Abstract: A method of determining a distance between a first device and a second device. The method comprises: performing an initial-ranging-operation, by exchanging two multi-frame ranging cycles between the first device and the second device, to calculate a clock ratio and a multi-frame-cycle-ToF. The method further comprises performing a plurality of single-message ranging cycles, wherein each single-message ranging cycle comprises: at a predetermined first-device-cycle-time after an earlier message is sent from the first device to the second device, the first device sending a single-ranging-message to the second device; determining a second-device-cycle-time as the time between the second device receiving the single-ranging-message and the earlier message being received by the second device; determining a current-message-ToF based on: the previous-message-ToF, the first-device-cycle-time, the clock ratio, and the second-device-cycle-time.

Abstract: An ultra-wideband, UWB, receiver module (213) comprising: an antenna for wirelessly receiving UWB signalling from a UWB transmitter module (212) and a processor. The processor is configured to: determine a channel impulse response, CIR, (519) of the wirelessly received UWB signalling, wherein the CIR comprises a plurality of channel taps each having a tap-response-value; identify a predetermined feature (520) in the CIR and an associated channel tap; and based on the channel tap that is associated with the identified feature (520) in the CIR (519), synchronize the UWB receiver module (213) for reception of subsequent UWB signalling.

Abstract: An ultra-wideband, UWB, receiver module (213) comprising: an antenna for wirelessly receiving UWB signalling from a UWB transmitter module (212) and a processor. The processor is configured to: determine a channel impulse response, CIR, (519) of the wirelessly received UWB signalling, wherein the CIR comprises a plurality of channel taps each having a tap-response-value; identify a predetermined feature (520) in the CIR and an associated channel tap; and based on the channel tap that is associated with the identified feature (520) in the CIR (519), synchronize the UWB receiver module (213) for reception of subsequent UWB signalling.

Abstract: A method of determining a distance between a first device and a second device. The method comprises: performing an initial-ranging-operation, by exchanging two multi-frame ranging cycles between the first device and the second device, to calculate a clock ratio and a multi-frame-cycle-ToF. The method further comprises performing a plurality of single-message ranging cycles, wherein each single-message ranging cycle comprises: at a predetermined first-device-cycle-time after an earlier message is sent from the first device to the second device, the first device sending a single-ranging-message to the second device; determining a second-device-cycle-time as the time between the second device receiving the single-ranging-message and the earlier message being received by the second device; determining a current-message-ToF based on: the previous-message-ToF, the first-device-cycle-time, the clock ratio, and the second-device-cycle-time.

Abstract: A method for optimizing power of a ranging sequence includes counting at least one cycle of a first clock during a Crystal Oscillator (XO)-mode to generate a first cycle count. A second clock is activated at an end of the XO-mode. The first cycle count is converted into a fractional correction value by multiplying the first cycle count by a ratio of a second period of the second clock divided by a first period of the first clock. A first alignment of the first clock to the second clock is determined at a beginning of the XO-mode. A second alignment of the first clock to the second clock is determined at the end of the XO-mode. An adjusted cycle count is determined by summating the fractional correction value with a summation of the first alignment and the second alignment divided by the first period.