Abstract: A portable unit for detecting a position with respect to a reference, particularly for substantially shielded environments, comprising a suitable power supply element. The unit comprises a control and processing processor, a device for three-dimensional orientation with respect to geographical references, at least one accelerometer, a screen, a memory component and respective data input and output interfaces. The processor is preset by the user by means of the input interface and is adapted to process instantaneously the data supplied during use by the orientation device and by the at least one accelerometer, displaying the processing on the screen and storing it in the memory component.