Novus NR2310D-ROG User manual

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
1
www.novuspower.com
NR2310D-R/O/G
10MHz Rubidium Frequency Reference, GNSS-Locked, Low
Noise, 10-Channel w/RS232, Display
(Ethernet, SNMP –Optional)
All information provided herein is theproperty of Novus Power Products
LLC. The information included may be reproduced without the permission or prior
approval of Novus Power Products LLC for the purpose of operating the equipment.

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
2
www.novuspower.com
Contents
Contents ...........................................................................................................................2
Safety................................................................................................................................4
Mounting ..........................................................................................................................5
Summary...........................................................................................................................6
The GNSS-Locked Reference..........................................................................................7
The Time Base..............................................................................................................8
The GNSS Receiver .....................................................................................................9
Stability Selection Types............................................................................................12
Dual-Time Base Frequency Verification (option) .....................................................19
External PPS Locking ................................................................................................19
The unit may be configured to lock to an external PPS signal. The signal must
conform to 3.3 V CMOS into a 1000 Ohm load. Rise time must be less than 10ns and
the pulse width must be greater than 10 ms...................................................................19
GNSS Antenna (recommended)-HS1,HS2 ....................................................................20
GNSS Antenna (recommended)-HS3,HS4 ....................................................................21
PPS .................................................................................................................................22
PPS source..................................................................................................................23
PPS Cabling................................................................................................................24
Cable Delays...............................................................................................................27
Pulse Width ................................................................................................................28
PPS Holdover .............................................................................................................29
NMEA - RS232..............................................................................................................29
Base Unit Block Diagram...............................................................................................32
Phase Noise Performance...............................................................................................33
Controls and indicators...................................................................................................34
Channel Status- Front panel LED’s ...........................................................................34
Oven- LED front Panel...............................................................................................34
Digital Display (Optional)..........................................................................................34
Time/Date/Lock Status...............................................................................................35
GNSS/GPS Status.......................................................................................................35
Channel Status............................................................................................................36
Alert Threshold...........................................................................................................37
Latch Channel Value..................................................................................................40
Save Configuration.....................................................................................................40
Fault Status.................................................................................................................41
Rubidium Status –Lock State....................................................................................42

USERS GUIDE
NR2310D-R/O/G
REVISION
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DATE
05/04/22
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UTC Mode..................................................................................................................43
GMT offset.................................................................................................................43
RS232 NMEA / Alert –DB9 Male (Optional) .........................................................44
Rear Panel - Outputs.......................................................................................................45
Channel 1 through 10 output connectors –BNC or SMA .........................................45
PPS –SMA (with GPS locking option) .....................................................................45
Alert –BNC-SMA......................................................Error! Bookmark not defined.
Power In......................................................................................................................45
Functional Description (Base NR2310D-ROG) ............................................................46
Outputs .......................................................................................................................46
Built-in Test....................................................................................................................46
Power Supplies...........................................................................................................47
Redundant power........................................................................................................47
Specifications .................................................................................................................48
Technical Specifications.............................................................................................48
Environmental and Mechanical..................................................................................51
LIMITED HARDWARE WARRANTY .......................................................................52

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
4
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Safety
This product has been designed and manufactured to recognized safety
standards and rules. The product is a sophisticated electronic instrument that
should be installed and operated by highly trained professionals.
Installation of this equipment should comply with all local electrical codes.
Utilization of this equipment in a manner inconsistent with the operating
instructions can be dangerous.
There are no user serviceable parts within the unit. Removal of the cover to
access interior parts will expose the user to dangerous voltages.
The unit may be powered from more than one power source. Care must be
taken to be certain all power sources are removed before installation or during
removal of the equipment.
The unit must be operated with a secure earth ground to the chassis. The
electrical path for earth ground is through the power connector. The power
switching device that controls power to the equipment must never interrupt the
chassis ground connection.
The equipment contains complex electronic components that can be damaged
by electrostatic discharge. Observe all recognize standards for the handling of
complex electronic devices to avoid high voltage discharge to the equipment.
Be certain the equipment chassis and operator are at equipotential before
handling the equipment.

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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Mounting
The equipment is meant to operate in a horizontal - top up configuration.
The equipment is meant to mounted into a 19 inch standard NEMA cabinet.
The unit occupies a single “1RU”. Mounting spaces above and below the
equipment may be used as required.
Please observe the operating temperature range for the equipment. If mounted
into a closed rack, be certain that the total heat load in the cabinet does not
result in an interior operating temperature that exceeds the equipment
maximum rated temperature.
If cooling must be used, care should be given to prevent cooling mechanical
vibration from the coupling into the equipment. Mechanical shock and vibration
may introduce noise into the electronic signals inside the equipment that may
degrade the performance of the equipment. For applications where there is
significant shock and vibration, Novus offers equipment with interior
mechanical design features to minimize the effects of vibration and shock on
the equipment performance.

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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Summary
The NR2310D-R/O/G is a high-performance ten channel, 10 MHz, GNSS-
locked Rubidium frequency reference. The core time base is a Rubidium
source that is disciplined with the timing information from the GNSS. The
Rubidium source is followed by a low noise OCXO locked to the Rubidium. The
ten channels provide a 13 dBm sine output that is transient, and fault
protected. The unit also provides a single channel PPS output and a RS232
port. The RS232 port provides NMEA 0183 data as well as proprietary data
streams for instrument status and control. The unit features a front panel
display for equipment status and control. An optional Ethernet port allows
remote access and control via SNMP. There are four levels of optional
reference control for improved Allan Deviation performance and PPS accuracy
and jitter. The platform also supports redundant power sources AC or DC. The
unit may optionally be configured to lock to an external PPS signal.

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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The GNSS-Locked Reference
Novus offers four levels of GNSS locked reference performance:
HS1 digital loop using basic radio
HS2 digital loop, basic radio, adding picosecond timing
HS3 digital loop, advanced radio, picosecond timing and thermal stabilization,
Allan Deviation
HS4 digital loop, advanced radio, picosecond timing, thermal stabilization,
Allan Deviation, and vibration isolation.
Novus offers a range of locked reference performance options. Timing
information from the GNSS is very much a function of the receiver used, the
processing of the received timing information and how the timing source - be it
an OCXO, a Rubidium or some other device - is controlled. Environmental
factors such as temperature, shock and vibration all impact the overall system.
Over the years, Novus has invested heavily in the design of locked references
and can offer four levels of GNSS locking performance. Each level of
performance is discussed to allow the system designer to determine the level
of performance required versus system cost constraints.
Method Option
GNSS Locked
PLL
Pulse
Stabilization
Temperature
Control
ADEV (1s) ADEV (100s) ADEV (1ks) ADEV(100ks)
Analog Loop PLL Standard
3.00E-10 5.00E-10 8.00E-12
HS1
3.00E-12 2.00E-11 5.00E-12 5.00E-12
HS2
3.00E-12 1.00E-11 4.00E-12 9.00E-13
HS3
3.00E-12 7.00E-12 4.00E-12 7.00E-14
Digital Loop PLL

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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The Time Base
The heart of the system is the reference. Novus offers OCXO and Rubidium
based references. Because of the relatively poor phase noise performance of
Rubidium, many of our customers select a Rubidium with a clean-up OCXO to
achieve high stability and low phase noise. Following is a plot of the phase
noise of a Rubidium reference and a Rubidium reference followed by a clean-
up OCXO.
Our Rubidium references offer a stability of < ±1 ppb/year compared to a
typical OCXO ±50 ppb/year. The Rubidium source consists of a voltage-
controlled crystal oscillator (VCXO) which is locked to a highly stable atomic
transition in the ground state of the 85Rb isotope.
Novus uses several vendors for the OCXO. The OCXO selected is based on
required phase noise, stability, and cost. There are other secondary
considerations such as size, power consumption, etc.
In addition to standard OCXO devices, Novus also uses double oven OCXOs
as an alternative to a single oven OCXO. As can be imagined, a double oven
OCXO offers improved temperature stability and is frequently a lower cost
alternative to a Rubidium source.

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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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

USERS GUIDE
NR2310D-R/O/G
REVISION
P
DATE
05/04/22
Page #:
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Depending upon the locking algorithm, the radio PPS variation can contribute
directly to phase noise and uncertainty.
Novus uses two types GNSS receivers depending upon the stability options
installed in the unit.