{"id":440,"date":"2019-04-08T01:21:17","date_gmt":"2019-04-08T01:21:17","guid":{"rendered":"https:\/\/geekblog.febo.com\/?p=440"},"modified":"2019-05-08T19:42:22","modified_gmt":"2019-05-08T19:42:22","slug":"gps-frequency-stability","status":"publish","type":"post","link":"https:\/\/blog.febo.com\/?p=440","title":{"rendered":"GPS Frequency Stability"},"content":{"rendered":"

I couldn’t find a nice graph showing the timing performance of a single-frequency, sawtooth-corrected, pulse-per-second output from a GPS. So I measured a CNS-II GPS Clock and a surplus telecom HP Z3805A GPS Disciplined Oscillator (GPSDO) against a high-performance Cesium standard for 30 days. Here are a whole bunch of pretty pictures of the results for my (or your) future reference.<\/p>\n

First, here are Allan Deviation, Time Deviation, phase difference, and frequency difference plots of the 30-day period (Note that the ADEV of the Z3805 at tau less than a few hundred seconds is limited by the noise floor of the TICC timestamping counter).<\/p>\n

\"z3805a_cns2-hp5071a_hp-30day-adev\"<\/a><\/p>\n

\"z3805a_cns2-hp5071a_hp-30day-tdev\"<\/a><\/p>\n

\"z3805a_cns2-hp5071a_hp-30day-phase\"<\/a><\/p>\n

\"z3805a_cns2-hp5071a_hp-30day-freq\"<\/a><\/p>\n

Here is a phase difference plot with 1000 second averaging; this gets rid of a lot of the fuzz and makes it easier to see trends.<\/p>\n

\"z3805a_cns2-hp5071a_hp-30day-phase-1000second_avg\"<\/a><\/p>\n

Here are some zoomed-in plots that show the short-term jitter of the sawtooth-corrected GPS and GPSDO.<\/p>\n

\"ppsz3805a-phase-zoom\"<\/a><\/p>\n

\"pps-phase-zoom\"<\/a><\/p>\n

\"z3805s-10minute-phase\"<\/a><\/p>\n

\"pps-10minute-freq\"<\/a><\/p>\n

\"pps-10minute-phase\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

I couldn’t find a nice graph showing the timing performance of a single-frequency, sawtooth-corrected, pulse-per-second output from a GPS. So I measured a CNS-II GPS Clock and a surplus telecom…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[54,7,2],"tags":[],"class_list":["post-440","post","type-post","status-publish","format-standard","hentry","category-gps","category-test-and-lab-equipment","category-time-and-frequency"],"_links":{"self":[{"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/posts\/440","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.febo.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=440"}],"version-history":[{"count":3,"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/posts\/440\/revisions"}],"predecessor-version":[{"id":455,"href":"https:\/\/blog.febo.com\/index.php?rest_route=\/wp\/v2\/posts\/440\/revisions\/455"}],"wp:attachment":[{"href":"https:\/\/blog.febo.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=440"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.febo.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=440"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.febo.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=440"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}