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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.

 

The Internal or External GPS selector refers to the function that allows the user to turn off the on-board GPS and use a computer to send GPS updates to the device.

If you are using the internal GPS, always select ‘Internal’.

Refer to the data communications protocol if you intend to supply external GPS.

MIP Monitor software also has a test function that allows you to input user selected GPS parameters.

 

The WSDA-RGD (with internal GX3 inertial sensor) is configured to produce the following messages on startup.

GPS Data (1 Hz):

  • UTC Time
  • LLH Position
  • NED Velocity

AHRS Data (100 Hz):

  • Euler Angles

From this output the WSDA logs:

GPS (1 Hz):

  • latitude
  • longitude
  • height above ellipsoid
  • height above MSL
  • horizontal accuracy
  • vertical accuracy
  • speed

AHRS (100 Hz):

  • roll
  • pitch
  • yaw

The WSDA-RGD does not log any data until it gets a valid time, if it is set to get time from GPS only it will not log any output from the GX3 until the UTC timestamp from the GX3 is valid, even though the GX3 is producing valid AHRS data.

This data is not user configurable and is not available as a live stream through LiveConnect.

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.

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).

 

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).

The DEMOD-DVRT and the DEMOD-DVRT-TC signal conditioners both have a Low Pass Filter.

http://www.microstrain.com/displacement/demod-dvrt

http://www.microstrain.com/displacement/demod-dvrt-tc

The filter is described as: 2 pole, active Butterworth, 3 dB down @ 800 Hz standard; factory adjustable 10 Hz-8 Khz

The filter is modified by manipulating resistors on the circuit board.

Resistors may either be removed or added or both.

These resistors may go into standoff sockets or require soldering/desoldering on the circuit board surface.

After the rework is done, good practice dictates that the signal conditioner and its paired sensor be recalibrated to reflect changes in noise characteristics.

We recommend that such work be done here at the factory.

 

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

If you are mixing new nodes and base stations with older nodes and base stations, please be cognizant of these different channel settings.

The Node Discovery function of Node Commander will help you sort out which nodes are on what channels; Node Discovery is channel independent and allows the base station to communicate with any node, no matter what channel it is on

Sampling methods such as synchronized sampling, low duty cycle, network broadcast, etc. require that all nodes are on the same frequency so you will want to insure that you have adjusted the channels settings of the nodes to suit.

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Contacts

  • LORD Sensing - Sales
    459 Hurricane Lane
    Suite 102
    Williston VT, 05495
    USA
  • +1-802-862-6629 (United States)
  • https://www.microstrain.com