Storage oscilloscopes

EE September 1986 STORAGE OSCILLOSCOPES In this article it will be assumed that the reader is reasonably familiar with conventional oscillo- scopes. These instruments are sometimes called real- time oscilloscopes, because the input signal(s) are projected onto the screen immediately. Two technologies In principle, there are two distinct storage tech- nologies: (1) analogue, in which the fluorescent screen serves as the memory, and (2) digital, which uses semiconductor memories. Analogue storage oscilloscopes are quite well-known instruments. They are fitted with special cathode-ray tubes (CRTs) that are provided with a storage mesh-see Fig. 1. Before the electron beam reaches the screen, it hits the mesh and dislodges a number of electrons. These so-called secondary electrons are gathered by a special collector. The parts of the mesh from which electrons have been dislodged are positive, and form a true copy of the signal. Afterwards, the flood guns in the CRT illuminate the Pho...