Position, Navigation, and Timing Technologies in the 21st Century

27 Chapter 59Figure 59.1 Track circuit principle.Figure 59.2 ERTMS level 1.Figure 59.3 ERTMS Level 2 (L2).Figure 59.4 ERTMS Level 3.Figure 59.5 The position error components.Figure 59.6 Standard deviation of the overbounding Gaussian distribution nor...Figure 59.7 Deployment of a virtual balise (VB) protecting a supervised loca...Figure 59.8 High‐integrity, high‐accuracy two‐tier architecture.Figure 59.9 Augmentation network architecture – 2nd Tier.Figure 59.10 Multipath effects in rail scenarios (yellow: standalone GNSS, r...Figure 59.11 Computation of confidence interval.Figure 59.12 Train localization geometry.Figure 59.13 Reference station sites.Figure 59.14 Stanford diagram – scenario #1 (Neri et al. [7]).Figure 59.15 Number of satellites used in the PVT estimation – scenario #1 (...Figure 59.16 Stanford diagram – satellite faults (Neri et al. [7]).Figure 59.17 Number of satellites used for PVT estimation – satellite faults...Figure 59.18 Baseline geometry.Figure 59.19 GPS+GLONASS RTK train locations (red circles) Rome–Cassino rail...Figure 59.20 A posteriori probability of each hypothesis (true track in blue...Figure 59.21 Train mileage versus time.Figure 59.22 Geometry‐free combination (L1‐L2) (Hsu et al. [11]; Beitler et ...Figure 59.23 Multiple‐track geometry.

28 Chapter 60Figure 60.1 UTM architecture (Aweiss et al. [24]).Figure 60.2 General hierarchy of guidance, navigation, and control (GNC) fun...Figure 60.3 Autonomy of a commercial multi‐copter platform in presence of GP...Figure 60.4 Geo‐fenced field next to a school.Figure 60.5 Conceptual boundaries for assured containment in NASA’s Safeguar...Figure 60.6 (a)Left: Modeled trajectory of a multi‐rotor UAS after flight te...Figure 60.7 Two approaches to estimate the time to closest point of approach...Figure 60.8 Horizontal distance to CPA or horizontal missed distance ( HMD ), ...Figure 60.9 Hazard Zone, Alert Zone, and Non‐Hazard Zone for the “τ mod”‐crit...Figure 60.10 Well clear threshold, or WCT; and NMAC (not to scale).This ...Figure 60.11 Depiction of predicted well clear using conflict probes. Top: C...Figure 60.12 Accounting for measurement uncertainty in UAS SAA (Jamoom et al...Figure 60.13 Examples of Ohio University sUAS operations in challenging envi...Figure 60.14 Observation of planar surfaces using multiple laser scans taken...Figure 60.15 Laser‐based terrain navigator with one or two laser range scann...Figure 60.16 Use of three laser range scanners (“a” and “b”) for 2D pose est...Figure 60.17 Example of an outdoor‐indoor flight scenario where the pose est...Figure 60.18 Left: GNSS (red) and laser‐based navigation (green) trajectorie...Figure 60.19 Visual odometry results using direct sparse odometry (DSO) (Eng...

29 Chapter 61Figure 61.1 Example use of public key cryptography for aviation data authent...Figure 61.2 Use of GNSS augmentation to support various flight operations, a...Figure 61.3 DME transponder response to interrogations from the aircraft DME...Figure 61.4 The ideal DME transmission is a pair of Gaussian pulses. The pul...Figure 61.5 TACAN amplitude modulation relative to azimuth showing the overl...Figure 61.6 Similarity between nominal DME and DME passive ranging operation...Figure 61.7 DME interrogation‐reply frequency pairings for different codes b...Figure 61.8 ILS Localizer showing notional gain patterns of the two carrier ...Figure 61.9 ILS avionics cockpit guidance display (aircraft needs to go up a...Figure 61.10 Instrument landing system (FAA [31]).Figure 61.11 Bearing measurement from VOR (θ). The angle measured is the sam...Figure 61.12 Angle measurement from NDB (γ). Angle measured depends on aircr...Figure 61.13 Captured over‐the‐air and ideal Mode S transmission.Figure 61.14 UAT frame and transmission structure.Figure 61.15 One‐second UAT frame is organized into two segments with guard ...Figure 61.16 Height difference with temperature difference of 5° from ISA st...Figure 61.17 Difference between GPS and baro‐altitude on balloon flight.

30 Chapter 62Figure 62.1 Mean magnitude of accelerations experienced by a spacecraft in c...Figure 62.2 Flowchart of the LEO POD process. (PPP: Precise Point‐Positionin...Figure 62.3 Large, systematic excursions in post‐fit residuals from orbit de...Figure 62.4 Available GPS signals to an Earth‐orbiting spacecraftOther G...Figure 62.5 The number of GPS main lobe signals (boresight angle of 44°) ava...Figure 62.6 One of the twin GRACE spacecraft. The GPS choke‐ring antenna (at...Figure 62.7 The Jason‐3 spacecraft. The twin, canted GPS choke‐ring antennas...Figure 62.8 Post‐fit residuals (pseudorange, top left, phase, top right) and...

31 Chapter 63Figure 63.1 Range of achievable GNSS navigation accuracies using absolute an...Figure 63.2 International fleet of space vehicles using GPS for far‐range na...Figure 63.3 Graphical illustration of PRISMA technology demonstration missio...Figure 63.4 Graphical illustration of MMS formation‐flying mission in high e...Figure 63.5 Graphical illustration of CPOD (left), https://www.nasa.gov. Tyv...Figure 63.6 Spherical coordinates.Figure 63.7 Contours of constant semi‐major axis (SMA) error (blue lines) sh...Figure 63.8 Target centered relative motion plot during STS‐69 in LVLH frame...Figure 63.9 Difference of real‐time onboard navigation solution versus post‐...Figure 63.10 Long‐term analysis of real‐time relative orbit elements (ROEs) ...Figure 63.11 GEONS’ 1 σ formal error (root‐covariance) over three orbits...

32 Chapter 64Figure 64.1 Summer Arctic sea ice extent 1980–2012.Figure 64.2 (a) Arctic airports and (b) transpolar air routes (Reid et al. [...Figure 64.3 Maximum extent of Arctic and Antarctic waters as described in th...Figure 64.4 Illustration of how angular rotations measured by compasses and ...Figure 64.5 GNSS setup for hydrographic surveying. This three‐antenna system...Figure 64.6 Ground tracks of (a) GPS and (b) combined GPS, GLONASS, Galileo,...Figure 64.7 Skyplot of GPS and EGNOS satellites at 71°30’ North in the Baren...Figure 64.8 The effect of snow accumulation on a GNSS antenna. The heavy sno...Figure 64.9 Typical layout and components of a Class‐3 Dynamic Positioning (...Figure 64.10 Different sensors and elements used for ice detection and safe ...Figure 64.11 Icebreaker escorting a seismic vessel through open drift ice on...Figure 64.12 Point cloud map of a LiDAR scan of a portion of the Helheim Gla...Figure 64.13 Benefits of information crowdsourcing and crowdsharing in ice n...Figure 64.14 The ESABALT crowdsourcing and crowdsharing ecosystem for improv...Figure 64.15 To model ship maneuverability, a finite set of directions in wh...Figure 64.16 Heat map of transit speeds in sea ice conditions with an optimi...Figure 64.17 SBAS ground segment: Reference stations of all current systems ...Figure 64.18 Orbits of the GPS constellation, SBAS GEO space segment, Quasi‐...Figure 64.19 SBAS aviation service level in 2015 using single‐frequency GPS....Figure 64.20 SBAS aviation service slated for 2026 using dual frequency and ...

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