How to buy an oscilloscope for observing digital signals
When using oscilloscope to observe digital signal in debugging embedded software, it usually adopts single trigger mode.In such applications, the quality of the waveform displayed by the oscilloscope is not very important, so all the products described in this article can meet the requirements.In the purchase of products, as long as meet the required specifications, the cheaper the better.
The major premise is that the bandwidth needs to reach 5 times the measured signal frequency, so that the amplitude error can be controlled at about 2%.If the maximum allowable error is 5%, the bandwidth is only 3 times the frequency of the signal being measured.In addition, the sampling rate should be at least five times that of the measured signal.
In debugging applications, the most important measure of digital signal is storage depth.The greater the storage depth, the longer the observable time.The target measurement time can be multiplied by the sampling rate and compared with the storage depth in the product catalog.
In practice, however, it is best to avoid running out of large storage depths.Because in the measurement process is usually observed for a period of time, the data is stored, and then scroll the screen to find the error.When the measurement time is too long, the data retrieval function of many low-cost oscilloscopes is insufficient, so it is difficult to find the problem.