Patent ID: 8054863

Claim:
A method of estimating range to an object comprising: transmitting at least one UWB signal; receiving at least one UWB signal; sampling the received UWB signal depending on a plurality of clock and/or sample pulses having a first frequency; providing a fractional signal having a second frequency that is lower than the first frequency and a phase that is dependent on the delay between when the UWB signal is actually received and when the received UWB signal is first sampled, wherein providing the fractional signal comprises: starting an oscillation signal A when the UWB signal is received, signal A having a third frequency which is similar to the first frequency; starting an oscillation signal B when the first clock or sample pulse occurs after signal A starts, signal B having a fourth frequency which has a relatively small frequency difference to the third frequency; multiplying signals A and B to generate signal C ; and providing the lower frequency component of signal C as the fractional signal; and determining the range based on at least a first number of clock or sample pulses between transmitting and receiving the UWB signal and the phase of the fractional signal.