Techniques for sending and receiving signals include pre-distorting signals before transmission across a communication path. By slicing the carrot in the longitudinal direction so as to pass through the core portion, a larger area of the core portion towards which the presence of nitrate ions is biased can be exposed, the contact area between the core portion and the blanching water can be increased and more nitrate ions can be eluted and removed at blanching time. Then, the light is incident along the second optical axis on a second prism disposed coaxially with the second optical axis, is bent by the second prism in a direction of a third optical axis, and passes through a photographic lens system disposed coaxially with the third optical axis. The measured channel gain is compared with a known channel gain to obtain an individual phase compensation for the selected drive line. The light reflected from the retroreflective surface strikes the second surface of the beam splitter and is reflected toward a display viewing zone provided at about the focal points of the reflected projectors. The head section and the tube member are forged from a tubular blank into a one-piece, entirely unitary structural component, with the head section outer conoidal hem and neck section formed as extensions of the tube member.