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3DM-GX3® -35

Microstrain 3dm-gx3-35 Attitude Heading Reference System With GPS

Miniature Attitude Heading Reference System (AHRS)

The 3DM-GX3® -35 high-performance, miniature Attitude Heading Reference System (AHRS) with GPS, combines MEMS sensor technology and a highly sensitive embedded GPS receiver. It incorporates a triaxial accelerometer, triaxial gyro, triaxial magnetometer, temperature sensors, and an on-board processor running a sophisticated fusion algorithm to provide orientation, inertial, and GPS measurements. Data from the GPS receiver is time synchronized with the inertial sensors and all inertial and GPS data are available as user-defined packets (either by polling or continuous stream). The 3DM-GX3® -35 provides a perfect platform for users to develop their own navigation solutions.

Microstrain 3dm-gx3-35 Attitude Heading Reference System With GPS

Best in Class

  •     precise position, velocity and attitude estimations
  •     high-speed sample rate & flexible data outputs
  •     high performance under vibration and high-g

Easiest to Use

  •     smallest, lightest industrial GPS/INS available
  •     simple integration supported by SDK and comprehensive API

Cost Effective

  •     reduced cost and rapid time to market for customer’s applications
  •     aggressive volume discount schedule

AHRS Specifications

Attitude and Heading

Attitude heading range

360° about all 3 axes

Accelerometer range

±5g standard

Gyroscope range

±300°/sec standard

Static accuracy

±0.5° pitch, roll, heading typical for static test conditions

Dynamic accuracy

±2.0° pitch, roll, heading for dynamic (cyclic) test conditions and for arbitrary angles

Long term drift

eliminated by complimentary filter architecture





Data output rate

Up to 1,000 Hz


sensors sampled at 30 kHz, digitally filtered (user adjustable ) and scaled into physical units; coning and sculling integrals computed at 1 kHz

Output modes

Acceleration, angular rate, magnetic field, deltaTheta, deltaVelocity, Euler angles, orientation matrix, quaternion, LLH position, NED velocity, ECEF position and velocity, DOP data, UTC time, GPS time, clock info, GPS fix, and SVI; NMEA GPS protocol records and UBX GPS protocol records available in advanced mode


A/D resolution

16 bits SAR oversampled to 17 bits

Interface options

USB 2.0 or RS232

Baud rate

9,600 bps to 921,600 bps

Power supply voltage

+3.2 to +16 volts DC

Power consumption

at full performance with GPS lock:
200 mA typ (250 mA max) when powered by Vpri (3.2V-5.5V)
850 mW typ (1.0W max) when powered by Vaux (5.2V-16V)



Operating temperature

-40 °C to +65 °C


44 mm x 24 mm x 14 mm - excluding mounting tabs, width across tabs 37 mm


23 grams



Shock limit

500 g

Software utility

CD in starter kit (XP/Vista/Win7/Wion 8 compatible)

Software development kit (SDK)

complete data communications protocol and sample code

CE Compliant

Sensor Specifications





Measurement range

±5 g


±2.5 Gauss


±0.1 % fs

±0.03 % fs

±0.4 % fs

In-run bias stability

±0.04 mg


Initial bias error

±0.002 g


±0.003 Gauss

Scale factor stability

±0.05 %

±0.05 %

±0.1 %

Noise density

80 µg/√Hz


100 µGauss/√Hz

Alignment error




User adjustable bandwidth

225 Hz max

440 Hz max

230 Hz max

Sampling rate

30 kHz

30 kHz

7.5 kHz max

GPS Specifications

GPS Receiver

GPS receiver type

50-channel u-blox 6 engine GPS L1 C/A code SBAS: WAAS, EGNOS, MSAS

Data output rate

1 Hz to 4 Hz


Cold starts:  27 sec

Aided starts:  4 sec

Hot starts:  1 sec

GPS tracking and navigation sensitivity

-159 dBm


Tracking:  -159 dBm

Cold starts:  -147 dBm

Hot starts:  -158 dBm

GPS velocity accuracy

0.1 m/sec

GPS heading accuracy


GPS horizontal position accuracy

position:  2.5 m CEP

SBAS:  2.0 m CEP

GPS timepulse signal accuracy

30 nsec RMS

< 60 nsec 99%

GPS acceleration limit

≤ 4 g

GPS altitude limit

no limit

GPS velocity limit

500 m/sec (972 knots)

GPS antenna connector

MMCX type


Accelerometer range

±1.7 g, ±16 g, ±50 g

Gyroscope range

±50°/sec, ±600°/sec, ±1200°/sec


#1567: How do I set the 3DM-GX3 back to its default settings?

Using MIP Monitor software, to reset the device to the factory defaults:

  • Establish communication as normal with the sensor.
  • Click Settings.
  • Click Load Default Settings and a message box pops up.
  • Click OK and the message box disappears.
  • Click Settings again.
  • Click Save Current Settings and a message box pops up.
  • Click OK and the message box disappears.

This process does not erase any hard and soft iron calibration that may be on the device.

The Hard and Soft Iron Cal software we provide must be used to do that.


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#1549: How do I write previously saved hard and soft iron calibration coefficients back to my 3DM-GX3?

Our MIP Monitor software, as written, will not allow you to save the 12 hard and soft iron calibration coefficients to a file, and then read that file back into the software to rewrite the values to the inertial sensor.

However, you cand accomplish the task by recording the values that are displayed (or take a screen grab).

This would be followed by using the data communications protocol EEPROM Write command to write the values back into the device.

This would require either a terminal program or the ability to write software, an understanding of how to construct the command packets, and a list of the EEPROM addresses involved.

Please contact your Lord MicroStrain support engineer for further details.


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#1525: How will the 3DM-GX3-35 work with the magnetometers turned off?

Without the magnetometer, the only heading reference is from the GPS and this heading reference can only be used on a platform that has some constant lateral motion.  This is the only way GPS can get a good heading.   Once a heading reference is obtained (either magnetometer or GPS heading) it can be maintained for a short time (less than 30 seconds typically) with just the gyroscopes.  This, of course, would have to be done through a fusion filter external to the -35.  The LORD MicroStrain 3DM-GX3-45 product actually has this functionality built-in.

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#1512: What is the difference between SINGLE BYTE and MIP protocol?

The main difference between single byte (SB) and MIP is as follows:

  • All MIP commands and data have a header and checksum.  SB only has a header (the echo of the command byte) and a checksum on the replies.  This means that the programmer has to create a header and calculate the checksum for a command before s/he sends the command.  This was not necessary with SB.
  • MIP setup and control commands (like start and stop continuous mode) send an ACK/NACK field with a reply.  SB does not.  The ACK/NACK field has an error code that can be used to confirm that a command was accepted.
  • MIP packets can contain multiple command and data fields.  SB commands and data only have one fixed field.

The reason we created MIP was the higher reliability for communications and control, plus the ability to have custom data messages.  SB was prone to phantom commands in a noisy environment.  In addition, SB had a limited number of data combinations available.

To move code from Single Byte to MIP with simple applications is fairly painless if you follow some guidelines.

  • You can “prebuild” all your setup and control commands and make them constants in your code.   You can plug the prebuilt packet constants into the same part of the code that you previously used to send a single byte command (In essence, you are sending a “multi-byte” command instead of a single byte command).  We have a “packet builder” tool in the MIP Monitor that will build the packet for you.  You can try out the command and then copy the packet and paste it directly into your code as a string constant.
  • When you design the MIP data message, make sure all the “data rate decimation” values are the same.  This will make all the data packets identical, which makes finding data in the packet similar to finding data in a SB data message (by using fixed offsets).


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#1508: What is the impedance on the GPS connector?

The impedance on the GPS connector is 50 ohms.

The 3DM-GX3 provides 3 volts power on the center pin of the connector (active antenna).



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#1505: What is the ECCN for the 3DM-GX3?

The ECCN is 7A994.

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#1480: How do I upgrade the firmware on my GX3 inertial sensor?

From time to time, MicroStrain releases firmware upgrades for its 3DM-GX3® inertial sensors. These firmware upgrades represent operating improvements, new functions, etc. In most cases, the user may download these upgrades and perform the upgrade using a simple step-by-step process. This technical note describes which firmware upgrades may be accomplished by the user and which firmware upgrades must be done at the factory. Familiarity with 3DM-GX3® operation is assumed. The upgrade procedure employs a Microsoft Windows computer and the Microsoft HyperTerminal utility.

Click here.



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#1479: Can I use the 3DM-GX3-35 with a Campbell Scientific datalogger?

Yes. We provide sample code for the Campbell Scientific CR1000 and CR3000 dataloggers.

Click here and navigate to the Sample Code on the Documentation tab.



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#1477: Can I use dataloggers with the inertial sensors?

Many inertial applications incorporate dataloggers. The datalogger can take many forms: hardware or software, analog or digital, simple or complex, and/or combinations of all. For our purposes, let’s work through a simple-digital-software datalogger. In this case, datalogger software is installed on a computer. The inertial sensor is connected to the computer via an RS-232 communication interface. The inertial sensor is pre-programmed to automatically send data when powered. The computer receives the stream of data and the datalogger software continuously records the stream to a data file.

Click here.


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#1476: How can I program the inertial sensor so that it outputs on start-up?

The LORD MicroStrain 3DM-GX3 inertial sensor family allows the user to pre-program the inertial sensor so that it continuously outputs specific data packets at specific sampling rates each time it is powered on. This functionality facilitates integration of the inertial sensor with other equipment and systems. For example, connection of the 3DM-GX3 inertial sensor to a datalogger becomes quite easy. The user pre-programs the 3DM-GX3 data output settings on his desktop, connects the 3DM-GX3® to the datalogger’s RS-232 port, powers the 3DM-GX3, and the datalogger records the inertial data. This technical note assumes some familiarity with your particular 3DM-GX3 inertial sensor and its accompanying MIP Monitor (Windows-based) software.

Click here.


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#1424: Is the 3DM-GX3-35 GPS PPS (pulse per second) signal available to outside devices?

The GPS PPS signal is available on pin 7. It can drive one high impedance TTL input.

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#1380: How can I get NMEA data packets from the inertial sensor?

NMEA packets can be had by putting the 3DM-GX3-35 or 3DM-GX3-45 in GPS Direct mode and manipulating the devices with the GPS manufacturer’s software.

Here are two technical notes which show how this is done:



NMEA packets can also be generated in the user's own application by gathering the navigation data output by the 3DM-GX3-35 or 3DM-GX3-45 and formatting it into NMEA packets. The inertial sensor feeds navigation data to the host computer, the host computer formats the navigation data into NMEA packets, and sends them out the serial port to a NMEA-ready device.


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#1361: How long is the cable for the GPS antenna?

The GPS antenna cable that ships with every 3DM-GX3-35 and 3DM-GX3-45 is 3 meters in length.

Cable length is important.  The longer the cable, the lower the signal strength.  If the user lengthens the cable, the signal strength will diminish.  The loss of signal strength can only be empirically determined by trying out a particular installation.  Loss of signal strength will manifest itself in the number of satellites seen, quality of data reception from satellites, etc.


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#1360: Does the GPS receiver use Differential GPS?

No.  The GPS Receiver only receives standard GPS signals.  It does not receive Differential GPS (DGPS) signals.  If the user requires DGPS input, the GX3 will accept DGPS via an external feed and in the case of the 3DM-GX3-45, incorporate it in its Kalman filter processing.  To be clear: the on-board GPS will be bypassed in favor of the external GPS.

Wikipedia GPS: http://en.wikipedia.org/wiki/Global_Positioning_System

Wikipedia DGPS: http://en.wikipedia.org/wiki/Differential_GPS



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#1342: How do I repair or return a LORD MicroStrain® product?

In order to return any LORD MicroStrain® product either for repair or return, you must contact us for a Return Merchandise Authorization number (RMA). If you purchased directly from LORD MicroStrain® in the United States, please contact your Sales or Support Engineer to obtain an RMA.  If you purchased directly from a LORD MicroStrain® distributor, please contact your distributor to obtain an RMA.

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#1340: Where do I purchase LORD MicroStrain® products?

If you are located in the United States, LORD MicroStrain® supplies you directly.  If you are in located in another country, LORD MicroStrain® products are available exclusively from LORD MicroStrain® distributors.  Please use this locator to determine your distributor: http://www.microstrain.com/support/international

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#1339: Does LORD MicroStrain® provide a trial period for its products?

To enable customers to try our standard products risk free, LORD MicroStrain® offers a 30 day return on the purchase of a starter kit. In order to take advantage of this offer, a purchase order or payment for the starter kit is required when the order is placed. 30 day trial details may be found at: http://www.microstrain.com/support/warranty

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#1338: How do I get support for my LORD MicroStrain® products?

LORD MicroStrain® Support Engineers are always available to support you in any way we can by phone, email, SKYPE or Live Chat from our home page.  Contact details may be found at: http://www.microstrain.com/support/contact-support

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#1337: What is the shipping policy for LORD MicroStrain® products?

LORD MicroStrain® insures all products shipments to their full value unless the customer specifically states a different method.

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#1336: What is the warranty for LORD MicroStrain® products?

LORD MicroStrain® warrants its standard products to be free from defective material and workmanship for a period of one (1) year from the original date of purchase.  Warranty details may be found at: http://www.microstrain.com/support/warranty

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#1331: What is the difference between static and dynamic accuracy?

The term ‘static’ accuracy refers to measurements made when the inertial unit is not moving and the on-board orientation algorithm has recovered from any sensor over-ranging.

The term ‘dynamic’ accuracy refers to measurements made while the inertial unit is moving and not exceeding the measurement range of the individual on-board sensors (accelerometers, gyroscopes, magnetometers).

The 3DM, 3DM-DH and FAS-A are designed to measure static rotations.

The 3DM-GX3 family is designed to measure both static and dynamic rotations.

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#1294: What is the 3DM-GX3-35 accuracy?

Static accuracy

±0.5° pitch, roll, heading typical for static test conditions

Dynamic accuracy

±2.0° pitch, roll, heading for dynamic (cyclic) test conditions and for arbitrary angles


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#677: What formulas are used to convert between the various orientation data quantities?

Here is a link to a detailed technical note: http://files.microstrain.com/Orientation%20Conversion%20formulas.pdf

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#664: Is it possible to use the RS-232 interface of LORD MicroStrain® inertial sensors with a serial port emulator (i.e., with a USB to serial adapter)?

Yes.  We have had good success with several types of off-the-shelf USB to serial port adaptors, such as those from IOGear and Keyspan, which may be purchased through any of the electronics products distributors.

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#598: Can the USB and serial interfaces of the 3DM-GX3 be used at the same time?

No – only one can be used at a time.  The device auto-senses which communication signal is attached (USB or serial), and only uses that channel for communications.

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#597: Where can I buy additional communication 3DM-GX3 and 3DM-GX3 OEM interface connectors?

The standard unit uses a specialized Ulti-Mate brand micro-DB9.  This technical note contains more details: http://files.microstrain.com/TN-I0023_Inertia-Link_3DM-GX2_3DM-GX3_Pin-Outs.pdf

The OEM unit uses a Samtec FTSH-105-01-F-D-K.  This technical note contains more details: http://files.microstrain.com/3DM-GX3-25_OEM_Footprint_and_Connector.pdf

LORD MicroStrain® suggests that you purchase additional connectors with your order.

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#596: How long can the communication cables be for the 3DM-GX3?

The 3DM-GX3 USB and RS-232 communication interfaces are built to satisfy the standard USB-IF and EIA specifications.  LORD MicroStrain® provides 6 foot cables as standard.  Many techniques can be used to extend the length of the communication interfaces including powered USB hubs, USB boosters, RS-232 extenders, etc.

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#595: What is the purpose of the double mounting holes on the 3DM-GX3 standard enclosure?

The 3DM-GX3 standard enclosure has been designed with precision alignment holes on the ‘ears’ of the enclosure to allow the user to install the unit with precise alignment to the rest of the components in the user’s application.

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#594: Does the 3DM-GX3 require calibration during use?

The 3DM-GX3 is calibrated at the factory.  The user is also provided with Hard and Soft Iron Calibration software to field calibrate the GX3 in situ.  This video further describes the function: http://www.microstrain.com/video/hard-soft-iron-calibration

Important note: Hard and soft iron calibration is not required for the 3DM-GX3-15 and the 3DM-GX315 OEM.  These units do not contain magnetometers.

From time to time the 3DM-GX3 may need recalibration. For example, as a result of coming in contact with magnetic influences (magnets, motors, etc.), residual magnetism may be picked up by the on-board components which will alter the calibration.  Another example: the 3DM-GX3 receives a severe shock, slightly altering the position of the circuit boards in relation to the enclosure, again altering the calibration.  In these cases the unit should be returned to the factory for recalibration.


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#593: Does the 3DM-GX3 have an analog out option?


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#592: Can I use multiple 3DM-GX3 at the same time?

Yes. Any number of units can be operated by a host at the same time. Several considerations surround this implementation (primarily computing power) and we suggest that you discuss your requirements with LORD MicroStrain® sales or a support engineer.

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#591: What are the power requirements of the 3DM-GX3?

For the standard units, here is a link to a detailed technical note: http://files.microstrain.com/TN-I0023_Inertia-Link_3DM-GX2_3DM-GX3_Pin-Outs.pdf

For the OEM units, here is a link to a detailed technical note: http://files.microstrain.com/3DM-GX3-25_OEM_Footprint_and_Connector.pdf




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#590: Can the 3DM-GX3 be installed in any orientation?

Yes, there are no limitations.  However, if a user requires a ‘zeroing’ of the axes, this must be done in the user’s external application.  Good practice dictates that the orientation matrix be used to calculate such zeroing.  Please also be aware of the mathematical singularity in Euler angles.

The user should be aware that the Euler angle formulation in general contains a mathematical singularity at Pitch = +90 or –90 degrees. In practice, poor numerical results will be present if the Pitch angle exceeds +/-70 degrees. In applications where the Pitch angle cannot be guaranteed to exceed these values, it is recommended that the orientation matrix output be utilized instead.

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#588: Are the 3DM-GX3 sampling rates adjustable?

Yes. The sampling rates are user adjustable.

For the -15 and -25, the user may set the sampling rate at up to 1000 Hz depending on the data quantity.

For the -35, the user may set the AHRS sampling rate up to 1000 Hz depending on the data quantity and the GPS sampling rate up to 4 Hz.

For the -45, the user may set the Navigation sampling rate up to 100 Hz.


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#587: At what baud rates can the 3DM-GX3 be operated?

The baud rate is user adjustable and may be set to 9600, 19200, 115200 (default), 230400, 460800, and 921600.

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#585: Can distortions of Earth’s magnetic field degrade the system accuracy of the 3DM-GX3?

Yes.  The presence of strong magnetic fields or large magnetic materials will distort Earth’s weak local magnetic field and this will influence the on-board magnetometers.  A hard and soft iron calibration software utility is provided to field calibrate the 3DM-GX3-25, 3DM-GX3-25 OEM, 3DM-GX3-35 and 3DM-GX3-45.

The 3DM-GX3-15 and 3DM-GX3-15 OEM do not contain magnetometers and are not affected by hard and/or soft iron interference.


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#584: What orientation output formats are available with the 3DM-GX3?

The following orientation outputs formats are available:

  • Acceleration
  • Angular Rate
  • Magnetic Vector
  • DeltaAngle and DeltaVelocity
  • Orientation Matrix
  • Quaternion
  • Euler Angles (pitch, roll and yaw)
  • ...and more.

A detailed description of these outputs can be found in the Data Communications Protocol manual of each product.



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#583: What communication interfaces are available for the 3DM-GX3?

The standard units support both USB and RS-232 interface.

The OEM units support both USB and TTL.

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#581: May I write my own software application for the 3DM-GX3?

Yes. We provide a complete data communications protocol manual which describes in detail each and every command and response that is available with the device.  Applications may be developed in any programming environment (C, VB, LabVIEW, Linux, Matlab, etc.) which supports serial communication.

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#580: What software do you provide for 3DM-GX3?

We provide a general application for Microsoft XP/Vista/Win 7 operating systems that configures, reads, displays and saves data generated by the device.  This application (MIP Monitor) supports both the USB and RS-232 communication interfaces.

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#579: How is the 3DM-GX3 packaged?

When you initially purchase a 3DM-GX3, a starter kit (SK) provides you with everything you need to get started! SKs include a 3DM-GX3 module, communication and power cables, software, manuals and GPS antenna if applicable.  In subsequent purchases you may only require additional modules or other individual components. Several communication interfaces are available creating several starter kit variations.

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#565: Can my 3DM-GX3-35 be upgraded to a 3DM-GX3-45?

No.  A 3DM-GX3-35 can not be upgraded to a 3DM-GX3-45.

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#541: What type of connector is used on the 3DM-GX3-35 and 3DM-GX3-45 GPS antenna?

The connector is an MMCX type connector.  The non-magnetic extension cable with SMA connector provided by LORD MicroStrain® must be used to isolate the magnetometers from magnetic connectors.

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#539: Since the 3DM-GX3-35 has on-board GPS, does it support any type of mapping software?

The 3DM-GX3-35® has a GPS direct mode to use the device in GPS only mode. This is compatible with existing NMEA and UBX applications.

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#536: Is there an option to turn off the 3DM-GX3-35 GPS and run just the AHRS?

Yes, it is easily done in software.

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#535: Is there a Kalman Filter implemented in the 3DM-GX3-35?

No. We do however have a Kalman filter on our 3DM-GX3-45 product.

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#521: Is the data output of the 3DM-GX3 -35 time-stamped?

Yes, several time stamps are available including AHRS time stamp, GPS synch time stamp and GPS correlation time stamp.

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RS232 3DM-GX3-35 AHRS starter kit
RS232 3DM-GX3-35 AHRS starter kit

Includes one 3DM-GX3-35-RS232/USB-M AHRS with internal GPS receiver, RS232 communication cable, software, non-magnetic antenna lead, GPS antenna and power supply.

USB 3DM-GX3-35 Starter Kit
USB 3DM-GX3-35 Starter Kit

Includes one 3DM-GX3-35-RS232/USB-M AHRS with internal GPS receiver, GPS antenna and cable, USB communication cable, software and non-magnetic antenna lead.  


Accurate navigation and orientation under dynamic conditions such as:

  • Primary and/or Secondary GPS-aided Navigation System
  • Unmanned Vehicle Navigation
  • Platform Stabilization, Artificial Horizon
  • Antenna and Camera Pointing
  • Health and Usage Monitoring of Vehicles
  • Reconnaissance, Surveillance, and Target Acquisition
  • Robotic Control
  • Personnel Tracking

Related Products

  • 3DM-GX3-153DM-GX3® -15 -- Product no longer stocked – limited availability - Miniature Inertial Measurement Unit And Vertical Gyro
  • 3DM-GX3-253DM-GX3® -25 -- Product no longer stocked – limited availability - Miniature Attitude Heading Reference System (AHRS)
  • 3DM-GX3-453DM-GX3® -45 -- Product no longer stocked – limited availability - Miniature GPS-Aided Inertial Navigation System