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A cellular repeater (also known as cell phone signal booster or cell phone signal amplifier) is a type of bi-directional amplifier used to improve cell phone reception. [citation needed] A cellular repeater system commonly consists of a donor antenna that receives and transmits signal from nearby cell towers, coaxial cables, a signal amplifier, and an indoor rebroadcast antenna.
A well-known practical application of diversity reception is in wireless microphones, and in similar electronic devices such as wireless guitar systems. A wireless microphone with a non-diversity receiver (a receiver having only one antenna) is prone to random drop-outs, fades, noise , or other interference , especially if the transmitter (the ...
However, NTT did not initially commercialize the system; the early launch was motivated by an effort to understand a practical cellular system rather than by an interest to profit from it. [8] [9] In 1981, the Nordic Mobile Telephone system was created as the first network to cover an entire country. The network was released in 1981 in Sweden ...
In a properly designed active system, no reengineering or rebalancing of the original system is required when the system is expanded. Optical fiber systems can provide coverage in areas up to 2 km from the signal source making them ideal for campus environments. An active system will always be more expensive than a passive system. [1]
For very low-power systems, such as mobile phones, signal strength is usually expressed in dB-microvolts per metre (dBμV/m) or in decibels above a reference level of one milliwatt . In broadcasting terminology, 1 mV/m is 1000 μV/m or 60 dBμ (often written dBu). Examples. 100 dBμ or 100 mV/m: blanketing interference may occur on some receivers
In the case of wireless transmission, it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) and/or multiple receiving antennas (reception diversity). In the latter case, a diversity combining technique is applied before further signal processing takes place.
This can be useful in locations with poor cell coverage where some other form of internet access is available, [2] especially at the home or office. The system offers seamless handoff, so the user can move from cell to Wi-Fi and back again with the same invisibility that the cell network offers when moving from tower to tower. [3]
Diversity combining, or voting, in two-way radio systems is a method for improving talk-back range from walkie-talkie and vehicular mobile radios. [5] System diagram for a water utility two-way radio system with voting. Water utility equipment sites. The receivers are connected to a device referred to as a voting comparator or voter.