[time-nuts] GPS Timing Source -- looking at buying

[Robert Atkinson]

Hi Chris,
You need the LVC to make sure you have the 1PPS available. The PC may have it in the cable but you can't be sure. The 18X is OK for NTP but a timing GPS in position hold is better. The Tbolt is good but has a ovened 10MHz oscillator that you don't need unless you want to keep time when the GPS is down. The Trimble Palisade (now Acutime2000) is designed for this application. I can supply a used one for £50 but you need to be able to knock up a power source and RS422 to 232 converter (probably not needed to the SPARC box). Manual is here http://www.dc2light.pwp.blueyonder.co.uk/Webpage/PALISADE-Manual.zip
 
Robert G8RPI.


--- On Fri, 9/7/10, Chris H <timenuts at archnetnz.com> wrote:


From: Chris H <timenuts at archnetnz.com>
Subject: Re: [time-nuts] GPS Timing Source -- looking at buying
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Friday, 9 July, 2010, 8:54


> > Which is the 18X and looking at the manual for it, it says it's 1pps with 1
> > microsecond accuracy.
> 
> Yup.  That URL is for the LVC version.  The PC version is the one powered 
> from a cigarette lighter.  (Your first line above says PC when I assume you 
> mean LVC.)

Sorry -- I had book marked the PC version -- but when I noticed the LVC
version, I checked the website, and they have them with bare wire -- so
no plugs at all..  

> > I am not really sure what to do -- and I have followed the mail list for a
> > while, but I think I might be looking in the wrong place...
> 
> Did you check the URL I sent?  And the ones at the bottom of that 
> page?

Yes -- that page looks fantastic, I am going to use that as my reference
guide :) when I actually get to put it all together...

> Look at the picture, or get the manual from the Garmin web site.  The LVC 
> comes with a connector so they can test it.  You cut it off and wire it to a 
> DB-9 and supply power one of several ways.  Then plug it into your serial 
> port.
> 
> 
> > I perhaps need to join an NTP mail list .. 
>   http://lists.ntp.org/listinfo/questions
> It's gatewayed to usenet:comp.protocols.time.ntp
> 
> Check out the archives.
> 
> 
> > When you say 'more sensitive' what do you mean by that?
> 
> Where are you going to put it?  The GPS antenna is built into the 
> hockey-puck.  You need to get the antenna into a good-enough position.  "more 
> sensitive" means it's easier to find a location that's good enough to get a 
> useful signal.
> 
> Trees are bad.  Houses are bad.  Mine mostly works inside my house.  It would 
> work better if I put it outside.

I guess they are weather proof.....
Looking at the wiring diagram at the bottom of that page, it appears
(and correct me again if I am wrong) I can run it down CAT5 cable, and
'i guess' that the 5meter limit on USB is just data, not power?? so Run
power down the CAT5 and bring the serial data back down as well - or I
might just need to put a power injector closer to the unit if I cant get
USB power that far as computers are about 20 - 30 meters from where the
best position is for the unit.

It will be put on a pole on the edge of the house, that has full clear
coverage of the sky - where my Discone antenna sits :) - very little
trees from that angle and no houses close by :)





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