2 Making Measurements104 Keysight U1273A/U1273AX User’s GuideMeasuring duty cycle1 To measure the duty cycle, position the rotary switch on one of the functionsallowing frequency measurements shown in Table 2-20.2 Press until the measurements are displayed as a percentage (%). Probethe test points, and read the display.Figure 2-40 Duty cycle displayThe duty cycle percentage of the input signal is shown in the primary display. Thevoltage or ampere value of the signal is shown in the secondary display. The bargraph does not indicate duty cycle but indicates the voltage or ampere value ofthe input signal.The pulse polarity is displayed to the left of the duty cycle value. indicates apositive pulse and indicates a negative pulse. To change the polarity beingmeasured, press .Press to cycle through the frequency, pulse width, and duty cyclemeasurements.Press for more than 1 second to exit the duty cycle measurement function.NOTE The duty cycle (or duty factor) of a repetitive pulse train is the ratio of thepositive or negative pulse width to the period expressed as a percentage, asshown in Figure 2-37.The duty-cycle function is optimized for measuring the on or off time of logic andswitching signals. Systems such as electronic fuel injection systems andswitching power supplies are controlled by pulses of varying wid th, which canbe checked by measuring the duty cycle.Hz % msLogExitDualHz % msLogExitDual
