In article , Huge
scribeth thus
On 2012-09-04, tony sayer wrote:
In article , Huge
scribeth thus
On 2012-09-03, Andy Burns wrote:
ARW wrote:

Huge wrote:

On 2012-09-03, ARW wrote:

Anyone know where they get the info from?

Android phones. They report their position to Google, who anonymise
and aggregate the data and use it to measure traffic flows.

So that is why some roads in the village are showing traffic details on
some
days why they are not showing on other days? No phone users on the road.

Bear in mind that unless the phone user has the phone in satnav mode,
the GPS is likely to be switched off, so the phone will be relying on
phone masts and glimpses of WiFi from access points it passes for
(relatively imprecise) location information, let alone determining speed
as a function of time between these imprecise locations.

Depending on cell size, the phone knows where it is at anything up to
centimeter resolution using information held by the cell itself.

Up to a centimetre resolution?. Your taking there of enhanced
differential GPS, not just the triangulation timing info a cell phone
may have....

OK, 50 centimetres. And only in places where there are enough femtocells;
Oxford Street is the canonical example. But I have seen it demonstrated by
a cellphone operator; you can tell whether people are inside a shop or
standing on the pavement outside.

Under ideal conditions possibly but seeing the amount of multipath
reflections in urban environments I doubt that accuracy is more than a
few instances..

Out in the sticks yes Voda manage to do a few hundred metres and to do
this thing properly you need three base stations in range which
sometimes is a tad difficult;!.


This company offer these services..


http://www.followus.co.uk/..



Obviously, in the countryside or anywhere else the cells are large, the
resolution falls dramatically - hundreds of metres (although this is a
guess.)


About right sometimes more distant;!..
--
Tony Sayer