[time-nuts] Need recommendation for GPS antenna for Oncore GPS module

[Attila Kinali]

On Sat, 3 Nov 2018 17:26:51 -0400
Toby Riddell <toby.riddell at prevtec.com> wrote:

> I was planning on having it mounted on a south-facing wall but below the
> roofline - does this sound okay for picking up satellites? It can poke
> above the roofline if needed as long as the mounts are on the wall (not the
> top of the roof).

Unless you have a European style roof, with lots of metal around, there
will be no benefit of placing the antenna below the roofline, as it will
be electrically the highest grounded object. Hence you will need some
lightning arrestors (go for satellite receiver equipment) anyways. This also
means that you can go above the roofline, to avoid multipath, which
is the single biggest contributor to timing jitter in GPSDOs with
non-ideal antenna positions. Recommended are 2-3m above any surrounding
obstacle, but I guess anything from 1m upwards is ok.

> Is there a recommended antenna? I am planning on feeding it into an Oncore
> GPS module which will then interface to a Soekris net4501 running nanoBSD
> and ntpns.

And brand antenna is good enough unless you want to go for below 10ns accuracy.
Brand names include Symmetricom/Microsemi, Trimble, Novatel, Leica, ....

			Attila Kinali

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