Novus NR8403 User manual

Users manual
NR8403
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Date:
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User Manual Model NR8403
Triple Channel Rubidium Reference with GNSS
Locking and Low Noise Options
All information provide herein is the proprietary property of Novus Power Products
L.L.C. The information included may be reproduced without the permission of Novus
Power Products L.L.C. without prior approval for purpose of operating the equipment.

Users manual
NR8403
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Contents
Summary............................................................................................................................. 4
2.1 Power ....................................................................................................................... 7
GNSS Receiver (option) ..................................................................................................... 8
GNSS Status.................................................................................................................... 8
UTC Mode...................................................................................................................... 8
GMT Offset..................................................................................................................... 9
Mechanical........................................................................................................................ 12
Antenna............................................................................................................................. 13
PPS (Pulse Per Second) .................................................................................................... 14
GNSS PPS Availability................................................................................................. 14
GNSS PPS Accuracy .................................................................................................... 15
PPS Holdover................................................................................................................ 15
Cable Delays................................................................................................................. 16
Rear Panel......................................................................................................................... 18
Channel Output –BNC (10MHz Option)..................................................................... 18
Antenna Input - SMA.................................................................................................... 18
DC Input........................................................................................................................ 18
3.4 RS232 DB9 (Status and NMEA)........................................................................... 19
Operations......................................................................................................................... 20
Channel Status .............................................................................................................. 20
Built in Test................................................................................................................... 21
Alert Threshold............................................................................................................. 21
Latch Channel Value..................................................................................................... 24
Save Configuration ....................................................................................................... 25
Fault Status.................................................................................................................... 25
UTC Mode.................................................................................................................... 26
GMT Offset................................................................................................................... 26
Functional Description...................................................................................................... 27
Outputs.......................................................................................................................... 27
Built in Test................................................................................................................... 28
6.0 Calibration................................................................................................................... 28
Programming Guide (RS232 Port: Status Only)............................................................... 28
RS232 Commands (Status Only, for GNSS, see Append. A) ...................................... 29
Technical Specification..................................................................................................... 33
Environmental and Mechanical .................................................................................... 35
9.0 LIMITED HARDWARE WARRANTY.................................................................... 35
Appendix A: GNSS Command Reference........................................................................ 37
Appendix C: $GPNVS Status Strings............................................................................... 37

Users manual
NR8403
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Users manual
NR8403
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Summary
The NR8403 is a three channel Rubidium source which options that include GNSS
locking and Ultra Low noise. A low power Rubidium source and low power OCXO are
used in the design to allow a compact design with little cooling air required. There is a
fan that is modulated by the processor to handle worst case temperature conditions.
The Rubidium source is a CPT device (Coherent Population Trapping). The main
advantage of the CPT atomic clocks compared to the traditional atomic clocks is the
absence of a microwave cavity, allowing substantial reductions in size, power, and cost
while maintaining the stability. While a Rubidium source provides outstanding stability-
phase noise performance may not be enough for many applications. The NR8403-O
option adds a low noise OCXO that is locked to the Rubidium source. The phase noise
plot below demonstrates the improvement in phase noise with the O- Option:

Users manual
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The base unit is standard Rubidium reference with no GNSS locking or phase noise
enhancement. The Rubidium source affords a stability of < 3E-10/month. The unit
consumes < 10 watts of power from a DC source that can be from -60 to +60 Vdc in three
ranges.
To further enhance long-term stability a GNSS locking options is available. A 26
Channel GNSS receiver is added that continually disciplines the Rubidium source to the
GNSS. The configuration is also available with the low noise OCXO- offering the best of
three core technologies.
The three 10 MHz outputs (0.5 Vrms into 50 Ohms), NMEA and PPS are fault and
transient protected.

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The RS232 interface provides access to the NMEA-0183 data from the GNSS receiver at
a baud rate of 38.4K. The baud rate can be changed through the RS232 port using
commands described in the Output Format Section (8.0). In addition to NMEA data, the
serial data also provides equipment status-
The PPS pulse is capable of driving into a 50 ohm load at 5 volt logic levels.
The discipling loop for the 10 MHz OCXO features an algorithm that affords very low
close in phase noise. The bandwidth is such that many of the low frequency artifacts of
the transmission path are successfully attenuated.
The PPS pulse is selectable as being directly from the GNSS receiver or synthesized from
the Rubidium source or low noise OCXO. The synthesized PPS has significantly
improved jitter versus the PPS directly from the GNSS receiver. In addition to selecting
the source of the PPS the user can program in cable delay compensation in 1 ns
increments and program the PPS pulse width.
The 4-line display in conjunction with the two push buttons provide local status and
display. For embedded applications, the unit is available without the display or
pushbuttons.
Synthesized PPS pulse jitter

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2.1 Power
The equipment will need a power source of approximately 15
watts- Steady state power is < 10 Watts
Power can be from an AC power adapter or a DC source. The
DC power required is specified at the time of ordering to be
within 1 of three ranges:
12VDC (10 to 15VDC)
24VDC (20 to 30VDC)
48VDC (40 to 60VDC)
The unit has reverse polarity protection and will operate within
any given range positive or negative.

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Power consumption is highest at turn-on as the crystal is
warming up or if it is a very cold environment. Under normal
conditions, warm is less than five minutes.
Power max < 10 Watts
Steady state power < 6 Watts
GNSS Receiver (option)
GNSS Status
On power up, the unit will display the Time and Date as well as the current status
of the GNSS receiver.
GNSS: The GNSS status indication allows the user to observe the Lock status of
the receivers, and the number of GNSS satellites in view. Before GNSS lock is
acquired, the status will be “Tracking” and the number of satellites will be shown.
When GNSS lock is acquired, the status will change to “Lock.”
Time and Date: The time zone will be UTC by default, but the hour can be offset
to the local time in the UTC Offset menu. Changes to UTC offset and Hour mode
will be reflected on this screen, but will not change the NMEA output data.
UTC Mode
The user can select how the time is displayed on the screen by choosing between
three formats: UTC, 24 hour mode, or 12 hour mode. Toggle through the modes
by pressing the SELECT button.

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If 24 hour mode or 12 hour mode is chosen, the GMT offset will be applied to the
displayed time. If GMT mode is selected, no offset will be applied to the
displayed time.
GMT Offset
The user can select how the time is displayed on the screen by choosing between
three formats: UTC, 24 hour mode, or 12 hour mode. Toggle through the modes
by pressing the SELECT button.
If 24 hour mode or 12 hour mode is chosen, the GMT offset will be applied to the
displayed time. If GMT mode is selected, no offset will be applied to the
displayed time.
The 26 channel GNSS receiver and companion elements
generate the GNSS PPS and NMEA serial link. The serial link
conforms to NMEA 0183 protocol.
GPS, GLONASS, QZSS, SBAS, Active Anti-Jamming and
Advanced Multipath Mitigation Functions.
Supports concurrent GPS, GLONASS, SBAS and QZSS.
Galileo Ready.
Sensitivity
GPS
Tracking: -161 dBm
Hot Start: -161 dBm
Warm Start: -147 dBm
Cold Start: -147 dBm
Reacquisition: -161 dBm
GLONASS
Tracking: -157 dBm
Hot Start: -157 dBm

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Warm Start: -143 dBm
Cold Start: -143 dBm
Reacquisition: -157 dBm
TTFF (Time to First Fix)
Hot Start: <5 sec (@-130 dBm)
Warm Start: 35 sec (@-130 dBm)
Cold Start: 40 sec (@-130 dBm)
・Active Anti-Jamming
・Advanced Multipath Mitigation
The receiver needs at least four satellite vehicles (SVs) visible
to obtain an accurate 3-D position fix. When travelling in a
valley, or built-up area, or under heavy tree cover, you will have
trouble acquiring and maintaining a coherent satellite lock.
Complete satellite lock may be lost, or only enough satellites (3)
tracked to be able to compute a 2-D position fix, or a poor 3D
fix due to insufficient satellite geometry (i.e. poor DOP). It may
not be possible to update a position fix inside a building or
beneath a bridge. The receiver can operate in 2-D mode if it
goes down to seeing only three satellites by assuming its height
remains constant. But this assumption can lead to very large
errors, especially when a change in height does occur. A 2-D
position fix is not considered a good or accurate fix; it is simply
“better than nothing”.
The receiver’s antenna must have a clear view of the sky to
acquire satellite lock. Remember, it is the location of the
antenna that will be given as the position fix. If the antenna is
mounted on a vehicle, survey pole, or backpack, allowance for
this must be made when using the solution. The GNSS receiver
provides power for the LNA in the antenna. The unit was
designed to provide 3.5 Vdc < 40 mA of current.