table of Contents
Chapter 1 Overview
Before the official start of the course, we need to understand what this course in the end the research content, there is going to help us live, what is the value in real life.
Signals and Systems, by definition, in fact, is the study of signals and systems, so-called signal that carries information tool . So there may be some obscure, more layman's terms, the signal is a carrier of information, such as the ancient war, war is a kind of signal, it carries a message - told soldiers have development of the war. Information theory learned friend can better understand it.
The system is produced, processed or device for processing signals , the focus of attention here is not the equipment, but its function (ie production, processing or signal processing), which means that the system is unnecessary entities. In this course, the system by mapping the relationship of mathematics to represent, after which point there will be a more detailed description.
This course is Signal system two objects and, more particularly, our research inseparable from the main line: First, how to characterize a signal, there are different methods for the characterization of the different characteristics of signals. Secondly, based on a characterization method for characterizing certain signal to study whether the system can be obtained. Finally, the above characterization methods and systems based on the signal, by trying to obtain a signal in response to the system. In other words, our main line is then to respond to signals from the system trilogy.
Now that we have for this class of emotional awareness, then start with the formal learning of it!
The basic idea 1.1 Signals and Systems
This is in fact part of an index designed to be a rough idea of the whole book to explain. As already mentioned, the course of the present study is to start from a different context signal characterization, Signal, and a signal in response to the system through the system. And you can see this in context, the starting point should be the first step: Characterization signal . In other words, as long as the appropriate method for characterizing a signal is found, then there is hope that research in accordance with our main line. There are four kinds of signals in the course of the present method for characterizing (or decomposition), are: time-domain representation, the frequency domain representation, Laplace and Z transforms . Similarly, these four methods is the core of the method of the course, which shows the different decomposition methods and research ideas for signals from different angles . As can be seen from here, the core idea of this course that is a signal decomposition .
1.2 practice Signals and Systems
In fact the signal system and has a very wide range of applications, give a very simple example in practice:
Careful friends may find that early in the old-fashioned tape recorder quick release will have a "strange noise" that is, the original sound tone will be significantly increased, because in the old-fashioned tape recorder, a quick release simply for time-domain signal compression (we will mention later), and compressed time-domain will result in widening the frequency domain, into the more high-frequency components, and therefore sounds "strange noise."
Today's audio playback device, most will not have a "strange noise" in fast-forward, fast-forward it is also why there are different performance results. That is because today's audio playback device during a fast discharge time-domain samples using a universal counter, i.e. discarded domain waveform, the waveform of the audio signal will not change when a portion of the width, there is relatively little high frequency component to enter, it achieves good results.
These are just a simple example application, signals and systems much more than that, artificial intelligence, information processing, communication systems, etc. can see the shadow of this course, even well-known in the history of the Titanic sinking and also knowledge about this course is (the nature mentioned in section Fourier transform)
1.3 Summary
This chapter is to outline the course before the official start of the set, you can master the following main points:
1. Definition signal
2. Definition of the system
3. signals and systems research methods (basic idea)
4. Create interest in learning
（2020-4-5 15:20)
