[time-nuts] Mounting GPS Antenna on Steel Roof

Matthew Smith matt at smiffytech.com
Tue Mar 4 16:16:47 EST 2008


Quoth Rob Kimberley at 2008-03-05 02:45...

> You mentioned Time Server..is this your only GPS or do you have other more
> accurate timing requirements? Unless you are working on nanosecond type
> accuracy, I don't see that mounting your antenna on the metal roof is going
> to cause you any practical problems. If all you are interested in is taking
> time from your GPS over Ethernet using NTP, then all will work fine.

Yes, this is all about running a network time server; my other
application is a GPS-driven Nixie clock, so that is even less critical.

My main concern has been about the receiver getting 'upset', similar to
Didier's experience with the Thuderbolt.

What I have worked out - mainly from the responses I have received and a
little from my own thought processes - is this:

1) Mounting on the ridge should probably be OK.

2) Other parts of the system are more likely to add inaccuracy than
multipath.

3) Errors will not be significant in the context of an NTP server.

4) The only way to find out is to try.


I will be doing (4) as soon as I've found the time to make up a TTL to
RS232 board.  I've already found that TrimbleMon will start under Wine,
although haven't been able to connect it to any hardware yet.  For the
purposes of experimentation, I will be putting the antenna up on the
ridge of my office roof - a much worse location than the main ridge as
it is lower down and has all sorts of other metal to get in the way.  (I
can get the antenna on my office roof by means of a pole with a bit of
Blu-Tak on the end; the main ridge requires someone on the roof and a
cable extension.)

Thanks again to all who have chimed in on this - really much appreciated.

Cheers

M

-- 
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
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