[time-nuts] time sync from cellphone TO microcomputer

[Jim Lux]

A couple of us were kicking around the idea of a low cost JT65-like HF 
modem implementation, which requires that the station be synchronized to 
1 second.

While this is trivial with a GPS receiver, we were thinking about a very 
minimalist implementation, with a smart phone as the control interface.

That brought up another discussion about whether it is possible to get 
time sync (at a better than 1 second, but potentially at the 
milliseconds level) across bluetooth or WiFi from a cellphone (Android 
or iDevice).

Say you wanted to "set the clock" on an Arduino or embedded processor. 
Could you do it via a wireless (or, I guess, a wired connection).

Has anyone done it?  the iPhone runtime environment is pretty sandboxed, 
and you might not be able to do that.