NAVCOM STARFIRE

Technicals

STARFIRE vs. DGNSS

As a Global Satellite-Based Augmentation System (GSBAS), the StarFire™ Network holds a significant advantage over differential GNSS (dGNSS) systems. Since no base station is required, the StarFire™ user is free to roam, with no limitations on range. StarFire™ provides one set of corrections for the entire world, as opposed to dGNSS systems’ baseline-dependent regional corrections, which are geographically limited.

GSBAS vs. DGNSS Systems

In order to evaluate the satellite positioning options available, the primary error sources contributing to the corrections need to be understood.

Reference and rover errors include:

• Satellite Clock
• Satellite Orbit
• Ionosphere
• Troposphere
• Multipath
• Earth Tides
• Receiver Clock
• Receiver Biases

How these are handled can be placed into two broad classes: differential GNSS (dGNSS) systems and Global Satellite-Based Augmentation System (GSBAS) systems.

DGNSS Systems

DGNSS provides relative positioning; these positioning options determine corrections at the Earth’s surface, either at individual sites or averaged over a region. These corrections are an amalgam of primary reference error sources and are transmitted to the user via radio or satellite link. User coordinates are determined relative to the reference site(s). Accuracy degrades with distance from the individual reference site or the regional boundary, primarily because of differential ionospheric and tropospheric effects, satellite orbits, and clocks. Examples of correction services include:

• Beacon dGNSS
• Commercial dGNSS
• RTK / Network RTK
• Widelane RTK

Widelane RTK is a relative newcomer, which is only available in the few areas of the world that require high accuracy on a regular basis for oil and gas exploration surveys.

GSBAS

Importantly, GSBAS systems provide absolute positioning, meaning they do not determine position relative to some fixed point of the Earth’s surface. Instead, they determine a position within a space-based reference frame, thus they may also be considered to be within the Space Domain group.

Satellite communication links are used for some dGNSS systems, so the term GSBAS does not relate to the communication link used but instead describes the nature of the corrections, i.e. that they are for the satellites. This class includes:

• Standalone GPS
• WAAS
• EGNOS
• MSAS
• StarFire™

Augmentation for Standalone GPS consists of satellite orbit and clock updates which are generated by the GPS Ground Control Segment and distributed to the user with an ionospheric model in the GPS signal structure. It is this basic principle of determining each error source instead of amalgamating them which distinguishes GSBAS from dGNSS.

Real-time GPS Satellite Data (SV Ephemeris Data)

• Fast position acquisition
• Enables low cost L1 GPS chipsets to acquire position in 6 seconds, as opposed to the typical 1 minute
• Allows for satellite monitoring in GPS operations
• Aids in mission planning and navigation simulation
• Typical customer: Military, Wireless Providers – LBS/E-911 services

Real-time StarFire Corrections

• Provides L1 chipsets with significantly greater position accuracy
• Improves accuracy from ~30m to 1.5m
• Typical Customer: Wireless Providers – LBS services

Real-time Satellite Data & Corrections

• Position is acquired in 6 seconds as opposed to 1 minute
• Accuracy is improved to 1.5m as opposed to ~30m.
• Typical customer: LBS service providers (i.e. child monitoring services)

Real-Time Timing Reference Data

• Low cost, high-resolution alternative to current timing elements
• Providers of cellular infrastructure have a cell-station requirement of providing timing resolution within 7 microseconds
• Our Timing Reference Data exceeds the 7 microsecond requirement with a provided resolution of 12.5 nanoseconds, at a fraction of the cost of typical solutions
• Typical customer: Wireless Providers – Infrastructure

Archived Satellite Data & Corrections

• Post processing of measurement data to achieve millimetre-level accuracy
• Potential Customer: Survey Industry