A Practical Guide To RF In Broadcast: The History Of Broadcast RF Technology

We start at the beginning… Wireless delivery of news, messages and data is older than wire itself!

In 776 B.C., the Greeks used a messenger pigeon to deliver the results of the first Olympiad. By about 400 B.C., the Chinese were using beacon fires to communicate messages from signal tower to signal tower along the Great Wall and into the interior for early warnings of enemy attacks. Today, we in the US call our corresponding emergency relay warning system EAS.

About 200 B.C., people also began using torches, flags, or gunshots to signal others. By about 900 A.D., messages in China could travel 1100 km (700 miles) in 24 hours. The first experimental electrical telegraph over a significant distance was built by Sir Francis Ronalds in 1816. He strung 8-miles of iron wire between wooden frames in his mother’s garden and sent pulses through the wire using electrostatic generators. Sir Francis Ronalds is considered by many to be the first electrical engineer. Electromagnetism was discovered in 1820 and it made the first wired commercial telegraph possible in 1837. The dots and dashes of American Morse code were first used in 1844.

In 1895, Guglielmo Marconi developed the first radio communication system, using a spark gap transmitter to wirelessly send Morse code over significant distances. The center frequency of spark gap transmitters was approximately 50 MHz, generally determined by the length of the antenna. Typical spark gap transmitters splattered signals across a broad portion of radio spectrum, and separate signals tended to interfere with one another. Radio began to be used commercially around 1900. By the end of 1901, Marconi had transmitted messages across the Atlantic. In these early days, radio waves were known as ‘Hertzian’ waves, named after Heinrich Hertz, who produced and detected electromagnetic radiation in 1888.

The “spark era” ended during World War I, when vacuum tubes, oscillators, and continuous wave transmitters were developed. They enabled amplitude modulation (AM), and the transmission and reception of sound using significantly less bandwidth than spark gap systems. In 1920, the first commercial radio broadcast was transmitted on KDKA, formerly known as “special amateur” radio station 8ZZ, Pittsburgh PA. Six days before KDKA’s historic first broadcast of election returns, the Department of Commerce (DoC) granted 8ZZ the first commercial radio station license for KDKA, assigning it a frequency of “360 meters for general broadcasting” (833 kHz). Four years later, 600 radio stations were on the air in the U.S. Most were transmitting their AM signal between 545 kHz and 909 kHz. In 1923, the DoC expanded the US broadcast band to 550 - 1350 kHz.

The FCC

The 1912 sinking of the RMS Titanic prompted the Radio Act of 1912. It was the first legislation to require licenses for radio stations, and restricted transmission to 1.5 MHz or higher, which was considered useless shortwave spectrum at the time. The Radio Act of 1912 marked the beginning of US federal licensing of amateur radio operators and stations, and it became law before commercial broadcasting was introduced to the general public. It was replaced by The Radio Act of 1927, which created the Federal Radio Commission. The Communications Act of 1934 abolished the Federal Radio Commission and required any station wishing to transmit radio signals to obtain call letters from a government-issued license.

The first commercial operator licenses were issued by the Department of Commerce and later by the Federal Radio Commission. When the FCC was created in 1934, it took over licensing radio stations and station operators. The FCC issued First and Second Class Radiotelephone Operator Licenses. In 1953 a Third Class permit was added to allow station DJs to operate transmitters. Written tests for FCC operator’s licenses were administered in FCC field offices, and they tested an applicant’s knowledge of broadcast radio and TV rules, regulations and procedures, electronics theory, and RF transmission. Operator’s licenses were renewable every five years without further testing. When commercial TV was ramping up after World War II, a First Class operator license was required to be a chief engineer and to work on TV transmitters.

In 1983, the FCC stopped testing for First Class licenses and began issuing the General Radiotelephone Operator License (GROL). A GROL requires a one-time test, administered at about a dozen Commercial Operator License Examination Managers (COLEMs) nationwide. Once issued, a GROL is good for life. It’s not necessary for engineering jobs in radio and TV broadcasting, but a GROL is one of the most recognized and respected TV engineering credentials in the business.

Amateur Radio

Until the first commercial radio stations were licensed all radio stations were amateur, which is why the early radio pioneers had amateur radio-style call letters such as W2XBS. During World War I the US Congress ordered amateur radio operators to cease operation and dismantle their gear. The 1917 restrictions were lifted when the war ended, and amateur radio service restarted in October 1919. During the 1920s, amateur stations around the world began communicating.

During World War II, the US Congress once again suspended all amateur radio operations. After the war, amateur radio service was restored, and many hams converted war surplus radios to amateur use.

Like commercial operator licensing, amateur radio licenses also require passing a written test about electronics and rules. Many people who made radio and TV engineering a career began with an amateur radio license.

Television

In 1927, Philo Farnsworth transmitted the first TV image which was a simple straight line. In 1928, W2XB became the world’s first TV station. It was one of the first TV networks interconnected with W2XBS, the NBC station in New York City. Today W2XB is known as WRGB in Schenectady NY. By 1931, RCA had achieved 120 lines of TV resolution.

Farnsworth’s success motivated many other pioneering scientists, physicists, and inventors around the world to experiment with and develop various mechanical and electronic means to scan visual images and view them on a remote screen. Many were granted patents. In 1941, patent deals were made, US TV transmission and receiver standards were agreed upon, and NTSC and commercial TV were born. Following the war, amateur radio operators and military-trained electronics specialists returning home from active duty were in the right place at the right time to jump-start the fledgling local TV broadcasting industry.

Technical progress in analog TV was incremental. The original NTSC defined transmission standards for black and white signals. A second NTSC standard was adopted in 1953 describing the analog color system. It brilliantly allowed color TV to be compatible with existing black and white receivers and made color TV all electronic and easy to broadcast. The first national color TV broadcast was the Rose Bowl Parade on New Year’s Day, 1954.

Over the following decade, most TV content remained black and white because color TV sets and color production gear were expensive until the mid-1960s. The first all-color, prime-time, network season was in 1966. That year the average color TV set cost about $500, equivalent to about $4600 USD today. That same year, RCA was selling the new TR-70 quad VTR for $82,500, equal to approximately $760,000 USD today.

The Future

A century after Farnsworth’s original 1927 TV accomplishment of wirelessly transmitting a crude straight-line image to a receiver and display, will stations in 2027 be regularly broadcasting 4K, 8K, 16K, ATSC 4.0, private datacasting, the broadcast internet or what? TV broadcasters are the unique owners of tall towers and high-power transmitters that blanket an entire market with strong RF signals on relatively low frequencies compared to the mostly 1 GHz and higher frequencies of cellular service and Wi-Fi. Perhaps in 2027 most sports and entertainment will be streamed or carried on 5G to provide sufficient bandwidth for more profitable and secure ATSC wireless transmission of private data. Follow the money.

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