Frequently Asked Questions about Oscilloscopes

　　It can be roughly divided into three categories: analog, digital and combination.

　　2. What is a digital oscilloscope?

　　An instrument that can reconstruct the waveform of an electrical signal after digitization and other post-processing.

　　3. What is a digital fluorescent oscilloscope?

　　An instrument that can digitize electrical signals and store, analyze, and display waveforms in real time as three-dimensional data (signal amplitude, time, and distribution of amplitude relative to time).

　　4. What is a mixed signal oscilloscope?

　　An instrument that combines the signal detail analysis capabilities of a digital oscilloscope with the multi-channel timing measurement capabilities of a logic analyzer.

　　5. What does the bandwidth of an oscilloscope mean?

　　When measuring AC signals, an oscilloscope usually has a maximum frequency. If the frequency exceeds this, the waveform measurement accuracy will decrease. This frequency is the bandwidth of the oscilloscope. The frequency at which the oscilloscope sensitivity decreases by 3dB is usually defined as the bandwidth of the oscilloscope.

　　6. What does the sampling rate of a digital oscilloscope mean?

　　When a digital oscilloscope digitizes a signal waveform, the number of times it collects data per unit time is the sampling rate.

　　7. What is real-time sampling? What is equivalent-time sampling?

　　Usually, sampling is performed in a fixed order, and the sampling order is the same as the order displayed on the oscilloscope screen. This is real-time sampling. The advantage of real-time sampling technology is that it can capture single-shot signals. Equivalent time sampling is also called repeated sampling. When the following two conditions are met: 1. The waveform must be repeated; 2. It must be able to trigger stably. The oscilloscope can obtain samples of different points of the waveform from multiple waveform cycles, and then fully restore the waveform on the screen. It includes two technologies: sequential sampling and random repeated sampling. Its advantage is that a very slow analog-to-digital converter can be used.

　　8. What is the waveform capture rate? What is the display update rate?

　　The digital oscilloscope will occupy CPU time when processing signals in the future. During this period, the oscilloscope cannot capture signals, which is called dead zone. Due to the existence of dead time, the digital oscilloscope cannot capture all signals 100%. The dead time can be effectively reduced through parallel technology, digital phosphor technology and other means. The waveform capture rate is the number of waveforms captured and displayed by the oscilloscope per unit time. Since the digital oscilloscope displays one screen with 512 points, the waveform capture rate multiplied by 512 is the display update rate.

　　9. What does the storage depth of a digital oscilloscope mean?

　　Storage depth, also called record length or acquisition length, is the number of sampling points that an oscilloscope can store.

　　10. What is a trigger?

　　In order to display the waveform stably on the oscilloscope screen, a condition needs to be set to make the oscilloscope start scanning. This condition is the trigger.

　　11. What is trigger inhibition (trigger lockout, HOLD OFF)?

　　The condition in which the trigger circuit cannot work for a period of time after the oscilloscope triggers a scan is called trigger inhibition.