USERS GUIDE
NR2310D-ROG
REVISION
N
DATE
031121
Page #:
9
www.novuspower.com
OCXO offers improved temperature stability and is frequently a lower cost
alternative to a Rubidium source.
A TCXO reference might be considered for a low-cost application. It offers an
aging stability that is on the order of ±1000 ppb/year. Phase noise is typically
not as good as that of an OCXO - but it is lower cost and consumes much less
power.
The GNSS Receiver
Disciplining a reference, a 10 MHz timing signal to a master reference with all
the noise due to atmospheric conditions, multipath and doppler effects is a
tremendous challenge.
There are likely hundreds of GNSS receivers available with a range of
functionality. Novus uses a few that are selected to meet the needs of our
reference and PPS (pulse per second) sources. PPS stability and accuracy
varies with each radio and cost rises with performance.
A significant part of the problem is the PPS being generated by the radio. No
two radio designs are the same and the algorithms that generate the PPS vary
widely. Following are two histograms for two different radios and their PPS
performance. One is Gaussian and the other is not. Also, the spectral content
of the PPS can vary greatly - often with low frequency content that adds to the
close in phase noise of the reference.
Stability/Year Temperature Adev@1 sec
ppb
ppb/ 0 to 70C
Seconds
TCXO
<+-1000
<+-1000
1.00E-09
OCXO
<+-50
<+-10
1.00E-10
Double OCXO
<+-10
<+-0.2
5.00E-12
Rubidium
<+-1
<+-0.1
5.00E-11
Timing Sources Comparison
