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OXTS Survey+ v3 User Manual

Gnss-aided inertial measurement systems
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Covers Survey+ v3
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The inertial experts.

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Summary of Contents for OXTS Survey+ v3

  • Page 1 Survey+ GNSS-aided inertial measurement systems User Manual Covers Survey+ v3 models The inertial experts.

  • Page 2: Legal Notices

    Document Revision: 190902 (See Revision History for detailed information). Contact Details Tel: +44 (0) 1869 814 253 Oxford Technical Solutions Limited Fax: +44 (0) 1869 251 764 Park Farm Business Centre Middleton Stoney Web: http://www.oxts.com Oxfordshire Email: support@oxts.com OX25 4AL United Kingdom Oxford Technical Solutions...
  • Page 3 RT-Range User Manual 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.

  • Page 4: Table Of Contents

    Table of contents Legal Notices __________________________________________________________________ 2 Copyright Notice _______________________________________________________________ 2 Revision ______________________________________________________________________ 2 Contact Details ________________________________________________________________ 2 Table of contents ______________________________________________________________ 4 Introduction __________________________________________________________________ 7 Easy operation ______________________________________________________________________ 8 Self-correcting ______________________________________________________________________ 8 Advanced processing _________________________________________________________________ 8 Related documents _____________________________________________________________ 9 Survey+ product family _________________________________________________________ 10 Survey+ (v3) _______________________________________________________________________ 10 Single antenna _____________________________________________________________________ 10...
  • Page 5 RT-Range User Manual Antenna placement and orientation _____________________________________________________ 21 Operation ___________________________________________________________________ 23 Front panel layout __________________________________________________________________ 23 Co-ordinate frame conventions_________________________________________________________ 26 Ethernet configuration _______________________________________________________________ 33 Wi-Fi configuration __________________________________________________________________ 37 Dual antenna systems _______________________________________________________________ 40 Inputs and outputs ____________________________________________________________ 43 Digital inputs and outputs_____________________________________________________________ 44 Configuring the Survey+ ________________________________________________________ 47 Overview _________________________________________________________________________ 47 Working through NAVconfig ___________________________________________________________ 48...
  • Page 6 Testing the internal GNSS and other circuitry ______________________________________________ 93 Using the orientation measurements _____________________________________________ 94 Operating principles ___________________________________________________________ 95 Internal components _________________________________________________________________ 95 Strapdown navigator ________________________________________________________________ 95 Kalman filter _______________________________________________________________________ 97 Revision history _______________________________________________________________ 98 Drawing list __________________________________________________________________ 99 Oxford Technical Solutions...

  • Page 7: Introduction

    RT-Range User Manual Introduction The Survey+ inertial navigation system (INS) device is an instrument for making precision measurements of motion in real time. From September 2019 the Survey+ became v3 with new functionality. v2 devices are now end of life and include: Survey+ v2 and Survey+L1 v2. To obtain high-precision measurements, the Survey+ uses mathematical algorithms developed for use in fighter aircraft navigation systems.

  • Page 8: Easy Operation

    Internal data logging enables the data to be reprocessed post-mission. Data can be collected in the unit, downloaded using “ftp” protocol, processed on a PC and viewed using the NAVsolve. Easy operation There is minimal configuration required to use the system. The configuration can be saved to the Survey+ so it can operate autonomously without user intervention.

  • Page 9: Related Documents

    Related documents This manual covers the installation and operation of Survey+ systems, but it is beyond its scope to provide details on service or repair. Contact OxTS support or your local representative for customer service-related inquiries. Additional manuals provide further information on some of the software and communication types mentioned in this manual.

  • Page 10: Survey+ Product Family

    Survey+ product family Survey+ (v3) Survey-grade GNSS receivers provide high-precision position and velocity measurements even in high multipath environments. GPS & GLONASS enabled as standard on primary and secondary receivers. Can be BeiDou enabled. The Survey+ with RTK support is dual antenna. 100 Hz is the standard output rate. 200 Hz and 250 Hz options are available.

  • Page 11: Glonass

    RT-Range User Manual The heading software in the Survey+ enables significantly better performance and coverage compared to GNSS-only solutions. GLONASS GLONASS capability adds the ability to utilise the Russian satellite constellation GLONASS as well as the American constellation GPS. This means an extra 24 satellites are available for the Survey+ to lock on to and obtain position and velocity updates from.
  • Page 12 is available in India; SDCM is available in Russia. Other parts of the world are not covered and cannot use this service. TerraStar is a subscription service. Survey+ systems that have TerraStar capability include the necessary hardware to receive corrections. It is necessary to pay a licence fee to activate these corrections.

  • Page 13: Scope Of Delivery

    RT-Range User Manual Scope of delivery Survey+ products are supplied complete with, software, standard cables, a tape measure, and a quick start guide. The user will have specified at the point of ordering which user cable and antennas (including antenna cables) they need for their application. Survey+ system components Table 2 lists all items that are delivered with each standard Survey+ model.

  • Page 14: Specification

    Specification Specifications for Survey+ products can be found in Table 3 and Table 4. These specifications are listed for operation of the system under the following conditions: • After a warm-up period of 15 minutes’ continuous operation. • Open-sky environment, free from cover by trees, bridges, buildings or other obstructions.
  • Page 15 RT-Range User Manual Table 3. Survey+ specifications Parameter Survey+ v3 (Dual Antenna) Positioning GPS L1, L2 GLONASS L1, L2 BeiDou L1, L2 Position accuracy 1.5 m CEP SPS 0.6 m CEP SBAS 0.4 m CEP DGPS 0.1 m CEP PPP 0.2 m 1...

  • Page 16: Common Specifications

    Common specifications Table 4. Survey+ common specifications Parameter Specification Calculation 3.5 ms latency Operating -10° to 50 °C temperature Vibration 0.1 g /Hz 5–500 Hz Shock survival 100 g, 11 ms Internal storage 32 GB The operating temperature range for the antenna is much wider since it can be mounted outside the vehicle. See specification below.

  • Page 17: Environmental Protection

    RT-Range User Manual For single antenna systems, the heading is calculated from the inertial measurements. The accuracies listed in Table 3 are achievable under dynamic conditions. Under static conditions the heading accuracy of single antenna systems will degrade. Non-ideal mounting of the GNSS antennas will reduce the heading accuracy, particularly for dual antenna systems.

  • Page 18: Conformance Notices

    Conformance notices The Survey+ 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.

  • Page 19: Software Installation

    C:\Program Files (x86)\OxTS on 64 bit operating systems or C:\Program Files\OxTS on 32 bit operating systems. The first time some OxTS applications are run, a firewall warning message similar to that shown in Figure 1 may be triggered. This is because the program is attempting to listen for, and communicate with, OxTS devices on the network.
  • Page 20 Figure 1. Windows Firewall warning message Ensure both Private and Public networks are selected to ensure the software can continue functioning when moving from one type to another. Oxford Technical Solutions...

  • Page 21: Hardware Installation

    If the vehicle experiences high shocks, then vibration mounts may be required. The Survey+ is compatible with the RT-Strut product from OxTS to provide a quick and secure vehicle mounting solution. Do not install the Survey+ where it is in direct sunlight as, in hot countries, this may cause the case to exceed the maximum temperature specification.
  • Page 22 then different antennas must be used. It is recommended to mount the antennas at least 30 cm from any edge where possible. For dual antenna systems, the secondary antenna should be mounted in the same orientation as the primary antenna, as shown in Figure 2. The antenna baseline should also be aligned with one of the vehicle axes where possible, either inline or perpendicular to the vehicle’s forward axis.

  • Page 23: Operation

    RT-Range User Manual Operation The top label and LEDs convey some basic information that aids configuration and troubleshooting. Once power is applied, the Survey+ requires no further input from the user to start logging and outputting data. This section covers some basic information required for operation of the Survey+. Front panel layout Figure 3 shows the layout of the front panel.
  • Page 24 Table 7. Survey+ v3 front panel descriptions Label no. Description Power LED Status LED GNSS LED User cable main connector Second user cable connector Primary GNSS antenna connector Secondary GNSS antenna connector WI-Fi antenna connector LED definitions The LEDs on the connector panel provide information about the current system state, but it is not possible for the LEDs to communicate everything the product is capable of measuring.
  • Page 25 RT-Range User Manual Table 8. GNSS LED states Table 9. Status LED states Table 10. Power (PWR) states Revision: 190902...

  • Page 26: Co-Ordinate Frame Conventions

    Co-ordinate frame conventions Measurements made by the INS are available in a number of different reference frames for use in different applications. IMU frame The IMU reference frame used by the Survey+ (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.
  • Page 27 RT-Range User Manual Figure 4. IMU co-ordinate frame and measurement origin Table 11 lists the directions that the axes should point for zero heading, pitch and roll outputs when the default mounting orientation is used. Table 11. Direction of axes for zero heading, pitch and roll outputs Axis Direction Vehicle...
  • Page 28 The down axis (D) is along the gravity vector. Figure 5. OxTS NED navigation frame definition The OxTS navigation frame is attached to the vehicle but does not rotate with it. The down axis is always aligned to the gravity vector and north always points north.
  • Page 29 The OxTS horizontal frame (sometimes called the level frame) is attached to the vehicle but does not rotate with the roll and pitch of the vehicle. It rotates by the heading of the vehicle. The definition of the OxTS Horizontal frame is listed in Table 14 and shown in Figure 7.
  • Page 30 Figure 7. OxTS horizontal frame definition The OxTS horizontal frame is attached to the vehicle. The longitudinal and lateral axes remain parallel to a horizontal plane. The longitudinal axis is also parallel to the vehicle’s heading when viewed from above.
  • Page 31 This is the vertical direction of the vehicle, pointing up. OxTS vehicle frame The OxTS vehicle frame is attached to the body of the vehicle. It is related to the INS through the rotations in the Orientation page of NAVconfig. It can be changed while the INS is running using the Quick Config tool of NAVdisplay.
  • Page 32 Figure 9. Vehicle frame definition The OxTS vehicle frame is attached to the vehicle and rotates with it in all three axes. The X-axis remains parallel to the vehicle’s heading, while the Y-axis points to the right and is perpendicular to the vehicle’s...

  • Page 33: Ethernet Configuration

    To configure the Survey+ for unrestricted data transmission it is necessary to use the Ethernet connection. The Survey+ v3 also supports Wi-Fi data transmission and the setup of WiFi is covered later in this manual. The operating system at the heart of the Survey+ products allows connection to the unit via FTP.
  • Page 34 1. Open the ‘Control Panel’ from the Start menu. 2. In category view, select ‘Network and Internet’ and then ‘Network and Sharing Centre’. 3. Select ‘Change adapter settings’ in the side panel. 4. Right-click the Ethernet option and select ‘Properties’. 5.
  • Page 35 RT-Range User Manual Note that it is possible to change the IP address of Survey+ systems. If the IP address has been changed then NAVdisplay should still be able to identify the address that the Survey+ is using, as long as the PC has a valid IP address and this is not the same as the RT’s.
  • Page 36 Connection details for Ethernet configuration The RJ-45 connector on the 14C00121x 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.

  • Page 37: Wi-Fi Configuration

    RT-Range User Manual Wi-Fi configuration The Survey+ can be configured via a Wi-Fi connection using the Wi-Fi access point inside the Survey+ itself. Like Ethernet, the use of FTP via a Wi-Fi connection allows the user to manage the data logged to the unit; files can be downloaded for reprocessing and deleted to make space for future files.
  • Page 38 Figure 13. Configuring the computer’s IP address for Ethernet data transmission Once you are on the same IP range as the Survey+ you can connect to the it via Wi-Fi. Via your PC’s network settings you should be able to select the ‘Survey+ as a Wi-Fi network’.
  • Page 39 RT-Range User Manual Figure 14. Connect to Wi-Fi on the Survey+. Wi-Fi settings are configured using NAVconfig and this process is explained later in this manual. Revision: 190902...

  • Page 40: Dual Antenna Systems

    Dual antenna systems It is often useful to have an understanding of how the Survey+ uses the measurements from the dual antenna system. This can lead to improvements in the results obtained. To use the measurements properly the needs to know the angle of the GNSS Survey+ antennas compared to the angle of the .
  • Page 41 RT-Range User Manual In the unlikely event that the RTK Integer solution is incorrect at the start then the Kalman filter can update the secondary antenna orientation incorrectly. If this happens then things start to go wrong. The Kalman filter becomes more convinced that it is correct, so it resolves faster, but it always solves incorrectly.
  • Page 42 Table 19. Typical heading error for when stationary in different environments Environment Typical error (3σ) Complete open-sky 0.6° (0.2° 1σ) Near trees, buildings 1° Next to trees, buildings 2° Typical figures using a 1 m base-line. For accuracy specification of 0.1° RMS a 2 m separation is required. Using a 2 m base-line can halve the figures shown here.

  • Page 43: Inputs And Outputs

    The system can output data on the serial port and Ethernet. The standard serial output of the Survey+ is a proprietary binary format, referred to as NCOM. OxTS offers C and C++ code that will interpret the packet. This can be used freely in users’ programs to decode the output of the Survey+.

  • Page 44: Digital Inputs And Outputs

    Digital inputs and outputs Table 20 describes each of the signals on the digital I/O connector J5 of the 14C00121 user cable. A more detailed explanation of each signal can be found below. Table 20. Digital I/O signals 1PPS output The 1PPS (J5-1) output is a pulse generated by the GNSS receiver.
  • Page 45 RT-Range User Manual Trigger 1 and 2 Trigger 1 (J5-2) and Trigger 2 (J5-4) can be used to generate events within the Survey+ for purposes of identifying external events, or to output a time/distance-based signal for the purpose of driving external events. Both Triggers are independently configurable in the Options page of NAVconfig.
  • Page 46 distance interval defined by the PPM settings. At the same moment the trigger signal is output, a position measurement will be internally generated and logged alongside the regular measurement data. To generate a real-time message in relation to the camera trigger, it is necessary to select the ‘Output on camera trigger option’...

  • Page 47: Configuring The Survey

    RT-Range User Manual Configuring the Survey+ To obtain the best results from your Survey+ it will be necessary to configure the Survey+ to suit the installation and application before using it. The program NAVconfig can be used to do this. This section describes how to use NAVconfig and gives additional explanations on the meanings of some of the terms used.

  • Page 48: Working Through Navconfig

    Working through NAVconfig NAVconfig is split into seven sections. Each section contains several tabs with settings that can be applied to the device. The sections are: Home, Ready Configuration, Hardware Setup, Interfaces, Environment, Advanced Tools and Write Configuration. When a device is connected via WiFi or Ethernet, the product name (including serial number) will be displayed at the top of the application.

  • Page 49: Start/Read Configuration Section In Navconfig

    RT-Range User Manual Figure 16. NAVconfig Home section Start/Read Configuration section in NAVconfig Figure 17. NAVconfig Start/Read Configuration section Revision: 190902...

  • Page 50: Read Configuration Section

    This section becomes available when you choose “New configuration” or “Modify configuration” from the Home section. It is important to ensure the correct Product type and version is selected. The settings available in NAVconfig vary depending on the product type and version chosen. The product model and generation (version) can be found on the label on your product.

  • Page 51: Hardware Setup Section In Navconfig

    RT-Range User Manual ‘Read settings from a raw data (RD) file:’ The Survey+ writes the configuration it is using to the internally stored RD file. This option extracts the configuration used and loads it into the configuration wizard. Specify an RD file by clicking the ‘Browse’… button. Read initial settings from device: If the Survey+is connected to the computer via Ethernet or WiFi it is possible to read the initial settings directly from the Survey+.
  • Page 52 Figure 19. A Survey+ device mounted on OxTS RT-Strut Use the Y axis points and the Z axis points box to specify which way the Survey+’s axes point in the vehicle. Figure 5 on page 28 shows the Survey+ axes’ directions. The Orientation page of the configuration wizard, shown in Figure 20, also has illustrations to visualise the orientation of the Survey+ in a vehicle based on the settings input.

  • Page 53: Primary Antenna Tab

    RT-Range User Manual Figure 20. NAVconfig IMU orientation tab in the Hardware Setup section For correct initialisation, it is necessary to get the heading orientation correct. The Survey+ gets its initial heading by assuming the vehicle is travelling forwards in a straight line. If the definition of the vehicle’s x-axis (forward direction) is incorrect in the Survey+ then it will not initialise correctly when the vehicle drives forwards.
  • Page 54 Figure 21 shows the Primary Antenna page. Figure 21. NAVconfig Primary Antenna tab It is necessary to tell the Survey+ the distance between its measurement origin (shown in Figure 5) and the GNSS antenna’s measurement point. This should be entered in the vehicle’s co-ordinate frame.

  • Page 55: Secondary Antenna Tab

    RT-Range User Manual Secondary Antenna tab If your system has two antennas, click the ‘Secondary GNSS antenna’ checkbox on the Secondary Antenna page (Figure 22) to allow the configuration to be entered. If it is not enabled, the Survey+ will ignore the secondary antenna and will not use it to compute a heading solution.
  • Page 56 Getting the angle wrong by more than 3° can lead the Survey+ to lock on to the wrong heading solution. The performance will degrade or be erratic if this happens. If the angle between the antennas cannot be estimated within a 3° tolerance then contact OxTS support for techniques for identifying the angle of the antennas.
  • Page 57 RT-Range User Manual The Lateral No-slip feature applies heading correction when the land vehicle is not slipping. When the vehicle is slipping the lateral acceleration is usually large enough that the normal heading corrections provide excellent results. When combined with a wheel speed input (see “Wheel speed input”) the drift of the Survey+ when GNSS is not available is drastically reduced.
  • Page 58 Figure 24. Measurement point for Lateral No-slip Measuring from the Survey+, measure the distances to the non-steered axle position in each axis in the vehicle co-ordinate frame. Select the direction from the dropdown lists and enter the distances. The measurements are made to an accuracy of 10 cm. Selecting an accuracy better than 10 cm does not improve results.
  • Page 59 RT-Range User Manual Figure 25. NAVconfig Lateral No-slip tab in the hardware Setup section When using No-Slip features, the Survey+ can estimate the slip angle offset of the Survey+ compared to the vehicle. After the Survey+ is initialised and warmed-up, use the Improve configuration option from the NAVconfig Home section to automatically read the Survey+’s slip angle offset estimate.

  • Page 60: Gnss Differential Corrections Tab

    GNSS Differential Corrections tab An Survey+ can be configured to use several different differential correction message types on connector J3. Figure 26 shows the Differential corrections properties window and Table 21 gives details on the correction types available. Figure 26. NAVconfig Differential corrections tab in the Hardware Setup section Oxford Technical Solutions...
  • Page 61 Survey+ will broadcast differential corrections it is receiving via a radio modem from an OxTS base station, using a WLAN device. Other OxTS devices that are on the network as the broadcasting Survey+, will then be able to receive the DGPS messages and use them.
  • Page 62 Regardless of whether DGPS corrections are received via NTRIP or a local base station, only RTCMv3 corrections are currently supported in networked DGPS mode. SBAS In Europe, North America, and Japan SBAS can be used for differential corrections. These services will improve the position accuracy of the Survey+. In North America the SBAS service is known as WAAS, in Europe it is known as EGNOS and in Japan it is known as MSAS.

  • Page 63: Interfaces Section In Navconfig

    RT-Range User Manual Interfaces section in NAVconfig This section contains options for configuring the interfaces of the Survey+ Some of these settings are feature code controlled so may not be visible to all users on all devices. Ethernet tab The Ethernet settings include configuring the Ethernet data output rate, packet type and Triggers for the Survey+.
  • Page 64 Oxford Technical Solutions...
  • Page 65 To configure the Wi-Fi as an Access Point, click on the option and the field to configure the Network details and router details will become available to edit. The Network name (SSID) will be by default OxTS Survey+ SN[serial number]. This can be changed to another name but cannot contain any of the following characters: [<], [>], [&], ['] and ["].
  • Page 66 Select a Packet type and Baud rate. By default, data on the serial port is output using 8- N-1, although odd/even parity and two stop bits are available by using Advanced commands. Please contact support@oxts.com for details on this. If the NMEA packet type is selected, the NMEA tab will appear in the properties window.
  • Page 67 RT-Range User Manual Table 22. Serial outputs Note that it is easy to overload the serial port if there are too many events. The software computes the number of characters that will be output each second and displays this at the bottom of the window.
  • Page 68 PPS / Triggers tab PPS will output 1 pulse per second synchronised to GPS time, providing a highly accurate time pulse for synchronising external devices. The output trigger on the digital I/O generates a pulse based on distance. Select the distance interval to generate the pulses on from the dropdown list, or type in a value.
  • Page 69 RT-Range User Manual GNSS environment Select a predefined value from the dropdown list. If the system is used predominantly in open-sky, then the Open skies setting should be used. In environments with a lot of GNSS multipath then Some obstructions or Frequent obstructions can be used depending on the environment.
  • Page 70 Table 23. NAVconfig heading lock options Heading lock Description Normal This option assumes the heading of the vehicle does not change by more than 2° while the vehicle is stationary. The heading accuracy recovers quickly when the vehicle moves. Tight This option assumes the heading of the vehicle does not change by more than 0.5°...

  • Page 71: Advanced Tools Section

    RT-Range User Manual Figure 27. NAVconfig Enable local co-ordinates in the Environment section Advanced Tools section This section contains several settings for Advanced users. By default, these settings are not switched on so you should navigate through the various tabs to review the settings that apply to your application.
  • Page 72 Wheel Speed Input The Survey+ be configured to include a wheel speed input. This reduces the drift in outputs when GNSS is not available. It is essential to use the Lateral and Vertical No-slip slip at the same time as wheel speed corrections. As with the Lateral No-slip feature, the wheel speed input can only be used on land vehicles;...
  • Page 73 RT-Range User Manual The distances from the measurement point on the Survey+ to the measurement point of the wheel speed encoder in the vehicle coordinate frame should be input. The directions can be selected from the dropdown lists. If the wheel speed is from a prop shaft then the distance should be measured half way between the two wheels.
  • Page 74 Figure 29. NAVconfig output smoothing properties window The smoothing of the position, velocity and orientation corrections can be controlled independently. Enter the maximum correction that can be applied every second. For example, if 0.1 m is entered for the position smoothing then the Survey+ will only correct a position error by a maximum rate of 0.1 m/s.
  • Page 75 RT-Range User Manual GNSS control tab The GNSS control tab contains advanced options that control how the GNSS information is managed in the Survey+. The GNSS Algorithm tab can be used to select the algorithm used for merging the GNSS and the inertial data in the Kalman filter.
  • Page 76 Using this algorithm, the Survey+ will accept precalculated position and velocity updates from the GNSS and use it to update the Kalman filter. The gx/ix™ raw data processing algorithm is OxTS’ tight coupling engine. It uses the raw data from the GNSS and custom algorithms to compute position and velocity tailored to the needs of the Kalman filter.
  • Page 77 RT-Range User Manual measurements after’ option and enter the number of GNSS measurements to reject before the system starts believing it again. Global Coordinate System tab The Survey+ can output position relative to different coordinate frames. You can change the coordinate frame settings in the Global Coordinate System tab within Advanced Tools in NAVconfig, shown in Figure 31.
  • Page 78 Using the Commands tab you can enter device-specific commands that apply specific features or perform actions onto the . The OxTS technical support team often use Survey+ these and can provide you with a list of useful commands if you request them at support@oxts.com.

  • Page 79: The Write Configuration Section Of Navconfig

    RT-Range User Manual The Write Configuration section of NAVconfig Changes to the Survey+ settings must be sent using Ethernet or Wi-Fi. It is necessary to configure your computer’s LAN and WLAN settings, so it is on the same network as the Survey+.

  • Page 80: Setting Up The Base Station

    Setting up the base station For correct operation of the higher accuracy systems it is necessary to use a base station GNSS receiver. All of the systems can be successfully used without a base station, however, the specification will only be met if a base station is used. The base station is a separate GNSS receiver that monitors signals from the GNSS satellites.

  • Page 81: Initialisation Process

    RT-Range User Manual Initialisation process Before the Survey+ can start to output all the navigation measurements, it needs to initialise itself. In order to initialise, the Survey+ needs all the measurements listed in Table 25. Table 25. Quantities required for initialisation Quantity Description Time...

  • Page 82: Warm-Up Period

    Warm-up period During the first 15 minutes of operation the system will not conform to specification. During this period the Kalman Filter runs a more relaxed model for the sensors. By running a more relaxed model the system is able to: •...
  • Page 83 RT-Range User Manual Figure 33. Example warm-up driving route At the start there is just a small amount of motion to get the Survey+ initialised. During this time the Kalman filter cannot improve the position accuracy because the position of the GNSS antenna is not known accurately and cannot be estimated without motion.
  • Page 84 Figure 34. Example warm-up accuracy estimates (a) Forward velocity. (b) Position accuracies. (c) Velocity accuracies. (d) Orientation accuracies. Oxford Technical Solutions...

  • Page 85: Improving The Configuration After A Warm-Up

    RT-Range User Manual You can see the Survey+ is nearly at specification after just this small amount of driving. However, experience tells us the Kalman filter will continue to make some improvements (not obvious) during the first few figures of eight. The main part of the motion occurs after 1100 s when the car was driven in a figure of eight for 6 minutes.
  • Page 86 Figure 35. NAVconfig home page – select Improve configuration Read configuration section in NAVconfig improved configuration wizard If you are connected to a device via Wi-Fi or Ethernet, then select “Read settings from a device” and choose the device from the available list. If the file has been logged to the PC already then you can choose ‘Read settings from a data (RD) file’...
  • Page 87 RT-Range User Manual Figure 36. Choose where to read configuration from Click ‘Next’ to continue. Confirm whether the improved data should be read from: The Device, or a File. Click ‘Next’ to continue. Revision: 190902...
  • Page 88 Figure 37. Confirm if configuration should be read from device or logged file The Select Settings screen will appear. From the list displayed, select the settings that you wish to view. These will be determined according to what is enabled on your device. Oxford Technical Solutions...
  • Page 89 RT-Range User Manual Figure 38. Choose which settings to optimise Select the settings that you wish to improve in the configuration from the options available. By clicking the down arrows, you can expand the settings and view the values that have been improved after the warm-up.

  • Page 90: Post-Processing Data

    The NAVsolve Wizard also gives the user the ability to change the NCOM binary output format to text. A full explanation of NAVsolve is given in the “NAVsolve manual”, which can be downloaded from the OxTS support website. Oxford Technical Solutions...

  • Page 91: Laboratory Testing

    RT-Range User Manual Laboratory testing There are several checks that can be performed in the laboratory to ensure the system is working correctly. The most fragile items in the system are the accelerometers, the other items are not subject to shock and do not need to be tested as thoroughly. Accelerometer test procedure To check the accelerometers are working correctly, follow this procedure.
  • Page 92 It is hard to do a more exhaustive test using the angular rate sensors without specialised software and equipment. For further calibration testing it is necessary to return the unit to OxTS. Note that the Survey+ is capable of correcting the error in the angular rate sensors very accurately.

  • Page 93: Testing The Internal Gnss And Other Circuitry

    RT-Range User Manual Testing the internal GNSS and other circuitry To check all the internal circuits in the Survey+ are working correctly and the navigation computer has booted correctly, use the following procedure: 1. Connect power to the system, connect the system to a laptop computer and run the visual display software (NAVdisplay).

  • Page 94: Using The Orientation Measurements

    Using the orientation measurements This section has been provided to clarify the definitions of heading, pitch and roll that are output by the Survey+. The Survey+ uses quaternions internally to avoid the problems of singularities and to minimise numerical drift on the attitude integration. Euler angles are used to output the heading, pitch and roll, and these have singularities at two orientations.

  • Page 95: Operating Principles

    RT-Range User Manual Operating principles This short section gives some background information on the components in the Survey+ and how they work together to give the outputs. A short overview of the algorithm is given and some explanation of how the software works. The section is provided as “interesting information”...
  • Page 96 Figure 41. Schematic of the strapdown navigator People familiar with inertial navigation systems will note that “angular rates” and “accelerations” are labelled as the inputs. In reality the DSP in the Survey+ converts these to “change in angle” and “change in velocity” to avoid problems of coning and sculling. Oxford Technical Solutions...

  • Page 97: Kalman Filter

    RT-Range User Manual Some other rotations are also missed in the diagram. The Survey+ does not use a wander angle, so it will not operate correctly on the North and South poles. The angular rates have their bias and scale factor corrections (from the Kalman filter) applied.

  • Page 98: Revision History

    The same principles are used in the Survey+. Position and velocity are compensated directly, but other measurements like accelerometer bias, have no direct measurements. The Kalman filter tunes these so the GNSS measurements and the inertial measurements match each other as closely as possible. The Kalman filter in the Survey+ has 25 states.

  • Page 99: Drawing List

    RT-Range User Manual Drawing list Table 30 lists the available drawings that describe components of the Survey+ system. Many of these drawings are attached to the back of this manual. Note that the ‘x’ following a drawing number is the revision code for the part. If you require a drawing, or different revision of a drawing, that is not here then contact Oxford Technical Solutions.

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