Repeater: how to choose the right one?


A repeater is a cellular amplifier that is designed to amplify the signal and mobile Internet of any cellular operator: Megafon, MTS, Beeline, Tele2, Yota.

Repeaters have a number of characteristics that you should be aware of when choosing. First of all, it is the operating frequency range, gain and maximum output power.

  • one . Frequency

Currently, mobile operators in the Russian Federation use 5 frequency bands, called Band:

  • Band 1 — 2100 MHz (3G standard)
  • Band 3 — 1800 MHz (standard 2G, LTE)
  • Band 7, 38 — 2600 MHz (standard 4G, LTE, LTE TTD)
  • Band 8 — 900 MHz (GSM standard 2G, 3G)
  • Band 20 800 MHz (LTE standard)

Band 38 uses the same frequencies as Band 7, but a completely different data transmission organization — TDD (Time Division Duplex). Reception and transmission are carried out on the same frequency and are separated only by time intervals. Unfortunately, introducing any error into the synchronization of this channel leads to a signal loss, so it is not possible to amplify the Band 38 signal with a repeater.

Each frequency range has its own minimum power level at which communication will be maintained.

Sample values ​​are given below:

  • 900MHz — 88dBm
  • 1800 MHz — 93dBm
  • 2100MHz — 98dBm
  • 2600MHz — 102dBm

A GSM repeater can amplify a cellular signal in one, two or more bands, but then the cost increases in direct proportion to the number of amplified bands.

Therefore, system planning should begin with determining the frequencies that should be amplified. To ensure high-quality communication, it is not at all necessary to amplify all frequencies. All subscriber devices have certain priorities and it is enough to amplify only those frequencies that are necessary in a particular case.

Let’s consider in more detail. All modern cell phones are designed to work on the Internet, so they have the appropriate preferences in choosing frequencies: 4G (LTE) -> 3G -> 2G.

In practice, the following picture of priorities can be presented:

LTE (4G)

  • 2600 MHz
  • 1800 MHz
  • 800 MHz

3G

  • 2100 MHz
  • 900 MHz

2G

  • 1800 MHz
  • 900 MHz

LTE (4G) in the Russian Federation is not yet used to transmit voice communications, but the connection of mobile devices to the operator’s tower primarily occurs in this network, regardless of frequency. Coordination of the parameters of an incoming or outgoing call also takes place in the 4G network, and for a conversation, the phone switches to another available 3G or 2G cellular network, the choice of which is determined by the base station. If you make a mistake in choosing an amplifier, the result may not meet expectations.

We recommend paying attention to 4G repeaters in our store:

Let’s look at examples:

Example 1. In the house, near the windows on the mobile phone, 1 bar of the 3G signal appears, but there is no connection. We installed a 900 MHz voice amplification system, the signal did not appear or was constantly interrupted. This happens because the smartphone connects to weak 3G as a priority, and only if the signal disappears completely switches to the 900 MHz band. At the moment of frequency switching, as a rule, the current connection is also interrupted, which means that the 3G signal (2100) should be strengthened.

Example 2. An amplification kit with a 3G repeater (2100) was installed in the office. The connection works satisfactorily, but often SMS messages appear with the text <>. Most likely there is a weak 4G signal in the room, the connection is established in this mode and only after coordination with the tower of the cellular operator it switches to the 3G signal. In this case, it may be worth adding the GSM 1800 band to the amplification system if a 4G signal is present at these frequencies.

As we can see from the examples presented, smartphones always tend to connect to a higher speed network, regardless of the signal strength, as long as it can distinguish it in the background radio noise. When choosing an amplifier, one must take into account this feature of modern cellular communications and amplify the desired frequencies.

The examples described above did not take into account the fact that different mobile operators in the same place can operate in different ranges. Then the selection of a repeater is impossible without serious hardware radio intelligence of the territory and it is better to entrust this choice to a competent specialist.

  • 2. Gain

Any GSM, 3G or 4G repeater amplifies a weak signal and this parameter differs depending on the model. Based on the parameters of the base station, a cellular signal amplifier is selected, the gain of which will be sufficient to solve the problem. In practice, there are cases when the input signal level is too high and the repeater is overloaded, not being able to fully realize its amplification potential. In this case, Titan amplifiers have gain control, manual and/or automatic.

  • 3 . Output power

To cover large areas with communication, more signal power is required than to solve typical problems, and such a parameter as the maximum output power of the repeater becomes relevant. No matter what signal is initially fed into the signal amplifier, it cannot deliver more power than its electronic output circuits allow. So, if you apply a signal of -35 dBm to a powerful amplifier with parameters of 65 dB / 17 dBm, you will not be able to get 30 dBm at the output, since the output transistors are simply not capable of delivering such a signal level, and the automation will adjust the gain to the desired level so as not to exceed the allowable 17 dBm. If more power is required to provide communication, a more powerful GSM repeater should be selected or a suitable linear amplifier should be added to the system.

  • four . Registration — Certification

According to Russian legislation, low-power transmitting devices, the power of which does not exceed the radiation strength of subscriber devices, are allowed for use without registration, if these devices do not affect the operation of the base tower.

When choosing repeaters for a cellular communication amplification system, one should be guided not only by technical characteristics and price, but also by the possible consequences of its use. An incorrectly installed amplifier or an unconfigured system can greatly interfere with the operation of operators’ base stations, which may eventually attract the attention of Roskomnadzor.

If the device is certified on the territory of the Russian Federation, has a certificate in the certification system in the field of communications, you will simply be asked to turn it off and in the future, you will have to use the services of a specialist who will find out the cause of the interference and configure the system. If the device does not have a certificate, your actions will be regarded as malicious, with corresponding consequences — equipment seizure, a fine, etc.

  • 5 . Effects of Cellular Booster System on Health

According to the sanitary norms and rules of the Russian Federation, the intensity of the electromagnetic field in the microwave range (0.3-300 GHz) should not exceed 0.1 W / sq.m.

The radiation power of antennas of a cellular communication amplification system usually does not exceed 30 mW, which is noticeably lower than the permissible limit, but sufficient for reliable signal reception by subscriber devices.

For comparison, the radiation power of a WiFi router familiar to us is from 100 to 200 mW. We expose ourselves to a much greater danger by staying close to a cell phone in a zone of poor signal reception, because in the network search mode, the phone can emit up to 2 W, which is more than 60 times more than the radiation of the repeater antenna. It is also important that for such radiation the phone needs energy and in this mode it depletes its battery in a matter of hours.

  • 6. Conclusion

Let’s say that in the proposed location of the external antenna, the program on the smartphone showed a signal level of -73 dBm. A directional Yagi antenna will add 12-14 dB to us. The repeater will increase the signal by 60-80 dB and the internal antenna will add another 2-5 dB. In total, at the output from the internal antenna, we will get 1-25 dBm. Depending on the frequency of the signal, an output power of 4-7 dBm is sufficient to provide high-quality communication for a small country house.

Now, knowing the frequency we need, the signal level and the characteristics of the equipment, we can calculate the required power of the amplification system and choose the right repeater or choose a kit in our store:

Оставьте комментарий

Ваш адрес email не будет опубликован.