Book excerpt: Today, increasing demands and expectations are being placed on GPS systems. Assisted GPS (A-GPS) has been developed to provide greatly improved capabilities, helping GPS work better and faster in almost any location. Offering a detailed look at all the technical aspects and underpinnings of A-GPS, this unique book places emphasis on practical implementation. The book reviews standard GPS design, helping you understand why GPS requires assistance in the first place. You discover how A-GPS enables the computing of a position from navigation satellites in the absence of precise time - a topic not covered in any other book. Moreover, you learn how to design and analyze a high sensitivity GPS receiver and determine the achievable sensitivity of a GPS receiver. The book provides detailed worksheets that show how to compute, analyze, and improve the processing gain from the signal strength at the antenna to the carrier-to-noise ratio (C/N0) at the front end, to the signal-to-noise ratio (SNR) after the correlators. This cutting-edge volume discusses special forms of assistance data, industry standards for A-GPS, and government mandates for location of mobile phones. You also find coverage of future global navigation satellite systems and how they can be designed specifically for instant-fixes and high sensitivity. The book features numerous tables, worksheets, and graphs that illustrate key topics and provide the equivalent of a technical handbook for engineers who design or use A-GPS.