Apparatus for estimating distance capable of adjusting coverage and resolution

An apparatus for adjusting a measuring range and a measuring resolution is provided to improve a measuring accuracy of a distance measuring device by changing a reference pulse frequency, a delay pulse frequency, and a duty ratio of the reference pulse. A reference pulse generator(11) includes a first programmable clock generator(111) and a first duty ratio controller(112) and outputs a reference pulse at a timing, when a first wireless communication device transmits a distance measuring signal to a second wireless communication device. A delay pulse generator includes a second programmable clock generator and a second duty ratio controller and generates a delay pulse at a timing, when a response signal from the second wireless communication device is received at the first wireless communication device, in response to the distance measuring signal. An overlap detector detects an overlap timing between the reference and delay pulses. A counter counts the reference pulse or the delay pulse up to the overlap timing. A distance calculator calculates a time between a transmission timing of the distance measuring signal and a reception timing of the response signal by using first and second frequencies and a counted result, and calculates a distance between the first and second wireless communication devices by using the calculated time.