Novus PICOPOD NR7000 User manual

Users manual
NR7000
Revision #:
B
Date:
102121
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NR7000
picoPOD
10, 50,100 MHz GNSS-Locked OCXO Reference
with NMEA, PPS and Auto-Cal
All information provided herein is the property of Novus Power Products
L.L.C. The information included may be reproduced without the permission
or prior approval of Novus Power Products L.L.C. for the purpose of
operating the equipment.

Users manual
NR7000
Revision #:
B
Date:
102121
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Contents
1.0 Summary ..........................................................................................3
2.0 Inputs / Outputs ..............................................................................7
2.1 GNSS Antenna ............................................................................................... 7
2.2 SAMTEC Connector (10-pin MiniMate)............................................................. 8
2.3 PPS (Pin)....................................................................................................... 8
2.4 10 MHz sine (SMA)......................................................................................... 9
3.0 Typical Phase Noise .......................................................................10
4.0 Built-in Test....................................................................................11
5.0 Power .............................................................................................12
6.0 GNSS Function ...............................................................................13
7.0 Programming Guide (STATUS Port) ..............................................15
7.1 Status Commands.........................................................................................16
7.2 Status Strings ($GPNVS)................................................................................17
8.0 Mechanical .....................................................................................18
9.0 Performance...................................................................................19
Technical Specifications ......................................................................................19
Environmental and Mechanical ............................................................................21
10.0 LIMITED HARDWARE WARRANTY ..............................................22
11.0 Appendix: GPS/GNSS Command Reference ..............................24

Users manual
NR7000
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B
Date:
102121
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1.0 Summary
The NR7000 is a GNSS-locked OCXO 10 MHz frequency
reference with auto-calibration. It features a 10 MHz Sine
output that is fault and transient protected.
The unit is also available at 50 and 100 MHz
The unit also provides a PPS and NMEA 0183 at full RS232
levels. The RS232 ports can also be configured to operate at
logic levels.
The master timing is from a 26 channel GNSS receiver that
supports GPS, GLONASS, SBAS, QZSS. By being able to
receive data from multiple satellite constellations, lower TIFF is
achieved. With twice the number of satellites in view, as a GPS
only configuration, achieving and maintaining lock in poor signal
environments is enhanced.
The signal source is a GNSS disciplined low noise OCXO,
actively controlled by a mixed-signal control loop. Typical
phase noise performance follows.

Users manual
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picoPod 10 MHz Phase Noise
picoPod 100 MHz Phase Noise

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OCXO Warm-up Characteristics
Power required is 5.0Vdc to 5.5Vdc. This must be a low noise
source. Local filtering is recommended. There is internal
filtering but noise on the input power, while attenuated, can
compromise phase noise. The input filtering should be near the
device using design methods that are consistent with RF
methodologies. The circuit below is recommended and uses
three capacitor technologies- aluminum electrolytic, tantalum
and ceramic.

Users manual
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The NR7000 continually monitors temperature and aging so
that, when the unit goes into holdover or loses GNSS lock, the
output frequency reverts to the last known locked frequency
value. The calibration feature continually monitors the
correction coefficients developed through GNSS timing
information. These are sampled multiple times per day and
stored in non-volatile memory and, in the event of a GNSS loss,
the saved coefficients are applied to the OCXO. This
effectively eliminates long-term crystal drift. Auto-Cal normally
keeps the reference ±10 ppb.
There are two RS232 ports - one for NMEA 0183 and the other
for unit status reporting. The NMEA port information and baud
rate can be selected via commands detailed in the Appendix.
The RS232 port provides the status of each channel and self-
test results. The RS232 signals are made available through one
DB-9 or a stacked DB-9 pair.
All inputs and outputs are electrostatic discharge protected. Any
output can be shorted indefinitely with no permanent damage to
the unit.

Users manual
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102121
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2.0 Inputs / Outputs
Each output is fault and electrostatic discharge protected. Each
output is independent and any output can be faulted for an
indefinite period of time with no permanent damage. Each
output is connected to a monitor circuit that detects a local fault
on the output. The fault status is indicated for each of the 10
MHz outputs on a LED on the PCB or via the RS232 link.
2.1 GNSS Antenna
SMA female antenna connection. Provides internal 3.3VDC
power at 45mA max. The Novus NA103 pole mount antenna 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 Specifications:
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

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VSWR 2.0 Max
DC Input 2.8V - 6V
Noise Figure <2.0dB
Power Consumption 25mA (typ)
2.2 SAMTEC Connector (10-pin MiniMate)
The NR7000 has a single locking 10 pin SAMTEC MiniMate
0.1” connector (part number IPL1-105-01-L-D-RA-K).
10 pin MiniMate pinout
The reserved pins should not be connected.
There is an optional auxiliary output configuration. This option
provides a programmable LVCMOS output that is an n-divisor
of the internal bus frequency.
Optional Auxiliary LVCMOS output
2.3 PPS (Pin)
The PPS is a one pulse per second, LVCMOS, 3.3V signal into
1KOhm. The pulse width is nominally 100 ms but can be
programmed at the factory or in the field with the serial port
(see Appendix A). The PPS may be advanced/delayed via
serial port commands in 1 ns to compensate for antenna
cabling delays.
+5Vdc RES PPS IN TX RES
GND GND PPS OUT RX RES
+5Vdc RES PPS IN TX AUX OUT
GND GND PPS OUT RX GND

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2.4 10 MHz sine (SMA)
8 +-2 dBm into 50 Ohms.

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3.0 Typical Phase Noise
10MHz Sine- Primary Output
Offset Frequency (Hz) Typical (dBc / Hz)
10 -102
100 -110
1K -140
10K -145
There are optional phase noise performance levels available -
contact factory.

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4.0 Built-in Test
There are a number of power supplies in the design to meet
special needs and noise reduction. Each supply is monitored
and a power failure will be reported through the $GPNVS status
strings.
Channel faults are also monitored and reported via serial
TX/RX.
The lock status is a combination of GNSS receiver lock and the
Kalman filter locking. A failure of the Kalman filter to lock is
considered a failure mode.

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5.0 Power
The platform is designed to operate from +5Vdc to 5.5Vdc.
The unit is also fused with a 5 Amp slow blow. Caution should
be exercised when connecting power to the NR7000. The unit
is reverse voltage protected with a TVS diode. Applying a
negative voltage will result in a surge current that can blow the
fuse.
Power is less than 2 watts. Power is highest at turn on as the
OCXO is warmed rapidly. Crystal power will start over 4 Watts
and drop to approximately 1.5 Watts after three minutes at
25°C.

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6.0 GNSS Function
The receiver needs to be able to see at least four satellite
vehicles (SVs) 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 3-D fix due to insufficient satellite
geometry (i.e. poor DOP). Inside a building or beneath a bridge,
it may not be possible to update a position fix. 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.
To measure the range from the satellite to the receiver, two
criteria are required: signal transmission time and signal
reception time. All GNSS 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.

Users manual
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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.
The GNSS lock status can be monitored on the RS232/serial
connector.
If the GNSS indicator remains unlocked for an extended period
of time, it could be an indication of an antenna, cabling or unit
malfunction. Confirm the antenna is still connected and has not
become obstructed from a clear view of the sky. To check the
unit, an alternate antenna can be tried in order to isolate the
malfunction. For further support, please contact the factory at
866-313-9401.

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Date:
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7.0 Programming Guide (STATUS Port)
The NR7000-OG can accept user commands which will provide
particular fault detection performance which may be customized
by the user, and saved in non-volatile flash memory.
If the user makes several changes which are intended to be
kept between power off cycles, the command
“$SAVEFLASH<CR><LF>” will update flash to reflect all current
settings.
Table 1 shows a complete list of input commands and
descriptions. As a general rule, a command can be input
without “=” or additional value, and the unit will respond with the
current setting’s value. If the input is not understood, the
microcontroller will return the value “$?<CR><LF>”
NOTE: All commands should be followed by <cr><lf>.
A checksum can be added to all input commands, and the
requirement for a checksum can be turned on. The checksum
method is the two-hexadecimal character representation of an
XOR of all characters in the sentence between, but not
including, the $ and the * character.
Example: $BAUDNV=38400*08

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7.1 Status Commands
Setting
Command
Response
Description
STATUS OUTPUT
$STAT<n>
<$GPNVS,1….>
Query NVS<n> String. Useful for status output
on demand when user does not require regular
string output.
$STAT1
Outputs current $GPNVS,1 string on demand.
$STAT2
<$GPNVS,2….>
Outputs current $GPNVS,2 string on demand.
$STAT14
<$GPNVS,14….>
Outputs current $GPNVS,14 string on demand.
SAVE ALL VALUES
TO FLASH
MEMORY
$SAVEFLASH
$SAVED TO FLASH.
$FLASH SAVE FAILED.
This command will translate all current
variables to flash string and write. Data is then
read back for verification, and result reported.
RESET ALL TO
DEFAULT
$RESETALL
$RESET FLASH VARIABLES.
Resets all user settings to default values and
overwrites flash memory with defaults.
INVALID INPUT
$?
Command not recognized.
REQUIRE
CHECKSUM
$CSUM
$CSUM=<current CSUM>
Query or set mandatory checksum on all
incoming STATUS port communication. For $PERD
commands, checksum is always required.
1 = Enabled, 0 = Disabled. Default = 0.
$CSUM=1
$GPNVS
$NVS<n>
$NVS7=1
Enables/Disables output of $GPNVS strings. For
$NVS<n>=<m>, where <n> is the $GPNVS string
ID, and <m> is the output frequency in seconds.
$NVS9=1
Example: $NVS9=0 disables output of
$GPNVS,9.
$NVS10=1
$NVS11=1
AUXILIARY
FREQUENCY
OUTPUT
$AUXFR=<INTEGER>
$AUXFR=<INTEGER>
Sets the auxiliary frequency output. For
100MHz units, even integer devisors of
50,000,000 are recommended. Remainders of
the calculation 50,000,000/AUXFR are truncated.
Enter $AUXFR=0 to disable output. If disabled,
allow 10 seconds for an enabled output to restart.
For 10MHz units, use even integer divisors of
70,000,000.
PPS PULSEWIDTH
$PULSW=<FLOAT>
$PULSW=<FLOAT>
Sets or returns the current PPS pulsewidth in
ms.
Range: 0.0001 to 500 [ms]
FREQUENCY
TOLERANCE
$FQTOL
$FQTOL=0.01
Sets the frequency tolerance of the lock
indication in Hz. (float)
RS232 BAUD
RATE
$BAUDNV
$BAUDNV=<current Baud
Rate>
Query Baud Rate on rear panel RS232. (Default
= 115200)
$BAUDNV=38400
Assign Baud rate to Rear Panel RS232 port.
Default is 115200. Available baudrates are 9600,
19200, 38400, 57600, 115200.

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7.2 Status Strings ($GPNVS)
See Appendix C $GPNVS String Definitions for detailed explanation
of $GPNVS status strings

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8.0 Mechanical

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9.0 Performance
Technical Specifications
10 MHz sine
1.0 ±0.1 for 10 MHz. 0.5 ±Volts @ 100 MHz,50 Ohm - SMA
Harmonics
Less than -30 dBc
Locked stability (AD)
<~E-12 after 1000 seconds
First year frequency stability
±100 ppb (long-term unlocked)
Temperature stability
±100 ppb (unlocked)
Yearly aging
±100ppb (unlocked)
Phase Noise dBc/Hz
10 MHz
10 Hz
-120
100 Hz
-130
1 kHz
-140
10 kHz
-150
50 MHz
10 Hz
-90
100 Hz
-115
1 kHz
-140
10 kHz
-145
100 MHz
10 Hz
-80
100 Hz
-110
1 kHz
-140
10 kHz
-145
PPS
Amplitude for 1PPS
3.3 Vdc CMOS (5 Vdc option)
Pulse width for 1PPS
Programmable 1 to 500ms in 1 ms steps
Rise time for 1PPS
<5ns
Accuracy
1σ10 ns Max accuracy < 40 ns
Connector
10 Pin 0.1” (Samtec IPL1-105-01-L-D-RA-K)
Load Impedance
500 Ohm
Location
Side Connector
Remote interface & control
Protocol
RS232 NMEA-0183: RMC,GSA,ZDA,GSV,NVS
Connector
Side connector
Location
side panel
Protocol
Bit plus stop

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Standard Baud Rates
Selectable: 9600, 19200, 38400, 57600 or 115200 bps
GNSS receiver
GPS L1 C/A, GLONASS L1OF, QZSS L1 C/A, SBAS L1 C/A
(Ready): Galileo E1B/E1C, QZSS L1S
Channels
26 channels (GPS, GLONASS, QZSS, SBAS)
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
Warm Start: -143 dBm
Cold Start: -143 dBm
Reacquisition: -157 dBm
With Novus recommended antenna
Antenna with LNA
Antenna power
3.5 Vdc, < 35 ma (on center conductor) (factory configurable to 5 Vdc)
Frequency
1574-1607 MHz
Nominal Gain
2 dBic
Amplifier gain
26 dB
Noise Figure
< 2.0 dB
Out of Band rejection
Fo±50MHz=60 dBc, Fo±60 MHz
Secondary Channel
Derived from 50 MHz master oscillator locked to 10 MHz. Sub 1 Hz to
25 MHz
Contact factory for valid synthesis values
Output impedance is 200 Ohm.
Power
5 -0.1,+0.5 VDC Peak power < 3 watts, steady state < 2 watts
Power connector
On ten pin connector
Mounting
4 –M3.5x0.6 threaded mounting holes
Chassis
Aluminum