[anthropo]

Hello,

i've asked this question on french sub forum but no response at the moment.

I have built a QAV210 with a revolution board and a mini ap gps.

Too much times i had to cancel the sessions because the gps didn't catch more than 6 satellites.  After many searches i came to think that the mini ap gps i bought was only seeing american satellites (ublox serie 7 ?) and in France that is not the top. Sometimes it sees 7 sometimes not. it's lotterie.

I had a spare bigger Neo M8N in stock, i installed it and re-calibrated magnetometer. Immediatly i had nearly 10 satellites. BUT when i switch to position Hold, i swings at times. Most of all, it jumps in the air more than 10 meters and i'm obliged to stop Position Hold. I thought to barometer, then i covered it with a foam. Same problem.

What do you think ? Is there a reason that i missed ? Is it the GPS ? Then do you have a good and cheap GPS to recommend ?

If i buy a DJI naza gps i am affraid that it can be the same with catching only american satellites.

Thanks for your help.

[TheOtherCliff]

Everything you say about American satellites is correct.  Neo6 uses only USA.  M8N uses Russian and Chinese sats too.

Also authentic DJI Naza GPS uses Neo6 inside so it only sees USA sats.  DJI Naza GPS clones usually use M8N so more sats.

I have several Neo6 GPSs that I use easily here in the USA.

I have heard that the tiny square GPSs do not receive very well so low sat count when using them?

[Mateusz]

Ublox modules are usually tuned to specific antennas and antennas are required to have enough clearance around (says how much in Ublox specification).
Many GPSs units using Ublox modules simply ignore that recommendation, which results in poorer than it should be reception.
Tiny antennas like Clif mentioned, are the worst.

Drotex GPS modules for example use bigger antennas and more clearance around https://drotek.com/shop/en/home/613-ublox-neo-m8n-gps-hmc5983-compass-xl.html
Though I don't know how that big shielding around GPS module affects the magnetometer, if it's not saturating it. I haven't actually tried any drotek GPS units, but they LOOK decent, though expensive.

Just check if GPS has also magnetometer.

[anthropo]

thank you. Now i understand