Model
E10-GPS
Operation Manual
E10-GPS Manual A5 4 December 2013
Page 7
Accuracy is comparable with that of the standard Caesium with an operating
life approximately 5 times that of Caesium. Moreover the stability of a
Rubidium frequency reference over short time-scales -100s of seconds-
betters that of Caesium (Caesium is more stable over longer time periods, in
the regions of hours to years).
There are, however, a few drawbacks to the use of Rubidium as a frequency
reference. In the past, these included the limited life of the Rubidium lamp
(since improved to >10 years), The Caesium is affected to a greater degree
than this, whilst the Hydrogen Maser operates differently and is not affected.
The thermal stability of Rubidium is inferior to that of Caesium or Hydrogen
Masers, and the Rubidium previously required frequency access to a primary
reference signal or synchronization source to maintain long-term Caesium
level accuracy.
The cost of a Rubidium frequency reference is significantly cheaper than a
Caesium, with a much reduced size and weight. Due to its small size, low
weight and environmental tolerance the Rubidium frequency reference is
ideal for mobile applications. Indeed, Rubidium atomic clocks are beginning
to be implemented into the new generation of GPS
satellites. This is in part
due to the extended life of the Rubidium physics package compared to that
of Caesium. The Rubidium is also extremely quick to reach operational
performance, within 10 minutes reaching 5 parts in 10
-11
.
