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

David Taylor david-taylor at blueyonder.co.uk.invalid
Sat Mar 22 06:26:36 UTC 2014

On 03/01/2014 10:54, Ralph Aichinger wrote:
> I am currently in the process of remodeling my house
> and a dedicated outdoor/roof mounted GPS antenna
> would be possible to mount without excessive cost.
> I probably would not see a huge difference for
> timing purposes, but what would your choice of
> an outdoor GPS antenna/receiver be? I am planning
> to put the NTP server (small Raspberry Pi, nothing
> fancy) into a rack maybe 10 metres of cable length away
> from the roof. Or would you move the NTP host itself
> to the attic and run Ethernet up?
> 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.
> 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.
> Or would you not bother at all, and just put some puck into
> the window (which probably works too)?
> /ralph

I would try with the Raspberry Pi with a GPS with built-in antenna in 
the attic, running an Ethernet/power lead up to the attic.  There are 
some examples here:


You can get a no-soldering GPS for the Raspberry Pi which includes the 
u-blox 7Q receiver (TCXO and PPS) and an SMA socket for a puck or 
outdoor antenna as described here:


In my own setup, I have several of those magnetic puck antennas just 
within a room on the top floor of a two storey building, and one Garmin 
GPS 18x LVC sitting on the roof.  Lightning protection is not an issue here.
Web: http://www.satsignal.eu

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