Operating instructions
OPTIMOD-AM DIGITAL INSTALLATION
2-55
Synchronizing Optimod to a Network Time
Server
[Skip this section if you do not wish to automatically synchronize your Optimod’s in-
ternal clock to a network timeserver, which may be part of your local network or lo-
cated on the Internet.]
1. Navigate to SETUP > NEXT > TIME DATE AND ID > NEXT > TIME SYNC.
A) Use the P
ROTOCOL control to choose either TIME PRO or SNTP.
Select
TIME PRO if the Optimod is behind a firewall that does not pass UPD
packets. T
IME PRO selects the Time Protocol as described in the standard
RFC868. This method uses TCP on port 37.
Select SNTP if your network timeserver supports the Simple Network Time
Protocol as described in standard RFC1769. This method uses UDP on port
123.
Ask your network administrator which protocols are available. SNTP is
slightly more accurate.
B) Using S
YNC PERIOD, choose how often your Optimod will automatically update
its internal clock to the timeserver you selected.
The choices are O
FF, 8 HOURS, and 24 HOURS.
If the connection to the timeserver fails (due to network overload or
other problems), your Optimod will try once per hour to synchronize un-
til it is successful.
C) Set the OFFSET to the difference (in hours) between your time zone and Uni-
Name IP Address Location
time-a.nist.gov 129.6.15.28 NIST, Gaithersburg, Maryland
time-b.nist.gov 129.6.15.29 NIST, Gaithersburg, Maryland
time-a.timefreq.bldrdoc.gov 132.163.4.101 NIST, Boulder, Colorado
time-b.timefreq.bldrdoc.gov 132.163.4.102 NIST, Boulder, Colorado
time-c.timefreq.bldrdoc.gov 132.163.4.103 NIST, Boulder, Colorado
utcnist.colorado.edu 128.138.140.44 University of Colorado, Boulder
time.nist.gov 192.43.244.18 NCAR, Boulder, Colorado
time-nw.nist.gov 131.107.1.10 Microsoft, Redmond, Washington
nist1.symmetricom.com 69.25.96.13 Symmetricom, San Jose, California
nist1-dc.glassey.com 216.200.93.8 Abovenet, Virginia
nist1-ny.glassey.com 208.184.49.9 Abovenet, New York City
nist1-sj.glassey.com 207.126.98.204 Abovenet, San Jose, California
nist1.aol-ca.truetime.com 207.200.81.113 TrueTime, AOL facility, Sunnyvale, Cali-
fornia
nist1.aol-va.truetime.com 205.188.185.33 TrueTime, AOL facility, Virginia
nist1.columbiacountyga.gov 68.216.79.113 Columbia County, Georgia
Table 2-1: NIST-referenced timeservers