Lecture GPS2 - Lecture GPS#2 Text Coverage Lecture Notes...

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Lecture GPS #2 Lecture Notes Text Coverage: Wolf and Ghilani: Study: Ch 13: 6 – 11. Problems: 13:11-20 A. GPS Hardware 1. GPS is revolutionizing many aspects of society. Automobile navigation systems are becoming commonplace. For example Rand McNally, the mapping company, markets a GPS auto navigation system for less than $100. Visit their website to review their street finder GPS solution for a laptop: Rand McNally - Welcome! 2. Low cost hand-held receivers are available from Magellan, DeLorme, Garmin, and Lowrance are available. For example, visit: GPS Receivers, Garmin GPS, Lowrance GPS, Magellan GPS and DeLorme GPS . These receivers are “CODE PHASE”, whereby the ranges are measured as a integer number of whole 300m code blocks plus a measured fractional one. Since the wavelength is large (300 m), the uncertainty in the measured fractional phase shift is also large; therefore 3 – 10 meters accuracy is the best to be expected. Code- phase receivers can be used alone for navigational solutions. If two are used in differential GPS, the accuracy can be improved by a factor of 10. 3. The basic L1 “carrier wave” of the GPS signal has frequency 1575.42 MHz. Dividing this into the speed of light gives the CARRIER WAVELENGTH of about 0.19 meters, 19 centimeters. Geodetic-grade receivers have more accurate clocks so that the integer count of the carrier wave’s 19 cm wavelength can be determined. Such a “CARRIER PHASE” receiver measures the fractional wavelength of the 19 cm carrier wavelength and therefore is much more accurate than a code-phase receiver. Typical accuracies approach 1 to 2 cm in X and Y coordinates plus 2 to 5 cm in Z. A second “carrier wave” is broadcast by the GPS satellite, the L2 signal, having a frequency of 1227.60 MHz. This second signal is not modulated into message packets of 300 m like L1, and therefore it can only be
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This note was uploaded on 05/19/2011 for the course GEM 3330 taught by Professor Gibson during the Spring '11 term at University of Florida.

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Lecture GPS2 - Lecture GPS#2 Text Coverage Lecture Notes...

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