EH-Link™

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.

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.

The wireless nodes all have 2 Mbytes of datalogging memory.  This 2 Mbytes is organized into 8,191 ‘pages’ of memory, each page holds 132 data points.  The maximum number of data points that can be held in memory can be calculated as follows: 8,191 pages x 132 data points/page = 1,081,212 total data points.

Now the question arises, ‘how long can a node datalog before its memory is full?’. The answer is that it varies depending on how many channels are being sampled and what sampling rate has been set. Here are two examples:

Let’s set a V-Link-LXRS so that channel 1 is active with a datalogging sampling rate of 2048 samples per second and we launch continuous datalogging.  Our calculation would be:

• 1 channel x 2,048 samples per second = 2,048 data points per second
• 1,081,212 data points / 2,048 data points per second = 527 seconds
• 527 seconds / 60 seconds per minute = ~9 minutes to fill the memory

Let’s set a G-Link-LXRS so that channels 1, 2 and 3 are active with a datalogging sampling rate of 32 samples per second and we launch continuous datalogging.  Our calculation would be:

• 3 channels x 32 samples per second = 96 data points per second
• 1,081,212 data points / 96 data points per second = 11,262 seconds
• 11,262 seconds / 60 seconds per minute = ~187 minutes to fill the memory

In FINITE sampling, the user sets a total number of samples to be taken which equates to a time period.  Because the sampling rate per second is known, the user can adjust the number of samples to be taken to determine how long the sampling period will be.

In CONTINUOUS sampling, the user does not set the total number of samples and therefore does not set the time of the sampling period.  By selecting CONTINUOUS sampling, the user is instructing the system to sample data until the user manually stops the sampling (via software), the power is cycled, the on-board datalogging memory is full, the battery dies, the power fails, etc.

LORD MicroStrain^® Wireless Sensor Networks provide several data acquisition modes including:

• Synchronized Sampling
• Armed Datalogging
• Streaming
• Duty Cycle

See the particular wireless node for specifics.