# Ecl EKF2 estimation help

**URL:** <https://discuss.px4.io/t/ecl-ekf2-estimation-help/10454>\
**Category:** Uncategorized\
**Created:** [April 12, 2019, 11:47am UTC](https://discuss.px4.io/t/ecl-ekf2-estimation-help/10454 "2019-04-12T11:47:05Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![S\_Vinha](https://discuss.px4.io/letter_avatar_proxy/v4/letter/s/eb8c5e/32.png) [@S\_Vinha](https://discuss.px4.io/u/S_Vinha)\
**Post date:** [April 12, 2019, 11:47am UTC](https://discuss.px4.io/t/ecl-ekf2-estimation-help/10454/1 "2019-04-12T11:47:05Z")

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Hello,  
I’m currently integrating GPS NMEA protocol by indoor beacons with 4cm accuracy (marvelmind).  
I’ve mounted everything and px4 gets the nmea setences that gives 3D position.  
Innitially I was geting some 2D position drift in hold mode and wrong altitude, but changing some parameters I fixed the position but the altitude is wrong.  
When I check the log of my flights, the variable gps\_global\_position-\> alt is really different from vehicle\_gps\_position-\> alt, while the vehicle\_gps\_position has the actual correct values ​​from altitude, given by the GPS.

I’m thinking that this could be a problem related with estimator, since the accurary of conventual GPS isn’t that low, and with that, I need to change some of EKF2 parameters.

Is there someone that can help me with this?  
Thanks!