Clock management in ultra-wideband ranging

The distance between two asynchronous impulse ultra-wideband (UWB) sensors can be obtained from round trip flying time through two-way ranging (TWR) transaction. The clock difference causes error in the flying time measurement account for the order of 10 nanoseconds propagation delay. This paper presents a clock management between UWB sensors in the TWR transaction. The ranging responder estimates the clock of ranging initiator by a delay-locked-loop circuit during reception of ranging frame. When replying the response, the ranging responder locks its clock frequency to the estimated clock of ranging initiator. Consequently the duration of TWR are measured by the same clock. The simulation over the UWB channel models results shows that the relative clock offset can be reduced to less than +/- 1.2ppm in the worst channel mode.