The present invention relates to a receiving system including an adaptive first equalizer associated with a first threshold detector, and a device which enables the timing of a transmitting system to be recovered for said receiving system from an equalized signal and a signal obtained by thresholding. The main body has a central region and a fringe region. Yet another embodiment may comprise a frame having a base component, a vertical component, and a cross-member component, a rotation mechanism rotatably coupled with the cross-member component, and a protractor having a freely rotatable arm configured to couple with the golf club and measure an angle at which the golf club is rotated about the rotation point along a swing path. At the mobile entity the data messages are stored for subsequent access by a user. In the securing region, the outer metal sheet has an opening delimited by at least two opposite securing flanges which project freely from the outer metal sheet and which are part thereof.