A method for determining a distance (d), comprising: providing a position detection apparatus, comprising: a first processing means; a first transmitting means; a first receiving means; providing a transponder comprising: a second processing means; a second receiving means; a second transmitting means; generating a pseudo random number sequence by means of the first processing means; transmitting the pseudo random number sequence by means of the first transmitting means; receiving the pseudo random number sequence by means of the second receiving means; modulating the received pseudo random number sequence by means of delaying the received pseudo random number sequence by a predetermined number of clock cycles from a group of at least two predetermined number of clock cycles, by means of the second processing means; transmitting the modulated pseudo random number sequence by means of the second transmitting means; receiving the modulated pseudo random number sequence by means of the first receiving means; detecting a path time of the pseudo random number sequence, by means of delaying and correlating the generated pseudo random number sequence with the received modulated pseudo random number sequence, wherein the delay time corresponds to the path time, by means of the first processing means; detecting by means of the first processing means comprising information about the group of at least two predetermined number of clock cycles, a clock correction factor for the transponder by counting a number of clock pulses between two correlation signal maximum of the generated pseudo random number sequence with the received modulated pseudo random number sequence, and by calculating the clock correction factor using the counted number of clock pulses and the information about the group of at least two predetermined number of clock cycles; calculating a flight time of the pseudo random number sequence between the position detection apparatus and the transponder by means of the path time and the clock correction factor by means of the first processing means; calculating the distance (d) between said position detection apparatus and said transponder by means of the flight time, by means of the first processing means. providing a position detection apparatus, comprising: a first processing means; a first transmitting means; a first receiving means; a first processing means; a first transmitting means; a first receiving means; providing a transponder comprising: a second processing means; a second receiving means; a second transmitting means; a second processing means; a second receiving means; a second transmitting means; generating a pseudo random number sequence by means of the first processing means; transmitting the pseudo random number sequence by means of the first transmitting means; receiving the pseudo random number sequence by means of the second receiving means; modulating the received pseudo random number sequence by means of delaying the received pseudo random number sequence by a predetermined number of clock cycles from a group of at least two predetermined number of clock cycles, by means of the second processing means; transmitting the modulated pseudo random number sequence by means of the second transmitting means; receiving the modulated pseudo random number sequence by means of the first receiving means; detecting a path time of the pseudo random number sequence, by means of delaying and correlating the generated pseudo random number sequence with the received modulated pseudo random number sequence, wherein the delay time corresponds to the path time, by means of the first processing means; detecting by means of the first processing means comprising information about the group of at least two predetermined number of clock cycles, a clock correction factor for the transponder by counting a number of clock pulses between two correlation signal maximum of the generated pseudo random number sequence with the received modulated pseudo random number sequence, and by calculating the clock correction factor using the counted number of clock pulses and the information about the group of at least two predetermined number of clock cycles; calculating a flight time of the pseudo random number sequence between the position detection apparatus and the transponder by means of the path time and the clock correction factor by means of the first processing means; calculating the distance (d) between said position detection apparatus and said transponder by means of the flight time, by means of the first processing means.