Why communication needs laws
A radio wave spreads in all directions and does not stop at a border. If two transmitters use the same frequency near each other, the receiver cannot tell them apart. This is called interference. The usable range of frequencies, the radio spectrum, is limited, like land in a city. So we need rules for who may use it, where, how strongly and for what.
The rules work at four levels: national radio law, international telecommunication law, law for wired networks and maritime communication law.
Radio Act and related national laws
Every country has a law about radio. Examples: the Radio Act in Japan; the Telecommunications Act, 2023 in India (earlier the Indian Telegraph Act and the Wireless Telegraphy Act); the Communications Act in the USA. A government regulator carries it out.
What the law usually says:
- Licence: a station may not transmit without a licence (a few low-power devices like Wi-Fi are free to use under limits). The licence names the frequency, power, place and purpose.
- Operator certificate: some work needs a trained, certified person, such as a ship radio operator or an amateur radio operator (who must pass an exam).
- Equipment standards: radios must be tested and approved so that they stay on their frequency and do not leak into others.
- Secrecy and honesty: messages must not be tapped or misused; false messages and deliberate jamming are offences.
- Inspection and penalty: the regulator can inspect stations, switch off illegal ones and impose fines or jail.
International telecommunication laws (ITU)
Waves, ships, aircraft and satellites cross borders, so countries also agree on shared rules. The body is the International Telecommunication Union (ITU), a United Nations agency (started in 1865 for the telegraph; headquarters in Geneva).
- Radio Regulations: an international treaty. It splits the spectrum into bands and gives each band to services: broadcasting, mobile phones, aircraft, ships, satellites, amateurs and so on. The world is split into three regions so that some bands can differ.
- World Radiocommunication Conferences meet every few years to update the treaty.
- Satellite orbits and frequencies are coordinated so that satellites do not disturb each other.
- Call signs: each country is given prefix letters, so a station's name shows where it belongs.
Countries then follow the ITU table in their own national law. The same frequency can be used again in places far apart, because a signal fades with distance.
Wired telecommunication laws
Telephone lines, optical fibre, cable networks and the internet backbone are wired (or cable) systems. Their laws cover:
- Licences for operators who run networks and sell services.
- Right of way: permission to dig roads, hang cables on poles and lay them under the sea or through buildings, with safety rules for the work.
- Interconnection: networks must connect to each other, so a call from one company reaches another.
- Customer protection: fair prices, quality of service, privacy of calls and data.
- Protection of cables: cutting or damaging a cable on purpose is a crime. Undersea cables carry most international internet traffic and are protected by international agreements, such as the old 1884 cable convention and the UN Convention on the Law of the Sea.
Maritime communication laws
A ship far from land can reach help only by radio, so the sea has its own strict rules. They come from the SOLAS convention (Safety of Life at Sea) and the ITU Radio Regulations. The system is called the GMDSS (Global Maritime Distress and Safety System).
- Equipment: every large ship must carry VHF and other radios, a satellite beacon (EPIRB, which sends a 406 MHz signal to satellites with the ship's identity and position), a radar transponder and a weather and safety message receiver (NAVTEX).
- Distress alert: pressing one button on the VHF set sends a Digital Selective Calling (DSC) alert. Then the voice call: MAYDAY, MAYDAY, MAYDAY, ship name, position, the problem and the people on board. Voice calls are made on VHF channel 16 (156.8 MHz).
- Priority: distress (MAYDAY) comes first, then urgency (PAN-PAN), then safety (SÉCURITÉ), then ordinary traffic. When a distress call is heard, all others must stop and keep quiet.
- Duty to help: a captain who hears a distress call must go to help if able.
- Rules for people: a ship radio licence and call sign, certified radio operators, a station log, regular tests. Sending a false distress alert is a serious offence.
Try it: build your own lane chart
On a long strip of paper draw a line and mark 100 equal parts. Give lanes to five "services" (for example school radio, fishing boats, an airport, a hospital, a hobby club). Rule: lanes must not overlap and each needs a gap between neighbours. Now try to add a sixth user. Where can it go? You just saw why the spectrum is limited and why rules are needed. Then use the 3D free play: slide tower B outside its lane and see what happens.
Key formulas and definitions
- Wavelength: λ = c / f, with c = 3 × 10⁸ m/s
- 1 MHz = 10⁶ Hz; 1 kHz = 10³ Hz
- Number of channels in a band = band width ÷ channel spacing
- Priority at sea: Distress (MAYDAY) > Urgency (PAN-PAN) > Safety (SÉCURITÉ) > Routine
- Key terms: licence, regulator, interference, ITU, Radio Regulations, GMDSS, EPIRB, DSC
Worked examples
1. VHF channel 16 uses 156.8 MHz. Find the wavelength of this wave.
λ = c / f = 3 × 10⁸ ÷ 156.8 × 10⁶ = 1.91 m, so a quarter-wave antenna on a boat can be only about half a metre long.
2. A regulator gives the FM band 88 MHz to 108 MHz with 200 kHz between neighbouring stations. How many stations fit?
Band width = 108 − 88 = 20 MHz = 20 000 kHz. Number = 20 000 ÷ 200 = 100 channels.
3. The old marine distress frequency was 2182 kHz. Find its wavelength.
λ = 3 × 10⁸ ÷ 2.182 × 10⁶ = 137.5 m. Long waves like this travel far over the sea, which is why they were used for distress calls.
4. Your ship is chatting on VHF channel 16 when you hear another ship say MAYDAY. What must you do?
Stop your own chat at once and keep silent. Listen and write down the ship's name, position and problem. If the coast station does not answer, and you are able, reply and offer help. Never joke or send a false call.
Common mistakes
- Thinking any person may transmit on any frequency. A licence is needed, except for approved low-power devices.
- Using more power to "be heard better". Too much power spills over into other lanes and breaks the rules.
- Mixing up the calls: MAYDAY means life in danger now; PAN-PAN is urgent but not life-threatening yet.
- Believing a country alone decides radio bands. The ITU table is agreed internationally, and countries follow it.