{"id":653,"date":"2013-08-02T21:59:36","date_gmt":"2013-08-03T01:59:36","guid":{"rendered":"http:\/\/fll-freak.com\/blog\/?p=653"},"modified":"2025-04-21T00:54:36","modified_gmt":"2025-04-21T04:54:36","slug":"all-is-not-lost-with-gps","status":"publish","type":"post","link":"https:\/\/fll-freak.com\/blog\/?p=653","title":{"rendered":"All is not lost with GPS"},"content":{"rendered":"<p>So after looking at the GPS data I collected, I figured I would try another data collection in 2D mode with the know altitude set. That would allow me to use one more satellite for horizontal position. I collected 12 hours of data and if was even worst than the 3D solution. So I got to thinking.<!--more-->What I was seeing (+- 4 meter errors) just did not make sense. GPS is good for much better than that by spec. True, if you have a bad constellation, your error can go out the window. But that was not my case. And then it hit me. The data I was collection was using an indoor GPS broadcaster. We have a GPS antenna on the roof and a radiator inside (FAA approved) that allows us to test GPS equipment indoors. Perhaps that was introducing errors?<\/p>\n<p>Sure enough it was. I took the GPS out to an open parking lot and collected 30 minutes of data and had error mostly inside a 1 meter radius. Here is the new wander plot:<\/p>\n<p><a href=\"http:\/\/fll-freak.com\/blog\/wp-content\/uploads\/2013\/08\/Wander.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-654\" alt=\"Wander\" src=\"http:\/\/fll-freak.com\/blog\/wp-content\/uploads\/2013\/08\/Wander-300x243.png\" width=\"300\" height=\"243\" srcset=\"https:\/\/fll-freak.com\/blog\/wp-content\/uploads\/2013\/08\/Wander-300x243.png 300w, https:\/\/fll-freak.com\/blog\/wp-content\/uploads\/2013\/08\/Wander.png 564w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>Much better. That rather large star shaped error was very early on in the data collect before the GPS had gotten all the almanac and ephemeris data.<\/p>\n<p>Now I can breath a sign of relief, and I can warn the other lab users not to trust the results from the broadcaster for accurate results.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>So after looking at the GPS data I collected, I figured I would try another data collection in 2D mode with the know altitude set. That would allow me to use one more satellite for horizontal position. I collected 12 &hellip; <a href=\"https:\/\/fll-freak.com\/blog\/?p=653\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24,7],"tags":[],"class_list":["post-653","post","type-post","status-publish","format-standard","hentry","category-avc","category-projects"],"_links":{"self":[{"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/653","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=653"}],"version-history":[{"count":2,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/653\/revisions"}],"predecessor-version":[{"id":999,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/653\/revisions\/999"}],"wp:attachment":[{"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=653"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=653"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fll-freak.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=653"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}