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RF spectrum management is necessary to prevent radio signals from interfering with one another. Electromagnetic waves from 1Hz to 3THz (where infrared begins) are considered radio signals and regulated by divergent international, national, and regional government authorities. If your transmission interferes with another, you’ll hear from the authorities.

The world’s first international organization was the International Telecommunications Union (ITU). It was established in 1865 to help develop telegraph networks between countries. The International Broadcasting Union (IBU) was founded in Geneva in 1925 to help regulate radio waves sweeping across Europe. The ITU-R was founded in 1927 as the International Radio Consultative Committee (also known as the CCIR) to manage RF spectrum. In the US, the Federal Radio Commission was also founded in 1927. It became the Federal Communications Commission (FCC) in 1934. 

TV Times

In the US, the National Television System Committee (NTSC) developed the first US analog TV transmission system in 1941. In 1953, a second NTSC standard was adopted to allow for color broadcasting compatible with the original black and white system. The US NTSC system transmits at 30 fps. The other two analog color formats are PAL and SECAM that are both 25 fps.

In 1947, the United Nations recognized the ITU as the agency for global communications. In 1949 the ITU became a UN agency. In 1950, the European Broadcasting Union (EBU) was formed. The CCIR became the ITU-R to manage the international RF spectrum in 1992. The EBU supported digital radio broadcasting (DAB) in the late 1980s and set up the DVB Project in 1993 to bring DTV to Europe.

In Japan, ISDB-T was the HDTV standard proposed by NHK Science & Technology Research Laboratories to the CCIR in 1973. In 1982, NHK developed Multiple sub-Nyquist sampling encoding (MUSE), the first HDTV digital compression and transmission system.

The Advanced Television Systems Committee (ATSC) was formed in the US in 1983 and represents the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries. It develops technical standards for digital terrestrial television and data broadcasting which became ATSC 1.0. ATSC 3.0 was approved for US transmission in 2017.

The Grand Alliance (GA) was a consortium created in 1993 at the request of the FCC to develop the American digital television (SDTV, EDTV) and HDTV specifications. As of today, everyone involved in societies, associations, alliances, and committees has provided valuable input to standardize OTA TV transmission technologies.

Standards or Legal Requirements?

Every country is similar but different, and the differences are beyond the scope of this story. Many of the differences are based on the frequency of national AC mains.  When TV broadcasting was developed, local AC was the most calibrated and stable frequency source readily available.

Countries with 60 Hz AC mains typically use frame rates based on 60 Hz, such as 30, 60 or 120 fps. Countries with 50 Hz AC mains typically broadcast 25 or 50 fps. Regardless of TV frame rate differences, the FCC and CCIR created a basic RF regulation template other countries generally followed.

Multiple government and private NGOs are involved in setting and assuring compliance with TV standards. Governmental organizations set and control Over-The-Air transmission standards primarily to mitigate signal interference issues. Formats and transmission compliance is controlled by the modulation method used.

RF technical standards are typically based geographically and what makes them unique are partly legacies, neighboring countries, and regions. Government regulators continue to maintain a tight focus on minimizing RF interference with transmission standards, compliance laws, enforcement, and station licenses that define the transmitter location, ERP, and antenna height.

As broadcast TV evolved from analog SD to digital HDTV, many governments allowed new modulation format standards to be based on industry standards. Defining industry standards and adapting rapidly changing new technologies is almost all up to TV broadcasters, manufacturers, and industry organizations such as SMPTE, ATSC, AES, the DVB Project, EBU, CEA, and others.

TV Station Licensing

The global mission of government station licensing, regulation and enforcement is to prevent radio signals from interfering with each other.

In the US for example, ‘Full Power’ TV stations are limited to 100 kW ERP on VHF channels 2-6, 316 kW ERP on VHF channels 7-13, and 5000kW ERP on UHF. ERP is based on horizontal polarization. The vertical ERP cannot exceed the horizontal ERP and is an important component of ATSC 3.0 signal transmission.

Field strength is measured in dB above 1 microvolt per meter (dBu). Stations must submit a service contour map when applying for a license or changing antennas. Service contours are typically used to identify potential interference problems. Typically, a good TV signal is “Grade B” or greater, which is above approximately 50 dBuV/m. Service contour maps can be predicted with the Longley-Rice radio propagation model or by physically measuring signals at various locations using a uniform receiver antenna height.

Low Power TV (LPTV) stations, TV Translator Stations and Class A TV stations can transmit an ERP of up to 3 kW on VHF and 15 kW on UHF. TV Translator Stations are usually limited to 1 kW ERP. There is no height limit for fill-in translators within the service contour of the primary station. The original translator band was UHF channels 70-83. 1kW ERP translator stations are typically numbered such as W70YX. Full power translator stations covering large regions with small populations are assigned individual four-letter call signs and licenses, as are LPTV stations.

Class A licenses were a one-time filing opportunity for existing LPTV stations to become Class A stations to obtain protected channel status during the DTV transition and repack. Class A television is a system for regulating some low-power television (LPTV) stations in the US. The amount of local programming a station broadcasts determines if that station is eligible for Class A status. “Local programming” covers material produced within the predicted Grade B contour of the station broadcasting the program or produced at the station’s main studio.

Operator Licensing

Again, every country is similar but different. The first US commercial operator licenses were issued in 1927, and a commercial operator license became a ‘ticket’ to qualify for broadcast engineering work. When commercial TV developed after World War II, a First Class Radiotelephone license (aka ‘First Phone’) was required to be a broadcast chief engineer and to work on TV transmitters. Until the Beatles recorded their first album in 1963, a First Phone was required to simply turn a broadcast radio or TV transmitter signal on or off. Obtaining an operator license from the FCC required passing written examinations. In 1983, the FCC stopped testing and grandfathered all current ‘First Phone’ license holders with lifetime General Radiotelephone Operator Licenses.

Relaxed FCC control such as unattended operation, digital technology, simplicity, and often automatic transmitter operation has made operator licenses practically obsolete for broadcasting. However, a new General Radiotelephone license requires passing a written test administered by a NGO, and it remains a legitimate career credential because it’s a tangible governmental validation of your electronics expertise. The General Radiotelephone Operator License Element 3 question pool is 600 questions. A passing grade is at least 75 out of 100 random questions from the pool. Challenge yourself here: FCC Exam Element 3. Answers are at the bottom of each page.

In 1975, the Society of Broadcast Engineers (SBE) established a Certification Program to recognize and raise the professional status of broadcast engineers by providing standards of professional competence. Certification requires passing a written examination.

SBE has exams for Certified Radio Operator (CRO), Certified Television Operator (CTO), Certified Broadcast Technologist (CBT), broadcast networking certifications, 7 levels of engineering certifications up to Certified Professional Broadcast Engineer (CPBE), and four specialist certifications including 8-VSB Specialist (8-VSB) and ATSC3 Specialist (ATSC3). The SBE has more than 5,000 members in 115 chapters across the US and in Hong Kong. There are also SBE members in more than 30 other countries.

Need to Know

For broadcast stations to succeed, they must comply with regulations and standards covering a plethora of rules and legal requirements. The Code of Federal Regulations (CFR) is the official legal print publication containing general and permanent rules published by the Federal Register. Applicable television rules in the US are; 47 CFR 73.601 to 73.699 eCFR :: 47 CFR Part 73 Subpart E -- Television Broadcast Stations as well as 47 CFR 73.1001 to 73.5009.  47 CFR 74.1 through 74.34. 47 CFR 74.701 through 74.797 covers LPTV and television translator rules 47 CFR Part 73 - RADIO BROADCAST SERVICES | CFR |US Law | LII / Legal Information Institute (cornell.edu).

TV engineers must be familiar with other regulations from local electrical and zoning codes, to knowing the rules for specialized systems such as the Emergency Alert System (EAS) in the US, J-Alert in Japan, various earthquake warning systems, and the Wartime Broadcasting Service of the BBC in the UK.

TV technology configurations, workflows and system details vary from station to station. Station engineers are the local technical experts everyone else looks to for remedies and answers.

TV engineers and particularly Chief Engineers have two principal missions: Keep content transmission flowing seamlessly and keep the station in compliance with local, state, and federal regulations and laws. The best strategy is to pro-actively do everything possible to minimize complaints.