# How to display GPS satellite trajectory with GPS precise orbit file **URL:** \ **Category:** CesiumJS\ **Created:** [December 30, 2021, 2:59pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709 "2021-12-30T14:59:02Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![xuch](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/xuch/32/3476_2.png) [@xuch](https://community.cesium.com/u/xuch)\ **Post date:** [December 30, 2021, 2:59pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/1 "2021-12-30T14:59:02Z")
Hello! I have displayed GPS satellite trajectory successfully with the GPS two-line parameters from [www.celestrak.com](http://www.celestrak.com). However, the precision of GPS satellite orbits is low because the orbits are predicted. When I am trying to display GPS satellite trajectory with GPS precise orbit in ECEF from precise ephemeris (sp3 file), they are not working in a circle. The reference frame in CZML file are set with FIXED, which means in a ECEF frame. I have tried both the cartesian’s and cartographicDegrees’s position.Anybody know where is the problem? Thank you! ![20211230225057](https://global.discourse-cdn.com/cesium/original/2X/5/52a93004142afa4c110d8bb121e85a991496984e.png) ---
**Author:** ![sergemorvan29](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/sergemorvan29/32/2085_2.png) [@sergemorvan29](https://community.cesium.com/u/sergemorvan29)\ **Post date:** [December 31, 2021, 8:18am UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/2 "2021-12-31T08:18:28Z")
You can perhaps be inspired by the student project for our association Terre Virtuelle: [https://github.com/MohammedAymane/Projet-Terre-Virtuelle](https://github.com/MohammedAymane/Projet-Terre-Virtuelle) ---
**Author:** ![xuch](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/xuch/32/3476_2.png) [@xuch](https://community.cesium.com/u/xuch)\ **Post date:** [December 31, 2021, 12:27pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/3 "2021-12-31T12:27:08Z")
Well done! It works when I use the orbit position from satellitesGNSS.json file in your project. But, I downloaded the igs21864.sp3 file on 2nd december from IGS website, the GPS satellite orbit coordinates is different from the coordinates in satellitesGNSS.json. Could you explain how you process the GPS orbit coordinates? ---
**Author:** ![sergemorvan29](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/sergemorvan29/32/2085_2.png) [@sergemorvan29](https://community.cesium.com/u/sergemorvan29)\ **Post date:** [December 31, 2021, 1:41pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/4 "2021-12-31T13:41:23Z")
Translation from TLE to Czml is a code in Python here : [https://github.com/kujosHeist/tle2czml](https://github.com/kujosHeist/tle2czml) A good explanation for orbital debris is here : [http://daoneil.github.io/spacemission/Apps/20160411\_Visualization\_of\_OrbitalDebris\_with\_Cesium\_and\_Satellitejs\_Tutorial.pdf](http://daoneil.github.io/spacemission/Apps/20160411_Visualization_of_OrbitalDebris_with_Cesium_and_Satellitejs_Tutorial.pdf) Ans others resources : [https://freesoft.dev/program/64413499](https://freesoft.dev/program/64413499) ---
**Author:** ![xuch](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/xuch/32/3476_2.png) [@xuch](https://community.cesium.com/u/xuch)\ **Post date:** [December 31, 2021, 2:00pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/5 "2021-12-31T14:00:45Z")
Thank you! The websites are the satellite orbit with TLE (two-line elements) from [www.celestrak.com](http://www.celestrak.com/). It works well. ---
**Author:** ![sergemorvan29](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/sergemorvan29/32/2085_2.png) [@sergemorvan29](https://community.cesium.com/u/sergemorvan29)\ **Post date:** [December 31, 2021, 4:06pm UTC](https://community.cesium.com/t/how-to-display-gps-satellite-trajectory-with-gps-precise-orbit-file/16709/6 "2021-12-31T16:06:42Z")
You’re welcome 😉