OXTS xNAV650 User manual

xNAV650
Hardware Manual
20 Years Navigation Experience in one small INS

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Legal notices
Information furnished is believed to be accurate and reliable. However, Oxford Technical Solutions
Limited assumes no responsibility for the consequences of use of such information nor for any
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Specifications mentioned in this publication are subject to change without notice and do not represent
a commitment on the part of Oxford Technical Solutions Limited. This publication supersedes and
replaces all information previously supplied. Oxford Technical Solutions Limited products are not
authorised for use as critical components in life support devices or systems without express written
approval of Oxford Technical Solutions Limited.
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out of the use of this software, even if advised of the possibility of such damage.
Copyright notice
© Copyright 2020, Oxford Technical Solutions.
Revision
Document Revision: 210311 (See Revision History for detailed information).
Contact details
Oxford Technical Solutions Limited
Park Farm Business Centre
Middleton Stoney
Oxfordshire
OX25 4AL
United Kingdom
Tel: [phone]
Fax: [phone]
Web: http://www.oxts.com
Email: [e-mail]

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Warranty
Oxford Technical Solutions Limited warrants its products to be free of defects in materials and
workmanship, subject to the conditions set forth below, for a period of one year from the Date of Sale.
“Date of Sale” shall mean the date of the Oxford Technical Solutions Limited invoice issued on delivery
of the product. The responsibility of Oxford Technical Solutions Limited in respect of this warranty is
limited solely to product replacement or product repair at an authorised location only. Determination of
replacement or repair will be made by Oxford Technical Solutions Limited personnel or by personnel
expressly authorised by Oxford Technical Solutions Limited for this purpose.
In no event will Oxford Technical Solutions Limited be liable for any indirect, incidental, special, or
consequential damages whether through tort, contract or otherwise. This warranty is expressly in lieu
of all other warranties, expressed or implied, including without limitation the implied warranties of
merchantability or fitness for a particular purpose. The foregoing states the entire liability of Oxford
Technical Solutions Limited with respect to the products herein.
Any use or misuse of the product in a manner not intended may impair the protection provided. Please
contact OxTS if you believe any service or repair is required on your product.

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Contents
Legal notices .......................................................................................................................................2
Copyright notice...................................................................................................................................2
Revision...............................................................................................................................................2
Contact details.....................................................................................................................................2
Warranty..............................................................................................................................................3
Introduction..............................................................................................................................................7
Related documents..............................................................................................................................7
Scope of delivery.................................................................................................................................8
Conformance notices ..............................................................................................................................9
Regulator testing standards.................................................................................................................9
Hardware description ............................................................................................................................10
Overview............................................................................................................................................10
LED definitions ..................................................................................................................................12
Dimensions........................................................................................................................................13
Coordinate frame...............................................................................................................................14
Interfaces...............................................................................................................................................15
Main connector..................................................................................................................................15
PPS................................................................................................................................................16
Serial..............................................................................................................................................16
Digital I/O .......................................................................................................................................17
User cable..........................................................................................................................................17
Antennas............................................................................................................................................18
Internal storage..................................................................................................................................18
Ethernet configuration .......................................................................................................................19
Connection details for ethernet configuration................................................................................19
Best practices........................................................................................................................................20
Mounting............................................................................................................................................20
Orientation and alignment..............................................................................................................20
Dual antenna systems.......................................................................................................................21
Multipath effects on dual antenna systems....................................................................................22
Antenna placement and orientation...............................................................................................22
xNAV650 orientation and alignment..................................................................................................23
Specifications........................................................................................................................................24
Notes on specifications......................................................................................................................26
Heading accuracy..............................................................................................................................26
Export control classification number..................................................................................................26
Software installation..............................................................................................................................28

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Operating principles..............................................................................................................................30
Strapdown navigator..........................................................................................................................30
Extended Kalman filter ......................................................................................................................31
Use with survey hardware.....................................................................................................................32
Data logging ......................................................................................................................................32
PPS and NMEA.................................................................................................................................33
PPS/Triggers .....................................................................................................................................34
PTP....................................................................................................................................................35
Cable modification.............................................................................................................................36
Appendix ...............................................................................................................................................37
Wiring guide for standard interfaces .................................................................................................37
Appendix 2 ............................................................................................................................................38
Drawings............................................................................................................................................38
Revision history.....................................................................................................................................40
List of figures
Figure 1: xNAV650 front view ...............................................................................................................10
Figure 2: xNAV650 top view..................................................................................................................11
Figure 3: xNAV650 dimensions and measurement origin point (mm)..................................................13
Figure 4: xNAV650 coordinate frame axes...........................................................................................14
Figure 5: xNAV650 main connector pin layout......................................................................................15
Figure 6: PPS waveform.......................................................................................................................16
Figure 7: xNAV650 user cable..............................................................................................................17
Figure 8: xNAV650 mounting points (mm)............................................................................................20
Figure 9: Dual antenna orientations......................................................................................................22
Figure 10: Windows Firewall warning message....................................................................................29
Figure 11: Schematic of the strapdown navigator ................................................................................30
Figure 12: NAVconfig LiDAR Scanner tab............................................................................................33
Figure 13: The PPS/Triggers tab in NAVconfig. ...................................................................................34
List of tables
Table 1: Supplementary manuals ...........................................................................................................7
Table 2: xNAV650 scope of delivery.......................................................................................................8
Table 3: xNAV650 points of interest .....................................................................................................11
Table 4: Power LED..............................................................................................................................12
Table 5: Status LED..............................................................................................................................12
Table 6: GNSS LED..............................................................................................................................12
Table 7: Main connector pin description...............................................................................................15
Table 8: PPS electrical specifications...................................................................................................16
Table 9: Digital I/O electrical specifications ..........................................................................................17
Table 10: xNAV650 user cable pin description.....................................................................................18
Table 11: xNAV650 performance specifications...................................................................................24
Table 12: xNAV650 inertial sensor specifications.................................................................................24
Table 13: xNAV650 physical characteristics.........................................................................................25

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Table 15: NAVsuite components ..........................................................................................................28
Table 16: Hardware integration manuals for surveying devices...........................................................32
Table 17: Epoch time configurations.....................................................................................................35
Table 18: Time epoch advanced commands........................................................................................36

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Introduction
Thank you for choosing the xNAV650 inertial navigation system (INS). The xNAV650 combines dual
GNSS receivers and a multi-core tactical-grade IMU into one self-contained package. This document
covers the technical information and hardware design instructions for the xNAV650 module to enable
you to successfully integrate it into your system.
The xNAV650 is OxTS’ newest Inertial Navigation System using the latest technology we have
developed in our smallest form factor yet. The intended use of the product is to deliver high quality
navigation data and diagnostics to the specification detailed within this manual and on the xNAV650
datasheet for a wide range of applications and vehicles. The unit can be used in land vehicles or on
drones, for example for LiDAR or camera surveying.
Related documents
This manual covers the installation and operation of the xNAV650, but it is beyond its scope to provide
details on service or repair. Please contact OxTS support or your local representative for customer
service-related enquiries.
Additional manuals provide further information on some of the software and communication types
mentioned in this manual. Table 1 lists related manuals and where to find them.
The xNAV650 Quick Start Guide is another useful tool for using your INS system.
Table1: Supplementarymanuals
Manual
Description
OxTS
Georeferencer
Use OxTS Georeferencer to calibrate your setup and create pointclouds.
https://support.oxts.com/hc/en-us/articles/360016436060
NAVconfig
Use NAVconfig to configure the settings on your INS and to tell it what the physical
and hardware setup is that you are using.
https://support.oxts.com/hc/en-us/articles/360018688799
NAVsolve
Use NAVsolve to process your raw data into NCOM navigation data.
https://support.oxts.com/hc/en-us/articles/360000225449-NAVsolve-manual
NAVgraph
Use NAVgraph to display your navigation data and diagnostics after processing.
https://support.oxts.com/hc/en-us/articles/115002433465-NAVgraph-Online-
manual
NAVdisplay
Use NAVdisplay to view your navigation data in real time.
https://support.oxts.com/hc/en-us/articles/115002433285-NAVdisplay-Online-
manual
NCOM
Manual
Use this manual for decoding and using the NCOM format.
https://support.oxts.com/hc/en-us/articles/360011890040-NCOM-Manual
NCOM C
Code Drivers
A collection of C functions that can be used to decode the binary protocols from
the INS.
https://github.com/OxfordTechnicalSolutions/NCOMdecoder
NMEA 0183
Description
NMEA description manual for the NMEA outputs.
https://support.oxts.com/hc/en-us/articles/360011890180-NMEA-Manual

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Scope of delivery
The xNAV650 is supplied with the items listed below in the basic kit. Other items such as antennas and
antenna cables are provided separately.
Table2: xNAV650scopeofdelivery
Item
xNAV650 basic kit
xNAV650 inertial navigation system
✔
Software USB
✔
Quick start guide
✔
Ethernet cable (2 m)
✔
Ethernet cross-coupler
✔
Declaration of conformity
✔

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Conformance notices
The xNAV650 complies with the radiated emission limits for 47 CFR 15.109:2010 class A of part 15
subpart B of the FCC rules, and with the emission and immunity limits for class A of EN 55022. These
limits are designed to provide reasonable protection against harmful interference in business,
commercial and industrial uses. This equipment generates, uses and can radiate radio frequency
energy and, if not installed and used in accordance with the instructions, may cause harmful
interference to radio communications. However, there is no guarantee that interference will not occur
in a particular installation. If this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and on, the user is encouraged to try
to correct the interference by one or both of the following methods:
▪Re-orient or relocate the receiving antenna.
▪Increase the separation between the equipment and the receiver.
The xNAV650 incorporates GNSS receivers. No GNSS receiver will be able to track satellites in the
presence of strong RF radiations within 70 MHz of either the L1 GPS frequency (1575 MHz) or L2 (1228
MHz).
The xNAV650 conforms to the requirements for CE.
The xNAV650 is certified for use with GNSS antennae with a gain of less than or equal to 35 dB.
Regulator testing standards
EMC
▪BS EN 61326-2-1:2013 - Electrical equipment for measurement, control and laboratory use.
▪BS EN 301 489-19 v2.1.1 (2019-04) –Electro Magnetic Compatibility (EMC) standard for radio
equipment and services; Part 19: Specific conditions for Receive Only Mobile Earth Stations
(ROMES) operating in the 1,5 GHz band providing data communications and GNSS receivers
operating in the RNSS band (ROGNSS) providing positioning, navigation, and timing data.
LVD
▪BS EN 61010-1:2010 - Safety requirements for electrical equipment for measurement, control, and
laboratory use.
RED
▪BS EN 303 413 V1.1.1 (2017-06) - Global Navigation Satellite System (GNSS) receivers. Radio
equipment operating in the 1 164 MHz to 1 300 MHz and 1 559 MHz to 1 610 MHz frequency bands.
RoHS
▪BS EN 50581:2012 –Technical documentation for the assessment of electrical and electronics
products with respect to the restriction of hazardous substances.
FCC
▪47 CFR 15.109 –Code of Federal Regulations –Title 47 (Telecommunication): Part 15 (Radio
Frequency Devices) –Subpart B (Unintentional Radiators) –Section 15.109.
▪ICES-003 Issue 6 January 2016 –Information Technology Equipment (Including Digital Apparatus)
–Limits and Methods of Measurement.

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Hardware description
Overview
The xNAV650 is a miniature GNSS-aided inertial navigation system. It combines dual multi-
constellation, multi-frequency xNAV GNSS receivers with a tactical-grade quad IMU array to provide a
compact centimetre-level navigation solution. Additionally, the system includes 32 GB data storage and
an on-board processor running the real-time strapdown navigator and Kalman filter.
The dual receiver integration allows greater heading accuracy with wider antenna baselines and
ensures stable heading performance even when stationary and during low dynamics. The custom built
quad IMU array consists of four individual IMU sensors that each combine 6-axis MEMS gyros and
accelerometers, providing improved performance, noise reduction and redundancy. The sensor fusion
between the GNSS receivers and inertial sensors is done seamlessly in real time for a continuous 100
Hz navigation output. Data is automatically logged to the 32 GB eMMC for added data protection.
The user must perform visual inspection of equipment before use to ensure there is no damage.
Figure 1 and Figure 2 show the key points of note on the xNAV650. The numbered labels are described
in Table 3.
Figure1: xNAV650frontview

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Figure2: xNAV650topview
Table3: xNAV650points ofinterest
Label number
Description
1
Main I/O connector (15-way Micro-D)
oPower
oEthernet
oPPS
oSerial TX/RX
oDigital I/O signal 1/2 (configurable)
2
Primary GNSS connector (SMA)
3
Secondary GNSS connector (SMA)
4
Measurement origin point
5
LEDs

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LED definitions
Tables 4, 5 and 6 show the descriptions for each of the LED functions.
Table4: PowerLED
Colour
Description
Off
There is no power to the system or the power supply has failed.
Green
Power is applied to the system.
Orange
The system is powered and an ethernet link is present.
Table5: StatusLED
Colour
Description
Off
The operating system has not yet booted (this occurs at start-up).
Red-green flash
The system is asleep. Contact OxTS support for further information.
Red flash
The operating system has booted but the GNSS receiver has not yet output a
valid time, position, or velocity.
Red
The GNSS receiver has locked-on to satellites and has adjusted its clock to
valid time (1PPS output now valid). The INS is ready to initialise.
Orange
The INS has initialised and data is being output, but the system is not yet real
time (the Kalman filter delay is a few seconds). It takes ~10 seconds for the
system to become real time.
Green
The INS is running and the system is real-time.
Table6: GNSSLED
Colour
Description
Off
The GNSS receiver has a fault (valid only after start-up).
Red flash
The GNSS receiver is active but has not yet determined heading.
Red
The GNSS receiver has a differential heading lock.
Orange
The GNSS receiver has a floating (poor) calibrated heading lock.
Green
The GNSS receiver has an integer (good) calibrated heading lock.

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Dimensions
Figure 3 shows the outer dimensions of the xNAV650, the mounting points, and the measurement origin
point. When making measurements required in the configuration files, measurements should be made
from the origin point.
Figure3:xNAV650dimensionsandmeasurementoriginpoint(mm)

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Coordinate frame
The IMU reference frame shown in Figure 4 is popular with navigation systems –where the positive X-
axis points forwards, the positive Y-axis points right and the positive Z-axis points down. The xNAV650
can be mounted in any orientation, it is not necessary for its axes to match those of the host vehicle.
The configuration file will specify the transformation from the IMU frame to the vehicle frame.
Figure4: xNAV650coordinateframeaxes

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Interfaces
Main connector
The main I/O connector on the xNAV650 is a 15-way Micro D-sub. Figure 5 shows the pin layout.
Figure5: xNAV650mainconnectorpinlayout
Table 7 shows the pin descriptions.
Table7: Mainconnectorpindescription
Pin #
Name (function)
I/O type
Description
1
Supply+
P
Power supply +
2
Supply+
P
Power supply +
3
Serial
I/O
Serial RS232 RX
4
Serial
I/O
Serial RS232 TX
5
ERX-
I
Ethernet receive -
6
ERX+
I
Ethernet receive +
7
ETX-
O
Ethernet transmit -
8
ETX+
O
Ethernet transmit +
9
I/O signal 2
I/O
Configurable I/O. Contact OxTS for options
10
I/O signal 1
I/O
Configurable I/O. Contact OxTS for options
11
Signal ground (isolated)
P
Isolated signal ground
12
PPS (isolated)
O
Pulse per second synchronisation output,
referenced to isolated signal ground (#11)
13
Signal ground
P
Signal ground
14
Supply-
P
Power supply -
15
Supply-
P
Power supply -

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PPS
The PPS output is a pulse generated by the GNSS receiver. The output is active even when the GNSS
receiver has no valid position measurement. The falling edge of the pulse is the exact transition from
one second to the next in GPS time. The pulse is low for 1 ms, then high for 999 ms and repeats every
second. The output is a low-voltage CMOS output, with 0.8 V or less representing a low and 2.4 V or
more representing a high. No more than 10 mA should be drawn from this output.
Table8: PPSelectricalspecifications
PPS
Typical
Min
Max
Output Voltage High (V)
3.3
2
3.3
Output Voltage Low (V)
0
-
0.8
Output Current (mA)
-
-
2
The signal is configurable to the rising or falling edge. For details, please refer to the support article for
NAVconfig or check the hardware section of this manual.
Figure6: PPSwaveform
Serial
The serial interface uses a standard 5V logic RS232. The exact transceiver used is the
SN65C3221EPWR. For full details you can read the datasheet from Texas Instruments
https://www.ti.com/lit/ds/symlink/sn65c3221e.pdf?ts=1612353780873&ref_url=https%253A%252F%2
52Fwww.ti.com%252Fproduct%252FSN65C3221E

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Digital I/O
Table9: DigitalI/Oelectricalspecifications
I/O
Typical
Min
Max
Input Low Voltage (V)
-
-20
0.5
Input High Voltage (V)
-
2
20
Output Voltage high (V)
3.3
2
3.3
Output Voltage Low (V)
0
-
0.8
Output Current (mA)
-
-
4
Note that triggers are pulled up internally to allow a switch to be used to short them to GND.
User cable
The standard xNAV650 user cable is designed for quick access to the main interfaces. Figure 7 shows
the cable diagram and Table 11 shows the pin descriptions for the interface connectors. At the end of
this manual there is a full page drawing of the user cable provided.
Power lines should be correctly terminated and insulated and wired up with a fuse somewhere between
the unit and power source before being connected to a power source. The user must again perform a
visual inspection of the cable equipment before use to ensure there is no damage.
Figure7: xNAV650usercable

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Table10: xNAV650usercablepindescription
J1 Pin
Wire colour from J1
Description
Terminate to
1
Black
Supply+
J3-1, Red
2
Brown
3
Red
Serial RX
J4
4
Orange
Serial TX
5
Yellow
ERX-
J2-6, Green
6
Green
ERX+
J2-3, White/Green
7
Blue
ETX-
J2-2, Orange
8
Violet
ETX+
J2-1, White/Orange
9
Grey
I/O signal 2
J4
10
White
I/O signal 1
11
White/Black
Signal ground (isolated)
12
White/Brown
PPS (isolated)
13
White/Red
Signal ground
14
White/Orange
Supply-
J3-2, Black
15
White/Yellow
Shield
Braid
Earth
Antennas
The xNAV650 has SMA connectors for the primary and secondary GNSS antennas. Antennas used
with the xNAV650 must at least be capable of tracking the GPS L1 signal for operation and additionally
the GPS L2 signal for RTK performance. Antennas capable of tracking L1 and L2 GLONASS signals,
E1 and E5b Galileo signals, and B1 and B2 Beidou signals should be used for optimal performance
and improved reliability.
The xNAV650 is certified for use with GNSS antennae with a gain of less than or equal to 35 dB.
When using the xNAV650 in a dual antenna configuration, it is recommended to use the same type of
antenna with the same cable lengths for both the primary and secondary receivers.
A suitable ground plane is required for the antennas to achieve good performance.
Internal storage
The xNAV650 uses a 32 GB eMMC for storage of hardware information, configuration files, and
navigation data. Files can be sent to, or retrieved from, the card via FTP or with the software utilities
provided (NAVconfig for configuration files and NAVsolve for data files).
The xNAV650 starts logging data automatically on power-up. Each individual raw data file (*.rd) can be
a maximum of 2 GB, equivalent to around one full day of logging at 100 Hz data rate with four GNSS
constellations. Once the 2 GB file limit is reached, a new file is started automatically to continue logging.

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If the 32 GB storage limit is reached, the system will start overwriting existing RD files, starting from the
oldest first.
Data from other devices can be logged directly onto the xNAV650 with the Generic Ethernet Logging
feature code. LiDAR units with data rates similar to the VLP-16 LiDAR or less are able to log directly
onto the INS. When data is recorded in this way the LiDAR data is recorded as a .lcom file. The data is
stored without ethernet headers so is not identical to a traditional PCAP file. The limit for recording data
can be as high as 5MB/s but 3MB/s is the specification given for reliable operation. This is more than
enough for a VLP16 LiDAR for example but not for a VLP32.
Ethernet configuration
To configure the xNAV650 for unrestricted data transmission it is necessary to use the ethernet
connection. The operating system at the heart of the xNAV650 allows connection to the unit via FTP.
The use of FTP allows the user to manage the data logged to the unit; files can be downloaded for
reprocessing. Configuration files for alternative configurations require FTP to put the configuration files
on to the xNAV650. The default username and password are both “user”.
The xNAV650 outputs its data over ethernet using a UDP broadcast. The use of a UDP broadcast
allows everyone on the network to receive the data sent by the xNAV650. The data rate of the UDP
broadcast is 100 Hz.
Each xNAV650 is configured with a static IP address, to enable communication by ethernet. The default
IP address will have the following format:
192.168.196.1xx
Where xx is the last two digits of the unit’s serial number.
The IP address of the computer being used to communicate with the xNAV650 may need to be changed
so it matches the subnet. For example, 192.168.196.32 should be available since this IP address is
never used by the xNAV650 by default.
Connection details for ethernet configuration
The RJ-45 connector on the 14C0222x user cable is designed to be connected directly to a network
hub. To extend the cable it is necessary to use an in-line coupler. This is two RJ-45 sockets wired
together in a straight-through configuration. Following the in-line coupler, a normal, straight UDP Cat
5e cable can be used to connect the coupler to the hub.
The xNAV can be connected directly to an ethernet card in a computer. To do this a crossed in-line
coupler must be used.

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Best practices
Mounting
It is essential to mount the xNAV650 rigidly in the vehicle. The xNAV650 should not be able to move or
rotate compared to the GNSS antennas, otherwise the performance will be reduced. In most
circumstances the xNAV650 should be mounted directly to the chassis of the vehicle. If the vehicle
experiences high shocks, then vibration mounts may be required.
Figure 8 shows the mounting points for the XNAV650. The mounting holes are suitable for M3 threaded
screws.
Figure 8: xNAV650 mountingpoints(mm)
Do not install the xNAV650 where it is in direct sunlight as this may cause the case to exceed the
maximum temperature specification.
Orientation and alignment
The orientation of the xNAV650 in the vehicle is normally specified using three consecutive rotations
that transform the system to the vehicle’s co-ordinate frame. Refer to Figure 4 for directions of axes.
The order of the rotations is:
oHeading (z-axis rotation);
othen pitch (y-axis rotation);
othen roll (x-axis rotation).
It is important to get the order of the rotations correct or the transformation may not apply correctly.
The xNAV650 can be mounted at any angle in the vehicle as long as the orientation is described in the
configuration. This allows the outputs to be rotated based on the settings entered to transform the
measurements to the vehicle frame.