First, analog and digital, is different
twentieth century forties good performance of electronic oscilloscope rise development needs of the times, radar and television waveform observation tools, 100MHz bandwidth oscilloscope synchronization successfully developed, this is the modern oscilloscope Foundation. The introduction of semiconductors and electronic computers in the 1950s promoted the bandwidth of electronic oscilloscopes to 100 MHz. In the 1960s, the United States, Japan, the United Kingdom, and France each contributed differently to the development of electronic oscilloscopes. The 6 GHz sampling oscilloscope and the 6 GHz multifunction plug-in oscilloscope marked the high level of science and technology at that time. Add logic oscilloscopes and digital waveform recorders. Analog oscilloscopes have not made much progress since then, and have begun to place digital oscilloscopes. The United Kingdom and France have even withdrawn from the oscilloscope market, and mid-range and low-end products are produced in Japan.
Analog oscilloscopes need to increase the bandwidth and require oscilloscope tubes, vertical amplification, and horizontal scanning to advance. To improve bandwidth, digital oscilloscopes only need to improve the performance of the front-end A/D converter, and there is no special requirement for the oscilloscope and scanning circuit. In addition digital oscilloscopes make full use of memory, storage and processing, as well as a variety of triggering and advance triggering capabilities. In the 1980s, digital oscilloscopes had risen to the fore and the results were so numerous that they completely replaced analog oscilloscopes. Analog oscilloscopes did retreat from the front desk to the back office.
However, some features of analog oscilloscopes are not available in digital oscilloscopes:
The operation is simple - all operations are on the panel, waveform response is timely, and digital oscilloscopes often require longer processing times.
High vertical resolution - continuous and infinite, digital oscilloscope resolution is generally only 8-10 bits.
Faster data updates - capturing hundreds of thousands of waveforms per second, digital oscilloscopes capture dozens of waveforms per second.
Real-time bandwidth and real-time display – The bandwidth of the continuous waveform is the same as that of the single waveform. The bandwidth of the digital oscilloscope is closely related to the sampling rate. When the sampling rate is not high, interpolation calculation is needed and the confusion waveform is prone to occur.
In short, analog oscilloscopes provide engineering technicians with visually pleasing waveforms that can be tested with confidence in the specified bandwidth. Human eyes are very sensitive in the five senses of the human body. The screen waveform is instantaneously reflected in the brain to make judgments. Subtle changes can be perceived. Therefore, analog oscilloscopes are popular with users.
Second, digital oscilloscope
The digital oscilloscopes of the 1980s are in transition and there are still many areas for improvement. Both TEK and HP in the United States have contributed to the development of digital oscilloscopes. They later even discontinued the production of analog oscilloscopes and produced only good performance digital oscilloscopes. Into the nineties, digital oscilloscopes in addition to increasing the bandwidth to more than 1GHz, more importantly, its overall performance beyond analog oscilloscopes. The so-called digital oscilloscope simulation phenomenon occurs, in other words, try to absorb the advantages of analog oscilloscopes, make digital oscilloscopes better.
Digital oscilloscopes first increased the sampling rate, from the initial sampling rate equal to twice the bandwidth, increased to five or even ten times, and the corresponding distortion introduced by the sine wave sampling was also reduced from 100% to 3% or even 1%. The sampling rate of 1 GHz bandwidth is 5 GHz, even 10 GHz.
Secondly, to increase the update rate of digital oscilloscopes to reach the same level of analog oscilloscopes, up to 400,000 waveforms per second, which is much more convenient for the observation of occasional signals and the capture of glitch impulses.
Again, using multiple processors to speed up signal processing capabilities, from multiple menus to cumbersome measurement parameter adjustments, to simple knob adjustments, or even full automatic measurements, is as easy to use as an analog oscilloscope.
Finally, digital oscilloscopes have the same afterglow display with the same screen as the analog oscilloscope, giving the three-dimensional state of the waveform, showing the amplitude, time, and amplitude distribution of the signal over time. A digital oscilloscope with this function is called a digital phosphor oscilloscope or a digital persistence oscilloscope.
Third, the digital oscilloscope must have the simulation function
The analog oscilloscope uses a cathode-ray oscilloscope to display the waveform. The bandwidth of the oscilloscope is the same as that of the analog oscilloscope. That is, the speed of the electron movement in the oscilloscope is proportional to the signal frequency. The higher the signal frequency, the faster the electron speed, the oscilloscope display. The brightness is inversely proportional to the speed of the electron beam, the height of the low frequency waveform is high, and the height of the high frequency waveform is low. The third-dimensional information of the signal can be easily obtained by using the brightness or gray scale of the screen. If the vertical axis of the screen indicates the amplitude and the horizontal axis indicates the time, the screen brightness can indicate the variation of the signal amplitude with time. This time-dependent fluorescence persistence (grey scale) effect is very effective for viewing mixed waveforms and sporadic waveforms. The analog storage oscilloscope is a representative product of this dedicated oscilloscope. Its highest performance reaches 800MHz bandwidth, and it can record about 1ns of fast transient incidents.
The digital oscilloscope lacks the persistence display function, because it is a digital processing, there are only two states, non-high or low, in principle, the waveform is also "yes" and "none" two displays. In order to achieve multi-level brightness changes such as analog oscilloscopes, special image processing chips must be used. For example, TEK uses DPX-type processor chips and has many functions such as data acquisition, image processing, and storage. The DPX chip is composed of 1.3 million transistors. Using 0.65um CMOS process, parallel flow structure, sampling rate 2GS/s. It is not only a data acquisition chip, but also a raster scanner that simulates the luminescence characteristics of the oscilloscope's screen phosphor. It uses a 16-level brightness grading to store waveforms on a 500-by-200-pixel LCD monochrome or color display screen every 0.33 seconds. Update once. Since the analog storage oscilloscope can only rely on photographic film recording waveforms, it is not very convenient for data storage. For example, the waveform with the highest probability appears in red, and the waveform with the lowest probability appears in blue, which is at a glance. Because the digital oscilloscope has reached the level of 1 GHz bandwidth, with the fluorescence display characteristics, the overall performance is better than analog storage oscilloscopes.
Four, digital fluorescent display
Last year, the famous electronic oscilloscope manufacturer TEK first introduced two series of digital fluorescent oscilloscope TDS500 (monochrome) and TDS700 (color), with 500MHz-2GHz bandwidth, the sampling rate of up to 2GHz, up to 4 channel input, belonging to high-end digital oscilloscope, price Above 10,000 USD. A TDS3000 series digital phosphor oscilloscope was produced this year, starting at only 3,000 US dollars, with a bandwidth of 500 MHz and a sampling rate of up to 5 GS/s, which is welcomed by users. Another LeCroy company specializing in digital oscilloscopes also introduced a digital persistence oscilloscope this year. Although the name is different from the digital phosphor oscilloscope, their functions are actually the same. The Waverunner series has a bandwidth of 500MHz, a sampling rate of 500MS/s, and up to 4 channels of input, starting at US,999.
The characteristics of these two series of digital oscilloscopes are described in more detail below:
Ordinary digital oscilloscopes need to use long-term recording and then signal processing in order to observe incidents. This method will miss the non-periodic signals and the dynamic characteristics of the signals. Digital phosphor oscilloscopes can display subtle differences in complex waveforms, as well as the frequency of occurrences. For example, watching television signals, including line scans, frame scans, video signals, and audio signals, as well as anomalies in television signals, are equally important for professionals and maintenance personnel.
TEK's TDS3000 digital phosphor oscilloscope offers a variety of test modules that can be inserted into the four modules from the top right corner of the front panel. For example, the trigger module can be used for logic state, logic pattern triggering, and pulse parameters (rising, falling edge, width, period, etc.); the TV module is dedicated to multiple formats (NTCS, PAL and SECAM) waveform recording; fast Fourier transform The (FFT) module can quickly display the frequency components and spectral distribution of the signal, analyze the impulse response, analyze the harmonic distribution, and identify and locate noise and interference sources. The TDS3000 Series oscilloscopes are portable, weigh less than 7 pounds, and are battery-operable, making them ideal for field use.
The persistence time constant of LeCroy's Waverunner series digital persistence oscilloscope can be changed, so it is very similar to analog storage oscilloscope. Its jitter and timing analysis (JTA) software package can quantify the signal displayed on the screen. For example, after digital processing, a bright line can be drawn under the pulse jitter waveform. The bright line length indicates the jitter range, and the brightest part indicates The most common jitter area. The number of accumulated waveforms reaches 100,000 and the result can be drawn as a histogram.
Waverunner oscilloscopes also have two test software packages: digital and measurement software packages, and waveform analysis software packages. The former can automatically measure and analyze 40 common parameters (such as pulse rise and fall time, maximum, minimum, deviation, etc.) and predict the trend of a certain parameter (such as measuring IC's range of transmission delay variation). The latter includes FFT analysis, up to a record length of 10 (6) points; high resolution method; envelope method; mask test; pass/fail test etc. Various test results use the different colors of the color display to display the results with different brightnesses, which truly allows the user's vision to obtain a rapid response and give full play to the three-dimensional effect of the afterglow gray scale.
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The development and transformation of an industry is inseparable from the related branch industries. For the mold industry, the mold production machine tool has a great role. 
