In a DWM1000 system with 4 anchors and 4 tags using TWR, what’s the theoretical maximum number of locations per tag per second? (Assuming a “location” for one tag consists of a range message from each of the 4 anchors.)
Sorry if I’m not using the proper jargon.
You’ll find the info in the DW1000 usermanual section 9 and APS016 (Moving from TREK1000 to a product). Both documents are available from https://www.decawave.com
It describes that speed/update rate will depend on a few factors like RF and data configuration. For example use 6.8Mb/s , use short a preamble a possible (e.g. 64 or 128), as each symbol is about 1 µs long. Depending on your application it may also make sense for the DW1000 not to use SLEEP / DEEPSLEEP modes as the IC needs a few ms wake-up time (for crystal to start up) to return to the active state.
I also would like to know clearly about this DWM1000. Thank you so much guys for the details.
If you were to do 4 ranges using TWR techniques and then calculate a position, 4 ranges, position and repeat as fast as possible then you could in theory get at least 250 Hz update rates if you are using custom drivers/firmware. How fast you can go with the decawave libraries I have no idea.
Hmm I cannot write a custom driver at this point in time. Maybe I will get better. Thank you for exactly answering my original question.
I guess I really want to know how fast can you go with the decawave libraries?
What is the “DWM1000 system with 4 anchors and 4 tags using TWR” … is this DWM1001 with PANS SW stack or is this some other DW software (e.g. TREK1000)?
It is same as Trek1000. The anchors and tags use the DWM1000 module not 1001.
Ok, then as Leo has already pointed out, TREK doc is a good place to see how location rate is derived… from frame lengths and inter-frame idle/processing/turnaround times, and a number of messages needed for a location which limit the max rate possible.