HDOP and Course of the GPS module (2138 - LS20031)

Support Other Pololu products
1

I have hooked up correctly the GPS module and it i’m able to communicate and set it up correctly. The position, speed and altitude seems ok but the HDOP has very high values, even in open sky with 8 satellites locked. Values up to 30 are quite common but they don’t seem to be accurate ad all, (i don’t have 90 meters of error on my measurements, they appear to be less than half meter). Does HDOP unit are different from the ones specified here? en.wikipedia.org/wiki/Dilution_o … _%28GPS%29

maybe 30 means 3.0 ?

I need to know this because I want to flag the GPS status to show the IMU how much to rely on the GPS to reduce the probability of catastrophic flyaways in my UAV

SYMBOL GPS_STATUS_NONE = 0 SYMBOL GPS_STATUS_NOT_FIXED = 1 SYMBOL GPS_STATUS_FIXED_HP = 2 'low HDOP < 4 and sats => 6, high precision SYMBOL GPS_STATUS_FIXED_LP = 3 'high LDOP > 4 and sats < 6 , low precision SYMBOL GPS_STATUS_ERROR = 4 'error

20150111_170731.jpg2322×4128 1.63 MB


20150111_170709.jpg2322×4128 1.65 MB

2

Hello.

I am sorry you are having trouble getting a good HDOP value. How are you reading the value? If you are using your own code, can you try seeing how it compares to the readings from an application like MiniGPS? You can find a link to that application under the Resources tab of the GPS’s product page.

By the way, I was not able to locate the GPS module in your pictures. Note that if you are using the unit near your other electronics, there could be some noticeable electromagnetic interference, which I think should increase HDOP.

-Jon