Seven groups of acronyms and engineering terms for specifications, proposals and technical conversations.
Satellites and signals
| Term | Meaning |
|---|
| GNSS | The umbrella term for global navigation satellite systems. |
| Galileo | The major US, Chinese, Russian and European satellite navigation systems. |
| PNT | Positioning, navigation and timing. |
| Pseudorange | A range observation from signal travel time, including clock and other errors. |
| Carrier phase | A precise carrier observation with an unknown integer ambiguity. |
| Integer ambiguity | The unknown integer cycle count in carrier-phase observations. |
| Multipath | Observations affected by signals arriving along multiple paths. |
| NLOS | Non-line-of-sight reception, potentially from reflections rather than a direct path. |
| Ionospheric / tropospheric delay | Atmospheric propagation delays. |
| Ephemeris / clock error | Satellite orbit information and clock offsets. |
| L band | A radio band used by GNSS; exact frequencies vary by signal. |
| Doppler | Frequency change caused by relative motion. |
| 1PPS | A one-pulse-per-second time-reference output. |
| Timing / holdover | Time synchronization and holdover when an external reference is unavailable. |
Precision augmentation
| Term | Meaning |
|---|
| SPP | Standalone positioning from a receiver’s satellite observations. |
| RTD | Differential positioning using reference-station information. |
| RTK | Real-time carrier-phase differential positioning. |
| Fixed / float solution | Solution states with resolved or unresolved integer ambiguities. |
| Re-convergence | Recovery to a target solution state after interruption. |
| CORS | Continuously operating reference stations or a reference network. |
| NTRIP | A protocol for transporting GNSS data over networks. |
| RTCM | Common standardized messages for navigation observations and corrections. |
| VRS | The virtual-reference-station method in network RTK. |
| SSR | Observation-space and state-space representations of corrections. |
| PPP | Precise point positioning using precise orbit, clock and related products. |
| PPP-AR | PPP with integer ambiguity resolution. |
| PPP-RTK | Precise augmentation combining products, ambiguity handling and regional information. |
| GBAS | Satellite-based and ground-based augmentation systems. |
LEO and satellite-to-ground integration
| Term | Meaning |
|---|
| GEO | Low Earth, medium Earth and geostationary orbits. |
| LEO-PNT / LEO-NA | LEO positioning/navigation/timing and LEO navigation augmentation. |
| Integrated communications and navigation | Coordinated communication links, navigation signals and system design. |
| Precise orbit determination | Estimating precise satellite orbits and related parameters from observations. |
| Qianfan | One of the LEO communication constellation projects. |
| Starlink | A SpaceX communication constellation; navigation applications require additional system conditions. |
| Satellite corrections | Delivery of correction information by satellite, subject to coverage and terminal capability. |
Inertial sensing and fusion
| Term | Meaning |
|---|
| IMU / INS | An inertial measurement unit and an inertial navigation system. |
| MEMS | Micro-electromechanical systems technology for compact devices. |
| Gyroscope / accelerometer | Sensors measuring angular rate and specific force. |
| Bias instability | A sensor-bias stability metric interpreted with its measurement conditions. |
| Inertial drift | Accumulating error from inertial integration. |
| Loose / tight / deep coupling | Integration using solution outputs, raw observations or receiver tracking loops. |
| Odometry | Displacement estimation from wheel or other motion information. |
| EKF | Filtering methods for combining observations and estimating system state. |
| Extrinsics and lever arms | Transformations and installation offsets between sensor frames. |
| Time synchronization | Aligning sensor data to a consistent time reference. |
Vision and intelligent navigation
| Term | Meaning |
|---|
| VIO / VO | Visual-inertial and visual odometry. |
| SLAM / LIO | Simultaneous localization and mapping, and lidar-inertial odometry. |
| Loop closure / relocalization | Recognizing revisited areas and recovering position within an existing map. |
| Bag of words | A representation used in tasks such as visual feature retrieval. |
| Point cloud / depth map | Discrete 3D points and pixel-wise depth representations. |
| Stereo | Depth estimation from two camera observations and disparity. |
| Global shutter | Simultaneous frame exposure that helps reduce rolling-shutter distortion. |
| mmWave radar | Range, velocity and related sensing using millimeter-wave signals. |
| LiDAR | Laser-based range and spatial measurement. |
| VLN / VLM / LLM | Vision-language navigation, vision-language models and large language models. |
| End-to-end navigation | Joint modeling from observations to navigation actions. |
| Semantic navigation | Navigation using environmental meaning and spatial relationships. |
| Embodied intelligence | Intelligence through physical sensing, action and environmental interaction. |
| Spatial computing | Digital representation and computation of spatial and temporal information. |
Applications and quality
| Term | Meaning |
|---|
| Integrity | The ability to provide trustworthy warnings when service requirements cannot be met. |
| Availability | The proportion of time meeting defined service requirements. |
| Low-altitude economy | Economic activities around low-altitude flight and associated services. |
| eVTOL / UAV / UAM | Electric vertical-takeoff aircraft, unmanned aircraft and urban air mobility. |
| AMR | Automated guided vehicles and autonomous mobile robots. |
| Precision agriculture | Fine-grained agricultural operations supported by positioning and data. |
| Digital twin | A digital representation linked to a physical system, with defined data and update mechanisms. |
Products and interfaces
| Term | Meaning |
|---|
| HopoEngine | HOPO’s multimodal positioning fusion engine. |
| NaaS | Navigation as a service; licensing and functions depend on the service plan. |
| ROS2 | Robotics middleware ecosystems; integration requires version and message checks. |
| SDK / API / NMEA | Development tools, programming interfaces and navigation message formats. |
| CAN / UART / SPI | Communication interfaces or buses with different roles. |
| IP54 / M12 | An ingress-protection rating and a connector format; check each against the specification. |
| OTA | Remote software updates requiring supported update and version-management mechanisms. |
Put terms into application context
Agriculture emphasizes pass spacing and coverage; logistics emphasizes transitions and docking; inspection emphasizes repeatable visits and consistent capture; mowing emphasizes boundaries, obstacles and charging coordination. Low-altitude and maritime projects also need application-specific communications, augmentation coverage and system requirements. A technical term does not establish a delivered product function.
