In industry and in everyday life, the use of various types of signal converters is widespread. These devices can be represented in the widest range of modifications, adapted to solve problems in different areas of the economy. What types of signal converters can be attributed to the most common? What may be the features of their operation?
What is the purpose of signal converters?
Signal converters are devices that can really be represented in a wide range of solutions. This term is actually collective and may refer to equipment used in different segments of the economy and classified according to completely different criteria. The main types of signals that can be converted by the devices in question:
- electric;
- sound;
- temperature;
- technological nature.
Depending on the tasks facing the user of the signal converter, modules processing several different types of data can be combined in the structure of the corresponding device. The conversion, thus, can be carried out within the framework of one type of signal (for example, from one frequency to another) or can be a mechanism involving the translation between different categories of signals. For example, electric to sound.
The most common device is the converter of analog signals to digital (and vice versa, if it is provided for by the structure of the internal modules of the device). Consider the features of his work.
Analog to digital converter
The device in question is intended to convert any analog signal - for example, represented by voltage indicators, into a digital form (allowing, for example, to write the corresponding signal to a file).
One of the main criteria for the performance of the apparatus in question is the capacity of the output data. Its value determines the signal-to-noise ratio.
Another significant parameter characterizing the quality of work of such a device as an analog converter is the speed of formation of the output signal. Among those devices that provide its optimal performance are those that belong to the parallel type. They carry out the formation of large signal flows using the required number of conclusions. This feature of the functioning of the apparatus in many cases determines the release of the corresponding converters, characterized by large dimensions. In addition, analog signal converters can have a fairly high level of energy consumption. However, given the efficiency of these devices, their marked features are often not considered as disadvantages.
Conversion of signals from analog to digital by parallel devices is very efficient. An even higher speed of the corresponding type of device can be achieved by connecting several devices, so that they can process the signal flows in turn.
An alternative to parallel solutions can be serial signal converters. They are usually less productive, but more energy efficient. Their use can be caused in cases where there is a question of ensuring the transmission of signals within the framework of a low-power infrastructure, or if a higher conversion speed than that provided by serial 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 meeting the criteria of profitability and productivity.
We noted above that analog-to-digital converters can include modules through which digital signals are converted to analog ones. There is a separate category of devices of the corresponding type. We study their features.
Digital to Analog Converters
If, for example, a TV for an analog signal is at the user's disposal, then its operation will be possible when the corresponding antenna is connected. Or, provided that the source signals are transformed into analog ones, which this TV can recognize. Their source may be, in turn, a digital antenna. Or, as an option, a signal received via the Internet.
The device in question thus converts a signal containing a digital code into current, voltage or charge, which is transmitted to analog modules for processing. The specific mechanisms of this transformation depend on the type of source data. For example, when it comes to sound, then at the input it is usually represented in pulse-code modulation. If the source file is compressed, then special 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 by modules for various purposes. For example, when providing playback of a television broadcast, a video signal amplifier can be used in addition to those modules that are used by the converter. In many cases, it is necessary in order to ensure high quality images when transforming an analog signal into a digital one. Also, a video amplifier is used if you need to transfer a picture over a considerable distance.
Television is not the only area of active use of the devices in question. Corresponding converters are included, for example, in the composition of CD-ROM players, which also transform a 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 presented as devices having the widest range of applications, as well as operating principles. Among the common varieties of ultrasonic transducers is an immersion unit, which is designed to transfer ultrasound to a water or other liquid medium with a certain frequency. This device can be used, for example, in order to clean various objects from contamination - in the bathtubs used for ultrasonic cleaning.
There are other areas of application of the devices in question. An ultrasonic transducer can be used to control the integrity of various structures, joints, and to check various objects for damage.
Linear and Pulse Converters
Considering the features of the use of converters, it will be useful to pay attention to the classification by which they are divided into linear and pulse. In fact, these criteria reflect the two most important principles for the operation of converters.
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 the signals both at the output and during their internal processing. However, if this operation is carried out only at the internal stage of signal processing, the corresponding device can generate practically the same indicators as in the case when the linear converter is involved. Thus, the concept of linear or pulsed processing can be considered only in the context of the principle of operation of the key hardware components of the device of the corresponding type.
Pulse converters are mainly used in those cases when the structure of the used infrastructure 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 they are used to process signals of lower power. Another factor in choosing these solutions is the use of transformer or capacitor devices as part of the infrastructure used, with which pulse converters have optimal compatibility.
In turn, a linear converter is a device that is used as part of an infrastructure in which low-power signals are processed. Or if there is a need to reduce interference resulting from the operation of the converter. It is worth noting that the efficiency of the considered solutions in high-power infrastructure is not the most outstanding, therefore these devices most often emit a greater amount of heat than pulse converters. In addition, their weight and dimensions are also significantly larger.
But, one way or another, in practice, the operation of the converter according to the pulse principle may imply the formation of its transfer function in a linear form. Therefore, before implementing the appropriate signal converters in the infrastructure, it is necessary to consider their internal structure for the applied signal processing scheme.
Measuring transducers
Another common category of solutions is transducers. What are their features? A measuring transducer is a device that can also be presented in a large number of varieties. Unites these devices fitness both for measurement and for the conversion of certain quantities.
The scheme of functioning of measuring devices of the corresponding type, in which the signal is processed in several stages, can be considered widespread. First, the converter accepts it, then transforms it into that quantity that can be measured, then it transforms it into some useful energy. For example, if an analog current measuring transducer is used, then electric energy is transformed into mechanical energy.
Of course, specific mechanisms for the application of appropriate solutions can be represented in an extremely wide range. The use of measuring transformations for scientific purposes as part of the infrastructure for conducting experiments and research is widespread. The majority of measuring transducers are united by their adaptability, first of all, to work with the application of standardized characteristics during signal processing or transformation. It can be noted that these characteristics may not always be intended for the end user of the converter. Their use in many cases is carried out in stealth mode. A person, using the appropriate signal converters, receives only the required signal, adapted for use for various purposes, at the output.
Thus, these solutions, as a rule, are not involved as independent types of infrastructure. They are part of more complex devices - for example, automation systems for measurements in production. Measuring transducers are most often classified into 2 main groups - primary and intermediate. It will be useful to consider the specifics of both.
Transmitter Classification: Primary and Intermediate Solutions
Devices belonging to the category of primary, as a rule, are used as sensors. That is, they are converters on which one or another measured quantity acts directly. The remaining devices are classified as intermediate. They are located in the measuring infrastructure immediately after the first and can be responsible for a large number of operations related to the conversion. What specific operations can a signal level converter of the appropriate type perform? These include:
- measurement of physical indicators by various values;
- various scale transformations;
- transformation of digital signals into analog and vice versa;
- functional transformations.
Note that such a classification can be considered conditional. This is primarily due to the fact that several primary transducers can be in the same measurement tool. Another reason to consider the classification considered conditional above is that in different types of infrastructure, measurements can be carried out according to dissimilar principles.
Optoelectronic Converters
Another type of device that is popular in various fields of economy is the electron-optical converter. He, like other types of devices considered by us above, can be presented in a wide range of designs. The electron-optical converters are united by a general principle of operation: it involves the conversion of an invisible object - for example, illuminated by infrared, ultraviolet or, for example, X-rays, into the visible spectrum.
In this case, the corresponding operation, as a rule, is carried out in 2 stages. At the first, invisible radiation is received at the photocathode, after which it is transformed into electronic signals. Which already at the second stage are converted into a visible picture and displayed on the screen. If it is a computer monitor, then the signal can be previously converted into a digital code.
Electron-optical converters are solutions that are traditionally classified into several generations. Devices related to the first include a glass vacuum flask. It houses the photocathode and anode. A potential difference is formed between them. When an optimal voltage is applied to the converter, an electronic lens is formed inside it, which is able to focus electron flows.
The second generation converters contain electron acceleration modules, as a result of which the image brightness is enhanced. Third-generation devices use materials that increase the sensitivity of the photocathode as a key component of an electron-optical converter by more than 3 times.
Features of Resistive Converters
Another common type of device is resistive converters. Consider their features in more detail.
These converters 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 converters are included in automation systems with sensors for pressure, temperature, light level, measuring the intensity of various types of radiation. The main advantages of resistive converters:
- 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 varieties of related devices. Among the most popular are temperature sensors. We 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 some cases, they make it possible to change the temperature with an accuracy of the order of 0.026 degrees Celsius. These devices contain 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 borne in mind that higher values of the excitation current supplied to the sensor increase its temperature sensitivity, but at the same time, they heat up the elements of the corresponding converter. In many cases, this leads to a decrease in its accuracy. Therefore, it is recommended to provide optimal excitation current indicators taking into account specific measurement conditions. The thermal conductivity of the medium in which the sensor is used, for example, air or water, can be taken into account. As a rule, the recommended indicators for the excitation currents are set by manufacturers of sensors of the corresponding type. However, they can vary significantly depending on the metals used in the design of the devices. , , , , . .
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