Improving GPS location accuracy

Question

Created Jul ’15

Replies 5

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I am getting poor results using core location to get a specific location point. The accuracy is often over 20 meters (~65 feet off) and never seems to be the same twice.

I'm ignoring cached positions (ignore if NSDate().timeIntervalSinceDate(geoLocation.timestamp) > 5) and taking the best horizontal accuracy of 10 readings.

I've tried both desiredAccuracy = kCLLocationAccuracyBest and kCLLocationAccuracyBestForNavigation. Both seem to give about the same fuzzyness.

I've also tried 100 reads from a stationary point and taken the average. Still bad.

Is this the expected accuracy? If so, how can navigation work? I understand that navigation can "snap" to a road segment, but if the resolution is over 20 meters off it would often pick the wrong road.

Any advice would be *hugely* appreciated.

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Answer 1

KMT OP

Jul ’15

>Is this the expected accuracy?

5 meters at best is typical. Remember, you're working with consumer grade devices.

What accuracy do you need?

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Answer 2

27Feathers OP

Jul ’15

I'd be thrilled with 5 meters.

With a margin of error +/- 20 meters, it means that I am doing something wrong?

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Answer 3

KMT OP

Jul ’15

Possible - what is your refresh rate and which device are you testing?

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Answer 4

27Feathers OP

Jul ’15

I do not have an explicit refresh rate. Is there an option to set that?

I have not set distanceFilter since I understand that the defaut is kCLDistanceFilterNone which reports on any movement.

Could it be that in order to get an accurate location, I have to be moving?

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Answer 5

ldwight OP

Mar ’16

Did you ever get an answer to this? I am trying to use locationManager and, with an unmoving phone the distance varies significantly!

I have tried using "requestLocation" to 1st get the most accurate fix, but subsequent location updates can be as much as 80 meters off.

Any help is greatly appreciated.

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