Chapter 1

Introduction

NovAtel's SPAN technology brings together two very different but complementary positioning and navigation systems namely Global Navigation Satellite System (GNSS) and an Inertial Navigation System (INS). By combining the best aspects of GNSS and INS into one system, SPAN technology is able to offer a solution that is more accurate and reliable than either GNSS or INS could provide alone. The combined GNSS + INS solution has the advantage of the absolute accuracy available from GNSS and the continuity of INS through traditionally difficult GNSS conditions.

1.1Fundamentals of GNSS + INS

GNSS positioning observes range measurements from orbiting GNSS satellites. From these observations, the receiver can compute position and velocity with high accuracy. NovAtel GNSS positioning systems are highly accurate positioning tools. However, GNSS in general has some restrictions which limit its usefulness in some situations. GNSS positioning requires line of sight view to at least four satellites simultaneously. If these criteria are met, differential GNSS positioning can be accurate to within a few centimetres. If however, some or all of the satellite signals are blocked, the accuracy of the position reported by GNSS degrades substantially, or may not be available at all.

In general, an INS uses forces and rotations measured by an Inertial Measurement Unit (IMU) to calculate position, velocity and attitude. This capability is embedded in the firmware of the SPAN-IGM. Forces are measured by accelerometers in three perpendicular axes within the IMU and the gyros measure angular rotation rates around those axes. Over short periods of time, inertial navigation gives very accurate acceleration, velocity and attitude output. The INS must have prior knowledge of its initial position, initial velocity, initial attitude, Earth rotation rate and gravity field. Since the IMU measures changes in orientation and acceleration, the INS determines changes in position and attitude, but initial values for these parameters must be provided from an external source. Once these parameters are known, an INS is capable of providing an autonomous solution with no external inputs. However, because of errors in the IMU measurements that accumulate over time, an inertial-only solution degrades with time unless external updates such as position, velocity or attitude are supplied.

The SPAN system’s combined GNSS + INS solution integrates the raw inertial measurements with all available GNSS information to provide the optimum solution possible in any situation. By using the high accuracy GNSS solution, the IMU errors can be modeled and mitigated. Conversely, the continuity and relative accuracy of the INS solution enables faster GNSS signal reacquisition and RTK solution convergence.

The advantages of using SPAN technology are its ability to:

Provide a full attitude solution (roll, pitch and azimuth)

Provide continuous solution output (in situations when a GNSS-only solution is impossible)

Provide faster signal reacquisition and RTK solution resolution (over stand-alone GNSS because of the tightly integrated GNSS and INS filters)

Output high-rate (up to 125 or 200 Hz depending on SPAN-IGM model and logging selections) position, velocity and attitude solutions for high-dynamic applications, see also Logging Restriction Important Notice on page 33

Use raw phase observation data (to constrain INS solution drift even when too few satellites are available for a full GNSS solution)

SPAN-IGM User Manual Rev 2

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Novatel OM-20000141 user manual Introduction, Fundamentals of Gnss + INS

OM-20000141 specifications

The Novatel OM-20000141 is a high-performance multi-GNSS (Global Navigation Satellite System) receiver designed for various applications including precision agriculture, autonomous vehicles, and surveying. This state-of-the-art device combines cutting-edge technologies to provide accurate and reliable positioning data, making it an indispensable tool for professionals in fields that rely on geolocation.

One of the standout features of the Novatel OM-20000141 is its multi-frequency support, allowing it to receive signals from GPS, GLONASS, Galileo, and BeiDou systems. This capability significantly enhances the accuracy and reliability of positioning information, particularly in challenging environments where signal interference can occur. By utilizing multiple frequencies, the OM-20000141 can mitigate errors caused by atmospheric disturbances and multi-path signals, resulting in improved precision.

In addition to its multi-GNSS capabilities, the receiver incorporates advanced RTK (Real-Time Kinematic) technology, enabling centimeter-level accuracy. This is particularly beneficial for applications that require pinpoint geolocation, such as precision agriculture, where farmers need to optimize crop yields and resource usage. The RTK technology allows users to achieve real-time positioning corrections, making it a vital tool for surveying and construction projects that demand high precision.

The Novatel OM-20000141 also features built-in connectivity options, including Bluetooth and USB interfaces, facilitating seamless integration with other devices and systems. This connectivity is crucial for enabling real-time data sharing and remote monitoring, enhancing the usability of the device in various operational environments.

Robustness is another significant characteristic of the OM-20000141. Designed to withstand harsh conditions, the receiver features a durable housing that protects it from dust, moisture, and extreme temperatures. This resilience ensures that the device operates effectively in all weather conditions, making it suitable for outdoor applications.

Furthermore, the receiver is equipped with intelligent positioning algorithms that optimize performance in urban canyons and dense foliage areas, where traditional GNSS receivers may struggle. By leveraging these algorithms, the OM-20000141 can maintain reliable positioning even in challenging environments.

Overall, the Novatel OM-20000141 stands out as a versatile and reliable GNSS receiver, merging advanced technologies to deliver high accuracy and reliability. Its exceptional features make it an invaluable asset for professionals in various industries, enhancing their ability to achieve precise geolocation and optimize their operations.