Hello everyone,
I would like to set up a demo to show Decawave’s position capacity when my tag is moving around the calibrated anchor-detection area. I’m thinking about placing my tag in a car. I would like to know what’s the speed limit of my car inside the anchor area to be correctly placed.
I assume this goes together with the samplig period so I woul very much appreciatte if you could give me some advice on how to set this parameters and what its maximum value is
Thanks
Hello Carolina
The quick answer is that it depends on the duration of the packet:
• For 110k, 128 byte packet with 4096 preamble, the max speed is 5 m/s or 11 mph.
• For 6.8 mbps, 12 byte packet with length 64 preamble, the max speed is 706 m/s or 1554mph.
You can have a look at TB001 Max DW1000 Speed.pdf (194.6 KB) for more information. I wasn’t able to find it on our website so I attached it to this message.
I hope this helps
Seppe
Hello Seppe,
Thanks a lot for this info. It was just what I was looking for. Could you tell me how long does it take for a tag to be detected when joining the network? lets say I have an anchor network in a room and a tag that moves around it. The tag goes out of the room and then comes back. How much time would it take it to be detected when coming back?
Thanks again
Hello Carolina
The time and range of the system depend on the type of RTLS scheme that is implemented, the radio TX power, the sampling frequency, the environment and the way the anchors are set up. We have an AN on the Max Range in DW1000 Systems that may be of help.
I’m assuming you are using PANS 2.0 (the system programmed by default on the DWM1001 devices).This system uses TWR (To Way Ranging) between tags and anchors in order to calculate an absolute position of the tag. One thing this system might be able to do for you is already tell you when a tag is in range of one anchor. This would’t give a full absolute position, but it would allow to quickly know a car entered, or is close to, the ranging “bubble”. In order for the absolute position to be calculated the tag needs to be found by at least 3 anchors. On top of that some calculation time is required.
I don’t know if we have any data on how fast this system can locate new tags, since this really depends a lot on the setup and the environment. At high enough sampling rates and in a properly configured environment the time to locate a tag is fairly short making it suitable for most RTLS use-cases. I suggest you test this for yourself and validate the speed for your use-case. While we can offer some generic information, we will not be able to provide an accurate answer.
csainz
In case you missed it the second video here shows a reasonably high speed transition from outside using GPS to inside using UWB. The UWB system starts outputting positions 200 ms after coming into range of sufficient the anchors, the reason for such a large delay is to allow for some smoothing and filtering in order to minimize the position noise.