[ntp:questions] Roof antenna, which one, would you bother?

Terje Mathisen terje.mathisen at tmsw.no
Fri Jan 3 11:31:48 UTC 2014

Ralph Aichinger wrote:
> I suppose something like the Garmin GPS 17x (mast mount
> GPS with serial output and PPS, intended for the marine
> market) would work fine, also be robust enough and
> cheap on the used market.

As long as it has that PPS signal, this is close to optimal.

My best performing NTP servers over many years have been those based on 
the old Oncore UT+ (from Synergy) which has the antenna & gps in an 
outdoor conical mount and balanced (RS422?) drivers to send the signal 
as long as you want down to the actual NTP server.
> Would mounting just an antenna (active or passive) also
> make sense, or would cable loss be too high?
> What would *your* roof top setup be? Cost is of course
> an important consideration, on the other hand, 100
> or 200 Euros for the GPS, antenna and mounting hardware
> is probably OK. I would prefer to do cabling jobs now,
> while I am in the process of doing a lot of "dirty" things.

At home I had the old Garmin 18 mounted on the metal siding of my roof, 
this provided near-360 visibility and a good ground plane for pretty 
much optimal reception.
> Or would you not bother at all, and just put some puck into
> the window (which probably works too)?

My current very cheap setup based on the Sure board (mounted in a 
plastic freezer box!) has the antenna inside the window facing south, 
seems to work more or less just as well as the old rooftop placement.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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