Real World Instrumentation with Python

Advanced Tools

There is a lot one can do with a tool like a DMM, but there are some things it simply cannot do. One application the DMM cannot handle is the direct measurement of electrical waveforms. Another is the visualization of logic signals on multiple parallel lines. For these situations, tools such as an oscilloscope and a logic analyzer can make the difference between knowing and just guessing.

The Oscilloscope

The oscilloscope is a very old instrument, and has been around in one form or another for at least 80 years (perhaps longer, depending on how one defines what an oscilloscope is). The reason for its success is its inherent usefulness for examining changing electrical signals over time. Early electronic oscilloscopes used vacuum tubes for signal amplification, and a specialized type of tube called an electrostatic cathode ray tube (CRT) for the primary display. An oscilloscope CRT is similar in operation to the CRT found in older computer monitors and television sets, except that it typically uses electrical fields rather than magnetic deflection fields to guide the beam onto the screen.

Modern oscilloscopes are digital instruments with LCD displays like those found in flat-screen monitors—the days of vacuum tube amplifiers are long past, and the CRT is quickly heading for obsolescence. Figure 6-7 shows the front panel of a simplified generic dual-trace digital oscilloscope.

Figure 6-7. Generic digital oscilloscope

Dual-trace oscilloscopes with the ability to display two ...