• How radio stations work. Homemade parts for the receiver and installation. Improvement of radio by Popov

    For a long time radios topped the list of the most significant inventions of mankind. The first such devices have now been reconstructed and changed in a modern way, but little has changed in their assembly diagram - the same antenna, the same grounding and oscillatory circuit to filter out unnecessary signal. Undoubtedly, circuits have become much more complicated since the time of the creator of radio, Popov. His followers developed transistors and microcircuits to reproduce a higher quality and energy-consuming signal.

    Why is it better to start with simple circuits?

    If you understand the simple one, you can be sure that most of the path to success in the field of assembly and operation has already been mastered. In this article we will analyze several circuits of such devices, the history of their origin and the main characteristics: frequency, range, etc.

    Historical background

    May 7, 1895 is considered the birthday of the radio receiver. On this day, the Russian scientist A.S. Popov demonstrated his apparatus at a meeting of the Russian Physicochemical Society.

    In 1899, the first radio communication line, 45 km long, was built between and the city of Kotka. During World War I, direct amplification receivers and vacuum tubes became widespread. During hostilities, the presence of a radio turned out to be strategically necessary.

    In 1918, simultaneously in France, Germany and the USA, scientists L. Levvy, L. Schottky and E. Armstrong developed the superheterodyne reception method, but due to weak vacuum tubes This principle became widespread only in the 1930s.

    Transistor devices emerged and developed in the 50s and 60s. The first widely used four-transistor radio, the Regency TR-1, was created by German physicist Herbert Mathare with the support of industrialist Jakob Michael. It went on sale in the US in 1954. All old radios used transistors.

    Study and implementation began in the 70s integrated circuits. Receivers are now being developed through greater integration of nodes and digital signal processing.

    Device characteristics

    Both old and modern radios have certain characteristics:

    1. Sensitivity is the ability to receive weak signals.
    2. Dynamic range - measured in Hertz.
    3. Noise immunity.
    4. Selectivity (selectivity) - the ability to suppress extraneous signals.
    5. Self-noise level.
    6. Stability.

    These characteristics do not change in new generations of receivers and determine their performance and ease of use.

    The principle of operation of radio receivers

    In the very general view USSR radio receivers worked according to the following scheme:

    1. Due to fluctuations in the electromagnetic field, alternating current appears in the antenna.
    2. The oscillations are filtered (selectivity) to separate information from noise, i.e., the important component of the signal is isolated.
    3. The received signal is converted into sound (in the case of radio receivers).

    Using a similar principle, an image appears on a TV, digital data is transmitted, and radio-controlled equipment (children’s helicopters, cars) operates.

    The first receiver was more like a glass tube with two electrodes and sawdust inside. The work was carried out according to the principle of the action of charges on metal powder. The receiver had a huge resistance by modern standards (up to 1000 Ohms) due to the fact that the sawdust had poor contact with each other, and part of the charge slipped into the air space, where it was dissipated. Over time, these filings were replaced by an oscillating circuit and transistors to store and transmit energy.

    Depending on the individual receiver circuit, the signal in it may undergo additional amplitude and frequency filtering, amplification, and digitization for further software processing etc. A simple radio receiver circuit provides for single signal processing.

    Terminology

    An oscillatory circuit in its simplest form is a coil and a capacitor closed in a circuit. With their help, you can select the one you need from all the incoming signals due to the circuit’s own frequency of oscillation. USSR radios, as well as modern devices, are based on this segment. How does it all work?

    As a rule, radios are powered by batteries, the number of which varies from 1 to 9. For transistor devices, 7D-0.1 and Krona batteries with a voltage of up to 9 V are widely used. The more batteries required simple circuit radio receiver, the longer it will work.

    Based on the frequency of received signals, devices are divided into the following types:

    1. Long-wave (LW) - from 150 to 450 kHz (easily scattered in the ionosphere). What matters are ground waves, the intensity of which decreases with distance.
    2. Medium wave (MV) - from 500 to 1500 kHz (easily scattered in the ionosphere during the day, but reflected at night). During daylight hours, the radius of action is determined by grounded waves, at night - by reflected ones.
    3. Shortwave (HF) - from 3 to 30 MHz (do not land, are exclusively reflected by the ionosphere, so there is a radio silence zone around the receiver). When the transmitter power is low, short waves can propagate over long distances.
    4. Ultrashortwave (UHF) - from 30 to 300 MHz (have a high penetrating ability, are usually reflected by the ionosphere and easily bend around obstacles).
    5. - from 300 MHz to 3 GHz (used in cellular communications and Wi-Fi, operate within visual range, do not go around obstacles and propagate in a straight line).
    6. Extremely high frequency (EHF) - from 3 to 30 GHz (used for satellite communications, reflected from obstacles and operating within line of sight).
    7. Hyper-high frequency (HHF) - from 30 GHz to 300 GHz (they do not bend around obstacles and are reflected like light, they are used extremely limited).

    When using HF, MF and DV radio broadcasting can be carried out while being far from the station. The VHF band receives signals more specifically, but if a station only supports it, then you won’t be able to listen on other frequencies. The receiver can be equipped with a player for listening to music, a projector for displaying on remote surfaces, a clock and an alarm clock. The description of the radio receiver circuit with such additions will become more complicated.

    The introduction of microcircuits into radio receivers made it possible to significantly increase the reception radius and frequency of signals. Their main advantage is their relatively low energy consumption and small size, which is convenient for portability. The microcircuit contains all the necessary parameters for downsampling the signal and making the output data easier to read. Digital processing signal dominates in modern devices. were intended only for transmitting an audio signal, only in recent decades the design of receivers has developed and become more complex.

    Circuits of the simplest receivers

    The circuit of the simplest radio receiver for assembling a house was developed back in Soviet times. Then, as now, devices were divided into detector, direct amplification, direct conversion, superheterodyne, reflex, regenerative and super-regenerative. The easiest to understand and assemble are considered detector receivers, from which the development of radio can be considered to have begun at the beginning of the 20th century. The most difficult devices to build were those based on microcircuits and several transistors. However, once you understand one pattern, others will no longer pose a problem.

    Simple detector receiver

    The circuit of the simplest radio receiver contains two parts: a germanium diode (D8 and D9 are suitable) and main phone with high resistance (TON1 or TON2). Since there is no oscillatory circuit in the circuit, it will not be able to catch signals from a specific radio station broadcast in a given area, but it will cope with its main task.

    For work you will need good antenna, which can be thrown onto a tree, and a ground wire. To be sure, it is enough to attach it to a massive piece of metal (for example, to a bucket) and bury it a few centimeters into the ground.

    Option with oscillating circuit

    To introduce selectivity, you can add an inductor and a capacitor to the previous circuit, creating an oscillating circuit. Now, if you wish, you can catch the signal of a specific radio station and even amplify it.

    Tube regenerative shortwave receiver

    Tube radio receivers, the circuit of which is quite simple, are made to receive signals from amateur stations on short distances- for ranges from VHF (ultra-short wave) to LW (long wave). Finger battery lamps work on this circuit. They generate best on VHF. And the resistance of the anode load is removed by low frequency. All details are shown in the diagram; only the coils and inductor can be considered homemade. If you want to take television signals, then coil L2 (EBF11) is made up of 7 turns with a diameter of 15 mm and a wire of 1.5 mm. 5 turns are suitable.

    Direct amplification radio receiver with two transistors

    The circuit also contains a two-stage low-frequency amplifier - this is a tunable input oscillatory circuit of the radio receiver. The first stage is an RF modulated signal detector. The inductor is wound in 80 turns with PEV-0.25 wire (from the sixth turn there is a tap from below according to the diagram) on a ferrite rod with a diameter of 10 mm and a length of 40.

    This simple radio receiver circuit is designed to recognize powerful signals from nearby stations.

    Supergenerative device for FM bands

    The FM receiver, assembled according to the model of E. Solodovnikov, is easy to assemble, but has high sensitivity (up to 1 µV). Such devices are used for high-frequency signals (more than 1 MHz) with amplitude modulation. Thanks to the strong positive feedback the coefficient increases to infinity, and the circuit goes into generation mode. For this reason, self-excitation occurs. To avoid it and use the receiver as a high-frequency amplifier, set the coefficient level and, when it reaches this value, sharply reduce it to a minimum. For continuous gain monitoring, you can use a sawtooth pulse generator, or you can do it simpler.

    In practice, the amplifier itself often acts as a generator. Using filters (R6C7) that highlight low-frequency signals, the passage of ultrasonic vibrations to the input of the subsequent ULF cascade is limited. For FM signals 100-108 MHz, coil L1 is converted into a half-turn with a cross-section of 30 mm and a linear part of 20 mm with a wire diameter of 1 mm. And coil L2 contains 2-3 turns with a diameter of 15 mm and a wire with a cross-section of 0.7 mm inside a half-turn. Receiver amplification is possible for signals from 87.5 MHz.

    Device on a chip

    The HF radio receiver, whose circuit was developed in the 70s, is now considered the prototype of the Internet. Shortwave signals (3-30 MHz) travel great distances. It is not difficult to set up a receiver to listen to broadcasts in another country. For this, the prototype received the name world radio.

    Simple HF receiver

    A simpler radio receiver circuit lacks a microcircuit. Covers the range from 4 to 13 MHz in frequency and up to 75 meters in length. Power supply - 9 V from the Krona battery. The installation wire can serve as an antenna. The receiver works with headphones from the player. The high-frequency treatise is built on transistors VT1 and VT2. Due to capacitor C3, a positive reverse charge arises, regulated by resistor R5.

    Modern radios

    Modern devices are very similar to radio receivers in the USSR: they use the same antenna, which produces weak electromagnetic oscillations. High-frequency vibrations from different radio stations appear in the antenna. They are not used directly to transmit a signal, but carry out the operation of the subsequent circuit. Now this effect is achieved using semiconductor devices.

    Receivers were widely developed in the middle of the 20th century and have been continuously improved since then, despite their replacement mobile phones, tablets and TVs.

    The general design of radio receivers has changed slightly since Popov's time. We can say that the circuits have become much more complicated, microcircuits and transistors have been added, and it has become possible to receive not only an audio signal, but also to build in a projector. This is how receivers evolved into televisions. Now, if you wish, you can build whatever your heart desires into the device.

    Electric current, flowing in any conductor, generates an electromagnetic field that spreads in the space surrounding it.
    If this current is alternating, then the electromagnetic field is capable of inducing (inducing) E.M.F. in another conductor located at some distance - transmission occurs electrical energy to a distance.

    This method of energy transfer has not yet received widespread use - losses are very high.
    But to transmit information, it has been used for more than a hundred years, and very successfully.

    For radio communication, electromagnetic oscillations are used, the so-called radio frequency range, directed into space - radio waves. For the most effective radiation into space, antennas of various configurations are used.

    Half-wave vibrator.

    The simplest antenna is a half-wave vibrator, consisting of two pieces of wire directed in opposite directions, in the same plane.

    Their total length is half the wavelength, and the length of an individual segment is a quarter. If one end of the vibrator is directed vertically, the ground can be used instead of the second, or even the common conductor of the transmitter circuit.

    For example, if the length of a vertical antenna is 1 meter, then for a radio wave 4 meters long (VHF band) it will present the greatest resistance. Accordingly, the efficiency of such an antenna will be maximum - precisely for radio waves of this length, both during reception and transmission.

    To tell the truth, in the VHF range, the most reliable reception should be observed when the antenna is positioned horizontally. This is due to the fact that transmission in this range is, in fact, most often carried out using horizontally located half-wave vibrators. Therefore, a half-wave vibrator (and not a quarter-wave vibrator) will be a more efficient receiving antenna.


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    Radio (translated from Latin “radio” means “I emit”, “I emit rays”) is a type wireless connection, which is designed to transmit and receive information. In this case, the signal is freely distributed in space using electromagnetic waves, which are also called “radio waves”.

    How does the radio work?

    The principle of operation is as follows: in order for information to be transmitted, the sending side models the necessary signal, which is characterized by a certain amplitude and frequency. On next stage, the signal forms a carrier (high-frequency) oscillation. After which the converted signal is emitted into space using an antenna. While the receiving side produces reverse actions: The antenna picks up the modulated signal and converts it using a low-pass filter (LPF). This action is performed in order to get rid of the carrier (high-frequency component). Thus, the receiving side extracts a useful signal from the received high-frequency oscillation. However, in some cases, due to interference and interference, transmission distortion may occur, as a result of which the received signal will differ from the transmitted one.

    Types of radio waves and frequency ranges

    The International Communications Union has adopted the following classification of frequency ranges:
    1. Myriameter waves (very low frequencies) - 3-30 kHz, wavelength - 10-100 km;
    2. Kilometer waves (low frequencies) - 3-300 kHz; wavelength - 1-10 km;
    3. Hectometric waves (medium frequencies) - 0.3-3 MHz, wavelength - 0.1-1 km;
    4. Decameter waves (high frequencies) - 3-30 MHz, wavelength - 10-100 m;
    5. Meter waves (very high frequencies) - 30-300 MHz, wavelength - 1-10 m;
    6. Decimeter waves (ultrahigh frequencies) - 0.3-3 GHz, wavelength - 10-100 cm;
    7. Centimeter waves (ultrahigh frequencies) - 3-30 GHz, wavelength - 1-10 cm;
    8. Millimeter waves (extremely high frequencies) - 30-300 GHz, wavelength - 0.1-1 cm.
    In the field of radio broadcasting, only a few types of radio waves are used: ultra-long (myriameter), long (kilometer), medium (hectometer), short (decameter) and ultra-short (high-frequency).

    Laws of Radio Wave Propagation

    Depending on the frequencies emitted by the source, each type of radio waves has its own characteristics and laws of distribution in space.

    Long waves are characterized by an increased degree of absorption by the ionosphere. A special role is played by ground radio waves, which propagate, “enveloping” the earth. If we talk about signal strength, then with distance from the transmission source, it decreases at a rapid pace.

    Medium waves are most perceptible to the ionosphere during the day, and the range of action at this time of day is determined by the surface wave. In the evening, the situation changes dramatically: medium radio waves are well reflected from the ionosphere, and the propagation area is determined by the reflected wave.

    Since the method of propagation of short waves is reflection by the ionosphere, a radio silence zone is formed around the signal transmitter (signal reception is practically impossible in it). Moreover, short waves propagate better during the day, and longer ones at night. If the power of the radio transmitter is reduced, radio waves of this type can propagate over considerable distances.
    High-frequency (ultra-short) waves are not reflected by the ionosphere and, as a rule, propagate in a straight line. However, in some conditions, namely due to differences in densities in different layers atmosphere, radio waves are able to “bend” globe. For of this type waves are characterized by high penetrating ability.

    A feature of high frequencies (HF) is their propagation within the line of sight. Such waves are used for wireless data transmission (WiFi) and mobile communications. Extremely high frequencies (EHF), like high frequencies, do not bend around obstacles and are used in satellite communication technologies. Hyper-high frequencies have the property of reflection (like light rays), the range of action is determined by the limits of visibility. The use of such electromagnetic waves is extremely limited.

    Mankind knows the following conditions for the distribution of radio waves. The signal can propagate in the atmosphere and void, while it cannot penetrate through water and solid objects. However, here's what's paradoxical. Thanks to phenomena such as wave diffraction and refraction, communication between points beyond the line of sight is still possible.

    A wave emanating from a transmission source can follow several paths at once. This phenomenon is called multipath. Due to changes in environmental parameters, the level of the received signal changes relative to time. Its fading results in the electromagnetic field at the receiving point being the sum of all time-shifted radio waves.

    Special effects arising from the transmission of radio waves

    1. The principle of antipodes says that a radio wave is well perceived at that point on the earth's surface that is approximately opposite to the point of signal transmission.
    2. fixed delay effect - an echo from a radio wave that has circled the Earth.
    3. long delay echo effect (LDE).
    4. Doppler principle - the dependence of the length of a radio wave on the speed of approach and distance from the transmission source (in the case of approach, the frequency increases, in the case of distance, it decreases).
    5. Luxemburg-Gorky effect - a change in high-frequency oscillations due to nonlinear effects resulting from the distribution of waves in the ionosphere.

    Conventionally, radio communication by wavelength can be divided into two types:
    - communication without the use of repeaters (VHF communication, DV communication, SV communication, etc.)
    - communication using repeaters (satellite, radio relay, cellular).
    A repeater is a special “intermediary” communication equipment that combines several radio transmitters, remote friend some distance from each other.

    Civil radio frequencies

    According to the decision of the Russian State Commission on Radio Frequencies, to ensure civil communications of physical and legal entities, three groups of permissible frequencies were identified:
    - “Citizen’s Band” - 27 MHz, with a transmission source power of up to 10 W.
    - “Low Power Device” - 433 MHz, with permissible power of radios up to 0.01 W.
    - “Personal Mobile Radio” - 436 MHz, with a transmission output power of up to 0.5 W.

    What is “ham radio communications”?

    Under the concept " amateur radio“implies a multifaceted technical hobby, which is expressed in radio communications in acceptable frequency ranges. The hobby of a radio amateur has several directions:

    • designing equipment for receiving and transmitting radio signals;
    • radio engineering sport (participation in competitions among radio amateurs);
    • compiling a collection of receipt cards and certificates of radio communications carried out;
    • conducting search work and organizing communications with remote amateur radio stations;
    • work with various types radiation;
    • communication on ultrashort waves using the principle of signal reflection (from the Moon, meteor showers, etc.);
    • work with low power transmission sources;
    • participation in various radio expeditions.

    Inventors of the first devices for radio transmission of information

    The founder of the first operating system for receiving and transmitting information using radiotelegraphy is considered to be an engineer from Guglielmo Marconi. In Russia, A. S. Popov is considered the inventor of radio broadcasts. However, as it turned out later, none of these invented a device for receiving and transmitting information on their own. Marconi combined the technological developments of A. S. Popov’s receiver and Heinrich Hertz’s transmitter into one device.

    However, after the American Nikola Tesla patented a radio communication device, he sued Marconi for the right to the founder of the development. This decision was caused by the primitivism of the invention of the Italian engineer in comparison with the fairly advanced device of the American. Tesla's system made it possible to convert acoustic sound into a signal, transmit it over a distance, and modulate the radio wave of receivers back into acoustic sound. All modern radio devices have a similar design, based on oscillating circuit technology.

    Popularity of the query "radio" in the search engine

    The most popular radio stations in Russia are:
    - Radio Premium
    -Love radio
    - Radio "Convertible"
    - Radio Automatic and guitar
    - Radio VANYA
    - Retro FM
    - Radio DACHA
    -
    - Russian radio. Golden gramophone.
    - Autoradio
    -
    - Road radio
    - Natalie
    - Russian radio
    - Radio Di-FM
    - Russian Hit
    - Mega Radio
    - Radio "Relax FM"
    - Europa Flus
    - Radio Russian chanson.

    As you can see, the request “radio” is quite popular among Russian speaking users, it was administered 8,915,477 times in a month.

    In network news agencies, this word “radio” was mentioned 1050 times in a month.

    Portable radios, car radios for ground use

    Radio station (walkie-talkie): principle of operation

    In a broad sense, a radio station means technical device or a set of devices that exchange data via radio waves. As can be seen from the definition, a fairly large range of devices can be called a radio station. In this article we will directly touch on land transceiver equipment.

    Radio station (walkie-talkie) consists of two main elements: a receiver and a transmitter, which have common nodes. To better understand the principle of operation of the walkie-talkie, let's look at these elements in more detail.

    The radio receiver is responsible for converting radio frequency signals into acoustic vibrations familiar to human hearing. A modern radio station uses double frequency conversion, which improves the quality of the reproduced voice. First, we receive the signal (C), it is filtered and amplified, then the frequency is lowered and C is transferred to a special decoder, which isolates the information component from the entire stream. Then another amplification occurs and the already processed sound data is output to the speaker. It's pretty general scheme receiver operation, which accessible language explains the principle and features of its functioning.

    The walkie-talkie transmitter performs diametrically opposite actions: it converts data (most often it is voice, but it can also be text messages) and sends it via radio waves to another subscriber. This process can be roughly described as follows: the transmitted information is layered onto the selected frequency and transmitted via an antenna into the air. The structure of the receiver and transmitter is similar, so here we will consider only one node, which has a fundamental difference. If the receiver uses a decoder during its operation, then the transmitter uses a modulator. The modulator converts voice information into a radio signal according to certain rules.

    Radio station (walkie-talkie) became widespread during the Second World War, when the need for operational communications over long distances increased exponentially. By the way, a stationary radio station was already in use at that time, but it was quite cumbersome. But during the war years the first portable radio station (walkie-talkie) appeared. It was designed by Motorola engineers. And although it was called portable, it is separated from modern walkie-talkies by a huge chasm of various modifications and changes.

    Radio station (walkie-talkie): classification

    A land radio station (walkie-talkie) has many various classifications, we will pay due attention to the main ones.

    By mobility:

    • – a convenient walkie-talkie that fits in your hand and can be easily carried over fairly long distances;
    • – not intended for transportation, often acts as a base station.

    By user type:

    • – created for permanent use in a specific area; the most important characteristics are battery capacity, convenience and ease of use, minimum set necessary functions, programming from a PC;
    • – designed to accompany hunters or tourists on their hikes; the user can independently program the radio depending on specific needs.

    According to the principle of operation:

    • – uses the principle in its work frequency modulation; such a walkie-talkie is a classic of the genre; the radio communications market is predominantly filled with analog models;
    • – encodes the signal using two numbers: 0 and 1; it allows you to have multiple conversations on one channel, and also provides an impressive set of additional functions, including sending SMS.

    By method of protection:

    • - the shell of such a radio has increased protection, which allows it to be used in explosive conditions, for example in mines.

    Also, all radios have varying degrees of protection from dust and moisture. Thus, some radio stations can function properly even after prolonged immersion under water.

    Radio station (walkie-talkie): frequencies

    Each land radio station (walkie-talkie) operates in a certain frequency range (HF). Conventionally, all frequencies can be divided into 2 large categories: unlicensed (do not require registration of the radio and allow free use) and licensed (require a special license). Main operating frequencies (H) of modern walkie-talkies.

    CB (27 MHz)– civil frequencies. A radio station (walkie-talkie) operating on this frequency with an output power of up to 10 W does not require registration or licensing (in the territory of the Russian Federation). Often used by truck drivers or taxi companies.

    UHF (400 - 520 MHz)– urban range, so if you want to communicate by radio in the city and the territorial spread of subscribers is small, then it is better to use these frequencies. In open areas, reception/transmission deteriorates significantly, since it is difficult for radio waves to overcome natural barriers (forests, steep terrain, etc. ).

    LPD (433.075-434.775 MHz)– license-free range for low-power radio stations.

    PMR (446.000 - 446.100 MHz)– one more frequency range, which does not require a license, is widely used in Europe. Distinctive feature is to be used in open areas, since waves are practically unable to bend around obstacles. A radio station (walkie-talkie) operating in PMR frequencies should not have a power of more than 0.5 W. This is the most popular range used for everyday active communication.

    VHF (136 - 174 MHz)– the most versatile range, as it works well both in open areas and in dense urban areas.

    Radio station (walkie-talkie): how to choose

    To begin with, the user must decide on the scope of application of the radio and the main tasks that it should solve. For example, if you want to go fishing and just chat with your comrades who are on the opposite bank, then you do not need advanced functionality or obtaining a license.

    At the same time, miners working in explosive conditions will urgently need such a feature as the intrinsic safety of the radio station.

    Once the user has decided on the tasks, he can begin to select a radio station. Key features to pay attention to:

    • Frequency range
    • Output power
    • Operating range
    • Operating time without recharging (battery capacity)
    • Size

    Other characteristic features of the walkie-talkie are secondary.

    We are sure that almost each of us has heard the words “walkie-talkie” and “radio station,” and almost everyone immediately asked the question: “What is a walkie-talkie?” “How is a walkie-talkie different from a radio station?”

    A technical device for conducting a radio communication “session” is called a “Radio Station” or in simple language"Walkie talkie." This article will focus on this device. We will look at certain concepts and terms that are used in radio communications and without which it can be difficult to explain how a walkie-talkie works.
    So let's begin.

    The word “radio” is on everyone’s lips. Many people know, or at least have a general idea, how everything happens when we turn on the radio and hear melodies or news that are pleasant or unpleasant to our sensitive ears.
    Why did we start with this? But because it is radio, as we are accustomed to know and use it, that is one of components the walkie-talkie (radio station) we are considering. We will call this part in a simple word"RECEIVER".
    The question arises: “Can we listen to our favorite radio stations (such as “Mayak”, “Chanson”) on our device under the same name radio station? Despite the tautology with the word “radio station”, the question is quite valid. So here's the answer - we can, but not on all walkie-talkies (radio stations). The fact is that a walkie-talkie (radio station), like any technical equipment, has its own very specific purpose and, accordingly, technical characteristics determined by the developer.

    One of the main technical characteristics, inherent in any walkie-talkie, is “FREQUENCY” (radio wave frequency). From the school physics course it is known that a radio wave is electromagnetic oscillation, and its main parameter is “Frequency”.
    Example:
    Many people have heard the following names: CB radio station, LPD (eLPiDi) radio station, PMR (PieMeR) radio station. These are all walkie-talkies, but they operate on different frequencies:
    CB (“Citizen Band”): 27 MHz
    LPD: 433-434 MHz
    PMR: 446 MHz

    There is also a concept that is directly related to frequency - “WAVELENGTH”.
    We are not in favor of boring you with higher mathematics, but for those who are interested, here is a little theory at the link. After wandering through the vastness of Wikipedia, you will learn something that many of those who have been using the radio station for years do not know. http://ru.wikipedia.org/wiki/Electromagnetic_radiation

    But let's move on.
    In addition to the “RECEIVER”, the radio station also has a “TRANSMITTER”. It is clear to everyone what the transmitter is transmitting. One of the characteristics of the transmitter is again “frequency”.
    Here we will immediately say that there are radio stations that operate in such a way that both the receiver and the transmitter operate at the same frequency. This is the so-called “Simplex” in narrow circles. Of course, you will immediately ask: “How can this be? Don't they interfere with each other? The answer lies on the surface: “So that the receiver and transmitter do not interfere with each other, they must work alternately.” This is exactly what happens when communicating on a walkie-talkie: we speak - they listen to us; they tell us - we listen. This kind of connection is also called a connection for polite people, because... otherwise no one will hear anyone, the air will simply be a mess.
    Another case is when the receiver and transmitter operate at different frequencies. In narrow circles this case is called “Duplex” or “Half-Duplex”. You ask: “What’s the difference?” The difference is this: “Duplex” is when the receiver and transmitter operate simultaneously (at different frequencies), and we speak and hear as in a normal “live” conversation. Example - any cell phone. But in “half-duplex” the receiver and transmitter work alternately, just like in Simplex, but at different frequencies, just like in Duplex.

    So, any radio station has a receiver and transmitter. But that's not all. There is also a “CONTROL UNIT”. What is he doing? He “manages”, or rather, monitors, controls, produces, limits, indicates, turns on, turns off...
    To begin with, the main thing is to remember and understand that such a block exists and that it is as important as the receiver and transmitter. An important point is that this block does not work fully automatically. You and I (the operator, the signalman, just the user) determine when and what to do. When we press the PTT transmit button (“push to talk”), we indicate to the control unit that we are now going to talk and that we need to put the radio into transmit mode. When we release the PTT button, the radio station goes into standby mode, subsequently from this mode we can switch to the receiving mode (here the unit will handle it itself, if there is a signal on our frequency) or, by pressing the PTT button, again into the transmitting mode, or we can and turn off the radio completely.

    Another block is the “POWER SUPPLY”. Since most radio stations do not have it in that fully functional form as the concept of “power supply” is usually understood, they often operate with the concept of “SUPPLY VOLTAGE”. What do you need to know about this concept? You need to know what voltage is needed for the radio to operate. Most car (stationary) radios require a 12-volt power supply to operate. This is due to the fact that large number users want to use the radio in the car. And in the car, as we know, the “on-board” power supply is exactly 12 Volts.
    Advanced users may object to us that the power supply in the car is 13.8 Volts! And we won't argue. It is 13.8V that should be considered the supply voltage in a car, but there are some subtleties of the car’s supply voltage in various modes of its operation, therefore everything is not so simple. Therefore, motorists have an established concept of “12 Volts”.
    There are even more important point in the matter of voltage - this is, as they say, “where is the plus?” and “where is the minus”??? Let us remind everyone that the plus (as a rule) is a red wire, and the minus (also as a rule) is black. But it never hurts to check and clarify!
    If, however, the radio station has a full-fledged power supply, then for us, as a rule, this means that the radio station needs to be connected to a regular 220 Volt network. Everything regarding the power supply of a radio station is always written in its description or operating instructions or passport.

    Nominally, we described what the radio station consists of - a receiver, transmitter, control unit and power supply, but, anticipating the question “What about the antenna?!” we will now move on to this point.
    Indeed, there is one more block, a device, you can call it whatever you like, without which it is better not to turn on the radio station - this is Her Majesty “ANTENNA”. The importance of this concept is difficult to overestimate for radio communications. What is an antenna for? We can say this - an antenna is needed to receive and transmit radio waves carrying our speech either from us to our interlocutor, or back from him to us. “What about the receiver and transmitter?” - you ask and you will be right. Strictly speaking, the antenna is the beginning of the receiver circuit and the continuation of the transmitter circuit. That’s why real radio experts devote so much talk and debate to it (the antenna). But for amateurs, the most important thing you need to know about an antenna is the antenna’s operating frequency. The passport of any antenna indicates the operating frequency(s). And one more important point regarding the antenna - almost any antenna (we mean automobile and stationary) has, even let’s say should have, a frequency adjustment.
    It turns out that the receiver, transmitter and antenna must operate at the same frequency? The answer is YES, this is the main condition for the successful operation of the radio station. Therefore, the first and most correct question regarding any radio station is “What frequencies does this radio station operate on?”

    In order to understand even better how a radio station works, to be able to compare and choose the one you need from the variety that the market is now replete with, we would like to mention here a few more important characteristics inherent in any radio station. Here is a list of the main characteristics of the radio station:
    frequency range;
    type of modulation;
    output power transmitter;
    receiver sensitivity;
    operating mode - Simplex, duplex, half-duplex;
    supply voltage;

    From this list we already know the “frequency range”, what the “simplex/duplex/half-duplex” mode and “supply voltage” are. Let's look at the rest.

    In simple terms, “TYPE OF MODULATION” is the way our speech is “transferred” to a radio wave.

    Again, a little theory for those who are hungry for knowledge. http://ru.wikipedia.org/wiki/%D0%9C%D0%BE%D0%B4%D1%83%D0%BB%D1%8F%D1%86%D0%B8%D1%8F;

    So, we are interested in “frequency” (FM. English FM) and “amplitude” (AM) modulations. But keep in mind that not all radio stations can operate in both types of modulation, or there are some restrictions on the use of FM or AM modulation in a particular country.

    "TRANSMITTER OUTPUT POWER."
    This is the power characteristic of the transmitter - like horsepower for a car engine. But here this power is measured in Watts. Strictly speaking, the more power the better, not always, because... We must not forget about the price - it directly depends on the power, and about the restrictions that the relevant authorities impose when allowing this or that power for free use.
    And one more point: if for normal operation It is enough, for example, for a CBS radio station, to have 10 watts, then why do you need to transmit 100, or even 200 watts on the air? You also need to remember that high power entails high consumption of power supply.
    RESULT: Everything needs a justified necessity that does not contradict the law!

    "RECEIVER SENSITIVITY"
    A characteristic showing the smallest signal a radio station can receive. Regarding sensitivity, we can say that the lower its value, and therefore the higher the sensitivity, the better. Sensitivity is measured in either microvolts (µV) or decibels (dB).

    The sensitivity of modern radio stations usually ranges from 0.16 - 0.5 µV or -123...-113dB, respectively. Although here it must be said that sometimes the sensitivity is deliberately “lowered” when receiving a signal from a powerful or nearby radio station.

    Here I would also like to pay attention to a very important part of the circuit of any receiver in any radio station - this is the “NOISE CANCELER”. The name itself says that the device deals with noise. What kind of noise do you mean?
    Have you ever paid attention to this effect - when in the evening, and especially at night (inveterate late-nighters will confirm), lovers of watching late-night TV shows have to reduce the volume of their TV, not only because everyone around them is sleeping, but also because it suddenly becomes easier to hear ? This happens because everything around seems to “freeze”, noisy neighbors, transport, not to mention factories, fall silent. There is something similar in the radio air, where there is a certain level of noise from the “activities” of man and nature. The most interesting thing is that this noise has a variable level, sometimes varying greatly not only from place to place, but also over time. Therefore, if there were no “squelch”, your radio would constantly “hiss” while in standby mode. Can you imagine what would happen to your head??? Therefore, the main function of the noise suppressor is to set the threshold of the receiver so that you hear signals slightly higher than the level of this airborne noise.

    We examined the basic terms and characteristics in relation to the concept of “radio station”. We hope that our “review” conversation will become a starting point to understanding what a radio station is.

    73! (code for "best wishes" used in radio communications)

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