Cable reel for winding and unwinding an electrically conductive cable having an unwindable end and a non-unwindable end, wherein a cable length measuring system for measuring a length (l 1, l 2) of at least one portion (10a, 10b) of the electrically conductive cable is arranged on the cable reel, wherein the cable length measuring system comprises at least one pulse generator and at least one pulse receiver and wherein the cable length measuring system further comprises: - a first coupling device (30.1) and a second coupling device (30.2), wherein - the first coupling device (30.1) comprises the pulse generator and - the second coupling device (30.2) comprises the pulse receiver, - a reflector device, and - an evaluation device which is operatively connected to the pulse generator and the pulse receiver, wherein - the pulse generator is adapted to couple a pulse into the cable, - the pulse receiver is adapted to receive the pulse coupled into the cable by the pulse generator, and - the reflector device is arranged on the unwindable end of the cable and is adapted to at least partially reflect the pulse coupled into the cable by the pulse generator, wherein the evaluation device is adapted to determine the length (l 1, l 2) of the at least one portion (10a, 10b) of the cable from the pulse transit times of the pulses coupled into the cable by the pulse generator and received by the pulse receiver, wherein - the first coupling device (30.1) of the cable length measuring system is arranged on the cable reel in such a way that the cable is guided past the first coupling device (30.1) or through the first coupling device when it is unwound from the reel and/or when it is wound onto the reel (30.1), wherein the first coupling device (30.1) can be arranged on the cable so as to be electrically isolated from the cable, and the second coupling device (30.2) is operatively coupled to the non-unwindable end of the cable, or - the second coupling device (30.2) of the cable length measuring system is arranged on the cable reel in such a way that the cable is guided past the second coupling device (30.2) or through the second coupling device when it is unwound from the reel and/or when it is wound onto the reel (30.2), wherein the second coupling device (30.2) can be arranged on the cable so as to be electrically isolated from the cable, and the first coupling device (30.1) is operatively coupled to the non-unwindable end of the cable. - a first coupling device (30.1) and a second coupling device (30.2), wherein - the first coupling device (30.1) comprises the pulse generator and - the second coupling device (30.2) comprises the pulse receiver, - the first coupling device (30.1) comprises the pulse generator and - the second coupling device (30.2) comprises the pulse receiver, - a reflector device, and - an evaluation device which is operatively connected to the pulse generator and the pulse receiver, wherein - the pulse generator is adapted to couple a pulse into the cable, - the pulse receiver is adapted to receive the pulse coupled into the cable by the pulse generator, and - the reflector device is arranged on the unwindable end of the cable and is adapted to at least partially reflect the pulse coupled into the cable by the pulse generator, wherein the evaluation device is adapted to determine the length (l 1, l 2) of the at least one portion (10a, 10b) of the cable from the pulse transit times of the pulses coupled into the cable by the pulse generator and received by the pulse receiver, wherein - the first coupling device (30.1) of the cable length measuring system is arranged on the cable reel in such a way that the cable is guided past the first coupling device (30.1) or through the first coupling device when it is unwound from the reel and/or when it is wound onto the reel (30.1), wherein the first coupling device (30.1) can be arranged on the cable so as to be electrically isolated from the cable, and the second coupling device (30.2) is operatively coupled to the non-unwindable end of the cable, or - the second coupling device (30.2) of the cable length measuring system is arranged on the cable reel in such a way that the cable is guided past the second coupling device (30.2) or through the second coupling device when it is unwound from the reel and/or when it is wound onto the reel (30.2), wherein the second coupling device (30.2) can be arranged on the cable so as to be electrically isolated from the cable, and the first coupling device (30.1) is operatively coupled to the non-unwindable end of the cable.