Asset Tracker V2 precision?

Hardware
1

Can anyone tell me how precise your readings are?
I currently have mine sitting in the garden on my terrace, using a small external antenna (according to its specs its an active one), covered by some abs plastic.

I am using @Lynd 's library that uses the ublox protocol, and when reading out the horizontal accuracy (which is supposed to be in mm if the comments are correct) I get something along the lines of 28146, which, converted, gives me 2814.6 cm or 28.146 meters. Is that what I can expect for an Asset Tracker sitting at about 5 meters from the backside of my house, having open view to the sky up and around (except for the house behind it of course).

It’s been standing there for at least 10 minutes now.

Another example:

{
"latitude":***
"longitude":***
"speed":0.261
"accuracy":34553
"sats":12
"fixQuality":3
}
2

The US Government claims maximum accuracy of ~5m. EDIT: reading more closely, this is not a theoretical limit... more about probability of accuracy for a majority of users.

For example, GPS-enabled smartphones are typically accurate to within a 4.9 m (16 ft.) radius under open sky (VIEW SOURCE AT ION.ORG). However, their accuracy worsens near buildings, bridges, and trees.

Taken from: GPS.gov: GPS Accuracy

There is some good information in that link about boosting accuracy using 2-frequencies and other augmentation systems.

3

Just asking, because they claim 2.5m in the docs, and if you check the JSON I posted you can see the system has 12 sats locked in (currently even 14) and is static.
I don’t care about 1m precision, but 10 would already be a serious improvement.

4

What is your precision between measurements with the Asset Tracker being static over several minutes?

I'm not familiar with the Library you are using.
My testing w/ the Asset Tracker V2 using the AssetTrackerRK Library was very positive.

The M8 w/ WAAS performs much better that what you are describing.
With decent satellite geometry: Accuracy should be well inside of 2 meters, with precision of 1-2 feet.

5

I have found that if I look up the lat and long i am given and dismiss the accuracy. I’m just about right on… I have also found that keep.Alive(150); helps for my 3rd party carrier

6

As long as the asset tracker doesn't move, the precision stays around the posted value.

The M8 w/ WAAS performs much better that what you are describing.

What's that?

7

The U-Blox M8 is the GNSS chip that’s in the Asset Tracker V2.
WAAS stands for Wide Area Augmentation System. Its a differential correction technology that is used by the GNSS receiver in North America.

1 Like
8

Ah right :slight_smile:
Is there anything special that needs to be done to use WAAS or is it something internal to the hardware?

9

You have to enable it. Take a look at the documentation for the U-Blox 8

10

Also, make sure you use the AssetTrackerRK library, not the official AssetTracker library. I discovered that some of the weird results are because the official library uses the Adafruit GPS parser, which uses float (4 byte) values. In the conversion to degrees, there’s a loss of precision. The TinyGPS++ parser (used by AssetTrackerRK) uses doubles (8 byte).

You can see this when graphing the location while driving slowly. The TinyGPS++ path (orange) looks pretty accurate, as it uses double floating point. You can see the rounding errors in the Adafruit (blue) path, which is calculated from exactly the same raw GPS data!

gps
gps1273×802 42.9 KB

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