Table of contents:
- What is the purpose of signal converters?
- A/D Converter
- Digital-to-analog converters
- Ultrasonic transducers
- Linear and pulse converters
- Measuring transducers
- Classification of measuring transducers: primary and intermediate solutions
- Intensifier tubes
- Features of resistive transducers
- Resistive temperature sensors
- Rheostat converters
In industry and in everyday life, the use of various types of signal converters is common. These devices can be presented 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 could be the features of their operation?
What is the purpose of signal converters?
Signal converters are devices that can really be presented in the widest range of solutions. This term is actually a collective one 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 the devices in question can convert are:
- technological nature.
Depending on the tasks that the user of the signal converter faces, the structure of the corresponding device can combine modules that process several different types of data. Conversion, therefore, can be carried out within the framework of one type of signal (for example, from one frequency to another) or be a mechanism that involves translation between different categories of signals. For example, electric to sound.
The most common devices include a 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.
The device in question is designed to convert any analog signal - for example, represented by voltage indicators, into digital form (allowing, for example, to write the corresponding signal to a file).
One of the main criteria for the efficiency of the device under consideration is the output data capacity. Its value determines the signal-to-noise ratio.
Another significant parameter that characterizes the quality of operation of such a device as an analog converter is the speed of output signal formation. Among those devices that provide its optimal performance are those that are of the parallel type. They form large signal flows using the required number of pins. This feature of the functioning 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, given the effectivenessoperation of these devices, their noted features are often not considered as shortcomings.
Conversion of signals from analog to digital parallel devices is very fast. To provide even higher speed for the corresponding type of devices, you can connect several devices, so that they can process signal streams in turn.
An alternative to parallel solutions can be serial-type signal converters. They tend to be less productive but more energy efficient. Their use may be conditioned in cases where there is a question of ensuring the transmission of signals within a low-capacity infrastructure, or in the event that a higher conversion rate than that provided by serial devices is not required.
It can be noted that there are mixed-type devices that combine the functions of serial and parallel converters. In many cases, they are the best solution in terms of meeting cost and performance criteria.
Above, we noted that analog-to-digital converters may include modules through which digital signals are converted to analog. There is also a separate category of devices of the corresponding type. Let's study their features.
If the user has, for example, a TV for an analog signal, then hisoperation will be possible when a suitable antenna is connected. Or subject to the transformation of the original signals into analog, which this TV can recognize. Their source can, in turn, be a digital antenna. Or, alternatively, 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 transferred to analog modules for processing. Specific mechanisms of this transformation depend on the type of initial data. For example, if we are talking about sound, then at the input it is usually presented in pulse code modulation. If the source file is compressed, then special software codecs can be used to convert the signals. In turn, the digital antenna usually transmits the signal for processing by hardware methods.
Devices that include the converters in question can be supplemented with 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 picture quality when converting an analog signal to digital. Also, a video signal amplifier is used if you need to transfer pictures 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 CD players,which also convert the digital signal to analog.
The next common category of devices is the ultrasonic transducer. It can be noted that it can be represented by devices that have 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 transmit ultrasound at a certain frequency into water or other liquid medium. This device can be used, for example, to clean various objects from contaminants - as part of baths used for ultrasonic cleaning.
There are other areas of application of the considered devices. An ultrasonic transducer can be used to control the integrity of certain structures, connections, to check certain 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 according to 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 signals both at the output and during their internal processing. However, in case ifthis operation is carried out only at the internal stage of signal processing, the corresponding device can generate virtually the same indicators as in the case when a linear converter is used. Thus, the concept of linear or pulse processing can only be considered in the context of the principle of operation of the key hardware components of a device of the corresponding type.
Pulse converters are mainly used in cases where the infrastructure used is expected to process 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 the pulse converters have optimal compatibility.
In turn, a linear converter is a device that is used within the framework of an infrastructure in which low-power signal processing is carried out. Or if there is a need to reduce the noise generated due to the operation of the converter. It is worth noting that the efficiency of the solutions under consideration in a high-power infrastructure is not the most outstanding, therefore, these devices most often emit a larger 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 involvethe formation of its transfer function in a linear form. Therefore, before implementing the appropriate signal conditioners into the infrastructure, their internal structure should be considered for the applied signal processing scheme.
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. What unites these devices is their ability to both measure and transform certain quantities.
It is common to consider the operation scheme of measuring devices of the corresponding type, in which the signal is processed in several stages. First, the converter receives it, then transforms it into a value that can be measured, after that it transforms it into some useful energy. For example, if an analog measuring current transducer is used, then electrical energy is transformed into mechanical energy.
Of course, specific mechanisms for the application of appropriate solutions can be presented in an exceptionally wide range. The use of measurement transformations for scientific purposes as part of the infrastructure for conducting experiments and research is widespread. What unites most measuring transducers is their adaptability, first of all, to work with the use of normalized characteristics when processing or transforming a signal. CanPlease note that these specifications may not always be intended for the end user of the inverter. Their involvement in many cases is carried out in a hidden mode. A person, using appropriate signal converters, receives only the required 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, measurement automation systems 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.
Classification of measuring transducers: 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 value acts directly. The remaining devices are classified as intermediate. They are placed in the measurement infrastructure immediately after the first ones and can be responsible for a large number of operations related to the transformation. What specific operations can be performed by a signal level converter of the corresponding type? These are commonly referred to as:
- measurement of physical indicators for various quantities;
- various scale transformations;
- transformation of digital signals into analog and vice versa;
- functional transformations.
Note that a similarclassification can be considered conditional. This is primarily due to the fact that several primary transducers can be located in the same measurement instrument. Another reason to consider the classification discussed above conditional is that in different types of infrastructure, measurements can be carried out according to dissimilar principles.
Another type of device popular in various sectors of the economy is an image intensifier tube. It, like other types of devices discussed above, can be presented in a wide range of designs. Electron-optical converters are united by a common 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 stage, invisible radiation is received by a photocathode, after which it is transformed into electronic signals. Which are already at the second stage converted into a visible picture and displayed on the screen. If it is a computer monitor, then the signal can be preliminarily converted into a digital code.
Intensifier tubes are solutions that are traditionally classified into several generations. Devices related to the first include a glass vacuum flask. It contains a photocathode and an anode. A potential difference is formed between them. When applying forAn optimal voltage converter inside it forms an electronic lens capable of focusing electron flows.
The second generation transducers have electron acceleration modules, resulting in enhanced image brightness. The third generation devices use materials that allow increasing the sensitivity of the photocathode as a key component of the electron-optical converter by more than 3 times.
Features of resistive transducers
Another common type of device is resistive transducers. 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 correct angular and linear movement. Most often, these converters are included in automation systems with sensors for pressure, temperature, illumination level, and measuring the intensity of various types of radiation. Main advantages of resistive transducers:
- no relationship between the accuracy of 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. Let's 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 about 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 taken into account that higher values of the excitation current supplied to the sensor increase its temperature sensitivity, but, at the same time, heat up the elements of the corresponding converter. This in many cases causes a decrease in its accuracy. Therefore, it is recommended to ensure optimal excitation current performance, taking into account the specific measurement conditions. The calculation can take, for example, the thermal conductivity of the medium in which the sensor is used - air or water. As a rule, the recommended indicators for 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. In addition, when using the sensors in question, it is necessary to take into account such an indicator as the limiting value for the operating current. Usually it is also determined by the manufacturer.
Resistive sensors are among the most common types of transducers in the household. This is largely due to the significant technological advantages of many of their varieties. For example, iftalk about thermistors - those are characterized by high sensitivity, compactness, low weight. The appropriate type of sensors can be used to measure the air temperature in various conditions. Their production most often does not involve significant costs. True, thermistors also have disadvantages - first of all, this is a high degree of nonlinearity, as a result of which they can be used in practice in fairly narrow temperature ranges.
The corresponding type of signal converters (their types and purpose 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 in certain parts of the equipment, as well as in the heated room;
- washing machines - in order to measure the water temperature and adjust it to various washing programs;
- irons - similarly to ensure the optimal ironing temperature within a particular mode of operation;
- electric stoves, as well as other types of equipment for cooking - also in order to ensure their functioning when certain user modes are activated.
Another popular type of resistive devices are rheostat converters. Their principle of operation is based on the measurement of electrical resistanceof one or another conductor under the influence of input displacement. In practice, this transducer includes elements that are adapted to move due to the influence of the measured value. Most often, the devices in question are included in voltage dividers or used as an integral element of measuring bridges.
If we talk about the advantages that characterize rheostat converters, then these include:
- no reactive effect on moving components;
- high efficiency;
- small size, can be used in infrastructure operating on both direct and alternating current.
At the same time, resistive converters of the corresponding type are not always reliable and in many cases require significant resources from the enterprise to maintain functionality.