Frequency analogy for process instrumentation

Conventional process instrumentation systems are critically examined. It is found that important process control problems cannot be satisfactorily solved because of drawbacks in the operational principles used by the systems. A new system employing frequency instead of amplitude for the transmission of the signals representing the process parameters has a number of advantages in comparison to conventional systems. The components required for such a new process instrumentation system are discussed. It is recommended to connect the process computer with a digital differential analyzer.