What determines coords.accuracy in the geolocation API when not using a position sensor?

Question

I tried the geolocation API with HTML5, and it seems that the results are more accurate than it reports:

• geolocation.coords.latitude shows ~ correct latitude
• geolocation.coords.longitude shows the correct longitude
• geolocation.address.street + geolocation.address.streetNumber even shows the correct address.

However, geolocation.coords.accuracy returns 18000 (meters), although the results are 1000 and times; more accurate.

I do not use any real positioning sensors such as GPS, and am currently testing the API on a desktop browser. I believe that there should be a position sensor on board, the accuracy value will be displayed by the position sensor. But - what determines the accuracy of positioning when positioning sensors are not used? Is this just a good guess by the browser? ("Better to be sure than sorry?")

Is there a spec or draft that I could study?

Answer 1

I think they give you 18,000 when you send only one wifi_tower to thwart abuse. When you give it a list, it returns lower values, for example 90. Thus, just knowing one access point is not enough, you need to know the environment.

The user agent may also be relevant.