Frequently Asked Questions (FAQ)

What is the coverage scope of the repeaters?

It is a question often asked which is not possible to answer without knowing a minimum of data on the implantation conditions of the repeater. The most important is the field strength received at the external antenna.

For GSM, if the signal is low (<-70 dBm), the area covered will be only a few meters or almost zero. With a correct field (approximately -50 dBm), coverage may reach several hundreds of m2.

For applications in UHF band, microrepeaters can cover several hundred m2 field levels captured in the order of -60 dBm. In case the received fields are weaker or surfaces to cover are larger, the use of high power repeaters is recommended.

In any case, we can advise you according to the size and position of your installation.

 

What is the sensitivity of a repeater?

The sensitivity of a repeater is the smallest signal value it can retransmit while maintaining a signal/noise ratio sufficient for proper operation of the signal.

It is directly linked to the concept of noise figure and bandwidth of the signal used.

In the case of a GSM signal, a conventional repeater has a sensitivity of around -110 dBm. In the case of a TETRA or TETRAPOL repeater, this value is about -120 dBm.

Because the gain of a repeater can not exceed ~ 90dB, the sensitivity of a repeater is rarely an important parameter because the signals it has to process have a value typically greater than -80 dBm.

 

What TETRA & TETRAPOL mean? What are the difference?

Both names refer to standards used in radio communications. TETRA is a global standard that runs on a TDMA in which a frequency may carry multiple radio channels that are temporally multiplexed.

TETRAPOL is a standard that was developed by EADS (formerly Matra Communications) which is used across European countries but more particularly in France by firefighters and police. This standard is based on the use of a frequency for a single radio channel.

These two types of radio standards have their advantages and disadvantages (speed + important for TETRA, greater scope for TETRAPOL), but currently, worldwide, TETRA is the most used.

   

What is a repeater?

A repeater is a bidirectional amplifier designed firstly to amplify the signals from the base station (relay) to the mobile and secondly to amplify the signals from the mobile towards the base station. Direction "base station to relay" is described as downlink (downlink in English), the other direction (mobile to relay broadcast) is called uplink (uplink in English). Uplink and downlink frequencies are generally differentiated and the difference between these two frequencies is called "duplex spacing".

   

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