[time-nuts] Mounting GPS Antenna on Steel Roof

[Bruce Griffiths]

Matthew Smith wrote:
>>> So my Trimble ACE II and Moto Oncore modules will tolerate RS232 levels 
>>> without conversion?  Are we absolutely sure on this - I don't want to 
>>> fry anything!
>>>       
>
> Bruce, Chris, thanks for the confirmation.
>
> I'll go back to the idea of using the MAX232 equivalent as originally 
> planned.
>
> I'm also putting one of these between the MAX232 and the GPS module:
>
> <http://focus.ti.com/docs/prod/folders/print/iso7231m.html>
>
> (That's for the Oncore; it's got two channels in one direction, one in 
> the other, making it ideal for TX/RX+PPS.  I'll probably use one of 
> these with a one-each-way for the Trimbles.)
>
> The GPS module will also be powered via a high-isolation DC-DC 
> convertor.  I don't consider anything that's going to sit between my 
> data network and an antenna overkill!
>
> Cheers
>
> M
>
>   
Matthew

Using an isolator of some kind is always a good idea to break ground 
loops and provide some fault isolation, however they do add some jitter 
(probably insignificant for your application).
Such isolators may be inadequate to prevent damage propagation in the 
the event of a lightning strike.
Fibre optic isolators using several meters of plastic fibre will be far 
more effective in that case.

Bruce