Digital oscilloscopes is triggered by waveform display, measuring, storage and data processing, etc, waveform, the unique advantages growing popularity. As a result of digital oscilloscopes and analogue oscilloscope between larger difference, if use undeserved, can produce bigger, thereby affecting the measurement error test tasks.

Distinguish real-time digital simulation bandwidth and bandwidth Bandwidth is one of the most important indicators oscilloscope. The bandwidth is an analogue oscilloscope fixed value, while the bandwidth of the digital oscilloscopes are simulated bandwidth and digital real-time bandwidth. Digital oscilloscopes by order of repeated signal sampling or random sampling technique can achieve the highest bandwidth for real-time digital oscilloscopes, bandwidth digital real-time bandwidth with highest frequency and digital waveform reconstruction technique factor K related (= the highest number of real-time bandwidth digital speed/K), generally not as an index directly. From the definition of two kinds of bandwidth can be seen only suitable for simulating bandwidth, repeated measurements of periodic signal, and is also suitable for real-time bandwidth digital signal and repeated measurements of single signal. It says the bandwidth of the oscilloscope, how can actually refers to the simulation, real-time bandwidth digital bandwidth is less than the value. For example TES520B TEK company of bandwidth for 500MHz, actually refers to the simulation, and 500MHz bandwidth for the highest number 400MHz achieve real-time bandwidth only than analog bandwidth. So in a single signal, the number of real-time reference digital oscilloscope, otherwise, it will give bandwidth measurement bring unexpected errors.

Relevant sampling rate Sampling rate is also called digital rate, refers to the unit of time, the analog input signal sampling frequency, often with MS/s. Sampling rate of digital oscilloscopes is an important index.

1 if the sampling rate, easy enough to mix superposition phenomenon appears If the input signal for oscilloscope sinusoidal signal, a 100 KHZ oscilloscope display of the signal frequency 50KHz, is this what is the row? This is the sampling oscilloscope, slow rate of mixed stack phenomenon. Mixed stack is displayed on the screen of the signal frequency waveforms than actual frequency, or even oscilloscope trigger indicator light, but that has been the waveform is still unstable. Mix the produce is shown in figure 1. So, for an unknown frequency waveforms, how to determine whether the waveform display is mixed stack? Can sweep through slowly changing quickly to rapidly t/div when the yankees gear, see whether frequency waveforms sharp change, if the parameter is mixed, waveform composite has occurred, The waveform in a shaking or when the yankees files quickly and stabilize mixed composite wave has occurred. According to the specific reason suggests, sampling rate at least above of high signal twice won't occur, such as a 500MHz mixed signals, need at least 1GS/s sampling rate.