F
ACTORY
D
EFAULTS OF
T
IME
S
ERVER
8030HEPTA/NCD
8030HEPTA/NCD Network Clock Device - V04.00
37 / 43
hopf
Elektronik GmbH
Nottebohmstr. 41
• D-58511 Lüdenscheid • Tel.: +49 (0)2351 9386-86 • Fax: +49 (0)2351 9386-93 • Internet: http://www.hopf.com • E-Mail: [email protected]
13
Factory Defaults of Time Server 8030HEPTA/NCD
The factory settings of the two modules of the Network Clock Device 8030HEPTA/NCD can
be found in the respective module description.
14
Glossary and Abbreviations
14.1 NTP-specific Terminology
Stability
The average frequency stability of the clock system.
Accuracy
Specifies the accuracy in comparison to other clocks.
Precision of a clock
Specifies how precisely the stability and accuracy of a
clock system can be maintained.
Offset
This value represents the time difference between two
clocks. It is the offset by which the local time would have to
be adjusted in order to keep it congruent with the reference
clock.
Clock skew
The frequency difference between two clocks
(first derivative of offset over time).
Drift
Real clocks vary in frequency difference (second derivative
of offset over time). This variation is known as drift.
Roundtrip delay
Roundtrip delay of an NTP message to the reference and
back.
Dispersion
Represents the maximum error of the local clock relative to
the reference clock.
Jitter
The estimated time error of the system clock measured as
the average exponential value of the time offset.
