Digital Oscilloscope Introduction_Digital Oscilloscope Parameter Meaning

Digital oscilloscopes are an indispensable tool for designing, manufacturing, and servicing electronic devices. With the rapid development of technology and market demand, engineers need the best tools to quickly and accurately solve the measurement challenges they face. As an engineer's eye, digital oscilloscopes are critical to meeting the current tough measurement challenges.

Digital oscilloscopes have become increasingly popular due to their unique advantages such as waveform triggering, storage, display, measurement, and waveform data analysis and processing. Due to the large performance difference between digital oscilloscopes and analog oscilloscopes, if used improperly, large measurement errors will occur, which will affect the test task. This article gives you a detailed introduction to the meaning of digital oscilloscope parameters.

Bandwidth is one of the most important metrics for an oscilloscope. The bandwidth of an analog oscilloscope is a fixed value, while the bandwidth of a digital oscilloscope has both analog bandwidth and digital real-time bandwidth. The maximum bandwidth that a digital oscilloscope can achieve with sequential sampling or random sampling techniques for repetitive signals is the digital real-time bandwidth of the oscilloscope. The digital real-time bandwidth is related to the highest digitized frequency and waveform reconstruction factor K (digital real-time bandwidth = highest digitization rate / K) It is generally not given directly as an indicator. As can be seen from the definition of the two bandwidths, the analog bandwidth is only suitable for the measurement of repeated periodic signals, while the digital real-time bandwidth is suitable for the measurement of repeated signals and single signals. The manufacturer claims that the bandwidth of the oscilloscope can reach megabytes, which actually refers to the analog bandwidth, and the digital real-time bandwidth is lower than this value. For example, TEK's TES520B has a bandwidth of 500MHz, which means that its analog bandwidth is 500MHz, and the highest digital real-time bandwidth can only reach 400MHz, which is much lower than the analog bandwidth. Therefore, when measuring a single signal, be sure to refer to the digital real-time bandwidth of the digital oscilloscope, otherwise it will bring unexpected errors to the measurement.

The acquisition system consists of a sample/holder and an analog to digital converter A/D. The sampling rate is the measurement of the digital oscilloscope sampling and A / D conversion rate, expressed in terms of how many samples per second, that is, MS / s. Where M stands for megabyte, S stands for sampling point, and s stands for time second. The higher the digital oscilloscope sampling and A/D conversion rate, the higher the resolution and sharpness of the displayed waveform, and the lower the loss rate of important information and events.

In analog oscilloscopes, rise time is an extremely important indicator of an oscilloscope. In digital oscilloscopes, the rise time is not even given as an indicator. Due to the measurement method of the digital oscilloscope, the automatically measured rise time is not only related to the position of the sampling point.

Although the rise time of the waveform is a fixed value, the results measured with a digital oscilloscope are far from each other because of the different sweep speeds. The rise time of an analog oscilloscope is independent of the sweep speed, and the rise time of a digital oscilloscope is not only related to the sweep speed, but also related to the position of the sample point. When using a digital oscilloscope, we cannot reverse the time measured according to the time of the analog oscilloscope. The rise time of the signal is pushed out.

The record length of a digital oscilloscope is defined as the number of sample points required to form a complete waveform, which determines the amount of data that can be captured by each channel of the oscilloscope. In the actual measurement, we are concerned with the recording time length of the oscilloscope for a waveform. Since the oscilloscope can only store a limited number of waveform sampling points, the waveform recording time is lengthened, the sampling rate is decreased, and the waveform recording time is inversely proportional to the sampling rate.

Modern oscilloscopes allow the user to select a record length to gain a deeper understanding of the details of the signal being measured. A stable sinusoidal signal requires only 500 points of record length; while parsing a complex digital data stream requires an oscilloscope with a record length of one million or more points.