Consistent RXM-SG GPS MODULE signal

garyg

Hi
I've build a few Parallax product projects over the past year or so.
I've been thinking about controlling a robotic platform using the Parallax RXM-SG GPS module.
After reading the information about this controller, I'm wondering about how consistent the GPS
location will be.
It seems like there is an error rate about 30 meters.
The error rate does not concern me if it is consistent.
I would like to control my robotic platform to the confines of my property.
I'm looking for information concerning how accurately I can position my platform within as few inches of resolution posible
but with consistent result.
Has anyone used one of these Parallax RXM-SG GPS modules to control a platform in a relatively confined area,
say about 120x250 ft.
How good is the repeatability of this GPS module.

Thanks for any suggestions or opinions.

garyg

Franklin

I think most consumer GPS units will state 5 meters. That means the reading can float within a 5 meter circle even if the unit is not moving. I have seen better results with mine but not consistently.

garyg

Thanks Franklin
I'm thinking that +- 2.5 meters is a bit more than what will work for me.
I'll be giving this more thought.
In the meanwhile, I'll be setting up my platform to be controlled by my RC radio transmitter.

gg

max72

It has been discussed in the past, and there also is an experiment on using two units to compensate the reading (poor man's DGPS), but with negative results.
With any affordable GPS units inches are out of range. Probably you could get there in ideal conditions, and not necessarily consistently with a couple of DGPS units (range is above 10k$).
Massimo

DocThomas

I know the goverment use to control how close we could get. And they keep it so things could not get to close only the milatery ect. had the good settings. I think they droped it down some so we can get closer but I think it is not as good as they get. I dont think they allow all the digets sent out to be used by just anybody.