is there any way to lower my HDOP


I have an APM25 with the ulblox gps, my HDOP numbers seem high. for example I have 9 sat's locked right now and my hdop is 1.7.

the lowest I have seen it is 1.4 with 10 sat's. I had read where peoples are around .9.

any idea's?



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  • Actually with UBlox it's PDOP we see in MissionPlanner and logs etc. Not sure why it is called hdop because it is not. See this issue:



  • http://

    Per this entry regarding DOP : 1-2 is very good, 2-5 is good. Yes, 1 is Ideal but, for our purpose ??? I'll be comfortable is 2-3 will bring the vehicle back to pretty close to where we started.

  • Hi,

    Yes, I have been trying to have a better diet but but was just kicked out of junk food anonymous :)

    Thanks for the DOP link, I wasnt exactly sure what hdop was except for a measure of accuracy (horizontally) but I knew the lower number the better.

    I am not sure what the CRS value is, and havent really looked too much at the logs yet... Wow, I have so much to learn/read, I actually just found the Appendix area in the wiki for arducopter and arduplane and all the info in there...  It is overwhelming what these guys (you guys) have accomplished  I wish I would have learned of the arducopter's existence a long time ago.. for now I am playing catch up...

    as far as the u-center showing lower hdop, there must be some other factors in calculating the hdop  or maybe electrical noise from the components on the copter???



  • I have the ublox GPS module outside my window, wires routed through the rubber seal and mission planner reports a hdop of 2.4. If I plug it out of the APM and plug it in a FTDI cable and run u-center, it reports 0.9-1.2.

  • I had a funny response regarding high fiber food, exercise, and low carbohydrate intake but...

    There have been several observations regarding the accuracy of the GPS but in general, the UBlox seems better in general.

    DOP - Dilution of Precision for those new to the concept.

    I looked over some of my logs and with the AC rev I am running, I only have a CRS value in the GPS line.

    What is yours?


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