On 2014-01-03, Ralph Aichinger <[email protected]> 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
Probably not. As long as your gps has a view of the sky (southern if in the northern hemisphere) your timing will be fine. > an outdoor GPS antenna/receiver be? I am planning Put almost anything into a plastic (not metal) can so the rain does not soak it. > to put the NTP server (small Raspberry Pi, nothing > fancy) into a rack maybe 10 metres of cable length away 10m=30ns delay, and since the Pi almost certainly cannot get the signal into itself that fast ( more like us ) that 10m shold not be a problem. (actually since termination is liable to be a problem, the actual rise time will be much longer than that. ) > 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. Or the cheapest Sure. Antenna outside, gps receiver inside. I had a roof mounted Garmin 18 (inside a plastic milk container) which lasted about 2 yr. > > Would mounting just an antenna (active or passive) also > make sense, or would cable loss be too high? Sure. it would be fine.-- antenna outside with its 5m lead into the attic where the receiver is located. > > 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. The mounting hardware could well be the most expensive thing. Mind you I would not do anything very fancy. All it needs to do is see the sky. > > Or would you not bother at all, and just put some puck into > the window (which probably works too)? With a south facing window probably. Even with an east facing window through trees it works for me. > > TIA > /ralph _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
