Signal concept

In the 18th century, the concept of a function entered into the theory of mathematics as a definite dependence of any quantity y on another quantity - the independent variable x , with a mathematical record of such a dependence in the form y (x) . Pretty soon the mathematics of functions became the basic foundation of the theory of all natural and technical sciences. Functional mathematics acquired particular importance in communication technology, where time functions of the form s (t), v (f), etc., used to transmit information, began to be called signals.

In technical branches of knowledge, the term "signal" (signal, from the Latin signum - sign) is very often used in a wide semantic range, without observing strict terminology. It is also understood as a technical medium for the transmission, treatment and use of information - electrical, magnetic, optical signal; and a physical process, which is a material embodiment of an information message - a change in any parameter of an information carrier (voltage, frequency, power of electromagnetic oscillations, intensity of a luminous flux, etc.) in time, in space or depending on the change in the values ​​of any other arguments (independent variables); and the semantic content of a particular physical state or process, such as traffic signals, audible warning signals, and the like.All these concepts are united by the final purpose of signals. This is certain information, messages, information about any processes, states or physical quantities of objects of the material world, expressed in a form that is convenient for the transmission, processing, storage and use of this information.

The term “signal” is very often identified with the concepts of “data” and “information”. Indeed, these concepts are interrelated and do not exist one without the other, but belong to different categories.

The concept of information has many definitions, from the broadest (information is a formalized reflection of the real world) to practical (information and data that are the object of storage, transmission, transformation, perception and management). At present, world science is more and more inclined to the point of view that information, along with matter and energy, belongs to the fundamental philosophical categories of natural science and belongs to one of the properties of the objective world, albeit somewhat specific. As for “data” (from the Latin datum - fact), it is a set of facts, results of observations, measurements about any objects, phenomena or processes of the material world, presented in a formalized form, quantitative or qualitative. This is not informationbut only the attribute of information is a raw material for obtaining information through appropriate processing and interpretation (interpretation).

Science and technology are international, and use mostly commonly accepted terms, most of which are in English. The term "signal" in world practice is generally accepted to characterize the form of data presentation, in which data is considered as a result of some measurements of the object of research in the form of a sequence of scalar values ​​(analog, numerical, graphic, etc.) depending on the change in any variable values (time, energy, temperature, spatial coordinates, etc.). Taking this into account, in what follows, the term “signal” in the narrow sense of this word will mean in some way an ordered mappingin a change in the physical state of an object - a material carrier of a signal, certain data on the nature of changes in space, in time or in any other variable of physical quantities, physical properties or physical state of the object of research. And since the data contain information both about the main target parameters of the object of research, and about various accompanying and interfering measurement factors, in the broad sense of this word, it can be considered that the signal is a carrier of general measurement information. In this case, the material form of signal carriers (mechanical, electrical, magnetic, acoustic, optical, and any other), as well as the form of display in any physical parameters or processes of the carriers, does not matter . An informative signal parameter can be any parameter of the signal carrier, functionally related to the values ​​of the information data.

A signal, in the most general sense, is the dependence of one quantity on another, and from a mathematical point of view it is a function. The most common representation of signals is in electrical form in the form of voltage versus time U (t). So, for example, the signal of the change in the magnetic field strength along the aerial survey profile is both the time sequence of the change in the electric voltage at the output of the aeromagnetometer sensor, and the recording of this voltage on the recorder tape, and the sequential values ​​of digital readings during the processing of the recorder tapes and inputting the signal into the computer.

A signal is an information function that carries a message about the physical properties, state or behavior of any physical system, object or environment, and the purpose of signal processing can be considered the extraction of certain information information that is displayed in these signals (in short, useful or target information) and transformation of this information into a form convenient for perception and further use.

Analysis of signals means not only their purely mathematical transformations, but also obtaining, on the basis of these transformations, conclusions about the specific features of the corresponding processes and objects. Signal analysis objectives are typically:

- Determination or evaluation of the numerical parameters of signals (energy, average power, root mean square value, etc.).

- Decomposition of signals into elementary components to compare the properties of different signals.

- Comparison of the degree of closeness, "similarity", "kinship" of various signals, including those with certain quantitative estimates.

The mathematical apparatus for signal analysis is very extensive, and is widely used in practice in all fields of science and technology without exception.

The term registration is inextricably linked with the concept of a signal signals, the use of which is as wide and ambiguous as the term signal itself. In the most general sense, this term can be understood as the operation of extracting a signal and transforming it into a form convenient for further use. So, when receiving information about the physical properties of any objects, signal registration is understood as the process of measuring the physical properties of an object and transferring the measurement results to a material signal carrier or direct energy conversion of any object properties into information parameters of a material signal carrier (as a rule, electrical ). But the term registration of signals is also widely used for the processes of separating already formed signals carrying certain information from the sum of other signals (radio communication, telemetry, etc.),and for processes of holding signals on non-volatile storage media, and for many other processes associated with signal processing.

With regard to this rate, the term registration will be understood the data recording (data logging) which pass through a specific point of the system or a certain way and are fixed in any tangible medium or in system memory. As for the process of obtaining information with the help of technical means that provide empirically finding the ratio of the measured value with the standard unit of this value adopted by definition, and the representation of the measured ratio in any physical or numerical form of the information signal, then for this process we will mainly use , a detection term .