to the slickline 20 is detected by the motion detector 54 the output of which is coupled to suitable detection and recording circuitry collectively referred to as a recording system 56 disposed inside the slickline unit 26 the detected acoustic wave indicate the presence of a casing collar or other type of threaded connection at the depth of the collar locator 18 at the time of signal detection an example of circuitry that may be included in some examples of a casing collar locator are shown schematically in fig2 a pipe coupling detection device 32 may be any type of magnetic casing collar locator device known in the art one such collar locator is described in u s pat no 7 224 289 issued to bausov et al as explained in the background section herein such pipe coupling detection devices include one or more magnets for inducing a magnetic field in the casing and a detection coil because of the change in magnetic field distribution in the vicinity of collars or threaded couplings when a detection coil is moved through such altered distribution magnetic field a voltage is induced in the coil the detected voltage is interpreted to determine the position of the threaded connection it is also possible to use contact arm type caliper tools as a pipe coupling detection device one such contact arm caliper is disclosed in u s pat.