GPS Services GroupC&C Technologies, Inc.,

www.cctechnol.com/cnav

 

C-Nav GPS System

C-Nav[RM] GPS SystemC-Nav GPS

Receiver

Interconnect Cable

C-Nav Control

Display Unit (CnC D.U.)

C-Nav[RM] is?• A Worldwide ‘global’ GPS solution (RTG)

• Provides deci-meter accuracy and stability

• Simple ‘plug-n-play’ installation and use

• Integrated ‘mast-head’ package minimizes equipment hardware requirements

• Subscription Service activation and deactivation for long or short term usage

• ‘Regional’ backup solutions (WCT & SBAS)

Global Corrected GPSvia StarFire Network

North & Central America (RTG, WCT, SBAS)

Western Europe / Mediterranean Sea (RTG, WCT, SBAS)

Far East Region (RTG, SBAS**)

Australia (RTG, WCT)

South America (RTG)

Eastern Europe / Mediterranean & Black Sea (RTG, SBAS)

African Continent (RTG)

Middle East, & Asian Continent (RTG)

Atlantic, Indian and Pacific Oceans (RTG)

** Waiting on MSAS

America’s RTG Performance

Europe-Africa RTG Performance

Asia-Australia RTG Performance

GcGPS Architecture

• Global network of dual frequency GPS reference receivers which transmit their RAW observables to processing / distribution hubs (NPH)

• Wide area communications used to broadcast corrections to users (StarFire)

• Dual frequency GPS navigation receivers combined with wide area communication receiver

• Measure / model key error sources (SV clock, orbit, local observed ionosphere, local troposphere)

Dual Frequency GcGPSPerformance and Limitations

• Performance– Decimeter level accuracy over very large areas

(regional, continental, global)

– Initialization time: 15 minutes to one hour (final accuracy)

– Very low position drift rate in steady state

• Limitations– Requires communication link to receive WADGPS

corrections (sat. comm., other)

– Potentially lengthy initialization time

Recent Improvements

• L1 phase navigation ‘smart’ position updates

• Upstream (50Hz) measurement processing restructure

• L1 phase nav. residual editing and cycle slip detection restructure

• RTG backing RTK

Onshore GPS Stress Testing

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-50

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150

-200 -150 -100 -50 0 50 100 150 200 250

Eastings (meters)

No

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Test Course Overview031220 StarFire dynamic runs

Shading Area Arefer to Picture #1

Shading Area Brefer to Picture #2

East Parking Lot Map

le A

ve.

Civic Center Dr.

A - Shading Areas - B

RTG w/o L1Pnav

RTG with L1Pnav

Overlay

Offshore Stress Testing

Vessel Setup

C-Nav Testing

C-Nav Testing

C-Nav Testing

C-Nav[2050] System

RTK and GcGPS Synergies

Q: If both RTK and dual frequency Starfire Wide Area DGPS (GcGPS) navigation solutions are available in the same system hardware/firmware, can they be combined to provide better performance?

A: Yes

Convential RTK Systems

Typical Architecture • RTK base station: stationary, dual frequency GPS

receiver generates local corrections

• Terrestrial communications link used to transmit base station corrections to the RTK rover

• RTK rover (navigator): dual frequency GPS receiver receives base station corrections and resolves carrier phase, integer ambiguities for satellites in view.

Convential RTK SystemsPerformance and Limitations

• Performance– Centimeter level accuracy (1cm + 1ppm)

– Effectively zero position drift rate

– Initialization time: a few seconds to a few minutes

• Limitations– Requires local base station and communication link to

receive RTK correction data.

– Operational area limited by range to base station• Range of communication link

• Range limit for ambiguity resolution

Exploiting RTK and WADGPS Synergies

• Initializing the WADGPS solution with RTK

• Coasting’ through RTK outages using Carrier Phase RTG measurements

• Re-initializing RTK using the WADGPS solution

RTK Base Station withline of sight

communications link

The Problem

Questions?

Refer to:

http://www.cctechnol.com/cnav

for additional material and information