The term two-way radio is a technology that allows individuals to keep in contact with each other using radio waves. Each user is given a radio unit which sends and receives audio and data sent over the radio waves. A two-way radio system can be as simple as two radios connecting directly to each other, or as complex as an encrypted network that covers an entire country.
You might know two-way radio by the name “walkie talkie”, which is the term used for unlicensed radio devices. The term two-way radio covers the unlicensed equipment and the licensed equipment.
How Does Two-Way Radio Work?
Two-way radio works by converting audio to radio waves that are then transmitted through the air. These radio waves are received by other radios which convert the radio waves back to audio.
The conversion to radio waves can be sent as an analogue signal or a digital signal, with digital transmission being the more modern technology. With digital radio, it is possible to send other types of data over the radio waves such as text messages and status updates. It is even possible to encrypt data when using digital radio to stop people using your network without your permission.
What Frequencies Do Two-Way Radio Use?
Two-way radio works between the frequencies of 30 MHz (Megahertz) and 1000 MHz, also known as 1 GHz (Gigahertz). This range of two-way frequencies is divided into two categories:
- Very High Frequency (VHF) - Range between 30 MHz and 300 MHz
- Ultra-High Frequency (UHF) - Range between 300 MHz and 1 GHz.
From these ranges, most two-way radio equipment falls into the 136 - 174 MHz and 403 - 527 MHz parts of the spectrum and must be licensed. Each country has its own organization tasked with allocating licenses, but some two-way radio frequencies are allocated as license-free (for instance, PMR446 at 446MHz)
Do I Need A Two-Way Radio License?It depends on what type of system you require. If you only need a small number of radios in a remote location over a small area then you might be able to use unlicensed radios (such as PMR446). If you require a larger area of coverage, require secure communications, have multiple teams who need to communicate separately, or are operating in a built-up area such as a town center then you will need to buy licensed equipment.
Radio licensing is a complex topic, but through Motorola Solutions extensive partner network, we can pair you with a local expert to help you find the solution that is right for you while aiding you through the licensing process for your region.
Can Two-Way Radio From Different Manufacturers Communicate With Each Other?Yes, and no; some functions are common across all manufacturers because they are defined by radio standards such as DMR. While basic functionality will work between systems (such as voice transmission), you might want to use features outside those defined by the standards.
Before deciding what equipment to purchase to extend your system, you should check what features you are already using and find out if any are unique to your current equipment. If they are not unique, you should still check with the manufacturers to ensure that interoperability testing has been performed between the systems.
What Distance Do Two-Way Radios Work Over?The answer to this question depends on the equipment you are using and the infrastructure you have installed around it. As an example, the International Space Station, orbiting at an altitude of 408 KM uses two-way radio to communicate with the earth, but there are very few obstructions between the station and the antennas so the signal is easily received. In comparison, an unlicensed radio operating inside a building may only work for around 100 meters.
Two-way radio systems can have infrastructure installed around the area of coverage which makes the range of the system only limited by the amount of equipment you can afford to install. Two-way radio repeaters can extend signals over a large area and can be joined together through other means such as the internet to create connected pockets of coverage (such as a multi-site university campus).
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