Measurement Journal Issue 6

precise repeatability. In most cases, using actual GPS-satellite signals received through an antenna does not provide this type of environment. A real-time GPS signal simulation, generated by a metric-grade RF signal generator, offers an excellent starting point for creating a calibrated and repeatable test environment. As GPS receivers are incorporated into mobile consumer products (e.g., cellular phones) it also becomes important to have a ﬂexible test environment. The source should therefore be ﬂexible enough to generate not only GPS signals, but other wireless standards as well. A series of six tests, described below, is not all-encompassing but can help in the evaluation of GPS receiver performance and provide a validation technique for GPS products in a controlled environment: time to ﬁrst ﬁx, warm start-time to ﬁx, reacquisition time, static-navigation accuracy, radio-frequency interference, and receiver sensitivity. For the purposes of this discussion, the GPS receiver used for these tests is the U-blox AEK-4T evaluation kit with U-center software. The GPS signals were created by the E4438C ESG vector signal generator with Option 409 GPS personality (Figure 3). The E4438C is a high performance, general-purpose RF signal generator capable of providing comprehensive support for today’s wireless signal formats. The GPS personality provides up to eight real-world GPS satellite signals that are based on pre-conﬁgured scenario ﬁles. These signals, including Doppler shifts, are synchronized with the actual satellite orbits so that they are consistent with the navigation message contained in the satellite signals (see the sidebar, Scenario generator and veriﬁcation). Figure 3. The Agilent Technologies E4438C ESG 19 Agilent Measurement Journal

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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