The Concept of a System ``Operating Surface'' as a Fundamental System Characteristic

The development of the concept of an operating surface of a measuring system yields as deductively derived special cases, the unbalance, reference-balance, null-balance, unbalance comparison, differential, and directional measurement methods. These apparently unrelated measurement methods now appear as special cases of a new general concept, which is a powerful tool in system analysis and design. The only differences between these apparently widely different methods are the boundary conditions on energy flow through the system.