Signal converters: types, operating principle and purpose

In industry and in everyday life, the use of various types of signal converters is common. These devices can be represented in the widest range of modifications, adapted to solve problems in different areas of the economy. Which types of signal converters can be attributed to the most common? What can be the features of their operation?

What is the purpose of signal converters?

Signal converters are devices that can indeed be represented in the widest range of solutions. This term is actually collective and can relate to equipment used in different segments of the economy and classified according to absolutely different criteria. The main types of signals that can convert the devices in question:

- Electrical;

- sound;

- temperature;

- technological nature.

Depending on the tasks faced by the user of the signal converter, modules that process several different types of data can be combined in the structure of the corresponding device. Transformation, thus, can be carried out within the same type of signal (for example, from one frequency to another) or be a mechanism that involves translation between different signal categories. For example, electric in sound.

The most common devices include the converter of analog signals to digital (and vice versa, if it is provided by the structure of the internal modules of the device). Let's consider features of its work.

Analog-to-digital converter

The device in question is intended for converting any analog signal - for example, represented by the voltage indices into a digital form (allowing, for example, to record the corresponding signal in a file).

One of the main criteria of the efficiency of the device in question is the bit-rate of the data at the output. Its value determines the level of the signal-to-noise ratio.

Another significant parameter that characterizes the quality of operation of a device such as an analog converter is the output signal generation rate. Among those devices that provide optimal performance are those that are parallel type. They generate large signal streams using the required number of pins. This feature of the device in many cases predetermines the release of the corresponding converters, characterized by large dimensions. In addition, analog signal converters can have a fairly high level of power consumption. However, taking into account the effectiveness of these devices, these features are often not considered to be disadvantages.

The conversion of signals from analog to digital parallel devices is very quick. Provide even faster performance of the respective type of device can be through the connection of several devices, so that they can process the streams of signals in turn.

Alternatives to parallel solutions can be serial signal converters. They are usually less productive, but more energy efficient. Their application can be conditioned in those cases when it is a question of ensuring the transmission of signals within the framework of an infrastructure of low power, or in the event that a higher conversion speed than that provided by consecutive devices is not required.

It can be noted that there are devices of a mixed type that combine the functions of serial and parallel converters. In many cases, they are the most optimal solutions in terms of compliance with the criteria of economy and productivity.

Above we noted that analog-to-digital converters can include modules by means of which digital signals are converted into analog signals. There is also a separate category of devices of the appropriate type. Let us study their features.

Digital to analog converters

If the user has, for example, a television for an analog signal, then its operation will be possible when connecting the corresponding antenna. Or if the source signals are transformed into analog signals, which the TV can recognize. Their source can be, in turn, a digital antenna. Or, as an option, a signal received via the Internet.

The device in question thus converts the signal containing the digital code into a current, a voltage, or a charge that is transmitted for processing to analog modules. The specific mechanisms of this transformation depend on the type of input data. For example, if we are talking about sound, then at the input it is usually represented in pulse-code modulation. If the source file is compressed, special software codecs can be used to convert the signals. In turn, a digital antenna usually transmits a signal for processing by hardware methods.

Devices, which include the considered converters, can be supplemented with modules for different purposes. For example, when providing a television broadcast, a video signal amplifier can be used in addition to those modules that are used by the converter. It is in many cases necessary in order to provide a high quality picture when the analog signal is converted to digital. Also, a video signal amplifier is used if you want to transfer a picture over a considerable distance.

Television is not the only sphere of active use of the devices in question. Corresponding converters are included, for example, in the composition of CD players, which also transform the digital signal into an analog one.

Ultrasonic transducers

The next common category of devices is an ultrasonic transducer. It can be noted that it can be represented by devices having the widest range of applications, as well as operating principles. Among the common varieties of ultrasonic transducers is a submersible unit, which is designed to be transmitted to water or other liquid medium by ultrasound with a certain frequency. This device can be used, for example, to purify various objects from pollution - in the baths used for ultrasonic cleaning.

There are other areas of application of the devices in question. The ultrasonic transducer can be used to monitor the integrity of certain structures, connections, and check certain objects for damage.

Linear and pulse converters

Considering the peculiarities of using converters, it will be useful to pay attention to the classification by which they are subdivided into linear and impulse. In fact, these criteria reflect the two most important principles of converter operation.

Those that are linear, can work on the principle of analog circuitry, in which the converted signals are formed at a smooth pace. The pulse converter assumes a more active representation of signals both at the output and at their internal processing. However, if this operation is carried out only at the internal stage of signal processing, the corresponding device can form the same parameters as in the case when a linear converter is involved. Thus, the concept of linear or impulse processing can be considered only in the context of the principle of operation of key hardware components of the device of the corresponding type.

Pulse transducers are mainly used in cases when the structure of the infrastructure used involves the processing of high-power signals. This is due to the fact that the efficiency of the corresponding devices in such cases is much higher than when using them for processing signals of lower power. Another factor in the choice of these solutions is the use of transformer or capacitor devices in the structure of the infrastructure used, with which the impulse converters have optimal compatibility.

In turn, a linear converter is a device that is used within an infrastructure in which low-power signals are processed. Or if there is a need to reduce the interference caused by the operation of the converter. It is worth noting that the efficiency of the solutions under consideration in the high-power infrastructure is not the most outstanding, therefore these devices most often allocate a greater amount of heat than pulsed converters. In addition, their weight and dimensions are also significantly larger.

But, in one way or another, in practice, the functioning of the transducer by the impulse principle can assume the formation of its transfer function in a linear form. Therefore, before implementing the appropriate signal converters in the infrastructure, you should consider their internal structure for the applied signal processing scheme.

Measuring transducers

Another common category of solutions is measuring transducers. What are their features? The measuring transducer is a device that can also be represented in a large number of varieties. Combines these devices with the ability to measure both the measurement and the transformation of certain quantities.

A scheme of functioning of measuring devices of the corresponding type can be considered as widely used, in which the signal is processed in several stages. First the transducer receives it, then transforms it into the value that can be measured, after - transforms into some useful energy. For example, if an analog current transducer is used, then the electrical energy is converted into a mechanical one.

Of course, specific mechanisms for the application of relevant solutions can be presented in an extremely wide range. It is common to use measuring transformations for scientific purposes as a part of the infrastructure for carrying out experiments and research. Combines the majority of measuring transducers with their adaptability, primarily to work with the application of normalized characteristics when processing or transforming a signal. It can be noted that these characteristics can not always be intended for the end user of the converter. Their involvement in many cases is carried out in a covert mode. Man, using the appropriate signal converters, receives only the desired signal, adapted for use in various purposes, at the output.

Thus, these solutions, as a rule, are not used as independent types of infrastructure. They are part of more complex devices - for example, a system for automating production measurements. Measuring transducers are most often classified into 2 main groups - primary and intermediate. It will be useful to consider the specifics of both.

Classification of measuring transducers: primary and intermediate solutions

Devices that belong to the primary category are generally used as sensors. That is, they are transducers to which a particular measured quantity acts directly. The other devices belong to the intermediate category. They are placed in the measuring infrastructure immediately after the first ones and can be responsible for a large number of operations related to the transformation. What specific operations can a signal converter of the appropriate type perform? To those it is customary to include:

- measurement of physical indicators for various values;

- Various scale conversions;

- transformation of digital signals into analog signals and vice versa;

Functional transformations.

Note that this classification can be considered conditional. This is primarily due to the fact that several primary transducers may be located in the same measurement instrument. Another reason to consider the above classification of conditional - is that in different types of infrastructure, measurements can be carried out according to dissimilar principles.

Electron-optical converters

Another type of device popular in various spheres of the economy is an electron-optical converter. It, like other types of devices discussed above, can be represented in a wide range of designs. The common principle of operation unites electron-optical converters: it involves the conversion of an invisible object - for example, illuminated by infrared, ultraviolet or, for example, X-rays, into the visible spectrum.

The corresponding operation, as a rule, is carried out in 2 stages. On the first, invisible radiation is received on the photocathode, after which it is transformed into electronic signals. Which already in the second stage are converted into a visible picture and displayed on the screen. In case this is a computer monitor, the signal can be pre-converted into a digital code.

Electron-optical converters are solutions that have traditionally been classified for several generations. The devices relating to the first have a glass vacuum flask. The photocathode and anode are located in it. Between them a potential difference is formed. When an optimum voltage is applied to the converter, an electron lens is formed inside the converter that can focus the electron fluxes.

In the second-generation converters, electron acceleration modules are present, thereby increasing the brightness of the image. In devices of the third generation, materials are used that increase the sensitivity of the photocathode as a key component of the electron-optical converter more than 3-fold.

Features of resistive transducers

Another common type of device - resistive converters. Let's consider their features in more detail.

These transducers are adapted to change their own electrical resistance when exposed to a particular measured value. They can also adjust the angular and linear displacement. Most often these transducers are included in automation systems with pressure, temperature, illumination level sensors , measuring the intensity of various types of radiation. The main advantages of resistive transducers are:

- Reliability;

- the absence of a relationship between the accuracy of the measurements and the stability of the supply voltage.

There are a large number of variations of the corresponding devices. Among the most popular are temperature sensors. Let us study their features.

Resistive temperature sensors

These signal converters have components that are sensitive to changes in ambient temperature. If it rises, then their resistance may increase. These devices are characterized primarily by very high accuracy. In a number of cases, they make it possible to vary the temperature with an accuracy of the order of 0.026 degrees Celsius. As part of these devices there are elements made of platinum - in this case, the resistance coefficient will be lower, or copper.

The use of resistive sensors is characterized by a number of nuances. So, it should be taken into account that higher excitation current values applied to the sensor increase its temperature sensitivity, but, at the same time, heat the elements of the corresponding converter. This in many cases causes a decrease in its accuracy. Therefore, it is recommended to provide the optimal excitation current parameters taking into account the specific conditions of measurement. In the calculation can take, for example, the thermal conductivity of the environment in which the sensor is used - air or water. As a rule, the recommended indices for the excitation currents are established by the sensor manufacturers of the corresponding type. However, they can vary significantly depending on the metals used in the design of the devices. In addition, when using the sensors in question, it is necessary to take into account such an indicator as the limiting value for the working current. Usually it is also determined by the manufacturer.

Resistive sensors are among the most common types of transducers in the farm. This is largely due to the significant technological advantages of many of their varieties. For example, if we talk about thermistors - they are characterized by high sensitivity, compactness, low weight. Appropriate type sensors can be used for measuring air temperature in different conditions. Their production often does not involve significant costs. True, thermistors have disadvantages - first of all, this is a high degree of non-linearity, so that they can be used in practice in fairly narrow temperature ranges.

Corresponding type signal converters (types and their designation can be determined on the basis of different classification criteria) are widely used in everyday life. For example, it is common to include temperature sensors containing platinum and copper elements in their composition:

- heating infrastructure - in order to measure the temperature of the coolant at one or another section of the equipment, as well as in a heated room;

- washing machines - in order to measure the temperature of the water and its adjustment for various washing programs;

- irons - the same way to ensure the optimum temperature of ironing within a particular operating mode;

- an electric stove, as well as other types of equipment for cooking food - also in order to ensure their functioning when activating certain user modes.

Rheostat converters

Another popular type of resistive devices is rheostat converters. Their principle of operation is based on measuring the electrical resistance of a conductor when exposed to input motion. In practice, this converter includes elements that are adapted to movement due to the effect of the measured quantity. Most often, the devices in question are included in voltage dividers or used as a component of measuring bridges.

If we talk about the merits that characterize the rheostat converters, then to such can be attributed:

- Absence of reactive influence on mobile components;

- high efficiency;

- small size, the ability to use in an infrastructure that operates both on permanent and alternating current.

At the same time, resistive transducers of the appropriate type are not always reliable and in many cases require the enterprise to invest significant resources in maintaining functionality.