Characteristics and working principle of digital fluorescence oscilloscope
DPO has made a new breakthrough in oscilloscope technology. It can display, store and analyze complex signals in real time, and use three-dimensional information (amplitude, temporality and multi-level brightness to display the frequency of amplitude components with different brightness) to fully display the signal. Features, especially the use of digital fluorescence technology, can display the history of signal changes over a long period of time through multi-level brightness or color.
The automatic measurement and waveform storage function of DSO once amazed many engineers, but it was soon discovered that when DSO measured high-frequency signals with low-frequency modulation, its display results were inconsistent due to its insurmountable aliasing distortion problem. This reminds me of the benefits of ART oscilloscopes.
DPO not only has the real-time brightness and alias-free display capability of the ART oscilloscope, but also has the automatic measurement and waveform storage functions of the DSO. There are great improvements in avoiding the shortcomings of both. Mainly manifested in:
(1) Fast waveform capture rate and super display capability
The application of digital fluorescent display technology enables DPO to simultaneously display multiple images of signals in different grayscales or colors. DPO can record 200,000 waveforms per second, and its signal data is 1,000 times more than that of a general DSO. It can capture 500,000 waveforms at a time. This fast waveform capture rate combined with superb display capabilities enables DPO to analyze any details of the signal. .
(2) Continuous high-speed sampling capability
Usually, DSO has an 8ms dead time between displaying two waveforms due to processing display data. Even a DSO that uses instavuTM sampling technology can only reduce this time to 1.7μs. ART oscilloscopes cannot capture waveform information during the retrace time. The DPO can continuously sample hundreds of thousands of waveforms at the highest sampling rate, overcoming the stagnation problem that exists in other oscilloscopes. The sampling rate of DPO is generally several 109 times per second. Such a high sampling rate allows the oscilloscope to have greater bandwidth.
working principle
The schematic block diagram of a digital fluorescence oscilloscope is shown in Figure 1. The core component is the DPX wave imaging processor composed of an application specific integrated circuit (ASIC).
Like DSO, the input signal is first amplified and A/D converted to obtain the sampled value of the signal. The sampled value is processed by the DPX waveform imaging processor to form a complete flow device waveform diagram with 500*200 pixels and containing three-dimensional waveform information. , in the case of uninterrupted capture process, the DPX imaging processor sends 30 waveforms per second to the waveform display memory. Under the control of the microprocessor, the collected waveforms are obtained on the display screen according to the contents of the display memory. . Realize a waveform display method such as "signal digitization → graphical → display". At the same time, the microprocessor performs automatic measurement and calculation functions in parallel.
Since the data acquisition and display systems of DPO operate independently, the oscilloscope can process the data required for display while maintaining the highest waveform capture rate, which means that the oscilloscope can capture all details of the waveform without interruption.
DPX consists of a data collector and a dynamic three-dimensional database called a digital phosphor. It organically combines rasterization (waveform imaging) and fast waveform capture rate to accumulate signal information in a 500*200 integer array. Each integer in the array represents a pixel in the DPO display. The different values lead to different brightness or color of the display pixels. As the signal is continuously sampled, this array is constantly updated, but unlike DSO, After a display cycle (a waveform) is completed, the sampling value of the new display cycle will not wash out the data of the last display cycle. If the two sampling plants have the same display point, only the duty of the corresponding array point will be changed. In this way Multiple waveforms can be displayed cumulatively. When the display points caused by multiple waveforms are different, the data of each point in the array is different, so the waveform display brightness is the highest, and other waveform information that occasionally appears will be displayed at a lower brightness.
DPO continuously samples at the maximum rate during operation, and uses the minimum time interval between samples to generate waveforms one after another, just like an ART oscilloscope (because DPO uses a deep three-dimensional database to save grayscale information, the past waveform information does not loss), the changes in the signal over a long period of time can be observed.
