NTP question

Mel Beckman mel at beckman.org
Wed May 1 20:55:31 UTC 2019


I use the TimeMachines unit a lot. Usually we deploy these near any outside window, typically putting the box in the ceiling and the running the GPS antenna on its 20’ cable (or whatever it is) down to the window glass.  Test different windows first before committing. Then use any of the may passive POE injectors to inject the TM’s power brick into the Cat5 and strip it out on the other end, over a little power plug jumper that plugs into the TM box. Works a treat!

 -mel beckman

On May 1, 2019, at 12:44 PM, Mehmet Akcin <mehmet at akcin.net<mailto:mehmet at akcin.net>> wrote:

thank you guys, looks like GPS based NTP is the way to go.

On Wed, May 1, 2019 at 3:36 PM Bryan Fields <Bryan at bryanfields.net<mailto:Bryan at bryanfields.net>> wrote:
On 5/1/19 3:22 PM, Mehmet Akcin wrote:
> hey there Nanog,
> I am trying to buy a GPS based NTP server like this one
> https://timemachinescorp.com/product/gps-time-server-tm1000a/
> but I will be placing this inside a data center, do these need an actual
> view of a sky to be able to get signal or will they work fine inside a data
> center building?

You will need a clear view to the sky for at least the antenna.

Most GPS "antennas" are an antenna and Low Noise Amplifier (LNA) which is
powered via 5-12v on the coax.  This sets the noise figure and gain of the
system, so you can run 50-100' of RG6 coax if needed.  You'll need a F to sma
adapter for this unit it looks like.  Don't worry about the impedance
mismatch, 50 to 75 ohm is not horrid, the RG-174 thin cable has more loss in
10' than 100' of RG6.

You will not want to use the low gain puck antenna, but rather get a proper
grounded/mounted/weatherproofed antenna such as the ubiquitous 26 dBi
Quadrifilar Helix antenna. https://www.ebay.com/itm/192899151132

Bryan Fields

727-409-1194 - Voice
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.nanog.org/pipermail/nanog/attachments/20190501/79cda068/attachment.html>

More information about the NANOG mailing list