[Ovmsdev] SIM808/SIM908 GPS accuracy

Edward Cheeseman cheesemanedward at gmail.com
Mon Feb 13 09:48:57 HKT 2017

> On 8/02/2017, at 11:45 PM, Edward Cheeseman  wrote:
>> On 8/02/2017, at 7:25 PM, HONDA S-2000 wrote:
>> That's assuming that any rewrite turns out to be an improvement, otherwise the code could stay as it was. Let us know what you find out.
> I’m going to suggest changing that one remaining floating point conversion out with another fixed point integer multiply, and leaving it at that.

My fork has both float operations replaced with integer multiplies. Ran the car around the block and positions were definitely good enough for what road I was on, usually within the lane, but sometimes the lane over from where I should be.

The two multiply operations look to be as accurate as the SIM808 +/- 0.000001 or about 0.1m.

I’m reasonably confident in these changes giving accurate results. https://github.com/evbuilder/Open-Vehicle-Monitoring-System/tree/lat-long-precision-fix


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