1. The undirectional measurement is a problem which often be seen in the engineering measurement.

2. Several typical methods of undirectional measurement were introduced in this paper, and their characteristics and scope of application were expounded.

3. Stakes: cut tie technicality energy and undirectional membrane consistent behavioural.

4. Diods have two active electrodes, and most are used for their undirectional current property.

5. The results show that the comparator is strongly code disjoint only if errors in the non-code inputs are undirectional.