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8.4 Time acceptance from external AFNOR-A/C, IRIG-B12x source
The stratum value is calculated same as with DCF/GPS synchronization (chapter 8.3).
As IRIG-B120 to 123 time codes do not provide information about the current year, the
DTS 4138 has to be synchronized first from another time source or the date has to be
set manually. The DCF input and the IRIG input cannot be used at the same time for
the synchronization (redundant time source with DCF and IRIG synchronization is not
possible).
AFNOR and IRIG-B126 contains the time and date information.
Attention:
After more than 5 days without power, the DTS 4138 loses the date
information. When synchronized with IRIG-B120 to 123 it has to be set
again manually.
8.5 Time acceptance from NTP
Acceptance:
As NTP RFC 1305 (www.ntp.org)
(see http://ntp.isc.org/bin/view/Servers/WebHome for internet-server)
Stratum in normal, synchronized operation:
Stratum value of DTS is always one step higher than that of the current NTP time
server
Stratum in case of an error
As NTP RFC 1305 (www.ntp.org)
8.6 NTP as backup
If DTS 4138 is synchronized with a DCF or GPS source, the NTP can be used as
redundancy source. This function is active, as soon as at least one timeserver is
configured in menu ‘2. Configuration’ ‘2. Time handling ‘4. NTP server’).
Stratum in normal, synchronized operation:
Equal Stratum value “Time Acceptance from an external source (DCF or GPS)”
Behavior in case of an error:
Failure of primary Source:
"St. est": Means: Expected NTP Stratum of the NTP sources
"St. est" = MAX(Stratum NTP candidates)
Means: "St. est" contains the stratum value of the poorest NTP source.
If internal Stratum > "St. est" + 1, then change to NTP as source takes place
(internal stratum is one step higher than that of the poorest available NTP source).
As soon as the primary source is available again, the changes are set back.
8.7 Time server
NTP v4 (compatible with v3) as per RFC 1305 (Port 123)
SNTP (UDP), RFC 2030 (Port 123)
TIME (TCP/UDP), RFC 868 (Port 37)
DAYTIME (TCP/UDP), RFC 867 (Port 13)
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