In the figure above, Oscium’s handheld oscilloscope measures the sine wave output from an Agilent 33250 Arbitrary Waveform Generator. It’s important to set the oscilloscope’s trigger threshold to an appropriate voltage threshold. This blog post examines what happens when the trigger level is either set too high or too low, and of course, when its set just right.
Setting iMSO’s Trigger Threshold
The figure below is a sine wave measured with Oscium’s iMSO-104 and shows the threshold tuning knob on the far right side of the screen. This tuning knob is sometimes referred to as a balloon in Oscium’s documentation. Regardless of the name, the threshold indicator is called out explicitly in this image so there is no confusion later on in the discussion.
The following drawing shows the appropriate trigger threshold position for the wave form measured. Notice how the trigger is placed below the maximum expected value and above the noise a jitter in the measurement.
What Happens: Too High Or Too Low?
Too Low: The noise region in the figure is exaggerated for illustration. Placing the threshold within the noise will cause the iMSO-104 to trigger with or without the signal being present. This is especially problematic when configuring the oscilloscope to capture a single. Like a mousetrap that reacts before the mouse approaches the bait, the oscilloscope will trigger off any random noise or jitter that meets or exceeds the threshold.
Too High: If the portable oscilloscope is set for a single trigger with the threshold too high, the oscilloscope simply will not capture a waveform. If so equipped, the oscilloscope with sit idle with the Armed indicator illuminated.
See iMSO-104 In Action:
The other way an oscilloscope operates is in Auto Trigger, where the instrument is triggered continuously. This is sometimes called a rolling capture. The following video clip shows iMSO-140 triggering on three types of waveforms, and includes instances where the trigger threshold is set appropriately and when its set too high.
Oscium's handheld oscilloscope is now available with universal platform support! So, if you're interested in using the scope on iOS, Android, PC or Mac, Oscium supports you. Please go to iMSO-204x for more information.