Oscilloscope usage: various sampling methods

I will not discuss the normal sampling method, but first look at the peak detection method. Peak detection is only effective under downsampling. The same signal is sampled under normal sampling and peak detection, as shown in the following two figures. The waveform obtained by the normal sampling method (the storage depth of the oscilloscope is intentionally reduced):

The waveform obtained by peak detection sampling method:

Peak detection is truly reflected when there is a narrow pulse. For example, if the input signal is a 50ns positive pulse, when observed under a large time base and the sampling rate is reduced to less than 20KSa/s, it is possible that the 50ns pulse signal cannot be captured.

50ns pulse signal:

When the sampling rate drops to a value smaller than the pulse width, that is, when it is 20M, it is possible that the pulse cannot be collected. Here is a more exaggerated point. Looking directly at the sampling rate of 2M and collecting 50ns pulses, it is found that there are many places where the pulse cannot be collected, as shown in the following figure:

Now let's look at peak detection:

Let's take a look at average sampling. As the name implies, average sampling is the averaging of multiple frames of waveforms. We use a simulated noise to observe. The waveform obtained by the normal sampling mode is as follows:

The results of averaging 4 times are as follows:

The results of averaging 1024 times are as follows:

Finally, let’s look at enhanced resolution. The enhanced resolution sampling mode can effectively improve the signal-to-noise ratio. Although the periodic waveform looks very similar to the average sampling mode, the enhanced resolution sampling mode does not rely on the periodicity of the signal and the stability of the trigger point. It is a process within one frame. The original waveform is as follows:

After using enhanced resolution, it becomes as follows:

This is the case of an equivalent increase of 0.5 bits. The following figure is the waveform provided by SDS2000X when the sampling is equivalent to an increase of 3.0 bits: