Why does the waveform storage already store the settings? What is the use of storing the settings?
First of all, the main difference between the two is that the storage space occupied by waveform storage is much larger than the setting storage space. Therefore, considering the memory space and cost, the two need to be saved separately. Secondly, there are also differences in the call-out between the two. The waveform recall oscilloscope is in the STOP state. The saved running status will not be changed when the settings are recalled, making it convenient to directly observe the waveform.
Each oscilloscope has a frequency range, such as 10M, 60M, 100M... The oscilloscope I am using is nominally 60MHz. Can it be understood that it can measure up to 60MHz? But when I use it to measure the square wave of 4.1943MHz, it cannot be measured. What is the reason?
Answer: A 60MHz bandwidth oscilloscope does not mean that it can measure 60MHz signals well. According to the definition of oscilloscope bandwidth, if you input a 60MHz sine wave with a peak-to-peak value of 1V to a 60MHz bandwidth oscilloscope, you will see a 0.707V signal on the oscilloscope (30% amplitude measurement error). If you are testing a square wave, the reference standard for choosing an oscilloscope should be the signal rise time. Oscilloscope bandwidth = 0.35/signal rise time × 3. At this time, your rise time measurement error is about 5.4%.
The probe bandwidth of the oscilloscope is also very important. If the system bandwidth composed of the oscilloscope probe including its front-end accessories is very low, the bandwidth of the oscilloscope will be greatly reduced. If a probe with a bandwidth of 20MHz is used, the maximum bandwidth that can be achieved is 20MHz. If a connecting wire is used at the front end of the probe, the performance of the probe will be further reduced, but it should not have much impact on the square wave around 4MHz because the speed is not very fast.
Also read the oscilloscope manual. For some 60MHz oscilloscopes, in the 1:1 setting, the actual bandwidth will be sharply reduced to less than 6MHz. For a square wave of about 4MHz, the third harmonic is 12MHz and the fifth harmonic is 20MHz. , if the bandwidth is reduced to 6MHz, the signal amplitude will be greatly attenuated. Even if the signal can be seen, it is definitely not a square wave, but a sine wave with an attenuated amplitude.
