[Firebug-cvs] firebug/web gps_tests.htm,1.5,1.6
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[Firebug-cvs] firebug/web gps_tests.htm,1.5,1.6
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From: David M. D. <do...@us...> - 2004-07-15 16:11:46
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Update of /cvsroot/firebug/firebug/web In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv32191 Modified Files: gps_tests.htm Log Message: Changed order of presentation of results Index: gps_tests.htm =================================================================== RCS file: /cvsroot/firebug/firebug/web/gps_tests.htm,v retrieving revision 1.5 retrieving revision 1.6 diff -C2 -d -r1.5 -r1.6 *** gps_tests.htm 15 Jul 2004 00:32:16 -0000 1.5 --- gps_tests.htm 15 Jul 2004 16:11:38 -0000 1.6 *************** *** 13,16 **** --- 13,84 ---- <body> + <h1> + GPS Receiver Accuracy + </h1> + + <p> + The accuracy of the LeadTek GPS receiver as advertised as + ± 5 meters. An investigation to assess this claim was + conducted in El Cerrito, California on April 11, 2004. + As can be seen by the figures below, the receiver ranges from + being very accurate to very inaccurate. + </p> + + <img src="./images/latitude.png" alt="latitude" /> + <img src="./images/longitude.png" alt="longitude" /> + + <p> + The preceding figures were produced using all of the + data emitted from the GPS receiver. Statistics + indicate that the mean and variance of the position + is correlated with the number of satellites used to + obtain the position fix. As the following table shows, + 5 satellites is the realistically minimum number + necessary to produce a fix within 5-10 meters of the + actual location. + </p> + + <img src="./images/orbits.png" alt="Position orbits" /> + <img src="./images/numsats.png" alt="Number of satellites" /> + + + <h1> + GPS Receiver Acquisition Time + </h1> + + <p> + All GPS units require a certain amount of time to acquire 4 + satellites, the minimum number needed for fixing a position + (3 for space, 1 for time). Most GPS receivers implement tracking + in a reduced power mode that enables fixes to be computed + very rapidly when switched to a fully alert state. For the + LeadTek 9546, test was performed to investigate the acquisition + times necessary for a sequence of cold starts. + </p> + + <p> + The tests were performed April 11, 2004 in El Cerrito + California. A simple test code exercising only the + GPS sensor was loaded onto Crossbow Mica2 mote. The + mote was run for approximately 18 hours, indoors, with + the GPS antenna located outside to enable satellite + acquisition. The antenna had clear view of more than + half the eastern hemisphere of the sky. + </p> + + <p> + As can be seen from the results, acquisition times range + from a few seconds to nearly 10 minutes to acquire 5 + satellites, a practical minimum necessary to achieve the + published accuracy of the device, ± 5 meters. + </p> + + + <img src="./images/acquisition_times.png" alt="Acquisition times for 5 sats" /> + + <img src="./images/acquisition_histogram.png" alt="Acquisition histogram for 5 sats" /> + + + <h1> GPS Receiver Performance Tests *************** *** 144,213 **** - <h1> - GPS Receiver Accuracy - </h1> - - <p> - The accuracy of the LeadTek GPS receiver as advertised as - ± 5 meters. An investigation to assess this claim was - conducted in El Cerrito, California on April 11, 2004. - As can be seen by the figures below, the receiver ranges from - being very accurate to very inaccurate. - </p> - - <img src="./images/latitude.png" alt="latitude" /> - <img src="./images/longitude.png" alt="longitude" /> - - <p> - The preceding figures were produced using all of the - data emitted from the GPS receiver. Statistics - indicate that the mean and variance of the position - is correlated with the number of satellites used to - obtain the position fix. As the following table shows, - 5 satellites is the realistically minimum number - necessary to produce a fix within 5-10 meters of the - actual location. - </p> - - <img src="./images/orbits.png" alt="Position orbits" /> - <img src="./images/numsats.png" alt="Number of satellites" /> - - - <h1> - GPS Receiver Acquisition Time - </h1> - - <p> - All GPS units require a certain amount of time to acquire 4 - satellites, the minimum number needed for fixing a position - (3 for space, 1 for time). Most GPS receivers implement tracking - in a reduced power mode that enables fixes to be computed - very rapidly when switched to a fully alert state. For the - LeadTek 9546, test was performed to investigate the acquisition - times necessary for a sequence of cold starts. - </p> - - <p> - The tests were performed April 11, 2004 in El Cerrito - California. A simple test code exercising only the - GPS sensor was loaded onto Crossbow Mica2 mote. The - mote was run for approximately 18 hours, indoors, with - the GPS antenna located outside to enable satellite - acquisition. The antenna had clear view of more than - half the eastern hemisphere of the sky. - </p> - - <p> - As can be seen from the results, acquisition times range - from a few seconds to nearly 10 minutes to acquire 5 - satellites, a practical minimum necessary to achieve the - published accuracy of the device, ± 5 meters. - </p> - - <img src="./images/acquisition_times.png" alt="Acquisition times for 5 sats" /> - - <img src="./images/acquisition_histogram.png" alt="Acquisition histogram for 5 sats" /> <hr> --- 212,218 ---- + <!-- Last lines, leave in place. --> <hr> |
