> Tags are mobile and are used to track the physical location of whatever they are integrated in - with centimeter precision (DecaWave promises maximum 10cm error). A tag recevies location data and distance to anchors within range. An onboard location engine calculates the x,y,z position of the tag.
> You can choose to use the default location engine or you can roll your own. This is relatively straight forward if everything is on the same plane. Slightly less so in R3 space. Google “trilateration algorithm” or “multilateration algorithm” to get started. The IEEEXplore archive alone, has 400+ papers on the subject.
> If using the built in location engine, keep in mind that the units used for anchor coordinates and distance estimates are millimeters.
> The update frequency is a function of the number of tags in the network. Using only one tag results in 150 Hz updates. Using 750 tags, you get 0.2Hz updates. Deploy up 9000 tags in a given anchor cluster and the update frequency drops to 0.0167Hz, which is still more than reasonable for many applications.
Why is the update frequency a function of the number of tags?
Say I have a tag A, why the update frequency of tag A is a function of the number of other tags (assuming we have tag B and C in the system.)? They should be unrelated to each other, right?
If this technology is an analogy to GPS, tag A should only communicate with Anchors, not other tags? And the anchors should only passively broadcast their time?
They probably need to do some type of multiplexing/sharing broadcast time because they're on a fixed frequency. More tags means each can broadcast less frequently. If you divide the single tag freq by 750 or 9000 you'll get the same results.
According to the DecWave web site [1] the anchors time stamp the arrival of the tag's beacon and pass it to a central host for trilateration. So the network is single-tasking, essentially.
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[ 3.3 ms ] story [ 26.8 ms ] thread> Tags are mobile and are used to track the physical location of whatever they are integrated in - with centimeter precision (DecaWave promises maximum 10cm error). A tag recevies location data and distance to anchors within range. An onboard location engine calculates the x,y,z position of the tag.
> You can choose to use the default location engine or you can roll your own. This is relatively straight forward if everything is on the same plane. Slightly less so in R3 space. Google “trilateration algorithm” or “multilateration algorithm” to get started. The IEEEXplore archive alone, has 400+ papers on the subject.
> If using the built in location engine, keep in mind that the units used for anchor coordinates and distance estimates are millimeters.
> The update frequency is a function of the number of tags in the network. Using only one tag results in 150 Hz updates. Using 750 tags, you get 0.2Hz updates. Deploy up 9000 tags in a given anchor cluster and the update frequency drops to 0.0167Hz, which is still more than reasonable for many applications.
Why is the update frequency a function of the number of tags?
Say I have a tag A, why the update frequency of tag A is a function of the number of other tags (assuming we have tag B and C in the system.)? They should be unrelated to each other, right?
If this technology is an analogy to GPS, tag A should only communicate with Anchors, not other tags? And the anchors should only passively broadcast their time?
[1] https://www.decawave.com/technology1/