[time-nuts] time-nuts Digest, Vol 156, Issue 30

Lee - N2LEE lee at n2lee.com
Sun Jul 30 12:16:16 EDT 2017

Chris, I have one NTP GPS based server running locally but I wanted to also setup the 
Mac with the Thunderbolt as a second NTP server. This way instead of using an external NTP
server as a backup I would have a second local server.

The Mac is Unix based and has a built in NTP server but it is normally disabled.
If I enable the server isn’t it going to pull its time from the system clock ?
This is the only reason I care about the system clock.

Maybe I am approaching this incorrectly. Maybe the question should be how to get a local
NTP server to use LH/Thunderbolt ?

> From: Chris Albertson <albertson.chris at gmail.com>
> Subject: Re: [time-nuts] Local System Time Sync
> Date: July 26, 2017 at 0:23:15 EDT
> To: Lee - N2LEE <lee at n2lee.com>, Discussion of precise time and frequency measurement <time-nuts at febo.com>
> You should be using NTP for that.
> Simply "syncing" the local clock to GPS is never the best thing to do.   If
> you think about it 50% of the time the local clock would have to go
> backwards and 50% forwards.  This means you could have the system time be
> at the same time twice or you have missing time intervals.
> The correct way is to adjust the RATE of the local clock so you never have
> missing or double time.   This is exactly the same as building a GPSDO.
> Every adjustment period you compare there PHASE of the local clock to GPS
> then adjust the RATE if required.     NTP does this.
> On Tue, Jul 25, 2017 at 7:45 PM, Lee - N2LEE via time-nuts <
> time-nuts at febo.com> wrote:

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