I am wondering if there is a proprietary binary code output from the compatible Arduino GPS chips, or if an NMEA output is fine?  This is because I want this magical GPS unit onboard: http://www.sxbluegps.com/sxblue-gps.html

Has anybody got a good felling about this sub meter accuracy gps.... it's pricey...  Is it a waste?

I figure it could help with keeping a stable waypoint fix.


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I found out that Mikrokopter has locked out anything but their 3-5 meter accuracy MKGPS chip... that killed it for me. I just jumped ship. :) I'm glad I haven't spent any money yet :)

The GPS fix is a big one for me....
We have a NMEA parser but it doesn't work very well. It's all open source, however, so if you can improve the code everyone would thank you!
I think you should send me a sample of the current output log, using Windows Hyper-terminal. It would be a start. I think that reading a standard NMEA output (>1Hz) is a good idea here, if it isn't already the case. I should look at the log, and compare it to the SXBlue output... if they are strung differently, that is an easy fix.


If you read the notes at the end of all the marketing blurb - and it becomes clear that the sub-meter accuracy referred to is subject to certain conditions - as it is with most modern day GPS modules with half decent firmware and onboard filter config i.e. it is capable of sub-meter accuracy, not that you will get sub-meter. accuracy. GPS accuracy can only ever be as accurate as the L/L2 downlink timings are - and they are subject to all the usual multi-path problems that stem from the condition of the atmosphere they have to travel through

1. SVs > 5, HDOP < 2, short baseline from reference station, and low multipath environment.
2. Dependant upon ionospheric activity and multipath

Add RTK and now you can achieve sub-1" accuracy and sub-2" repeatibility! (95% of the time - the rest of the time it will drift a couple inch either way) - ask any John Deere tractor driver who has StarFire/RTK GPS system on his tractor.
Thanks for that Peter.

So, no go on better accuracy? Is this unit a waste of cash for Arducopter considering the price difference between it ($1650)

Can the on-board GPS in say the Arducopter be used as rover with say a vehicle antenna as a base to improve accuracy?

I understand atmospheric conditions, and respective satellite reception... I'm looking for a way to help the GPS fix on a platform.

Gerard, also what are you trying to achieve with this sub meter accuracy? General accuracy also varies a lot on different areas. If you plan to have position hold for quad less than 1 meter on X/Y plane.. Hmm i'm afraid that it's more or less impossible to have it in real life especially if there are wind. Hold on 3-5 meters is more like possible to achieve. Yes if wind conditions and everything are perfect it is possible to hold quad almost still but only in optimal conditions.

I personally don't see any real reasons to get that expensive GPS. If you want to have higher update rate than what MTEK provides, I've just tested new uBlox LEAH 6 chips and we got really good update rates and accuracy with that. Downside is that those new GPSes are not our yet so it will take awhile untill we have them.

It you let us know a bit more about your application, maybe we can point towards right direction.
I need to output to an ascii file to be used for stereosopic viewing. You are right... I am in R&D so I got a bit excited late last night about seeing the "sub-meter accuracy" SXBlue system. The more I have read into it the more I realize that it is:
1) expensive
2) not going to work
3) overkill even if it could work in theory

I guess the reall questions to ask are:

a) How much onboard gps hold accuracy is needed to capture a single stereo pair and georeference it?
"perhaps it is better to be looking for stability and holding the cameras to a north up azimuth for stereo pair"
b) Can the current unit output x,y,z,roll,pitch,yaw,time to an ascii file and save it to an onboard SD card?
"This would be ideal as it would eliminate post-processing for me :)"

it gets time from gps
roll, pitch and yaw does it have
altitude from gps and baro
-> yes you could make it do that for you ;)
I think I'll have to watch out for this if I'm using gimbals and camera mounts eh? Is there a way to use the pitch roll and yaw from the camera mount instead, and the x, y, time from the gps... and the z from say a barometric reading:)

All to one file on an SD, or transmitted to a base station maybe would be better?


you can log every info the copter has to eeprom, to SD card or send it direktly to the ground
Good to know. I' let you know when I get there. Thanks for saving me a bunch of time on all of this.


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