Tower Mount Amplifiers or TMA are used in Land Mobile Radio networks to improve the characteristics of the signal on the receiving end, allowing portables, mobile phones and handsets to achieve an increased range and capabilities. The setup can be as simple as an amplifier in a box or more complicated when it includes an interface for monitoring the transmission line or the signal itself. One thing is for sure, Combilent and TX RX™have your needs covered with 25+ years of experience in the most reliable and advanced TMA and other RF site equipment.
Why use a Tower Mount Amplifier?
When we take a look at a receiving system, we know that loss of signal before the first stage amplifier directly affects the noise figure. Reasons for signal loss and attuation include free space path loss, terrain and other obstructions. Even within the feedline itself the signal attenuates over distance.
Signal loss without noise reduction decreases the sensitivity of the system so this is something you want to prevent from happening.
A way to get more signal to the receiving antenna would be by increasing the power output of the transmitter (antenna with more gain or placing it higher). However, this does not preserve the noise ratio. That is what Tower Mount Amplifiers are for. They are used in receive systems to protect sensitivity, maintain signal vs. noise ratio, improve coverage and to eliminate losses caused by transmission line.
Please note that a Tower Mount Amplifier is not required when the loss between antenna and receiver is < 1,5 dB.
How to select the right Tower Mount Amplifier?
Simply said, a tower mount amplifier is that it is an amplifier in a waterproof box at the top of a radio site tower used to amplify received signals within the designated passband by a filter or preselector to keep unwanted signals out of the receive system.The TMA is mounted as near as possible to the receive antenna, keeping jumpers as short as possible. Any electronics mounted on the tower must be waterproof and wind and lightning protected. Although we refer to the equipment as a TMA, the system needs a control unit mounted in the equipment shelter at the base of the tower.
Land Mobile Radio systems come in 2 different versions: Standard or Diversity. Standard systems use a single receive antenna, feedline and single input on receivers. In case of diversity all equipment is doubled in the receive path.
The next decision is which type of control unit to use, which mostly depends on which type of receiver is used. Radio manufacturers build up their radios in two different methods: One that distributes the received signal to multipe receivers and one that distributes multiple signals to an individual receiver.
In the simplest case a control unit (CU) with built-in splitters and couplers for 1 or 2 outputs. The other option is a control and distribution unit (CD&U) with multiple outputs to multiple receivers.
Please note that the control units must match the TMA.
Why choose Combilent Group?
Combilent and TX RX™ are leaders in TMA since 1995. They have worked with all major LMR radio manufacturers to build life critical application radio infrastructure equipment. They continue to produce state-of-the-art TMA’s that incorporate survivability, connectivity and security for public safety systems.
New TMA’s are being designed on a new platform that will allow for future enhancements and expandability. This platform will allow for future innovation, taking current TMA models forward. The TMA’s of the future will be more flexible within the family platforms to meet customer needs. Based on current chip sets and on-board computers, future enhancements will be implemented without full redesign.
For example, the TX RX™ 44x family of products are designed with a single circuit board in the TMA, making them streamlined in construction and assembly. Lightning arrestors or surge protectors are being integrated into the design. Splitters, couplers and filters continue to get smaller, making the TMA on the tower and the control deck in the rack smaller, lighter, easier to install.
Contact your local partner Heynen for more questions regarding the solutions of Combilent Group. They will help you select the right TMA for your upcoming project.
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