[ntp:questions] SNTP server + ntpd 4.2.4 client

Richard B. Gilbert rgilbert88 at comcast.net
Wed Mar 19 14:45:59 UTC 2008

Steve Kostecke wrote:
> On 2008-03-19, Noob <root at localhost> wrote:
>>Does the GPS18LVC provide an oscillator to serve time even when there 
>>are not enough satellites in sight?
> No. You'll have to pay (much) more than $70-$80 if you want a good
> hold-over oscillator.

With something like 27 NAVSTAR (GPS) satellites aloft, there should 
almost always be seven or eight above the horizon.  Satellites more than 
ten degrees above the horizon are preferred!

I've never used the GPS18LVC (I have a Motorola M12+T) but if you know 
your exact location you only need one satellite to get the time.  There 
are four equations in four unknowns (lattitude, longitude, elevation, 
and time).  Not knowing any of these variables, you need four 
satellites.  Once you know your location a single satellite is 
sufficient to solve for time.

More information about the questions mailing list