Novus NR2110-R User manual

USERS MANUAL
NR2110-R/O/G
REVISION
B
DATE
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NR2110-R/O/G
10MHz Frequency Reference, PPS, GNSS-Locked, Dual Channel,
with Rubidium Holdover
All information provided herein is the property of Novus Power Products LLC. The
information included may be reproduced without the permission of Novus Power
Products LLC for the purpose of operating the equipment.

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Contents
Summary.........................................................................................................................3
Controls and Indicators –Front Panel.............................................................................5
GNSS Status...............................................................................................................7
GNSS Receiver - Standard .............................................................................................9
Sensitivity....................................................................................................................9
TTFF (Time to First Fix).............................................................................................10
PPS Availability.........................................................................................................12
Cable Delays.............................................................................................................13
Pulse Width...............................................................................................................13
Factory Default Settings............................................................................................13
GNSS Receiver-High Performance...............................................................................14
Status LEDs..............................................................................................................16
Power Supply Status (with optional DC supply).........................................................16
Alert Threshold..........................................................................................................19
Latch Channel Value.................................................................................................22
Save Configuration....................................................................................................22
Fault Status..................................................................Error! Bookmark not defined.
UTC Mode....................................................................Error! Bookmark not defined.
GMT Offset...................................................................Error! Bookmark not defined.
Power Switch ............................................................................................................23
Rear Panel....................................................................................................................23
Channel Output - BNC...............................................................................................23
Antenna Input A/B - SMA ..........................................................................................23
Antenna Connection (with GNSS option only)...........................................................24
DC Input....................................................................................................................24
AC Input....................................................................................................................25
RS232 DB9 (Status)..................................................................................................25
RS232 DB9 (NMEA)..................................................................................................26
Ethernet Port.............................................................................................................27
Functional Description...................................................................................................27
Phase Noise..................................................................................................................28
Outputs .....................................................................................................................29
Built-in Test...............................................................................................................29
Power Supplies .........................................................................................................29
Crystal...........................................................................................................................29
Calibration.....................................................................................................................36
Programming Guide (RS232 Status Port)......................................................................36
7.1 RS232 Commands (Status Port) .........................................................................37
Status String ($GPNVS,1) Fault Bytes ......................................................................40
Status String ($GPNVS,2) Channel Values...............................................................41
Status String ($GPNVS,3) Power Supply Values......................................................42
Technical Specification..................................................................................................43
Performance..............................................................................................................43
Environmental and Mechanical..................................................................................44
LIMITED HARDWARE WARRANTY.............................................................................45
Appendix: GNSS Command Reference.........................................................................47

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Summary
The NR2110-R/O/G is a dual channel precision GNSS/GPS locked 10MHz and
PPS. The amplifier is a low phase noise design to preserve the integrity of the
reference signal. All outputs are transient, and fault protected.
This unit is a versatile timing platform that can be configured to meet several
synchronization applications. With atomic holdover capability, the unit provides
critical timing in GPS-denied or unreliable environments.
Features:
-atomic holdover maintains timing accuracy (< 50 usec /24 hours)
-precision 10 MHz frequency reference
-optional frequencies synthesized from GPS locked 10 MHz (10 KHz to 10
MHz)
-1.544, 2.048 or 5 MHz outputs available
-PPS output (LVCMOS) 20 ns rms
-RS232 NMEA
-LCD display provides time, status
-optional dual time base
-optional high performance GNSS receiver
When locked to the GPS, the NR2110-R/O/G operates as a GPS/GNSS locked
frequency reference and PPS source. While locked to the GPS, the OCXO
reference is continually being disciplined in frequency and its internal PPS is
aligned to UTC PPS within <50 ns. If GPS is lost, the unit uses the disciplined
Rubidium or OCXO as the master time reference. The PPS remains aligned to
UTC PPS with a drift rate of <40us/day (Rb) less than 5 ms/day (OCXO)
(assumes 24 hours of GPS locked).
The unit features auto-calibration, which ensures the most recent OCXO
compensation coefficients are stored in non-volatile memory. The compensation
values eliminate drift due to aging and/or temperature and are stored and applied
to the OCXO during loss of GPS lock conditions. These coefficients are updated
after two hours of continuous GPS locked state. This effectively eliminates long-
term OCXO changes.
Excellent aging characteristics are achieved using intrinsically low-jitter overtone
SC cut crystals in a temperature-controlled oven. There are two 10MHz outputs
on the rear panel (BNC) connector. Low phase noise is achieved by the inherent
crystal characteristics and appropriate design techniques for noise mitigation.

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TYPICAL PHASE NOISE PERFORMANCE
Offset Frequency, Typical
Offset (Hz)
Standard (dBc/Hz)
10
-125
100
-145
1K
-155
The NR2110-R/O/G delivers a low phase noise curve, which can be seen in the
sample production test below.
NR2110-O/G PHASE NOISE MEASUREMENT
The unit features extensive reporting via the rear panel RS232 port - equipment
status, output voltage on each channel. By being able to monitor the output
voltage, the user can detect cabling issues that cause an impedance change and
replace cabling before it completely fails. Reporting is also easily accessible via
the front panel display.

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Nominal power is global AC power, but a DC power option can be ordered that
acts as the back-up power supply. Nominally 24 Vdc, this port is used for power
when AC power fails. Switching between power sources is automatic and there is
no transient power outage at the equipment level. The primary power supply is
followed by low noise linear converter assemblies.
The optional dual time base adds an additional GNSS receiver that monitors the
primary GNSS receiver, detects when the timing source is out-of-tolerance and
sends an email and alert locally. The redundancy can be duplicated all the way to
the antenna or a single antenna can be used with a splitter located inside the
chassis.
Controls and Indicators –Front Panel
The three LEDS provide a comprehensive status of the unit:
ALERT:
This LED should always be GREEN. There are several self-tests executed within
the unit and the summation of these tests is that the unit is functional. A RED
indication is a failure, and the unit should be removed from service.
OVEN:
This LED serves several functions:
GNSS Lock Status: Flashing GREEN indicates that the unit has not achieved
GNSS lock. The flashing state of this LED should not exceed 15 minutes. If it
stays in the flashing state too long or is found to be going in and out of the
flashing state- there may be a problem with the antenna or cabling to the
antenna. Monitoring the GNSS strings on the serial port will advise locking status
in more detail.

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Rubidium Lock: The Rubidium must achieve a fixed temperature to
achieve a plasma that can be used for timing. This will take on the order of
15 minutes.
Fault: a flashing indicator warns of a faulted 10 MHz output. If this state is
observed, remove the 10 MHz loads and install a 50 Ohm load and confirm the
fault is cleared. The Novus status strings will assist with troubleshooting a fault
problem.
$GPNVS
1
hhmmss
mmddyy
A
nn
0x00
0x00
0x00
*
XX
1
2
3
4
5
6
7
8
9
10
# Description Range
1. Identifier $GPNVS
2. String ID 1
3. Time (UTC) hhmmss
4. Date mmddyy
5. GPS Lock (Valid) “A” = Valid, “V” = Not Valid
6. # of Sats in View Greater of GPS or GNSS count
7. Channel Fault Byte 0x00 to 0x3F (Hex OR’d value)
8. Power Supply Fault Byte 0x00 to 0x3F (Hex OR’d value)
9. Error Message Byte 0x00 to 0x0F (Hex OR’d value)
10.NMEA Checksum *XX (xor’d value of bytes between $ and *)
Example:
$GPNVS,1,233518,092516,A,10,0x00,0x00,0x00*62
Time: 23:35:18; Sep. 25, 2016, GPS locked; 10 Satellites in view; No channel
faults; No power supply faults; No error messages.

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GNSS
On power-up, the GNSS receiver will begin the process of searching and locking
to available satellites. The systems to be used can be programmed and the
default will depend upon the receiver selected.
Novus offers two levels of GNSS receivers. The basic receiver is a 26 channel
GNSS receiver. The receiver and companion elements generate the GNSS sine
wave, 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.
The more advanced receiver meets the most stringent 5G timing requirements, is
ideal for global deployments due to GPS, BeiDou, Galileo, and GLONASS
reception, and is unaffected by ionospheric errors. The module provides
differential timing mode for highly accurate local timing and built-in security for
highest robustness against malicious attack
Standard PPS 25ns(1σ) (@-130 dBm) 50ns(1σ) (@-150 dBm)
High accuracy PPS 5ns(1σ) (@-130 dBm) 10ns(1σ) (@-150 dBm) with vibration
and thermal isolation.
The PPS stability also effects the Allan Deviation for the reference.

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High Stability Allan Deviation
Standard Receiver Allan Deviation Performance:

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The PPS source can be either directly from the radio or from the stabilizer.
This is software selectable.
GNSS Receiver - Standard
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

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GLONASS
Tracking: -157 dBm
Hot Start: -157 dBm
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 experience difficulty 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
knowing all satellite positions and measuring the signal transit times, the user’s
position can be accurately determined.

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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 is the
option of setting the NEMA PPS relationship to be for the edge that occurred last.
Advise factory for the desired configuration.
There are several attributes for the PPS that can be controlled via the RS232
port. What can be controlled is a function of the configuration being used. The
PPS source can be from the receiver, the Rubidium, or a synthesized PPS.
Standard Receiver Source:
Factory default is 200ms and can be programmed in 1 ms increments to 500 ms.
High Performance Receiver:
When the Rubidium option is chosen, the PPS generated by the Rubidium is
used and cannot be programmed.
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 shown below.

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For applications requiring a more stable PPS –a source such as an OCXO or
atomic reference should be considered. The PPS can also be enabled or
disabled based upon a calculated accuracy.
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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GNSS Receiver-High Performance
It meets the most stringent 5G timing requirements, is ideal for global
deployments due to GPS, BeiDou, Galileo, and GLONASS reception, and is
unaffected by ionospheric errors. The module provides differential timing mode
for highly accurate local timing and built-in security for highest robustness against
malicious attack.

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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
will continue to monitor each channel and a deviation beyond the set limits would
be reported as a failure on the front panel and via RS232.
The channel status feature can quickly detect a cabling failure. Any change in
the load impedance will change the output voltage with respect to the divider
formed by the output impedance of the amplifier and the load impedance. Failing
cables and connectors can be detected early.
The status is accessible over the RS232 serial bus via DB9.

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Status LEDs
There are three status LEDs which provide a quick indication of valid unit
operation.
Alert LED: The Alert LED will illuminate flashing RED to indicate a GNSS failure
or a power supply failure. The Alert LED will not flash RED if any valid input
signal is present.
Oven LED (OCXO option only): The Oven LED will illuminate RED to indicate
an oven failure.
Fault LED: The Fault LED will illuminate flashing RED to indicate a channel
fault, when any single channel is outside the user-defined threshold.
Power Supply Status (with optional DC supply)
The power supply status screen provides DC voltage values of the two available
power supply sources. The 90-250V AC input is internally connected to an
internal 24V AC-DC convertor which powers the internal supplies with 24V. This
is diode connected with the external 24V DC input, which can be used in addition
to, or in place of, the AC input.
The values of both DC supplies are measured internally to validate connections.
The measured values of the AC/DC convertor and the DC input are reported in
the third and fourth fields of the second $GPNVS status string.
For details on the status strings, see Programmer’s Guide.

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In addition to direct value measurements, each redundant system has a power
supply status byte which is reported in the third $GPNVS status string, in the
seventh and eighth fields respectively.
Any measurement of the power supply which results in an alert condition will be
reported in the power supply status byte.
0x80 = External AC not connected.
0x40 = External DC not connected.
If the optional external DC power supply is requested, redundant power
supplies will operate on either the AC input or DC input, and function
independently. All functionality and reporting for an individual power
supply and amplifier is independent of its redundant copy.
If a communications failure is reported, the backup system will
automatically switch to the redundant system.

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24V DC Option Mating Connector
RT060102SNH –mating connector
https://www.amphenol-sine.com/RT06102SNH-Plug-Female-4-Contacts-Contact-
Sizes-16-20-13A-5A350V-Shell-Size-10_p_1056.html
RT0L-10CG-S2 –Strain Relief
https://www.amphenol-sine.com/RT0L-10CG-S2-Long-Backshell-straight-Shell-
Size-10-Cable-Range-50-85mm_p_1340.html
MS16M23F –Socket Contact for Holes A & B
https://www.amphenol-sine.com/MS16M23F-Socket-Contact-Size-16-Machined-
Gold-Flash-Wire-Range-75-15mm%C2%B2-16-18-AWG-Compatible-to-part-
RC16M23J-192991-0041_p_921.html
MS20W23F - Socket Contact for Holes 1 & 2
https://www.amphenol-sine.com/_p_941.html
Ais V+ and is a Red 18 AWG wire
B is V- and a Black 18 AWG wire
1is Ground is a Green 22 AWG wire
2is Chassis Ground is a Green 22 AWG wire
Note this view is the
back of the
RT060102SNH
mating connector
and the same as on
the NR2310D-R/O/G.

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Alert Threshold
The alert threshold screen allows the user to adjust the tolerance from the
reference voltage which, if exceeded in either direction, the output channel will
report a fault status. The default threshold 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 output channel has a reference voltage which can be set by latching the
channel’s current value in the latch channel average screen. The output
reference voltage can be set individually by writing the value serially with the
$SET command. After saving the current configuration on a channel, any
subsequent deviation on that channel which exceeds the alert threshold
percentage will trigger an alert.
Steps to ensure correct alert configuration:
1. Connect distribution cabling to the 10MHz output.
2. Set alert threshold to desired range.
3. Save current channel voltage with the latch channel values screen.
4. Save current settings on the save configuration screen.

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The alert threshold can be optimized so that a channel short or an
impedance change will cause an alert.