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Technical Information > How Do Two Way Radio Repeaters Work?

How Do Two Way Radio Repeaters Work?

What is a Radio Repeater?

In general, radio waves Digital or Analog travel in straight lines, this is known as “line of sight”. They can go around and through some things things but even things like trees, can drastically affect the strength and clarity of the signal.  This causes problems when you’re operating a radio system in a built-up, hilly or mountainous offroad area.  Sometimes, even on flatter terrain, the sheer distance between the transmitting radio and the receiving radio weakens the signal to an unacceptable quality, or the signal may be lost altogether.

So how do two way radio systems work over greater distances, or when there isn’t a clear line of sight between the operators? Radio repeaters are the solution.

you need a Motorola digital repeater

How does a radio repeater work

A Motorola Digital radio repeater simultaneously receives a radio signal and re-transmits it at a higher power so it can cover greater distances. This enables communication between radio users where obstructions, hills, trees, or distance are a problem.

Repeater stations usually have their antennas mounted high up on top of a tall building or hill above the trees etc. The positioning of the repeater is critical for good operation.

Carefully chose a location which is ideally central to your area that you are looking to cover, so their range is much greater. The boosted signal from a repeater can also improve the clarity of the transmission.

Motorola repeater add it all works ok

Repeaters receive radio waves on one frequency, called the “input” frequency, and then re-transmit the information on its “output” frequency. Therefore if you use two way radios with a radio repeater service, they will be programmed to transmit on the repeater’s input frequency and receive on its output frequency. Our experts can help you program that in to your radios.

Radio repeater systems are widely used by commercial businesses that operate over large or built-up areas, emergency services, public transport and amateur radio enthusiasts. They are also used on large sites such as a warehouse or hotel as this type of building can be difficult to cover due to its structure.

Motorola’s latest generation of digital repeaters uses the very latest technology and offer outstanding performance. Both the DR3000 and the SLR100 are available in VHF or UHF.

Contact us for more information and expert advice about repeaters for mobile or portable radios. 

Installing a Radio Repeater

Installation of two-way radios can range from somewhat complex to incredibly easy, depending on the configuration. High-power repeaters usually require two antennas, one for receiving and one for transmitting. The typical repeater for shorter distances, however, requires only one repeater antenna, which transmits and receives to two-way radios, usually hand-held devices. These are relatively simple.

External Antenna for Repeater

In two antenna installations, placement of the antennas is critical to prevent the receiving antenna from taking in energy from the transmitting antenna. The antennas are placed at different heights and a minimum of 2.5meters apart to minimize this interference.

To make installation easier, some repeaters have what’s called a built-in or add-on duplexer that allows the unit to transmit and receive on the same antenna at the same time. Essentially, the duplexer contains circuits that isolate the transmitter from the receiver. This way, the transmitters radio frequency doesn’t damage the receiver.

Regardless of the use of one or two antennas, a high-performance antenna is usually positioned at the coverage areas tallest point with the repeater. When strategically located at the most elevated point of a communication site, height greatly enhances the overall operation and performance of a repeaters signals, however excesivly long antenna leads will resault in greater loss than height gains, mount repeater so lead runs can be kept to a minimum. Antennas are preferably mounted with line-of-sight to all radio users.

Before installing a repeater, a site survey and radio coverage test are vital to its proper performance. This type of testing and level of planning becomes helpful as it saves time, money and resources. Investing in these recommended practices on the front end can essentially eliminate poor equipment performance and ineffective communication later, and possibly when it matters most.

Repeater Site Survey

Conducting a radio coverage site survey and finding the right installation location is one of the most important steps in setting up a radio repeater. Positioning of the antenna is critical to the overall success of the radio communication that is depending on the repeater. Finding a prime spot is essential.

Choosing a place for a repeater should be relatively easy. Line of sight is very important in radio communication. Trees, electrical towers, hillsides and other dense structures or objects can impede signal transmission. That’s not to say you must have line of sight. Just know that if you don’t your range will be reduced.

Not sure if you need a repeater? Contact Harris Race Radios experts on 64 21 682912 for free advice about getting the best signal on your two way radio system.

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