VHF echo repeaters
The article briefly introduces readers to the principles of repeaters, gives an explanation of the need to use them. Describes one of the easiest ways to organize a radio network — building an echo repeater.
Designed for an erudite reader who is familiar with radio communications not only within the school curriculum.
Ever since the Ministry of Communications, then still the Soviet Union, has determined the procedure for acquiring and registering civilian radio communications, the era of radio citizens of our country has begun.
huge country. The first band allocated to personal radio communications was the so-called CB-band (from the Citizen Band) civilian band, sometimes also called the 27 MHz band. Now it works except taxi services, and several security structures. Low frequency of radiation does not allow building small-sized antennas, due to their inefficiency. Therefore, portable equipment for this range is practically not found.
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The next breakthrough step was the allocation of 433 MHz for civil communications, and later 446 MHz. The first is wider, has 69 frequency channels. The second is only eight. At such a frequency, it is actually possible to make an effective antenna, the size of which does not exceed, as a rule, 17 cm. Yes, and radio electronics have changed dramatically in the direction of reducing the size of the equipment. Now the best representatives of wearable radio stations are no larger than a mobile phone.
At present, such radio stations are sold in tons: in specialized stores, in sports and tourist departments, in mobile phone stores. A lot of equipment is being brought from China. I will not dwell on the nomenclature now, for this purpose we will devote a separate article. Radio communication has become mobile, convenient, affordable and free of charge ̶ such devices do not require registration.
The 433 MHz radio stations are used by security guards, installers, surveyors, builders, hunters, tourists, and even the most populous people. The short range of stations allows the same frequency resources to be used repeatedly. That is, several groups of people can simultaneously talk on the same channel. And at all without interfering with each other. As a rule, it suits everyone.
It happens that not all. Sometimes it is necessary to cover a large area, or even a whole city. And here the problems begin. From the ground level, radio stations rarely operate with a range greater than 3-5 kilometers, and even that is not always guaranteed. Moreover, the range of 433 MHz is generally characterized by sharp
fading signal (slightly turned and there is no connection). And here begins. Stationary antennas on the roofs of houses, automotive with magnets, directional "wave channels". With external antenna radio station
start to work far, but it turns out that the subscriber with the antenna on the roof is tied to his house. What is not ice. After all, it would be desirable that the small station on the belt was always heard by everyone and heard all. And here it comes to the aid of repeaters.
The principle of operation of the repeater is simple: take the signal and transmit it. In real-time repeaters, the signal is transmitted at the same time point at which it is received. So that the outgoing signal does not interfere with the incoming signal, a division of the frequencies of reception and transmission is used: the signal is transmitted at a frequency different from that on which it is received.
Located on a high building, hill, mountain peak, the repeater can provide high-quality radio coverage of a fairly large area. And from a small station it will be possible to communicate with all subscribers tuned to this channel. Even in motion.
Unlike the principle, the hardware implementation of a real-time repeater is a rather difficult technical task. Somehow I will talk about the creation of such a device.
Often there is no possibility to build a full-fledged repeater. The reasons may be different ̶ high cost of equipment, lack of additional frequency resources (remember, you need to have two frequencies), the inability to install bulky antenna equipment and others. A reliable connection requires blood from the nose. In such cases, a device called an echo-repeater comes to the rescue. It is often called a simplex repeater. Slang names ̶ turnip, echo turnip, parrot are also used in everyday life.
In principle, the echo-repeater differs from the real-time transponder in that the reception and transmission of a signal do not occur simultaneously, but in turn. Reception first, then transmission. In this case, the frequency of reception and transmission can not be divided.
Consider the components of the echo repeater and the logic of its work. The signal received by the antenna over the antenna cable (in the communication technology called feeder) is fed to the input of a radio station tuned to a specific frequency. At this moment the digital tape recorder turns on and records what is coming from the air. As soon as the signal disappears, the radio station switches to transmission, and the tape recorder is in playback mode of the recorded message. For the subscriber, it looks like a replay of what he just said on the air.
The undoubted disadvantages of this mode are the complication of communication, the lengthening of the negotiation time by half, the limited recording time of the tape recorder. However, with a certain skill, repeats even help
̶ it becomes clear what quality the signal reached the repeater. In addition, the construction of an echo repeater is simple and fairly affordable.
Thus, a group of people united by a common interest, taking some inconvenience in conducting radio communications, can quickly build an echo repeater and start using it. Of course, it is necessary to take into account that the legality of such devaysin has not yet been determined at all, that is, they are neither allowed nor prohibited. In some cases, supervisors simply turn a blind eye to such devices, if at all they find out about them.
Now about the hardware of the device. In theory, the repeater must have an external antenna, a reliable station and high-quality power supply. As a "brain" that turns a normal radio station into a repeater, you can apply both hardware and software solutions. The first are built-in ITEC 806-25 boards, ER-310 external units and self-made audio recording chips. The second is a special program running on a PC. In a pinch, for example, to support a tourist group with communication, you can simply hang a portable station on a tall tree. The layout options can be many, it all depends on the skill of the installer.
Consider the simplest version of the echo repeater. It has been tested many times in real conditions and has proven its reliability.
An Icom F4-GT device with a standard battery and an ITEC 806-25 board were taken as a radio station. The board is inserted into a special slot located in the depths of the station. It is activated using special settings in the station itself. Everything! You can use it with a standard antenna, or you can use an adapter and connect an external, for example, quarter-wave pin. It was in this configuration that the echo-repeater on Mount Hez provided a group of tourists on Arakhley with a connection to Chita (Trans-Baikal Territory). The cost of this kit is approximately 12,000 rubles.
Now echo-repeaters work in various areas of life, providing a reliable connection to a large number of people, being sometimes the only means of communication. But according to the author, they are still becoming archaic, and real-time repeaters are gradually being supplanted. About the construction of one of them ̶ in the following articles.
Photos from trips related to the installation of similar repeaters in the Siberian taiga can be viewed here . You can also read some of the details that are not reflected in this post and familiarize yourself with our other DIY projects.
Designed for an erudite reader who is familiar with radio communications not only within the school curriculum.
Ever since the Ministry of Communications, then still the Soviet Union, has determined the procedure for acquiring and registering civilian radio communications, the era of radio citizens of our country has begun.
huge country. The first band allocated to personal radio communications was the so-called CB-band (from the Citizen Band) civilian band, sometimes also called the 27 MHz band. Now it works except taxi services, and several security structures. Low frequency of radiation does not allow building small-sized antennas, due to their inefficiency. Therefore, portable equipment for this range is practically not found.
')
The next breakthrough step was the allocation of 433 MHz for civil communications, and later 446 MHz. The first is wider, has 69 frequency channels. The second is only eight. At such a frequency, it is actually possible to make an effective antenna, the size of which does not exceed, as a rule, 17 cm. Yes, and radio electronics have changed dramatically in the direction of reducing the size of the equipment. Now the best representatives of wearable radio stations are no larger than a mobile phone.
At present, such radio stations are sold in tons: in specialized stores, in sports and tourist departments, in mobile phone stores. A lot of equipment is being brought from China. I will not dwell on the nomenclature now, for this purpose we will devote a separate article. Radio communication has become mobile, convenient, affordable and free of charge ̶ such devices do not require registration.
The 433 MHz radio stations are used by security guards, installers, surveyors, builders, hunters, tourists, and even the most populous people. The short range of stations allows the same frequency resources to be used repeatedly. That is, several groups of people can simultaneously talk on the same channel. And at all without interfering with each other. As a rule, it suits everyone.
It happens that not all. Sometimes it is necessary to cover a large area, or even a whole city. And here the problems begin. From the ground level, radio stations rarely operate with a range greater than 3-5 kilometers, and even that is not always guaranteed. Moreover, the range of 433 MHz is generally characterized by sharp
fading signal (slightly turned and there is no connection). And here begins. Stationary antennas on the roofs of houses, automotive with magnets, directional "wave channels". With external antenna radio station
start to work far, but it turns out that the subscriber with the antenna on the roof is tied to his house. What is not ice. After all, it would be desirable that the small station on the belt was always heard by everyone and heard all. And here it comes to the aid of repeaters.
The principle of operation of the repeater is simple: take the signal and transmit it. In real-time repeaters, the signal is transmitted at the same time point at which it is received. So that the outgoing signal does not interfere with the incoming signal, a division of the frequencies of reception and transmission is used: the signal is transmitted at a frequency different from that on which it is received.
Located on a high building, hill, mountain peak, the repeater can provide high-quality radio coverage of a fairly large area. And from a small station it will be possible to communicate with all subscribers tuned to this channel. Even in motion.
Unlike the principle, the hardware implementation of a real-time repeater is a rather difficult technical task. Somehow I will talk about the creation of such a device.
Often there is no possibility to build a full-fledged repeater. The reasons may be different ̶ high cost of equipment, lack of additional frequency resources (remember, you need to have two frequencies), the inability to install bulky antenna equipment and others. A reliable connection requires blood from the nose. In such cases, a device called an echo-repeater comes to the rescue. It is often called a simplex repeater. Slang names ̶ turnip, echo turnip, parrot are also used in everyday life.
In principle, the echo-repeater differs from the real-time transponder in that the reception and transmission of a signal do not occur simultaneously, but in turn. Reception first, then transmission. In this case, the frequency of reception and transmission can not be divided.
Consider the components of the echo repeater and the logic of its work. The signal received by the antenna over the antenna cable (in the communication technology called feeder) is fed to the input of a radio station tuned to a specific frequency. At this moment the digital tape recorder turns on and records what is coming from the air. As soon as the signal disappears, the radio station switches to transmission, and the tape recorder is in playback mode of the recorded message. For the subscriber, it looks like a replay of what he just said on the air.
The undoubted disadvantages of this mode are the complication of communication, the lengthening of the negotiation time by half, the limited recording time of the tape recorder. However, with a certain skill, repeats even help
̶ it becomes clear what quality the signal reached the repeater. In addition, the construction of an echo repeater is simple and fairly affordable.
Thus, a group of people united by a common interest, taking some inconvenience in conducting radio communications, can quickly build an echo repeater and start using it. Of course, it is necessary to take into account that the legality of such devaysin has not yet been determined at all, that is, they are neither allowed nor prohibited. In some cases, supervisors simply turn a blind eye to such devices, if at all they find out about them.
Now about the hardware of the device. In theory, the repeater must have an external antenna, a reliable station and high-quality power supply. As a "brain" that turns a normal radio station into a repeater, you can apply both hardware and software solutions. The first are built-in ITEC 806-25 boards, ER-310 external units and self-made audio recording chips. The second is a special program running on a PC. In a pinch, for example, to support a tourist group with communication, you can simply hang a portable station on a tall tree. The layout options can be many, it all depends on the skill of the installer.
Consider the simplest version of the echo repeater. It has been tested many times in real conditions and has proven its reliability.
An Icom F4-GT device with a standard battery and an ITEC 806-25 board were taken as a radio station. The board is inserted into a special slot located in the depths of the station. It is activated using special settings in the station itself. Everything! You can use it with a standard antenna, or you can use an adapter and connect an external, for example, quarter-wave pin. It was in this configuration that the echo-repeater on Mount Hez provided a group of tourists on Arakhley with a connection to Chita (Trans-Baikal Territory). The cost of this kit is approximately 12,000 rubles.
Now echo-repeaters work in various areas of life, providing a reliable connection to a large number of people, being sometimes the only means of communication. But according to the author, they are still becoming archaic, and real-time repeaters are gradually being supplanted. About the construction of one of them ̶ in the following articles.
Photos from trips related to the installation of similar repeaters in the Siberian taiga can be viewed here . You can also read some of the details that are not reflected in this post and familiarize yourself with our other DIY projects.
Source: https://habr.com/ru/post/130074/
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