The use of radio communications to support humanitarian operations is generally considered an acceptable and legal practice in most countries of operation, however there are a few countries where radio communication may be banned or heavily constrained. Even if the use or of radio communications is considered legal, there will almost certainly be a national registration process where owners and operators of radio networks will need to apply for and obtain licenses for lawful use.
Constraints of Radio Communications
Distances – Depending on the type of radio, the size of the antenna and the energy source behind the radio, radios may only be able to communicate up to a few kilometres. In urban environments or places with dense vegetation, hills or canyons, this distance may be even less. Agencies or personnel utilising radio communications should have an understanding of the capabilities of the devices they are utilising, and ideally the IT, security and logistics personnel of a humanitarian organisation should have a sense of what geographic areas might be supported by the type of equipment in use.
Dead Spots – even Even in areas of overlapping radio coverage, there may still be dead spots, brought on by structures, hills, vehicles, or other materials that might block radio signals. When conducting operations, personnel should be aware of that dead spots may occur, and may need to periodically conduct a radio check to determine if radio is still usable in a specific stationary location.
Interference – Radio signals can and will interact with other electronic equipment. Household appliances such as microwave ovens or other equipment using radio waves such as traditional broadcast TV might impact or impair radio operation. Objects with large electrical charges also produce electromagnetic fields that might impact radios as well – telephone power lines, large transformer boxes, and even large generators may affect a signal. Avoid installing or using radio equipment under or near power lines or radio towers used by other companies or agencies.
Mobile Radio Unit
Mobile Radio/handset units "transceivers" – radio equipment that can both send and receive a signal. Some radio units are completely self-contained and come with batteries to power the device for several hours or a full day, while others require external power sources, like those mounted to vehicles. Additionally radios can be defined as mobile – radios that travel around with persons or vehicles, or as stationary – radios that are permanently connected to a ground station.
Vehicle Mounted Radio
Point to Point – when a radio units communicate with each other directly without a base station or a repeater between them, they are conducting point to point communication. Depending on the type of radio and the frequency used, point to point communication may be very limited. Most handheld radios that run off of batteries don’t have the energy output or large enough antennas to push signals very far, and will be limited to hundreds of meters of point to point communication.
Networked/Relayed Communication – When two radio units communicate using at least one intermediary device, such as a base station, that communication is not point to point, and can be called a networked or relayed connection.
- Antenna Gain - The factor by which input power to the antenna will be multiplied to provide higher output power. Higher output power results in greater broadcast distance and signal strength.
- Antenna Bandwidth - The range of frequencies over which antenna operates satisfactorily. The difference between highest and lowest frequency points is referred as antenna bandwidth.
- Antenna Efficiency - The ratio of power radiated or power dissipated in the antenna structure to the power input to the antenna. Higher antenna efficiency means good amount of more power is radiated into the three dimensional space and less is the power losses lost within antenna.
- Antenna Wavelength - If wavelength is the distance a radio frequency wave travels during one cycle period, the antenna wavelength is the size of the antenna based on the wavelength. The longer the wavelength, the longer the antenna.
- Antenna Directivity - It is the ability of the antenna to focus EM waves in particular direction for transmission and reception.
The concept of duplex communication is an oversimplification of how most mobile radios work, however. A true duplex configuration requires two more independent antennas, each broadcasting on a slightly different frequency so that signals can be broadcast and received simultaneously. Simultaneous broadcasts would in effect allow users to both talk and hear voice commands at the same time, not to too dissimilar to modern phones.
The act of intentionally calling from one radio to another to ensure proper connectivity is known as a “radio check.” The need and frequency of radio checks depend on the security constraints of the organisation and the operating contexts. In any context, it is advisable to conduct regular checks to ensure operational continuity. Unlike modern mobile phones, many radios generally cannot identify signal strength, and users may not know if they are within communication range or not.
- Updating a manual tracking system indicating where vehicles are.
- Conducting daily radio checks.
- Sending out updates or emergency signals.
When conducting daily radio checks, radio operators should have a list of all personnel and call signs, and should keep a running daily tally of who may be in the area and who is responding to radio checks. While conducting routine checks on vehicles in movement, radio operators may be expected to update movement boards or even record movements on a map. The rules and requirements for both routine checks and movement monitoring will depend on the needs of the agency and the security context.
Depending on the contexts, users may be required to keep a radio near them and on at all times. To facilitate this, all users should have access to:
- Spare batteries.
- Charging equipment.
- Carrying equipment (cases, clips).
- Maintenance instructions.
The act of programming a radio might include pre-defining:
- Frequencies of operation.
- Communications channels.
- Radio specific IDs for direct calling.
- Password protection.
- Encryption or other special functions.
Not all radios have the same functions, and even different models of radio coming from the same manufacturer might have a different set of functions. As an example, not all radios units will have the ability to establish direct calling links or offer higher levels of security such as encryption – these are usually specified at the time of procurement.
At a bare minimum, radios used by humanitarian agencies should have programmable frequencies and multiple communications channels:
- The specific frequency of use is usually defined by state or national authorities, and use of unauthorised frequencies may result in punishment. Different types of radio equipment have a defined spectrum in which they can operate, but within this band there are numerous specific frequencies that multiple parties may use at the same time without interfering with each other.
- The communications channels used are usually defined by the humanitarian agency. It is very common to define channels numerically (1, 2, 3…) however some agencies may wish to use specific names such as “calling channel” and “emergency channel” for clarity sake. A properly programmed radio will display the pre-defined channel name on the readout screen, if available. In instances where multiple agencies are using the same network, the channel names/numbers are usually defined by the lead agency controlling the network.
Programming radio equipment can be a very very complicated task. Different manufacturers of radio equipment have different proprietary hardware and software packages to enable programming, and there is no one single method of programming all radios.