Novus NR2316-OG User manual

Users manual
NR2316-OG
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User Manual Model NR2316-OG
16 Channel GPS Locked OCXO
Frequency Reference
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. with out prior approval for purpose of operating the equipment.

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Contents
1.0 Summary....................................................................................................................... 3
2.0 Controls and Indicators –Front Panel .......................................................................... 7
2.1 GNSS Status.............................................................................................................. 8
2.2 GNSS Detailed Status............................................................................................... 8
2.3 Channel Status .......................................................................................................... 9
2.4 Status LEDs ............................................................................................................ 10
2.5 Power Supply Status............................................................................................... 11
2.6 Alert Threshold....................................................................................................... 13
2.7 Latch Channel Values............................................................................................. 16
2.8 PPS Status............................................................................................................... 16
2.9 GPS Select .............................................................................................................. 18
2.10 Save Configuration ............................................................................................... 19
2.11 Fault Status............................................................................................................ 20
2.12 UTC Mode............................................................................................................ 21
2.13 GMT Offset........................................................................................................... 21
2.14 Power Switch........................................................................................................ 22
3.0 Rear Panel................................................................................................................... 23
3.1 Channel Ouputs - BNC........................................................................................... 23
3.2 Antenna Input A/B - SMA...................................................................................... 24
3.3 DC Input.................................................................................................................. 24
3.4 AC Input.................................................................................................................. 25
3.5 RS232 DB9 Front (NMEA/Status)......................................................................... 26
3.6 RS232 DB9 Rear (Linux Console Debug).............................................................. 27
4.0 Functional Description................................................................................................ 28
4.1 Phase Noise............................................................................................................. 29
4.2 Outputs.................................................................................................................... 30
4.3 Built in Test............................................................................................................. 30
4.4 Power Supplies........................................................................................................ 30
5.0 Crystal......................................................................................................................... 31
6.0 Calibration................................................................................................................... 36
7.0 Programming Guide (RS232 Port: Front and Rear) ................................................... 37
7.1 RS232 Commands .................................................................................................. 38
7.2 Status Byte Key....................................................................................................... 43
8.0 Technical Specification............................................................................................... 46
8.1 Performance............................................................................................................ 46
8.2 Environmental and Mechanical ...............................Error! Bookmark not defined.
9.0 LIMITED HARDWARE WARRANTY.................................................................... 48
10.0 Appendix: GNSS Command Reference.................................................................... 50

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1.0 Summary
The NR2316 is a 16 Channel precision GNSS/GPS locked 10MHz frequency reference.
The amplifier is a low phase noise design to preserve the integrity of the reference signal.
All outputs are transient and fault protected.
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 eight hours of continuous GPS
locked state. This effectively eliminates long-term OCXO changes.
Excellent aging characteristics are achieved through the use of intrinsically low jitter
overtone SC cut crystals in a temperature controlled oven. There are ten outputs on the
rear panel (BNC) connectors. Low phase noise is achieved by the inherent crystal
characteristics and appropriate design techniques for noise mitigation.
Units can be customized to any number of channels, can be changed to PPS output, or
can be mixed to be 8 sine + 8 PPS outputs, etc.
Typical Phase Noise performance:
Offset Frequency, Typical
Offset (Hz)
Standard (dBc/Hz)
10
-110
100
-135
1k
-145

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The NR2316-OG delivers a low phase noise curve, which can be seen in the sample
production test below.
NR2316-OG Phase Noise Measurement

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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.
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 converters assemblies.

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2.0 Controls and Indicators –Front Panel
This section describes the functionality of the front panel controls and indicators.
Two buttons above the status LEDs provide navigation through the menus.
In general, the NEXT button advances through the menus to the next screen,
while the SELECT button chooses between the available values on a menu.
Menus that allow selectable adjustments are the Input Threshold, Alert Threshold,
and the Attenuation setting. To adjust these values from the front panel, hold
down both buttons for two seconds, until the value begins to flash. To leave the
menu with the new value, hold down both buttons until the value is solid.

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2.1 GNSS Status
On power up, the NR2316-OG will display the Time and Date as well as the
current status of both GNSS receivers.
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.
2.2 GNSS Detailed Status
The GNSS Status Menu gives the user a quick reference for the quality of the
GNSS satellite signal and length of time that each receiver has been locked.
To toggle between each receiver, press the SELECT button. The screen will
display which receiver status is being viewed.
The user can then see number of GPS satellites in view, number of GLONASS
satellites in view, and the UTC time and date that lock occurred on the selected
receiver.

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2.3 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
±55% 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
would 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 current threshold limits are displayed in addition to the actual measured
value. These values reflect the percentage threshold defined in the Alert
Threshold settings. If the output value is too low to give a valid reading. The
display will read “LOW.”
The status is displayed on the front panel and is accessible over the RS232 serial
bus via DB9. Channel Statuses can be cycled into view or can remain on a single
channel. This feature can be accessed via the NEXT button, by advancing to the
Channel Status screen. To cycle through channels in sequence, press the
SELECT button.

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2.4 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.
Oven LED (Onboard GPS): The Oven LED will illuminate steady green if all
onboard GPS/GNSS units are locked. The LED will flash green if at least one unit
is unlocked.
Fault LED: The Fault LED will illuminate flashing red to indicate a Channel
Fault, when any single channel is outside the user defined threshold.

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2.5 Power Supply Status
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 12V/24V AC-DC convertor which powers the internal supplies with
12V/24V. This is diode connected with the external 12/V24V DC input, which
can be used in addition to, or in place of, the AC input. The external DC input
can be ordered to accommodate a variety of DC input levels. Contact Novus for
options.
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.
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 option is included).

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Redundant power supplies operate on either the AC input or DC input, and
function independently.
If a communications failure is reported, the backup system will automatically
switch to the redundant system.

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2.6 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 channels will
report a fault status. The default threshold value is set at ±55% percent from the
current state of the amplifier, and is user programmable in 5% increments, from
±10% to ±60%.
Each channel has a Reference Voltage which can be set, all at once, by latching
the channels’ current value in the Latch Channel Average Screen. Each channel’s
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 channels 1 through 16.
2. Set Alert Threshold to desired range.
3. Save current channel voltages 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.

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Example:
The output of channel 1 is connected to a high impedance input and reports
1.25Vrms at the output. The output of channel 2 is connected to a 50ohm
terminated input, and reports 0.90Vrms at the output.
Alert threshold is set to +/-20%.
The current state is saved in the Save Configuration screen.
The Channel 1 alert will report when:
-The Channel 1 output is higher than 1.50Vrms
-The Channel 1 output is lower than 1.00Vrms
The Channel 2 Alert will report when:
-The Channel 2 output is higher than 1.08Vrms
-The Channel 2 output is lower than 0.72Vrms
To adjust the Alert Threshold from the front panel, hold the NEXT and SELECT
buttons down simultaneously for two seconds. The percentage value will begin
flashing. To increase the value, press the SELECT button. To decrease the value,
press the NEXT button.
When the desired value is reached, press the NEXT and SELECT button
simultaneously to leave the settings mode.
The Alert Threshold settings can be modified via the RS232 serial port with the
$FLTTHR command.
For details on the Alert Threshold, see Programmer’s Guide.

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2.7 Latch Channel Values
The Latch Channel Values Screen allows the user to save the current channel
output values for use as the Reference Value for Alert settings.
A channel Alert is triggered when a channel output voltage exceeds or falls below
a percentage of the Reference Value. This Reference value is 1.10Vrms as a
default, but can be set by the user.
There are two ways to set the Reference Voltage. The RS232 serial port allows
for setting an individual channel’s reference voltage with the $SET command.
The user can also use the Latch Channel Values to take a snapshot of ALL current
outputs, and use these as the reference values.
2.8 PPS Status
The PPS from the active GPS is monitored to verify output is active. The PPS
output can be disabled or enabled, as well as set to AUTO, which disables the
PPS during a user defined Warm Up period and after a user defined Hold Over
period has been exceeded.

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The $PWH (PPS Warmup/Holdover) setting can be changed via the serial port to
one of the three available settings:
$PWH=0
Off: PPS is disabled regardless of Warmup/Holdover status.
$PWH=1
Auto: Disabled during Warmup, Disabled after Holdover is exceeded.
(Enabled after warmup, during valid holdover)
$PWH=2
On: PPS is enabled regardless of Warmup/Holdover status.
Each GPS/GNSS may be addressed separately, and the settings can be viewed on
the PPS Enable/Disable screen.
The GPS settings will be displayed for each GPS receiver, whether AUTO PPS,
ENABLD PPS, or DISABLD PPS. If the option of a second GPS was not
ordered, N/A will be indicated.
The PPS measurement will indicate ACTIVE PPS if the output measures a PPS
present. If the PPS is not present due to the Warmup Period not having been
completed, while in AUTO PPS mode, the screen will indicate WARMUP WAIT.
If the GPS has remained unlocked for a period which exceeds the user defined
Holdover Period, the PPS status will indicate HLDOVR ERR.
Status of the Warmup and Holdover counters can also be monitored from the
$GPNVS string 11, which includes Warmup Complete and Holdover Valid fields,
as well as frequency valid fields.

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If a dual GPS/GNSS option is installed, the currently selected GPS PPS will be
noted with an arrow. This arrow indicates the actual source of the PPS. In addition, the
Active GPS will be noted with an arrow as well. The arrow will indicate switching to
backup in the case of failure of the primary, or loss of lock, as set in GPS Select setting.
2.9 GPS Select
The GPS Select screen is present on the NR2316 option with dual GPS/GNSS receivers.
This screen allows the user to specify which GPS Source is the primary output source for
the PPS and 10MHz outputs.
There are four settings, and these are the same as the serial command $GPS:
Setting
Description
Serial
Command
GPS 1
GPS 1 is used as output regardless of lock status or error
$GPS=0
GPS 2
GPS 2 is used as output regardless of lock status or error
$GPS=1
AUTO (1)
GPS 1 is default, if locked and no errors, else GPS 2 is used
$GPS=2
AUTO (2)
GPS 2 is default, if locked and no errors, else GPS 1 is used
$GPS=3
To cycle through the selections, use the SELECT button. To save, go to the Save
Configuration Screen, or use the serial $SAVEFLASH command. The default setting is
Auto (1).
The GPS Select setting also determines the output of the GPS/GNSS specific strings to
the serial RS232 and the SNMP GPS specific settings. The strings that follow the
specified GPS are the RMC, GNS, GSA, GSV, ZDA, and NVS (strings 7 through 11).

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2.10 Save Configuration
The Save Configuration screen allows the user to save the current settings for
Alert Threshold, Input Threshold, Attenuation, Input Select, Reference Voltage
and any other settings that have been modified via the RS232 port.
To save the current settings, press the SELECT button twice.
The Save Configuration action is equivalent to the $SAVEFL command on the
serial port.

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2.11 Fault Status
The Fault Status screen allows a quick overview of any Channel faults from the
front panel. The total fault count is listed, as well as a visual flashing indication
of any channels that are beyond the threshold values.
Press SELECT to advance to the System Fault Screen.
The System Fault Screen indicates any failures in the primary system or the
redundant backup system. All internal power supplies are monitored (24V, +8V,
-8V, 5V) on both the primary and backup systems. A failure on one of these
supplies will be indicated with a “PS FAIL” fail warning for either system. A
communication failure would be indicated by a “Com FAIL” indicator. Either of
these fault statuses will result in the change of the primary to the backup system.
The individual statuses of the internal power supplies are also available via the
RS232 serial port.
The presence of a valid DC input voltage is indicated on this screen, as well as a
valid AC power input. If either of these supplies are not present, a “FL”
indication will be shown next to the appropriate input.