GPS Press Releases

01/18/2011 - Spirent Federal Makes SVN 49 Anomaly Scenarios Available to Public

Spirent simulator users can assess impact of anomaly on receiver equipment

YORBA LINDA, California - (January 18, 2011) - Spirent Federal announced today that Space Vehicle Number (SVN) 49 anomaly scenario files are available for download on the Spirent Federal website at The free scenario files allow Spirent simulator users to assess the impact of the SVN 49 anomaly on receiver equipment.

SVN 49 was launched on 24 March 2009 as a standard replenishment satellite with L1 and L2 signals and a L5 demonstration payload. Observations of the L1 and L2 signals exhibited larger pseudorange errors than expected which grow with elevation angle with respect to the receiver antenna.

To date, SVN 49 has its health status set to unhealthy; however, at some time in the future, the status may be changed to healthy. Since there is no straightforward way to correct the anomalous L1 and L2 behavior, assessment of the impact on receiver equipment is desirable ahead of the status adjustment.

To this end, Spirent Federal has produced the test scenarios to allow generation of the anomalous L1/L2 signals with a healthy status. Extensive simulation testing has resulted in receiver performance which accurately reflects the expected live-sky performance.

SVN 49 anomaly simulation will be discussed in detail at Spirent Federal's 2011 GPS Simulation Training Conference, 15-17 March in Anaheim, California. Register at by 28 January and receive the advance-registration price of only $250. View full agenda at

For more information, visit Spirent Federal at the ION-International Technical Meeting, 24-26 January 2011 in San Diego, where the paper, "Methodology for Modeling the SVN 49 Anomaly for Static Scenarios," will be presented in the GNSS Modernization session.

About Spirent Federal Systems
Spirent Federal Systems was formed in July 2001 by Spirent Communications as a wholly owned subsidiary and United States proxy company. Spirent Federal markets and sells products in North and South America with value-added features and ongoing customer support. Spirent Federal Systems is headquartered in Yorba Linda, California, with support and sales offices throughout the US.

About Spirent's Positioning Technology Division
Spirent is the first choice of major manufacturers, integrators, test facilities and space agencies worldwide for GNSS testing and simulation solutions. Today, Spirent simulation systems are used throughout the world through a broad range of clients in more than 30 countries. Spirent delivers navigation and positioning test equipment and services to all sectors of the navigation and positioning community, from government agencies through to high volume commercial markets.

About Spirent Communications plc
Spirent Communications plc. (LSE: SPT), a global leader in test & measurement, inspires innovation within development labs, networks and IT organizations to enable customers to deploy communications networks, services & applications, and devices that enrich life. Our extensive portfolio of solutions test data centers, high speed Ethernet networks and services, 3G/4G wireless networks and devices, network security, and global navigation satellite systems. With solutions used by more than 1,700 customers in 30 countries, the world's largest equipment manufacturers, service providers, enterprise and governments rely daily on Spirent to help ensure their success. Based in Sunnyvale, CA, Spirent Communications has 1,300 employees worldwide.

Spirent Communications plc Ordinary shares are traded on the London Stock Exchange (ticker: SPT). The Company operates a Level 1 American Depositary Receipt ("ADR") program with each ADR representing four Spirent Communications plc Ordinary shares. The ADRs trade in the US over-the-counter ("OTC") market under the symbol SPMYY and the CUSIP number is 84856M209. Spirent Communications' sales to the United States government are made through Spirent Federal Systems Inc (

Spirent, Spirent Communications and the Spirent logo are trademarks or registered trademarks of Spirent Communications plc. All other trademarks or registered trademarks mentioned herein are held by their respective companies. All rights reserved.

This document may contain forward-looking statements which are made in good faith and are based on current expectations or beliefs, as well as assumptions about future events. You can sometimes, but not always, identify these statements by the use of a date in the future or such words as "will", "anticipate", "estimate", "expect", "project", "intend", "plan", "should", "may", "assume" and other similar words. By their nature, forward-looking statements are inherently predictive and speculative and involve risk and uncertainty because they relate to events and depend on circumstances that will occur in the future. You should not place undue reliance on these forward-looking statements, which are not a guarantee of future performance and are subject to factors that could cause our actual results to differ materially from those expressed or implied by these statements. The Company undertakes no obligation to update any forward-looking statements contained in this document, whether as a result of new information, future events or otherwise.

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