chetuk
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Will gps with raspberry work inside home?

Tue Sep 25, 2018 5:28 pm

Hi Experts,

Will gps with raspberry work inside home?
Which would you prefer cheap and good for a gps locating robot?
Like to send to X coordinates and stop and return to initial coordinate Y
Will have accuracy?


/Chetuk

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DougieLawson
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Re: Will gps with raspberry work inside home?

Tue Sep 25, 2018 5:49 pm

You need line of sight with the sky. It may work on a window sill, but beyond that it won't without an external antenna.
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bensimmo
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Re: Will gps with raspberry work inside home?

Tue Sep 25, 2018 7:27 pm

The Ublox M8030 (Ublox Neo8k) based work quite far into my kwork and house where the old neo6would not. They can pick up all the newer 'gps' arrays too.

But like all these GPS*, it'll not be good indoors and unless you are sending something 100m+ and want it to return to withing 5m ish of where it came from GPS is not what you want. You'll need something else as well.

When I ride my bike (and my phone etc) or datalog with a pi for similar.
I can be on the path, in the road or going through the houses and.
Depending on how it feels that day.

* There are newer versions, suppose to have far improved results, but I've not seen any cheaply on the market for Pi style usage.
(Nor expensive versions either).
And that's not indoors either.

wolf.z
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Re: Will gps with raspberry work inside home?

Tue Sep 25, 2018 7:44 pm

chetuk wrote:
Tue Sep 25, 2018 5:28 pm
Will gps with raspberry work inside home?
Raspberry: yes. GPS: no.
chetuk wrote:
Tue Sep 25, 2018 5:28 pm
Which would you prefer cheap and good for a gps locating robot?
none, not even a very expensive one.
chetuk wrote:
Tue Sep 25, 2018 5:28 pm
Like to send to X coordinates and stop and return to initial coordinate Y
Will have accuracy?
There has happened much effort on how to track movement of a robot indoor for decades. Try purely mechanical tracking or, motion capture with a multi-camera setup or some kind of inertia system if you require accuracy better than 100 meters indoor. Just a rough guess, may be more uncertainty.

drgeoff
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Re: Will gps with raspberry work inside home?

Tue Sep 25, 2018 11:49 pm

DougieLawson wrote:
Tue Sep 25, 2018 5:49 pm
You need line of sight with the sky. It may work on a window sill, but beyond that it won't without an external antenna.
You do not need line of sight with the satellites. The signals pass through many types of roofing and flooring materials but they do get attenuated in the process. Depending on the actual attenuation and the sensitivity of the specific GPS receiver it may or may not work. My old Garmin Geko 201 struggles if not near a window in my bungalow whereas my newer GPS-equipped phones and tablet do work just about anywhere inside here.

However accuracy/repeatability of a consumer grade GPS receiver is typically a few meters at best (even outside receiving strong signals) which may not be good enough for the intended application.

stevend
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Re: Will gps with raspberry work inside home?

Wed Sep 26, 2018 7:16 pm

It also depends on the weather.
I have a cheap USB-connected 'disc' GPS connected to a Pi. During the extended period of high pressure a couple of months ago, bringing hot dry weather, the GPS would pick up in the middle of a 2-storey house. Weather got wet - and it would only work outside. Damp air attenuates radio signals more than dry air.

IanS
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Re: Will gps with raspberry work inside home?

Mon Oct 01, 2018 11:31 am

Unless your idea of accuracy means 'probably within sight', cheap GPS is not good enough. I have a single non-moving receiver (by a east facing window, which is not ideal) which I only really need the time signal from, but I did track the position over an hour or so, plotting it every few seconds. It wandered around within about a +/-50 meter area.
You might be able to do something using two identical receivers, one of which is stationary, and look at the relative positions of the two. This is pretty much how DGPS (Differential GPS) works, and can give very high accuracy.

You still need to get the signal through the roof though.

ElEscalador
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Re: Will gps with raspberry work inside home?

Mon Oct 01, 2018 12:45 pm

You will not get adequately accurate results with gps for an indoor robot. Sorry. Localization (the robot knowing where it is) is one of the biggest challenges in robotics. I am struggling to get results accurate and repeatable enough for indoor use. Although, I think I'd be much further along if I weren't stubborn and would use ROS instead of writing all my own code. So actual GPS - no, but I did stumble on this system on Amazon that uses ultrasound and it calls itself an indoor GPS. You put beacons around then a receiver calculates location. I have no experience or even heard testimonies about how well it works. I am curious but am also determined to make my robot navigate without having to prepare it's environment so I'll probably never buy one. https://www.amazon.com/Marvelmind-Preci ... indoor+gps. If it works as well as it says, this plus a compass/gyroscope to keep track of heading should be pretty great.
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klricks
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Re: Will gps with raspberry work inside home?

Mon Oct 01, 2018 1:09 pm

A GPS repeater can greatly improve GPS accuracy indoors.
A quick Google found this: https://www.gps-repeaters.com/
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wolf.z
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Re: Will gps with raspberry work inside home?

Mon Oct 01, 2018 8:36 pm

klricks wrote:
Mon Oct 01, 2018 1:09 pm
A GPS repeater can greatly improve GPS accuracy indoors.
A quick Google found this: https://www.gps-repeaters.com/
Nope. A repeater can greatly improve reception. Any increase in accuracy? Only holds true for position of the receiveing end's antenna of the repeater: All GNSS devices indoor/receiving repeated signals will show the accurate position of mentioned particular repeater receiving antenna.

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