The difference between real-time oscilloscope and sampling oscilloscope
sampling oscilloscope
Sampling oscilloscopes are designed for capturing, displaying, and analyzing repetitive signals. Trigger capabilities are also set up for repetitive signals. When the first trigger condition is met, the sampling oscilloscope will capture a set of non-contiguous samples spaced apart by time. The oscilloscope delays this trigger point and begins the next set of acquisitions, placing the captured points on the display along with the first set of samples. Repeating this operation in infinite persistence mode creates a waveform that eliminates the need for continuous acquisition. Triggering and delay are technical elements used to control the time resolution between triggers to achieve high measurement accuracy. Since only a few points are captured and processed per trigger, memory depth is not a critical specification. Sampling rate is not a key technical specification either. However, the accuracy of the time interval between the first trigger condition and the next trigger condition is what matters most.
Real-time oscilloscopes are often called DSO (Digital Storage Oscilloscope) or MSO (Mixed Signal Oscilloscope). Most oscilloscopes on sale today are real-time oscilloscopes. Real-time oscilloscopes have bandwidths ranging from a few MHz to tens of GHz, and prices range from a few hundred dollars to hundreds of thousands of dollars. Sampling oscilloscopes are often called DCA (Digital Communications Analyzers), with bandwidths ranging from tens of GHz, and are mainly used to analyze high-speed serial buses, optical devices, and clock signals. As bandwidth increases, sampling oscilloscopes and real-time oscilloscopes begin to overlap in multiple application areas.
The path to digitization for real-time oscilloscopes and sampling oscilloscopes is basically the same. The input signal passes through the front-end signal conditioning circuit of the oscilloscope, is digitized, is saved to the memory, and is finally displayed on the screen. However, the underlying technology of the two oscilloscopes is quite different.
real time oscilloscope
The real-time oscilloscope includes trigger ASIC technology, allowing the user to specify events of interest such as rising voltage threshold, setup and hold violations, or pattern triggering. In normal acquisition mode, when the oscilloscope's trigger circuit observes this event, the oscilloscope will capture and save consecutive sampling points near the trigger point, and update the display with the captured data. Real-time oscilloscopes can operate in single capture mode or continuous capture mode. In single-shot mode, the oscilloscope performs a single acquisition and displays a set of consecutive samples based on the memory depth and sample rate settings.
After the oscilloscope captures a single trace, the user can pan and zoom to any event of interest. In continuous operation mode, the oscilloscope continuously acquires and displays each condition that matches the trigger specification. Variable persistence or infinite persistence allows multiple captured signals to be overlaid on the original signal. Continuous mode allows the user to view the device under test in real time. Rise time or pulse width measurements, mathematical functions or FFT analysis can be performed in single acquisition or continuously repeating acquisition modes. Most real-time oscilloscopes with bandwidths below 6GHz include 1MΩ and 50MΩ inputs for use with a variety of probes and cables.
Real-time oscilloscopes are defined by three important technical specifications: bandwidth, sampling rate and memory depth. When choosing a real-time oscilloscope, there are other more important technical specifications that need to be considered.
