Hi everyone, being new to UWB ranging, I would like to ask, in a TWR scenario at an open space environment, would the ranging accuracy depend at some degree on the distance between the two nodes? For example, if the nodes are 10 meters apart, is it more likely that our ranging is accurate compared to if these were 50 meters away?
Range accuracy is relatively insensitive to transmission distance until the signal starts to fade at the limits of range. Basically, as long as the leading edge detection algorithm inside the chip has enough signal to noise ratio to work with, it produces good results.
As you get to the limit of signal strength, the system will start to produce worse results. This comes in two forms, a generally noisier estimation of the leading edge resulting in less precision, and the leading edge being so weak that a multipath edge is mistakenly detected as the arrival time leading to a potentially large jump in distance reading.
There are also errors introduced when the signal is strong. See this app note regarding distance bias versus signal strength:
This bias is introduced by delay effects with varying signal amplitude.
Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
mikec@ciholas.com
+1 812 962 9408
Thank you for your time Mike.