What is Multipath?
Multipath is the phenomenon whereby a radio signal arrives at a receiver’s antenna by more than one path. This occurs by the reflection, diffraction, or scattering of radio waves from atmospheric ducting, reflection from water bodies or terrestrial objects (like mountains), etc.
Does Multipath impact signal strength?
Yes, multipath propagation of radio signals causes fading of the transmitted signal, which can be indicated by fluctuations in signal strength when received by the signal receiver.
How do I mitigate Multipath?
Pe-position base station or node to mitigate possible multipath interference.
Ensure a clear path to the antenna for the strongest signal, enhancing the strength of the strongest signal AND reducing the strength of the weaker signals.
Learn More: Mutipath Propagation
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.
Microsoft Excel displays the timestamp contained in the wireless node data files incorrectly. If you were to open the CSV file with Microsoft Notepad, you will see that the timestamp is shown properly. In order to get Excel to show the human readable time, follow the below procedure:
- Highlight all of column A (column with the timestamp)
- Right click on highlighted region and select Format cells...
- Select the Number Tab in the window that open and choose Custom from the Category box
- Scroll to the bottom of the list in the Type box, find this entry: m/d/yyyy h:mm and click it
- Add to the entry an :ss.000 so it now looks like this: m/d/yyyy h:mm:ss.000
- Click OK
The timestamp will now be correct.
