Labels:text | screenshot | rectangle | diagram | parallel | number | line OCR: UNIPOLAR AND POLAR SIGNALING + 0 1 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 A. Unipolar nonreturn to zero B. Unipolar rotum to zero 0 1 0 1 1 0 1 0. 0 1 0 1 1 0 1 0 0 0 C. Polar nonreturn to zero D. Polar return to zero Figure 1. With unipolar signaling the mark signal, usually representing a 1, is indicated by a positive voltage or current, while zero voltage or current represents a space or 0. Polar signaling represents warks (or Is) with a positive voltage or current, while spaces (or Os) are represented by a negative value. Return to zero signaling requires that cach mark signal start and finish at zero within the allotted time for a bit.