Novus NR8403 User manual

Users manual
NR8403
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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.

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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

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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:

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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.

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To measure the range from the satellite to the receiver, two
criteria are required: signal transmission time and signal
reception time. All GPS satellites have several atomic clocks
that keep precise time and are used to time-tag the message
(i.e. code the transmission time onto the signal) and to control
the transmission sequence of the coded signal. The receiver
has an internal clock to precisely identify the arrival time of the
signal. Transit speed of the signal is a known constant (the
speed of light), therefore: time x speed of light = distance.
Once the receiver calculates the range to a satellite, it knows
that it lies somewhere on an imaginary sphere whose radius is
equal to this range. If a second satellite is then found, a second
sphere can again be calculated from this range information.
The receiver will now know that it lies somewhere on the circle
of points produced where these two spheres intersect.
When a third satellite is detected, and a range determined, a
third sphere intersects the area formed by the other two. This
intersection occurs at just two points. A fourth satellite is then
used to synchronize the receiver clock to the satellite clocks.
In practice, just four satellite measurements are sufficient for
the receiver to determine a position, as one of the two points
will be totally unreasonable (possibly many kilometers out into
space). This assumes the satellite and receiver timing to be
identical. In reality, when the receiver compares the incoming
signal with its own internal copy of the code and clock, the two
will no longer be synchronized. Timing error in the satellite
clocks, the receiver, and other anomalies mean that the
measurement of the signal transit time is in error. This,
effectively, is a constant for all satellites since each
measurement is made simultaneously on parallel tracking
channels. Because of this, the resulting ranges calculated are
known as “pseudo-ranges”.
To overcome these errors, the receiver then matches or
“skews” its own code to become synchronous with the satellite
signal. This is repeated for all satellites in turn, thus measuring
the relative transit times of individual signals. By accurately

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knowing all satellite positions and measuring the signal transit
times, the user’s position can be accurately determined.
Mechanical
6.101
.382
.085
.499
5.099
O.150
1
0
NR8403
Power
www.novuspower.com
NovusPowerProductsLLC
PPS
10MHz
3
2
1
NMEA
0
0
6.291
1.537
1.053
1.720
2.382
3.043
The 4 line display and two buttons provide status and control
functionality. The display also features a “saver” function that
dims the display if no button presses are made in 30 minutes.
An activation of either buttons restores the display brightness.
For embedded systems, the unit is available without the display
or pushbuttons.

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Antenna
Antenna 1 - SMA
SMA female antenna connections. Provides internal 3.5VDC
power at <30mA max. The Novus NA103 pole mount antennas
or the Novus NA106 magnetic mount antenna are
recommended for optimal performance.
The receiver and companion elements generate the PPS and
NMEA serial link. The serial link conforms to NMEA 0183
protocol. The 26 channel high-sensitivity, high-accuracy Multi-
GNSS receiver supports TRAIM, GPS, GLONASS, QZSS,
SBAS, Active Anti-Jamming and Advanced Multipath Mitigation
Functions.
Typical Antenna Specs:
Frequency Band 1574 –1607 MHz
Antenna Gain 2 dBic @ 90°
Amplifier Gain @ 3.0Vdc: 26dB (typ)
Polarization RHCP
Out-of-band Rejection >60dBc @ f0 ± 50MHz
Impedance 50Ω
VSWR 2.0 Max
DC Input 2.8V - 6V
Noise Figure <2.0dB
Power Consumption 25mA (typ)

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PPS (Pulse Per Second)
The PPS (one Pulse Per Second) relationship with the NMEA
data is shown below:
The serial data timing is for the next rising edge of the PPS
pulse.
There are a number of attributes for the PPS that can be
controlled via the RS232 port with the radio:
GNSS PPS Availability
There is a TCXO that is used to maintain the PPS in the event
of GNSS loss. The radio can be programmed to either have the
PPS stop when GNSS lock occurs or continue with the stability
of the internal TCXO. The TCXO has a stability as shown
below.

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The PPS may also be selected from an internal synthesizer
operated from the 10 MHz. This source is much more stable
with pulse-to-pulse jitter below 1 ns while being within 100ns of
the received PPS.
GNSS PPS Accuracy
15ns(1σ) (@-130 dBm)
50ns(1σ) (@-150 dBm)
The nominal accuracy of a PPS signal that is directly from the
radio is on the order of 25 ns rms. The signal will also have ~5
ns of jitter. The jitter is due to the characteristics of the
transmission channel - multi-path and other radio effects. The
long-term accuracy of the PPS is excellent. There are
numerous reference documents produced by NIST that define
accuracy.
For those applications where the 5 ns of jitter is unacceptable,
there is a more stable source. To solve the jitter problem, a
stable oscillator is locked to the PPS and the output of the
oscillator is then counted down to 1 Hz to have a jitter level that
is dominated by the oscillator and associated electronics. PPS
jitter can be improved from the 5 ns range to less than 1 ns
PPS Holdover

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PPS holdover is concerned with the stability of the PPS when
GNSS lock is lost. The circuitry discussed to improve jitter also
improves holdover. If the oscillator is an OCXO - then a PPS
drift of 5 to 10 ppb/day is achievable (< 1ms). A Rubidium
source can be used to achieve drift rate well over an order of
magnitude better than the OCXO < 20 usec/day.
Cable Delays
The unit can be programmed to compensate for PPS errors due
to cable length. A compensation factor of +/-100000 ns can be
used.
Pulse Width:
The pulse width can be programmed from 1 to 500ms.
Factory Default Settings:
PPS on when estimated accuracy is within 1 usec.
Pulse width is 200ms.

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Rear Panel
NMEA
123
10 MHz
PPS
Novus Power Products LLC
www.novuspower.com
Power
NR8403
1
Channel Output –BNC (10MHz Option)
There are three 10MHz output on the rear panel, BNC 50Ω
Antenna Input - SMA
SMA female –Internal 3.5V Supply, 30 mA max to power an LNA located at he
antenna. Located jut above the Channel 1 BNC.
DC Input
The power connector is a 4 pin terminal block connector:
(Phoenix Contact part #1844236 or ON-Shore Tech Part# OSTOQ041251)
and the unit ships with its mate pictured below:
(Phoenix Contact part #1840382 or ON-Shore OSTTJ0411530)
Wires can be installed and secured with a slotted screwdriver.
Pin assignments:
1. V-
2. V+
3 Relay Contact
4. Relay Contact
1

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The unit is designed to operate from 12 VDC nominal power and is reverse
polarity protected.
Pin 1 is designated on the panel and is the far right pin as directly viewed.
3.4 RS232 DB9 (Status and NMEA)
An RS232 port is provided for NMEA output from the GNSS receiver, and for the
optional status of the 10MHz source .
Status(10MHz Option): The embedded processor provides status strings, as well
as command responses. Configuration and status commands are detailed in the
NTP0100 Programmer’s Manual Section 5.0. (default 38400 baud)
NMEA: The GPS/GNSS receiver provides NMEA-0183 formatted serial data.
(default 38400 baud)
RS232 Serial Port: Rear Panel Pin Connections
Pin
Function
I/O
1
Optional PPS
O
2
NMEA port / Command Port TX
O
3
NMEA Port / Command Port RX
I
4
NC
5
GND
GND
6
NC
7
NC
8
NC
9
NC
NMEA Configuration: The default settings for the rear panel RS232 port are
38400 baud, 8 bits, 1 stop bit, no parity. The baud rate may be changed per
instructions in section

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Operations
At the application of power the Rubidium begins its lock process. The locking time is
typically less than 5 minutes. If the low noise OCXO option is purchased then the OCXO
must lock to the Rubidium. The OCXO has its own warm-up time illustrated below.
OCXO Frequency Error from Cold Start
Channel Status
The Channel Status can be determined by reading the actual RMS value on the
output of each stage. This is compared to a threshold limit that is set by the user as
a percentage variation from a saved value. The default variation value is set at
±25% percent from the current state of the amplifier, and is user programmable in
5% increments from ±10% to ±60%.
The range of acceptable Channel Amplitude can be narrowed around a connected
balanced line, such that a Channel Status below the Alert Threshold indicates a
shorted line, while a Channel Status above the Alert Threshold window indicates
a potential disconnected cable.
The threshold value at which a channel alert is triggered can be programmed on
the Alert Threshold screen, or programmed via the RS232 port. Once set, the unit
-1.60E+02
-1.40E+02
-1.20E+02
-1.00E+02
-8.00E+01
-6.00E+01
-4.00E+01
-2.00E+01
0.00E+00
2.00E+01
1
13 25 37 49 61 73 85 97
109 121 133 145 157 169 181 193 205 217 229 241
Error in Hz
Time in seconds
Frequency Error 1 to 250 seconds