How reliable is GPS speed on a Windows 7 phone

Question

I am developing an application for Windows Phone 7, and I want to tell the user how fast they go. Something as simple as ...

Current speed: 20 km / h Maximum speed: 33 km / h Average speed: 25 km / h

I think I have two options: 1) use an accelerometer 2) use GPS

I am wondering if people have any suggestions for using the method.

I would prefer to use GPS (as it is much easier to extract), but I know that the GPS position is often inaccurate for various reasons, but how accurate is the speed?

Answer 1

Speed ​​and direction are generally more accurate than absolute position - this is because speed and direction are not calculated by tracking successive position measurements (as you would expect). Rather, these values ​​are usually estimated using the Doppler shift of satellite signals, which for technical reasons is less affected by factors that tend to distort the absolute position.

In contrast, an accelerator will probably not be very useful for measuring speed, since speed and acceleration are two different things.

Answer 2

GPS will be very accurate. Accurate data comes from satellites, and it is used for many GPS applications. To get good data, you need to receive from three of them. Users can have only one or two satellites. If you have only one satellite, the only thing you can get is time.

Limitations in accuracy may depend on the receiver, so it may vary depending on the actual hardware on the phone, and not on the Windows 7 operating system.

I can’t talk with the code that Microsoft wrote that interprets the data, but I’m sure that they did just like any other software company. I have not heard of any flaws in this area specific to MS.