As the operation speed of integrated circuits is faster and the integration level is higher, it is possible to withstand more complex multi-dimensional digital signal processing. So it has only recently appeared in a new field. Nevertheless, multi-dimensional signal burial still provides solutions to the following problems. These problems are: computer-aided tomography (CAT), that is, the synthesis of X-ray projections from different directions to reconstruct a three-dimensional part of the human body. Figure, the design of the source sonar array and the earth resources through the satellite. In addition to many attractive and easy-to-do applications, multi-dimensional digital signal processing also has a strong mathematical foundation. This not only allows us to understand its implementation, but also when new problems arise, it should also be timely solve.
A typical signal processing task is to transfer information from one signal to another. For example, a photo can be scanned, sampled, and stored together in the computer's memory. In this case, the information is The visible light beam is converted from a variable density of silver particles, then transformed into an electrical waveform, and finally the sequence of numbers is changed, and then the sequence of numbers is used. The arrangement of the magnetic domains on the disk indicates that the CAT scanner is a more complex, processed, and finally displayed on the fluorescent screen or film of the CRT. Digital processing can increase the information, but it can rearrange the information so that the observer can more easily understand it. The observer can directly observe the cross-sectional view without having to watch the projections of multiple different measurement surfaces. ,
People are interested in the information contained in the signal, regardless of the form of the signal itself. It may be generalized that signal processing involves two basic tasks—rearrangement of information and compression of information.
Digital signal processing involves the processing of signals represented by a sequence of numbers, while multidimensional digital signal processing involves the processing of signals represented by multidimensional arrays, such as the sampling of images and the time waveforms of samples received from several sensors simultaneously. deal with. Because the signal is so it can be processed with digital hardware, and at the same time the signal processing operation can be specified as an algorithm.
It is self-evident to motivate people to adopt digital methods. The digital method is both effective and flexible. We can use the digital system to make it adaptive and easy to reassemble. You can easily convert digital algorithms from one vendor's device to another vendor's device, or implement dedicated digital hardware. Similarly, digital algorithms can also be used to process signals as a function of time or space. Digital algorithms are naturally associated with logical operators such as pattern classification. Digital signals can be stored without errors for a long time. For many applications, digital method â…¨ and other methods are simpler. For other applications, there may be no other methods at all. Multi-dimensional signal processing is different from one-dimensional signal processing. Multi-operations that want to be implemented on multi-dimensional sequences, such as sampling, filtering, and exchange, are used for one-dimensional sequences. One-dimensional letter bows are very different.
Signal processing is still very different from one-dimensional signal processing, which is caused by three factors; (l) two-dimensional usually contains a much larger amount of data than one-dimensional problems; (2) processing multi-dimensional systems It is not as complete as a one-dimensional system; (3) Multi-dimensional signal processing has more degrees of freedom, which gives the system design tone unmatched flexibility in one-dimensional situations. Although all recursive digital filters are implemented using difference equations, the difference equations are fully ordered in the one-dimensional case, while the difference equations are only partially ordered in the multidimensional case, and there is flexibility in the The dimensionality is small, and the discrete transmission (CDET) can be calculated using the Fast Fourier Transform (CEPT) algorithm, while in the multidimensional case, there are many and each OFT can be calculated with multiple AFT algorithms. In the one-dimensional case, we can adjust the rate. And you can also adjust the pumping arrangement.
On the other hand, multidimensional polynomials cannot be factorized, while one-dimensional polynomials can be factorized. Therefore, in a multidimensional situation, we cannot talk about isolated poles, qi, isolated zeros and isolated roots. Therefore, multi-dimensional signal processing is quite different from one-dimensional signal processing.
In the early 1960s, the idea of ​​using a digital system to imitate an analog system led to the development of various methods for handling one-dimensional digital signals. In this way, following the theory of analog systems, many discrete system theories were created. Later, when digital systems could imitate analog systems well, people realized that digital systems could also perform more functions at the same time. Due to this understanding of Ding and the powerful promotion of digital hardware technology, digital signal processing has been developed, and today many common methods have become unique to digital methods. There is no equivalent analog method. When developing multi-dimensional digital signal processing , The same development trend can be observed. Because there is no continuous-time (or simulated) two-dimensional system theory to follow, the original two-dimensional system was based on a one-dimensional system. In the late 1980s, most two-dimensional signal processing used separable two-dimensional system. There is almost no difference between a separable two-dimensional system and a one-dimensional system used for two-dimensional data. Subsequently, a unique multi-dimensional algorithm was developed, which is equivalent to the logical reasoning of the one-dimensional algorithm. This is a period of failure. Many two-dimensional applications require a large amount of data, and iT lacks the decomposition theory of two-huai polynomials. Many one-dimensional methods cannot be well extended to two dimensions. We are now in the embryonic era of cognition. The computer industry helps us solve the problem of data volume due to the miniaturization of its components and the increasingly low prices. Although we are always limited to mathematical problems, we still realize that multidimensional systems also give us new degrees of freedom.
All of the above make this field both challenging and endlessly fun. The combination of electronic information technology and software integration, where the traditional industry can use electricity information technology, can still use human resources or under low production conditions or Traditional machinery. Dianyu Information Technology should be limited, there are various reasons in different fields and different levels, but there is a common reason for the lack of understanding. Without understanding, there is no response. In fact, there is a substantial difference between the one-dimensional and two-dimensional signal processing theories, and between the two-dimensional and higher dimensions, in addition to the computationally complex differences in tolerance, it seems that the difference is small.
Usually,10 & 20 layers PCB are HDI board,but some are not .Some with big trace width and space,holes are over 0.3mm too. We have much experience in doing 10 Layer PCB & 20 layer PCB.
A ten-layer board should be used when six routing layers are required. Ten-layer boards, therefore, usually have six signal layers and four planes. Having more than six signal layers on a ten-layer board is not recommended. Ten-layers is also the largest number of layers that can usually be conveniently fabricated in a 0.062" thick board. Occasionally you will see a twelve-layer board fabricated as a 0.062" thick board, but the number of fabricators capable of producing it are limited..
High layer count boards (ten +) require thin dielectrics (typically 0.006" or less on a 0.062" thick board) and therefore they automatically have tight coupling between layers. When properly stacked and routed they can meet all of our objectives and will have excellent EMC performance and signal integrity.
A very common and nearly ideal stack-up for a ten-layer board is shown in Figure 12. The reason that this stack-up has such good performance is the tight coupling of the signal and return planes, the shielding of the high-speed signal layers, the existence of multiple ground planes, as well as a tightly coupled power/ground plane pair in the center of the board. High-speed signals normally would be routed on the signal layers buried between planes (layers 3-4 and 7-8 in this case).
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