Elevator position measurement system

An elevator car position measurement system (300, 500) for an elevator system (200, 400) comprising an elongate tension member (226) operably connected to an elevator car (220) and configured to move the elevator car (220) within the hoistway (240), the elevator car position measurement system (300, 500) comprising:

• a pulse generator (202) configured for transmitting a pulse (334) along the elongate tension member (226) from a first location on the elongate tension member (226) towards a second location on the elongate tension member (226);
• a detector unit (218) configured to receive the pulse (334) from the pulse generator (202) after the pulse (334) has been transmitted along a length of the elongate tension member (226) and to record a time at which the pulse (334) is received;
• wherein (i) the pulse generator (202) is arranged to move within the hoistway (240) dependent on a position of the elevator car (220) within the hoistway (240) or (ii) the detector unit (218) is arranged to move within the hoistway (240) dependent on the position of the elevator car (220) within the hoistway (240),
• wherein the length of the elongate tension member (226) between the pulse generator (202) and the detector unit (218) along which the pulse (334) is transmitted changes dependent on the position of the elevator car (220) within the hoistway (240), and
• wherein the elevator car position measurement system (300, 500) is configured to calculate the length of the elongate tension member (226) along which the pulse (334) is transmitted based on the recorded time, and determine the position of the elevator car (220) within the hoistway (240) based on the determined length.