[APBeta] [OT] GPS

[Paul Rodman]

On Jul 4, 2009, at 1:12 PM, Tony Barry wrote:

> FYI
>
> Silicon Chip Magazine has a project for a GPS unit that should be  
> good to about 250msec of real time.
>
> www.silchip.com.au
>
> (This is an unsolicited advert!)
>
> Regards,
> Tony Barry
>
> (who is trying to track the ISS on an LX90 and finding it **very**  
> hard).

The problem is the unknown finite delay with getting the time back  
from the GPS via a serial protocol. Specialised GPS units have a wired  
pulse output that can synchronise the time to within a few  
microseconds, with aid of some fancy hardware/firmware/software. I  
looked at this once for a wireless network project where we wanted to  
be able to tag all transmissions with a synchronised time stamp for  
debugging purposes.

Paul R.

BTW, the link above didn't work.