ABSTRACT
In the early days, phase measurement was not easy. The input and output waveforms could be compared on an oscilloscope, but the estimate of phase was somewhat rough and ready. If an x – y oscilloscope was used, output could be plotted as y against the input’s x, enabling phase shifts of zero and multiples of 90° to be accurately spotted. The task of taking a complete frequency response was a tedious business (Figure 11.1).
