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USERS MANUAL
NR2110-R/O/G
REVISION
B
DATE
120120
Page #:
33 of 47
www.novuspower.com
Typical Phase Noise Performance-Rubidium with OCXO
When the stability of an atomic or crystal source is not sufficient, a GNSS
disciplined source is an option. A GNSS receiver is installed and timing
information from the GNSS is used to discipline the timing device. Timing
accuracy to a few ppb is readily achievable.
The GNSS is used to provide timing for a DDS (direct digital waveform
synthesizer). While the DDS has outstanding long-term accuracy, the short-term
stability is very poor due to the nature of the timing source. A GNSS timing
source has considerable short-term instability due to the numerous radio effects -
multi-path, signal weakness etc. In order to develop a stable reference, the
GNSS timing waveform is used to discipline a low noise source with a Kalman
filter.
A good example of the improved jitter performance of a Kalman filter is shown
below: