Display, Recording, and Presentation of Measurement Data

This chapter discusses about coveting the techniques available to either display measurement data for current use or record it for future use. Measurement signals in the form of a varying electrical voltage can be displayed either by an oscilloscope or else by any of the electrical meters. Electronic displays enable a parameter value to be read immediately, thus allowing for any necessary response to be made immediately. Now that computers are part of the furniture in most homes, the ability of computers to display information is widely understood and appreciated. The earliest recording instruments used were various forms of mechanical chart recorders. Mechanical chart recorders are a long-established means of making permanent records of electrical signals in a simple, cheap, and reliable way, even though they have poor dynamic characteristics, which means that they are unable to record signals at frequencies greater than about 30 Hz. The fiber optic recorder uses a fiber-optic system to direct light onto light-sensitive paper. Hybrid chart recorders represent the latest generation of chart recorders, and basically consist of a potentiometric chart recorder with an added microprocessor. The two formats available for presenting data on paper are tabular and graphical ones. A tabular presentation allows data values to be recorded in a precise way that exactly maintains the accuracy to which the data values were measured. Presentation of data in graphical form involves some compromise in the accuracy to which the data are recorded, as the exact values of measurements are lost.