Absorbing UWB signal

Hey,
is it possible to get a stable signal if the tag is behind an obstacle? With obstacle I mean a thin huge paper or bedsheet (3x2m) that is spanned with two wooden or metal pedestals. Using big signal absorbers completely killed the tags signal. I would need a signal behind something that is an obstacle, in order to get the information (that you can’t see), what’s going on behind.
Thanks a lot.
Best regards,
blubbus

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Depends on the obstacle.

At UWB frequencies, certain materials are UWB transparent (mostly) and other materials block it completely.

It will usually go through fabric, paper, wood (if not too thick or wet), drywall/gypsum, glass (if not leaded or metal coated), ceiling tile, plastics, etc.

It will not go through water, masonry, concrete, metals, humans, animals, wire mesh, and metal screen.

That sounds very doable.

Here is an example of our system being used to perform music more than 3 years ago. The stages the two “drummers” are standing on are made from 3/4" plywood and contain 28 anchors inside them. The UWB system is measuring the location of the wrist tags and that information, along with inertial data, is used to real time create sounds. The tags operated at 240 Hz, very high rate, to minimize latency.

The point is that carpet plus 3/4" plywood of the deck was no problem. Wood does have water content, and it did attenuate the signals some amount, but it wasn’t overly large.

We have also done a lot of through the walls UWB work. In standard commercial construction, using thin steel studs and gypsum drywall, the system penetrates the walls pretty well. Here is a quick demo video showing system performance penetrating a number of walls:

Each wall is metal studs on 16 inch centers with two layers of 5/8" drywall and paint.

If the walls are concrete or CMU block, then UWB signal is generally blocked entirely. If the walls have metal foil insulation inside them, that will also usually block the signal. So it really depends on the nature of the materials to assess how well UWB will track in any given situation.

The best way to visualize the UWB signal is a super elongated rugby ball with the tips at each node and the middle diameter being about 30 cm. If the things blocking the signal are covering too much of the 30 cm disc, then the signal may not get through. So a steel stud in the middle between nodes is not a problem, but a steel stud right in front of a node will be a major problem.

Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
mikec@ciholas.com
+1 812 962 9408

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Hi, Sir,
How long will the tag’s battery last? Working on TDOA or TWR?

I assume this is in reference to the 240 Hz tags used in the music generation application.

The tag has a 300 mAH, 1 WH battery and doing this application it will last about 1 day at 100% utilization, which is far more than the application requires. The tag is also sending gesture and inertial data through UWB which uses more power than just doing UWB.

The system uses our own location algorithm that we call multitime. It has similar operational characteristics as TDoA, namely tag beacons once to multiple anchors to be located, but a different mathematical treatment in the location engine than geometric TDoA. The tags are precisely scheduled to maximize air time. Each performer had 4 tags (two hands, two feet) for a total of 960 locates per second.

Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
mikec@ciholas.com
+1 812 962 9408