Measurement Journal Issue 6

Several types of augmentation systems have been created to improve the accuracy and reliability of the GPS receiver (Table 1). These systems provide additional information beyond what is available from the individual GPS satellites. Some systems use additional satellites to transmit external information to the GPS receivers, others use ground-based reference stations, and still others integrate navigation systems to calculate location ﬁxes. Table 1. GNSS augmentation systems Identifying the test requirements Even as GPS technology becomes more common, GPS receiver manufacturers, OEM integrators and contract manufacturers struggle for standard tests to verify receiver performance. Veriﬁcation is required both to validate GPS receiver functionality and to objectively evaluate competing GPS IC performance. Veriﬁcation procedures require a controlled environment that facilitates Augmentation system Satellite-based augmentation system (SBAS) Differential GPS Inertial navigation systems Assisted GPS System features • Provides correction data (clock errors, atmospheric attenuation) for increased accuracy • Many regional systems currently are active • Wide Area Augmentation System (WAAS) USA • European Geostationary Navigation Overlay Service (EGNOS) • Quasi-Zenith Satellite System (QZSS) Japan • Multi-functional Satellite Augmentation System (MSAS) Japan • Commercial systems, StarFire, OmniSTAR • Fixed ground-based reference stations • Broadcast differences between measured and computed pseudoranges • Uses computer, accelerometers, gyroscopes, and other motion-sensing devices • Typically used in automotive and missile guidance systems • A-GPS leverages existing base stations of telecom systems • Incorporates “Assistance Server” to enhance performance such as time to ﬁrst ﬁx (TTFF) and signal sensitivity • Assistance Server provides: • General location information based on cellular network • Location information by comparing fragmentary cell phone GPS signals and its own satellite signal • Orbital data for the GPS satellites enabling the handset to lock quickly (TTFF) • Known ionospheric conditions Agilent Measurement Journal 18

Table of Contents Feed for the Digital Edition of Measurement Journal Issue 6

Measurement Journal Issue 6 Using a Few Words to Convey a Deeply-Held Spirit Charting a Unique Path to Technology Innovation Contents Announcing First Commercial GC/MS Metabolites Library Assessing Nonlinear Behavior Testing Combines Form and Function Testing Multiplay Networks Higher Sensitivity LC/MS Easing Military Radio Test Stepping Up Calibration Accuracy Increasing Spectrum Analyzer Bandwidth 3GPP Tool Supports TS 36 Standards The Olympic Story Spotlights Agilent's Continuing Contribution to Technology Innovation Ensuring a Level Playing Field in Competitive Sports GPS: Coming of Age Resolving Design Issues in HSPA Mobile Devices Achieving Accurate Results with Oscilloscope-Based Jitter-Analysis Software RF Handheld Testers Guarantee Traffic Stability Under Olympic-Sized Stress Conditions Utilizing LAN-Based Instrumentation to Measure Total Harmonic Distortion in Remote Facilities IMT-Advanced: 4G Wireless Takes Shape in an Olympic Year EPO Doping: A Speed Engine, Turbo-Charged by Chemistry

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