The Hantek DSO5102P 100MHz 2-channel digital storage oscilloscope offered by Circuit Specialists boasts advanced features you won’t find on most analog oscilloscopes, especially at a price point this low. These unique functions are useful for troubleshooting glitches and dropouts in complex digital data as well as identifying problems in analog signals up to 100 MHz. Let’s go over a brief tutorial that illustrates the usefulness of pulse mode triggering and fast-Fourier transform (FFT) display mode.
Pulse mode triggering is useful for detecting digital signal abnormalities and troubleshooting elusive digital signal corruption. In pulse mode the user has the option to select the trigger signal based on the width of the pulse of interest. The choices are “equal to,” “not equal to,” “less than,” and “greater than” an adjustable pulse width ranging from 20 nanoseconds to 10 seconds.
Let’s take a look at how to use pulse mode triggering to detect a runt pulse in a digital pulse train. Select pulse mode triggering from the trigger menu and choose the criteria (“equal to,” “greater than,” etc.). You can then dial in the specific pulse width by first pressing F4 to activate the pulse width control and adjust it using the V0 knob. In our example we’ll select the “less than” criteria and adjust the pulse width to 20us, which is the pulse width of a normal pulse.
This enables us to immediately detect runt pulses produced by a defective integrated circuit. Detecting and identifying runt pulses with an oscilloscope that doesn’t have this feature is extremely difficult and time-consuming, requiring countless hours of tweaking the trigger level control in an attempt to catch the runt pulse. The oscilloscope screenshot below shows a stable signal train indicating the presence of the non-standard runt pulse.
The Hantek DSO51102P digital storage oscilloscope also features fast-Fourier transform (FFT) display mode, which provides you with a means of easily detecting distortion in an analog waveform. This FFT feature enables you to view a waveform in voltage-versus-frequency instead of the standard voltage-versus-time typically found on most oscilloscopes. You will use this mode of operation to quickly determine the harmonic content of a periodic signal. For instance, a pure 1 KHz sine wave should produce an FFT display with frequency content only at 1 KHz.
Since a pure sine wave is unobtainable in reality, a real waveform will show minimal frequency content at other frequencies that are multiples of 1 KHz — 2 KHz, 3 KHz, 4 KHz, etc. — and a distorted waveform will have significant frequency content at its multiples. Harmonic distortion would then produce a waveform with excessive amplitude values above 1 KHz. The screenshot below shows a 1 Khz since wave applied to an amplifier that is producing distortion.
The FFT display of the distorted signal shows excessive amplitude at 3 Khz. The display of the same waveform viewed on the standard oscilloscope display is included to show that the level of distortion is not as obvious as what we see on the FFT display.
The examples above were used to highlight two of the many features that make the Hantek 5102P digital storage oscilloscope an incredible value. These features will prove invaluable the next time you need to debug or troubleshoot complex digital and analog circuits.