Review and types of walkie-talkies. Selecting a radio. How to choose portable radios Types of walkie-talkies and radio stations
The target audience is all potential and actual consumers of a product (service) who remain interested in it for a certain time or are ready to change their preferences in favor of this product (service) under marketing pressure, the sale of the product for which, firstly, is beneficial to the seller in a given period time and, secondly, possible.
The specific content of the concept “audience” depends on what is taken as the starting point. There are several bases for classifying the audience. The audience can be identified according to a variety of criteria, namely:
by media: audience of print, radio, television; at the end of the 20th century, the Internet audience began to form;
by channel levels: audience of all-Russian (federal), republican, regional, regional, district radio;
the audience of a program, radio station, radio magazine, column, series, even the presenter;
by socio-demographic characteristics (age, gender, nationality, education, religious affiliation, profession, etc.): youth, women, workers, military, Russian-speaking audiences.
Research in this area shows that even the audience of one radio station is noticeably divided into male and female. Thus, female radio listeners of Radio Russia prefer radio plays, radio plays, literary readings, programs about family relationships and raising children; radio listeners - sports, journalistic and socio-political programs. The persistence of differences made it possible to create a special “women’s” radio “Nadezhda” (“everything must be seen through a woman’s eye”, “a woman’s world, but also a different view even on familiar problems” - this is her credo);
by income level of radio listeners (especially in commercial broadcasting). There is a radio for the rich, for people of average income. The concept of many radio stations is based on a focus on a certain material standard of living for listeners;
by lifestyle, profession: programs for those at home; for those who work at a computer; for motorists; for summer residents;
by interests: audience of sports programs; classical and pop music; religious programs.
Media sociologists distinguish between “real” and “potential” audiences. Knowing who is actually listening and who can become a listener of a particular station or program is very important for radio workers.
It should be remembered that the identification of different types of audience is to a certain extent arbitrary. A person can be a representative of different types of audience at the same time (intersection of audiences) or not be part of any of them. In a situation of competition on the air, the penetration of market relations into it, the concept of audience, its detailed and carefully worked out classification has ceased to be a subject of purely theoretical interest - it is a matter of survival, the very existence of radio stations and programs.
Market researcher Michael Hedges divides radio listeners into four segments:
radio fans,
radio fans,
music fans and news fans.
Fans of specific radio stations make up the largest segment (46%). They prefer one or two stations and spend up to 8 hours a day or more listening to them. The majority of radio fans are women between the ages of 25 and 44. Radio fans make up 34%. They listen to four to five different radio stations a week, with no particular preference. Most are under 35, although this segment includes a large number of women 55 and older. Only 11% of the population listens exclusively to music on the radio. Music listeners include both men aged 25 - 45 years, as well as many older people. And finally, some radio listeners choose radio stations based on their need for news and information. They are almost always over 35 years old and prefer one or two stations, listening to them for short periods of time.
Radio can be classified in terms of transmission method and power. The actual reception radius of a radio station depends on the height of the antenna, the quality of the equipment, etc.
There are two types of radio stations: AM radio and FM radio. The first type includes amplitude modulation (AM) stations, which can change the amplitude of the electromagnetic waves they produce. These waves go around the contour of the Earth during the daytime, and at night they are directed into the sky and reflected from the upper layers of the atmosphere, which greatly increases the radius of their propagation.
The actual power, or strength, of an AM signal depends on how much power is allowed by the FCC. Stations with a broadcast range of 25 miles are considered local radio stations. Most local stations allow 100-250 watts of power. Regional radio stations can cover an entire state or multiple states. The most powerful stations can use a signal power of up to 50 thousand watts. The relative power of each radio varies depending on the assigned frequency. The lower the frequency, the further the signal will travel.
Frequency modulation radio stations (FM stations) differ from amplitude modulation radio stations (AM stations) by the change during broadcasting not in the magnitude (amplitude) of the signal, which remains constant, but in its frequency. Due to the fact that the signal from FM stations travels within line of sight, its reception range is determined by the height of the radio antenna. Typically 50 miles is the maximum distance for such signals. However, the quality of the FM signal is far superior to that of the AM signal.
In addition to AM and FM stations, cable radio was introduced in 1990. This technology uses cable television networks to broadcast music radio programs. The premise behind cable radio is that cable TV could use some extra revenue and consumers are tired of radio advertising. These radio broadcasts usually do not contain advertising and cost $7-12. An example is DigitalMusicExpress, which offers 30 shows throughout the day with CD-quality sound.
DAB - digital radio broadcasting - already existed in Europe, and since 1995 it has been used in the USA. DAB delivers superior sound quality. Listeners can listen to the same station throughout the country. DAB provides higher quality sound, reduces interference and potentially expands your audience. This technology is opposed to other technologies such as CDs.
Speaking about methods of studying radio audiences, the following are distinguished:
Editorial mail analysis;
Questionnaire;
Interview;
Document analysis;
Observation;
Audiometry;
Music tests;
ORGANIZATION OF WORK AND OPERATION PROCEDURE FOR THE MAIN TYPES OF WIRED COMMUNICATION FACILITIES
The use of wired communications by police officers is regulated by the Law “On the Police” of the Russian Federation (Section 3, Article 11, Clause 29 “A police officer has the right to freely use for official purposes communications facilities belonging to enterprises, institutions, organizations, public associations and citizens”).
Operational wire communication is, first of all, a tool with the help of which the chief or duty officer of an internal affairs agency organizes the work of employees subordinate to him. Various ATS services can use this same concept. The peculiarity of this connection is that it allows you to quickly connect simultaneously not only with the group, but also with all subscribers connected to this system (circular communication) makes it possible to hold operational meetings using special loudspeaking devices. Such communication in internal affairs bodies is sometimes called intercom communication. It provides for the establishment of not only direct communication between the heads of duty officers of the internal affairs agency and the units and squads subordinate to them, but also feedback.
Using telephone communication, a police officer can obtain the necessary certificate from the address bureau, the traffic police and other institutions. To ensure unhindered receipt of certificates, such institutions have introduced passwords (tracks) that are usually valid for 24 hours.
Each employee of the internal affairs bodies, using telephone or telegraph communications, must adhere to the following rules:
Transmit information over the telephone in a clear and clear voice;
Conduct the text of the telephone message at such a speed that it would be possible to record it;
In case of poor hearing and difficult to pronounce words, they are transmitted by letter, and digital codes by numbers, for example: “object”: “Olga”, “hard sign”, “Elena”, “Konstantin”, “Tatyana”, and “672” - six, seven, two;
It is prohibited to transmit data containing official secrets.
Along with telephone communications, internal affairs bodies widely use telegraph communications.
Radio stations (r/st) are intended for organizing operational and official radiotelephone communications in the divisions of the Ministry of Internal Affairs of the Russian Federation. Οʜᴎ operate in the range of 140-174 MHz and allow you to establish simplex non-tuning and search-free communication on one of the fixed channels.
A distinctive feature of r/st is that they do not tie the operator to any place, as is the case when using wired communications, but allow him to move around calmly, ᴛ.ᴇ. stay mobile.
From the point of view of mechanical and climatic requirements, in accordance with GOST, r/st, depending on operating conditions, are divided into the following groups:
1. Stationary r/st- designed for work in heated above-ground and underground capital structures, as well as in the open air and in objects with high humidity. The distinctive features of this group of r/st are the following:
Powered from an industrial network, and in case of its loss there are backup power sources;
They have the highest output power compared to other types of r/st.
Mobile r/st- designed for installation on cars, motorcycles, boats, helicopters.
Portable, wearable, portable r/st- designed for work outdoors or in temporary structures, designed for long-term movement by people and all types of transport. A distinctive feature is that they are all powered by a rechargeable battery.
Wearable radios– portable intercoms operating in the ultrashort wavelength range have low radiation power. The systems belong to the class of personal mobile radio systems using technologies
- PMR (personal mobile radio);
- LPD (low power device).
Radio stations do not require licensing and are approved for use in Europe. They have found application among young people for communication with each other, their users are security services, they are popular among intelligence services, they can be useful for employees of small enterprises, on tourist trips, i.e. where clear line of sight for radio communications can be ensured.
Range
This type of intercom operates in the range from 446 MHz to 446.1 MHz (wavelength up to 1 m) for PMR. The change step of 6.25 kHz allows you to implement 8 different channels for conducting official conversations. In the case of LPD (low power device) devices, this is the 433 MHz range. In this range, up to 70 channels can be organized in 25 kHz steps. To ensure high sound quality, radio stations operate in frequency modulation broadcasting mode.
Specifications
The characteristics that determine the scope of application of these devices, in addition to the frequency range and number of channels, include:
- range;
- radiation power;
- type of shell;
- capacity of the battery.
The radiation power of devices of this class does not exceed 0.5 W, which is enough to organize communication at a distance of 6-12 km under direct visibility conditions. These figures can be significantly lower in real conditions if they are used in rough terrain, among a large number of buildings, in wooded areas, which are considered as obstacles to the propagation of radio waves.
The battery capacity, as a rule, is enough for half a day in active use mode. It is desirable that this element be replaceable and rechargeable.
The case, preferably, should be strong and waterproof.
Other characteristics: number of tones, display, speakerphone and headset expand the possibilities of using the device.
Manufacturing companies
The most popular manufacturers of this class of devices are:
- Alan;
- Kenwood;
- Hytera;
- Midland;
- Motorola and others.
The developments of these manufacturers are presented in the section “ Radio stations" Foxmart online store.
The proposed wearable radios are some kind of competition for mobile communications, both in terms of the cost of the devices and the cost of radio communications.
This review examines aspects of the emergence of radio, its development paths and modern standards.
Radio communication is another step in human evolution
Communication is one of the most important tools for the development of any biological species, thanks to which collective experience becomes the property of each individual. Living in a social group increases the competitiveness and survival of a species among others. If in the animal world various genetically endowed abilities are used for communication, for example, communication through smells or echo impulses, then humans mainly use the voice, which initially has very limited use. In search of superiority, people have always sought to extend communication beyond visual contact, inventing ever new forms of remote communication.
One of the greatest inventions that laid the foundation for such communications was radiotelegraphy. On May 7, 1895, mine officer A.S. Popov was able to demonstrate the transmission of electromagnetic pulses over a distance of up to 60 meters, which began the story radio communications. Of course, this invention gave a new impetus to human activity and laid the potential for the growth of scientific and technological progress for several centuries to come. Now the physics of the process data transmission through radio waves is used in all wireless technologies, such as, for example, mobile and satellite communications, Wi-Fi, Bluetooth, and many, many others.
Development radio communications entailed the evolution of human life. New fundamental research, inventions and experimental developments have made it possible to reduce the size of receivers and transmitters, combining them into one, to use various standards and protocols for data and voice transmission, and to integrate reliable control and indication systems into communication devices. As a result, as the energy efficiency of the transmitted signal increases, greater distances are covered.
Radio communication began to be introduced into the lives of people and machines everywhere. Efficiency and clear interaction during rescue operations, combat, and complex work can significantly reduce financial costs and increase the efficiency of ongoing actions. Millions of people have been saved thanks to radio communications, not to mention those who, with its help, create and transmit new information to the world around us, work, create and can be heard by those who really need it. Nowadays, an incredible amount of information is transmitted over wireless networks, and all of this has one main goal - communication should unite society!
At the heart of today's radio communications are the modern principles of constructing wireless networks and technologies for creating devices that satisfy these principles. With the development of electronics, first of all, the frequency spectrum of information transmission has expanded, and behind this the approach to radio communications itself has changed through the improvement of radio stations.
There are currently three forms of transceivers:
- Base radio station- is carried out mainly in a form factor for a 9-inch rack, includes a receiver-transmitter, controls and displays, an information input and display device, or a speaker for sound playback, although this is not a mandatory component for this type of radio station.
- Mobile radio station- designed for use on mobile objects, such as vehicles, ships, airplanes and others, equipped, just like the stationary one, with transceiver circuits, controls and displays, a push-to-talk switch, a speaker, external outputs for power supply and interfacing with antenna-feeder devices.
- - has minimal dimensions, convenient for operation with one hand, also - a receiver and transmitter, controls, information display, built-in battery, antenna and microphone with speaker. There are also subtypes of radio stations in the form of repeaters, but due to their low prevalence, their use is less noticeable.
Main differences between the three types radio stations among themselves - this is the power of the emitted signal, sensitivity, information output system, frequency range, intended purpose and form factor. If base station is designed to solve a wider range of tasks of communicating between a group of subscribers at a considerable distance from each other (using different communication channels), while a portable one, on the contrary, serves to cover a small area with communications and, as a rule, is an individual means of interaction with other subscribers.
They occupy a leading place in distribution among the population, and despite their relative imperfection, they have penetrated into many sectors of human activity, such as the service sector, construction, and production, thereby gaining significant potential for further development. However, at the moment there is no portable radios, operating in the short wave range 3-30 MHz. This advantage is only available to stationary and mobile radio stations, which is due to the physics of propagation of radio waves in this range and the complexity of implementing such a transceiver in the format portable radio.
The advantage of conventional radio communications over mobile, satellite and other types lies, first of all, in the absence of additional infrastructure. Due to the absence in the topology of unnecessary nodes - transmission lines, any additional elements subject to wear and tear, the depreciation of which must be paid additionally, as well as financial costs directly for the communication itself, radio communication remains the most accessible means of operational communication. The state actively regulates this segment, limiting the use of frequencies so as not to interfere with specialized services, and also to keep the entire radio frequency spectrum in a controlled state. Thus, there are three frequency ranges open to users:
- 27 MHz or the so-called CB (CB), used mainly on the roads for communication between motorists
- 433 MHz
- 446 MHz
protection
The radio station usually includes a transceiver, an antenna, a power source (a small battery for powering a portable radio station, a car battery for a car radio station) and operational documentation. In addition, radio stations may include chargers, control panels and various accessories, for example, a manipulator.
The radio station operates in two main modes: reception and transmission. When the radio station is operating in receive mode, the radio signal received by the antenna is sent through the antenna unit to a high-frequency amplifier (UHF). UHF is designed to amplify the received signal to a level at which high-quality demodulation is possible, as well as to ensure the necessary selectivity of the receiver. The demodulator converts the received high-frequency modulated signal into a low-frequency signal fed to the input of a low-frequency amplifier (LF), which amplifies it to a value that ensures normal operation of the final reproducing device - loudspeaker (Gr).
When the radio station is operating in transmit mode, sound signals received by the microphone (Mkf) are converted into electrical signals of audio frequency. The ULF amplifies these electrical signals to the level necessary for the operation of the modulator. The modulator transfers electrical audio signals to the carrier (operating) frequency of the transmitter (modulation of the carrier frequency of the transmitter with audio frequency signals). A power amplifier (PA) is designed to create a given level of power of high-frequency oscillations (transmitter output power) in the antenna.
The frequency synthesizer produces high-frequency signals necessary for the operation of the receiver and transmitter.
For modern VHF FM radio stations, the following main operating modes (reception and transmission) can be distinguished:
reception on duty;
reception with noise suppressor turned on;
reception with noise suppressor turned off;
tone call transmission;
message transmission.
Currently, fire protection uses both domestic radio stations (Viola, Sapphire, Granit, Signal, etc.) and radio stations from foreign companies (Motorola, Vertex, Standard, Kenwood, etc.).
All types of radio stations have several versions. For example, radio stations of the “Viola” type have the following versions: “Viola-Ts” - central; “Viola-AS” – subscriber landline; “Viola-AP” – subscriber station for installation on fire trucks; “Viola-AA” – subscriber for installation on operational vehicles; “Viola-L” – linear (repeater); “Viola-AM” – motorcycle subscription service; "Viola-N" - wearable