmentation System)

The Wide Area Augmentation System (WAAS) “is the American satellite-based augmentation system (SBAS). WAAS is managed by the Federal Aviation Agency (FAA) and is specially developed for the civil aviation community. Operational since 2003, the system currently supports thousands of aircraft instrument approaches at more than one thousand airports throughout North America…The WAAS program is continuously in evolution…There are currently plans to improve the capability of the system, in parallel with the evolution of SBAS standards, towards a dual-frequency augmentation service.”³⁶

Augmentation and Surveying Techniques

Differential GNSS

Differential GNSS “is an augmentation system involving enhancement to primary GNSS data through use of a network of ground-based reference stations…This network enables the broadcasting of differential information to the user in order to improve position accuracy; integrity is not ensured. There are several differential GNSS techniques, including Real Time Kinematics (RTK).”³⁷

Geodetic Control Point

A geodetic control point is a monumented, or otherwise marked, survey point. As part of a larger geodetic control network, it is established for the purpose of providing geodetic reference for mapping and surveying activities.³⁸ Geodetic control points help to obtain precise accuracy in surveying—often in the order of millimeters.³⁹ A particular point is normally identified by a number, an alphanumeric symbol, or a concise, intelligible name, which is usually stamped on the disk marker.⁴⁰

PPK (Post-Processed Kinematics)

Post-processed kinematics (PPK) “is a technique similar to RTK, but the baselines⁴¹ are not processed in real time. PPK involves the use of one or more rover receivers and at least one reference receiver remaining stationary over a known control point.⁴² GNSS data is simultaneously collected at the rover and reference receivers. The data is downloaded from the receivers, and the baselines are processed via software.”⁴³

PPP (Precise Point Positioning)

Precise point positioning (PPP) “is a positioning technique that removes or models GNSS errors to provide a high level of position accuracy from a single satellite receiver. A PPP solution is dependent on GNSS satellite clock and orbit corrections, which are generated from a network of global reference stations. Once corrections are calculated, they are delivered to the end user via satellite or the internet…A PPP system is similar in structure to an SBAS system, providing corrections to a satellite receiver to increase position accuracy. However, PPP systems typically provide a greater level of accuracy—up to three centimeters—and allow for a single correction “stream” to be used worldwide.”⁴⁴ This technique is notably available on Android devices.

RAIM (Receiver Autonomous Integrity Monitoring)

Receiver autonomous integrity monitoring (RAIM) “is a technology developed to assess the integrity of GPS signals in a GPS receiver system. RAIM is of special importance to safety-critical GPS applications, such as aviation or marine navigation. GPS does not include any internal information about the integrity of its signals. It is possible for a GPS satellite to broadcast slightly incorrect information that will cause navigation information to be incorrect, but there is no method for the receiver to determine this fault using standard techniques.”⁴⁵ “RAIM detects faults with redundant GPS pseudorange measurements. That is, when more satellites are available than needed to produce a position fix, the extra pseudoranges should all be consistent with the computed position. A pseudorange that differs significantly from the expected value may indicate a fault in the associated satellite or another signal integrity problem.”⁴⁶ Of note, RAIM is considered available if 24 GPS satellites or more are operative.⁴⁷

RTK (Real Time Kinematics)

Real time kinematics (RTK) is a specific “differential GNSS technique. RTK provides high positioning performance in the vicinity of a base station…The technique utilizes a base station, one or several users,⁴⁸ and a communication channel allowing the base to broadcast information to the user in real time…The base station will transmit its well-known location to all in-view satellites. Utilizing this data, a user is then able to determine their location relative to the base with high precision. The user is then positioned globally…The RTK technique can yield accuracies of a few centimeters to the true position and is extensively used for surveying.”⁴⁹

RTKlib

RTKlib “is an open source GNSS toolkit for performing standard and precise positioning. Through use of raw GNSS data, RTKlib is capable of real-time and post-processing computing to accurately determine a position. It is possible to use precise point positioning (PPP) or real time kinematics (RTK)…With professional receivers and antennas, it is possible to achieve centimeter accuracy. Low-cost single frequency equipment can achieve decimeter accuracy…The software supports all major satellite constellations –GPS, GLONASS, Galileo, BeiDou, QZSS, and SBAS…The RTKlib toolkit runs on Windows, Linux, and Android.”⁵⁰

Receiver Capabilities

Dual-frequency

A dual-frequency GNSS receiver utilizes two signal frequencies. Through use of a second frequency, these receivers can correct for transmission delays caused by the ionosphere, which is the greatest single contributor to inaccuracy.⁵¹ Use of a second signal also provides greater signal redundancy, allowing for better error corrections and improved satellite availability, particularly in tree cover and urban canyons. With error-checking algorithms that can identify faulty satellite signals, dual-frequency GNSS receivers provide measurements that are not only accurate, but trustworthy. Manufacturers are currently developing dual-frequency GNSS receivers for smartphones,⁵² and related prices are expected to lower to the $50-range by 2021.⁵³

Frequency

Frequency is “the particular wavelength at which a [GNSS] broadcasts or transmits signals.”⁵⁴

Multi-constellation

A multi-constellation GNSS receiver can “access signals from several satellite constellations, such as GPS, GLONASS, BeiDou, and Galileo…As a larger number of satellites can be in its field of view, a multi-constellation GNSS receiver benefits from reduced signal acquisition time; improved accuracy of position and time; and a reduction of issues caused by obstructions such as buildings and tree cover…Redundancy is also built into a multi-constellation GNSS receiver. If a particular signal is blocked due to the working environment, there is a very high likelihood that the receiver can locate a signal from another satellite constellation.”⁵⁵

Multi-frequency

A multi-frequency GNSS receiver utilizes more than two, or multiple, signal frequencies. Use of the technology is an effective method to remove ionospheric error from position measurements and improve accuracy. A multi-frequency GNSS receiver also provides greater protection against signal interference.⁵⁶ Low-cost multi-frequency GNSS receivers are expected to appear on the market in the near future.⁵⁷

Single-frequency

A single-frequency GNSS receiver only utilizes one frequency to determine a position measurement. These measurements are vulnerable to interference and are accurate, at best, to roughly five meters.⁵⁸ A single-frequency GNSS receiver is adequate for most daily civilian uses, and Wi-Fi signals can be used to augment accuracy in developed areas. But related measurement errors are insufficient for survey work, which should be accurate to the one to ten centimeter range. Most smartphones use single-frequency GNSS receivers.

Signals & Frequencies

E5

E5 is a GNSS band, and refers to two GNSS signals, E5a and E5b. They are two of the four Galileo signals. Several Galileo system services are available through E5a and E5b, notably Open Service (OS) and the Safety-of-Life (SoL) service. Open Service is free and available for positioning and timing applications. The Safety-of-Life service provides increased guarantees regarding integrity monitoring, and will be available globally. E5a and E5b are both public assets, and are compatible with L1 and L5.⁵⁹ The frequency of E5a is 1176 MHz and the frequency of E5b is 1207 MHz.⁶⁰

E6

E6 is a GNSS signal. It is one of four Galileo signals. The Public Regulated Service (PRS), a Galileo system service, is provided on E6. “PRS is encrypted and is meant to assist public security and civil authorities. The service is under government control, providing significant jamming protection, with likely applications including emergency services, law enforcement, intelligence services, and customs…The frequency of E6 is 1278 MHz…and it is part of the radio navigation satellite service (RNSS) for Galileo.”⁶¹

L1

L1 is a GNSS band. It is one of two main frequencies broadcast by GPS. L1 “is the most important band for navigation purposes, and it is the basis for the majority of current GPS applications. Signals are transmitted using a number of codes: the open Coarse/Acquisition (C/A) code signal is the most important signal for mass market applications; the P Code is used for precision measurements; the modernized military signal (M-Code) is designed exclusively for military use; the L1C code is the new civil signal…The frequency of the L1 band is 1575 MHz.”⁶² It was subject to Selective Availability measures, enforced by the United States Government, until 2000.⁶³

L1C

L1C is a GNSS signal. “It will be the fourth civilian GPS signal, designed to enable interoperability among international navigation satellite systems…Design will also improve mobile signal reception in cities and other challenging environments…The name L1C refers to the radio frequency used by the signal –1575 MHz or L1– and to the fact that it is for civilian use…The United States and Europe developed L1C as a common civil signal for GPS and Galileo…The United States will launch its first L1C signal with GPS Block III.⁶⁴

L2

L2 is a GNSS band. It is one of two main frequencies broadcast by GPS. At first, the L2 band was available only to authorized users, such as the United States Armed Forces. These users were issued encryption keys for access to data. This policy prevented both civilians and foreign governments from obtaining precise GPS coordinates without the assistance of ground-based augmentation systems. Several civilian companies eventually discovered how to use the L2 band without an encryption key and patented their various techniques. As a result, the policy of restricted access to L2 was reversed by the United States Government. Yet the related patents continue to restrict competition in the development of dual-frequency receivers.⁶⁵ L2C, a preoperational civilian signal, may soon replace the original L2 signal.

L2C

L2C is a GNSS signal. “It is the second civilian GPS signal, designed specifically to meet commercial needs…When combined with the legacy L1 C/A signal in a dual-frequency GNSS receiver, L2C enables ionospheric correction, boosting accuracy…and enables faster signal acquisition, enhanced reliability, and greater operating range. L2C also broadcasts at a higher effective power than legacy signals, strengthening reception under tree cover and even indoors…The name L2C refers to the radio frequency used by the signal—1227 MHz or L2—and the fact that it is for civilian use…The first GPS satellite featuring L2C launched in 2005. Every GPS satellite fielded since has included an L2C transmitter…However, the signal is still considered preoperational.”⁶⁶

L5

L5 is a GNSS signal. “It is the third civilian GPS signal, designed to meet demanding requirements for safety-of-life transportation and other high-performance applications…L5 is broadcast in a radio band exclusively for aviation safety services. It features higher power, greater bandwidth, and an advanced signal design. Future aircraft will be able to use L5 in combination with other signals to improve accuracy, via ionospheric corrections, and robustness, via signal redundancy. In addition to enhancing safety, L5 will increase capacity and fuel efficiency within US airspace, railroads, waterways, and highways…The name L5 refers to the U.S. designation of the radio frequency used by the signal, 1176 MHz…The U.S. Air Force began broadcasting civil navigation (CNAV) messages on L5 in April 2014, but it is still preoperational.”⁶⁷

Selective Availability

“Selective availability (SA) was an intentional degradation of public GPS signals implemented for American national security reasons. In May 2000, at the direction of President Bill Clinton, the United States Government discontinued its use of Selective Availability in order to make GPS more responsive to civil and commercial users worldwide. In September 2007, the United States Government announced its decision to procure [GPS Block III] without SA. This made the May 2000 policy decision permanent and eliminated a source of uncertainty for GPS performance.”⁶⁸

GNSS Raw Measurements

Carrier-phase

“The carrier-phase measurement is a measure of the range between a satellite and a GNSS receiver. It is expressed in units of cycles of the carrier frequency.⁶⁹ The carrier-phase measurement can be expressed with very high precision—in the order of millimeters—but the total number of cycles between satellite and GNSS receiver is ambiguous.”⁷⁰

Code-phase

The code-phase measurement is a measure of the travel time of a signal from a satellite to GNSS receiver. It is also used to calculate positioning. The code-phase measurement is based on pseudo-random code—C/A code or P Code—and is expressed in sequences of zeros and ones. After differential correction, the code-phase measurement technique results in one to five meter accuracy.⁷¹

Doppler

“The Doppler effect, or the Doppler shift, is the change in frequency for an observer, such as a GNSS receiver, moving relative to its source, such as a particular satellite.”⁷² Using Doppler data, a GNSS receiver can estimate its velocity,⁷³ augment its position, and determine its range rate.^{74 75}

GNSS Raw Measurements

“GNSS raw measurements, such as pseudoranges, Doppler measurements, and carrier-phase measurements, are directly accessible to application developers via smartphones that feature Android 7.0 or higher. This access creates the possibility of using alternative, and possibly more advanced, techniques for position, velocity, and time (PVT) computations.”⁷⁶ Use of GNSS raw measurements can lead to increased GNSS performance—notably increased accuracy—as well.⁷⁷

GNSS Raw Measurements Task Force

The GNSS Raw Measurements Task Force was launched by the European Global Navigation Satellite Systems Agency (GSA) in June 2017, following the release of GNSS raw measurements on Android.⁷⁸ “The task force aims to share knowledge and expertise on Android raw measurements and their use, including the potential for high accuracy positioning techniques. The [GNSS Raw Measurements] Task Force includes GNSS experts, scientists and GNSS market players, and promotes a wider use of [GNSS] raw measurements.”⁷⁹

GNSS Software-Defined Receiver

A GNSS software-defined receiver “is a GNSS receiver that has been designed and implemented following the philosophy of software-defined radio…Traditionally, GNSS receivers have been implemented in hardware, which is conceived as a dedicated chip that is designed and built with the single purpose of being a GNSS receiver. In a GNSS software-defined receiver, all digital processing is performed by a general purpose microprocessor. In this approach, a small amount of inexpensive hardware is still needed to digitize a signal from a satellite. The microprocessor can then use this raw digital data to implement GNSS functionality.”⁸⁰

Pseudorange

“The pseudorange is an approximation of the distance between a satellite and a GNSS receiver…The pseudorange of a particular satellite is obtained by multiplying ‘the time taken for a signal to reach the receiver’ by ‘the speed of light’…As there will inevitably be accuracy errors in the time measured, the term pseudorange is used in place of range.”⁸¹

Common Sources of Signal Interference

Integer Ambiguity Resolution

Integer ambiguity resolution occurs when a GNSS receiver must reinitialize because a signal was interrupted. This process is often necessary when an automobile passes through a tunnel or is within an urban canyon—locations where a GNSS receiver can lose sight of satellites. Once the satellites are back in view, the GNSS receiver can re-establish an accurate position fix, usually in a matter of seconds. Dual-frequency receivers allow for more rapid integer ambiguity resolution. Of note, this capability is a serious advantage within the autonomous vehicle sector, as highly urban areas will be its primary market.

Ionospheric Delay

“Ionospheric delay is the amount of additional transmission time a signal incurs as it passes through the ionosphere,”⁸²—a region of the earth’s atmosphere extending from 60 kilometers to 1,000 kilometers in altitude.⁸³ The amount of ionospheric delay varies with the frequency of the passing signal, and also varies based on the electron density of the ionosphere. This density, in turn, can vary based on geographic location and sunspot activity.⁸⁴

Multipath Interference

Multipath interference is generated when a signal arrives via multiple paths at a GNSS receiver, rather than from a direct line of sight. Reflected signals can interfere with signals that reach the GNSS receiver directly from a satellite. The principle cause is close proximity of a GNSS receiver to reflecting structures, such as buildings. Multipath interference can also be caused when a signal is transmitted by a satellite with low elevation.⁸⁵

Deliberate Signal Interference

GNSS Spoofing

GNSS spoofing “is the broadcast of false signals with the intent that the victim receiver will misinterpret them as authentic signals. The victim [receiver] might deduce a false position fix, a false clock offset, or both. A coordinated sequence of false position or timing fixes could induce dangerous behavior by a user platform that believes the false fixes. For example, [GNSS] spoofing has been used to send a hovering drone into an unplanned dive and to steer a yacht off course.”⁸⁶

Location Spoofing

“Location spoofing refers to a variety of emerging online geographic practices that allow users to [intentionally] hide their true geographic locations.”⁸⁷ There are presently a number of location spoofing, or mock location, applications available to users. Many are readily available on Android devices. The applications will usually alter a user’s latitude and longitude.⁸⁸ The proliferation of location spoofing in recent years has created controversy and debate regarding the reliability and convenience of crowdsourced geographic information.⁸⁹

Meaconing

“Meaconing is the interception and rebroadcast of navigation signals. These signals are rebroadcast on the received frequency, typically with higher power than the original signal…Consequently, aircraft or ground stations are given inaccurate bearings…Meaconing is often used in warfare to confuse enemy navigation…Successful meaconing can cause aircraft to be lured into ambush-ready landing zones or enemy airspace, ships to be diverted from their intended routes, bombers to expend ordnance on false targets, and ground stations to receive inaccurate bearings or position locations.”⁹⁰

Proof of Location

Proof of Location (PoL), or location assurance, is a concept that would allow a user to record their location, and the related timestamp, at their choosing.⁹¹ The user could then reveal this information at their discretion through presentation of a location claim. “Proof of Location can provide consensus [about] whether [a user] is verifiably at a certain point in time and space.”⁹²

Related Technology

Connected Car

“A connected car is a car equipped with internet access, and usually also with a wireless local area network (LAN). This allows the car to share internet access with other devices, both inside and outside the vehicle. Often, a connected car is outfitted with special technologies that tap into the internet or wireless LAN and provide additional benefits to the driver,”⁹³ such as real-time traffic, roadside assistance, and parking services. Connected cars are often considered as part of the Internet of Things.⁹⁴

Orthophoto

“An orthophoto is a uniform-scale photograph, or a photographic map…A conventional perspective aerial photograph contains image displacements caused by the tilting of the camera and terrain relief, or topography.”⁹⁵ An aerial photograph can also be distorted by the curvature of the earth if taken from a very high altitude. “These images do not have uniform scale, and distances therefore cannot be measured accurately using the photographs. The effects of tilt and relief [can be] removed from an aerial photograph via a rectification process to create an orthophoto. Since an orthophoto is uniform in scale, it is possible to measure directly on it, similar to other maps. An orthophoto can [also] serve as a base map onto which other information can be overlaid.”⁹⁶

TaaS (Transportation-as-a-Service)

Transportation-as-a-Service (TaaS), or Mobility-as-a-Service (MaaS), “describes a shift away from personally-owned modes of transportation and towards mobility solutions that are consumed as a service.”⁹⁷ “TaaS may take a variety of forms, offering more consumer choices and business opportunities.”⁹⁸ Ride-hailing, on-demand delivery services, car sharing, bike sharing, and public transportation services are all forms of Transportation-as-a-Service. In the future, TaaS may include autonomous driving services.⁹⁹

Organizations and Initiatives

ESA (European Space Agency)

“The European Space Agency (ESA) is an intergovernmental organization of 22 member states dedicated to the exploration of space…Headquartered in Paris, ESA has a worldwide staff of about 2,000 and an annual budget of about €5.25 billion. The ESA space flight program includes: human spaceflight, mainly through participation in the International Space Station program; the launch and operation of unmanned exploration missions to the Moon and other planets; Earth observation, science, and telecommunication; designing launch vehicles; and maintaining a major spaceport in French Guiana.”¹⁰⁰

GSA (European Global Navigation Satellite Systems Agency)

The European Global Navigation Satellite Systems Agency (GSA) “is the European Union (EU) agency that aims to ensure that essential public interests are properly defended and represented in connection with [the EU navigation satellite programs]: Galileo and EGNOS…It is also responsible for managing and monitoring the use of the navigation satellite programs’ funds…The GSA was established in 2004 and is based in Prague.”¹⁰¹

MAST (Mobile Application to Secure Tenure)

The Mobile Application to Secure Tenure (MAST) project is a United States Agency for International Development (USAID) initiative to address land tenure insecurity and related socioeconomic problems. “The project [included the use of] an easy-to-use, open-source smartphone application [to] capture the information needed to issue formal documentation of land rights. Coupled with a cloud-based data management system to store geospatial and demographic information, the [MAST] project was designed to lower costs and time involved in registering land rights” through community mapping.¹⁰² Importantly, the initiative also made land administration processes more transparent and accessible at the local level. MAST has been implemented in Tanzania, Zambia, and Burkina Faso.