Radio … we use it every day. In today’s world, commercial and public broadcast radio stations, in addition to Internet and Satellite radio, continue to be major sources for delivering news, entertainment, general information and data transmission.
Whether you listen to AM, FM, digitally-enhanced “HD” radio, Satellite radio, Internet web-based stations or participate in amateur “ham” radio transmissions, you are using radio. Even your cell phone or pager uses radio waves and frequencies to operate. Yes, radio is definitely a part of our lives. So, what is radio, who invented the radio? History of radio.
Inventors of Radio
The Electric Telegraph (1838-1922) – The electric telegraph revolutionized long-distance communication, replacing earlier semaphore communication lines. In addition to its primary use for point-to-point messages, other applications were developed, including printing telegraphs (“tickers”) used for distributing stock quotes and news reports.
News and Entertainment by Telephone (1876-1929) – While the telegraph was mainly limited to transmitting Morse code and printed messages, the invention of the telephone made distant audio communication possible. And although the telephone was mostly used for private conversations, there was also experimentation with providing home entertainment. In 1893 a particularly sophisticated system, the Telefon Hirmondó, began operation in Budapest, Hungary — one of its off-shoots, the United States Telephone Herald Company and its affiliates, did not meet with the same financial success.
Personal Communication by Wireless (1879-1922) – After Heinrich Hertz demonstrated the existence of radio waves, some were enchanted by the idea that this remarkable scientific advance could be used for personal, mobile communication. But it would take decades before the technology would catch up with the idea.
Radio at Sea (1891-1922) – The first major use of radio was for navigation, where it greatly reduced the isolation of ships, saving thousands of lives, even though for the first couple of decades radio was generally limited to Morse code transmissions. In particular, the 1912 sinking of the Titanic highlighted the value of radio to ocean vessels.
Early Radio Industry Development (1897-1914) – As with most innovations, radio began with a series of incremental scientific discoveries and technical refinements, which eventually led to the development of commercial applications. But profits were slow in coming, and for many years the largest U.S. radio firms were better known for their fraudulent stock selling practices than for their financial viability.
Pioneering U.S. Radio Activities (1897-1917) – Marconi‘s demonstration of a practical system for generating and receiving long-range radio signals sparked interest worldwide. It also resulted in numerous competing experimenters and companies throughout the industrialized world, including a number of important figures in the United States, led by Reginald Fessenden and Lee DeForest.
Alternator-Transmitter Development (1891-1922) – Radio signals were originally produced by spark transmitters, which were noisy and inefficient. So experimenters worked to develop “continuous-wave” — also known as “undamped” — transmitters, whose signals went out on a single frequency, and which could also transmit full-audio signals. One approach used to generate continuous-wave signals was high-speed electrical alternators. By 1919, international control of the Alexanderson alternator-transmitter was considered so important that it triggered the formation of the Radio Corporation of America. However, within just a few years alternator-transmitters would become obsolete.
Arc-Transmitter Development (1904-1928) – A more compact — although not quite as refined — method for generating continuous-wave radio signals was the arc-transmitter, initially developed by Danish inventor Valdemar Poulsen. Because arc-transmitters were less complicated than alternator-transmitters, a majority of the early experimental audio transmissions would use this device.
Audion and Vacuum-tube Receiver Development (1907-1916) – Lee DeForest invented a three-element vacuum-tube detector which he called an Audion, but initially it was so crude and unreliable that it was little more than a curiosity. After a lull of a few years, more capable scientists and engineers, led by AT&T’s Dr. Harold Arnold, improved vacuum-tubes into robust and powerful amplifiers, which would revolutionize radio reception.
Pre-War Vacuum-tube Transmitter Development (1914-1917) – AT&T initially developed vacuum-tubes as amplifiers for long-distance telephone lines. However, this was only the beginning of the device’s versatility, as various scientists and inventors would develop numerous innovations, including efficient continuous-wave transmitters, which would eventually replace the earlier spark, arc, and alternator varieties. Vacuum-tube transmitters were also used for an increasing number of broadcasting experiments, however these fledgling efforts came to an abrupt end on April 6, 1917, when the United States entered World War One. At that time, all radio stations not needed by the government were closed, and it became illegal, for the duration of the war, for the general population to listen to any radio transmissions, from any source.
Pioneering Amateurs (1900-1917) – Radio captured the imagination of thousands of ordinary persons who wanted to experiment with this amazing new technology. Until late 1912 there was no licencing or regulation of radio transmitters in the United States, so amateurs — known informally as “hams” — were free to set up stations wherever they wished. But with the adoption of licencing, amateur operators faced a crisis, as most were now restricted to transmitting on a wavelength of 200 meters (1500 kilohertz), which had a limited sending range. They successfully organized to overcome this limitation, only to face a second hurdle in April, 1917, when the U.S. government shut down all amateur stations, as the country entered World War One.
Radio During World War One (1914-1919) – Civilian radio activities were suspended during the war, as the radio industry was taken over by the government. Numerous military applications were developed, including direct communication with airplanes. The war also exposed thousands of service personnel to the on-going advances in radio technology, and even saw a few experiments with broadcasting entertainment to the troops.
Expanded Audion and Vacuum-tube Development (1917-1924) – The wartime consolidation of the radio industry under government control led to important advances in radio equipment engineering and manufacturing, especially vacuum-tube technology. Still, some would look toward the day when vacuum-tubes would be supplanted by something more efficient and compact, although this was another development which would take decades to be realized.
Amateur Radio After World War One (1919-1924) – Although there was concern that amateur radio stations would not be allowed to return to the airwaves after the war, in 1919 the wartime restrictions were ended. And the next few years would see tremendous strides, as amateurs adopted vacuum-tube technology and began to explore transmitting on shortwave frequencies, which resulted in significant increases in range and reliability. However, although they had laid much of groundwork that led to the development of broadcasting, in early 1922 amateur radio stations were explictly banned from making entertainment broadcasts.
Broadcasting After World War One (1918-1921) – Although still unfocused, scattered broadcasting activities, taking advantage of improvements in vacuum-tube technology, accelerated after the end of the Great War. Initially there was a shortage of equipment, especially vacuum-tubes, due to ongoing patent disputes, and many of the early efforts were government related or by persons who had access to surplus military equipment. But the experiments continued to expand, as the radio industry returned to civilian control.
Big Business and Radio (1915-1922) – Once the radio industry finally became profitable, major corporations – including the American Telephone & Telegraph Company, General Electric, and Westinghouse – moved into the field. Meanwhile, in 1919, due to pressure from the U.S. government, American Marconi’s assets were sold to General Electric, which used them to form the Radio Corporation of America.
Broadcasting Becomes Widespread (1922-1923) – Led by Westinghouse‘s 1920 and 1921 establishment of four well-financed stations — located in or near Pittsburgh, Boston, Chicago and New York City — there was a growing sense of excitement as broadcasting activities became more organized. In December, 1921, the Department of Commerce issued regulations formally establishing a broadcast service. Then, in early 1922, a “broadcasting boom” occurred, as a sometimes chaotic mix of stations, sponsored by a wide range of businesses, organizations and individuals, sprang up, numbering over 500 by the end of the year.
The Development of Radio Networks (1916-1935) – The introduction of vacuum-tube amplification for telephone lines allowed AT&T to experiment with sending speeches to distant audiences that listened over loudspeakers. The next step would be to use the lines to interconnect radio stations, and in December, 1921 a memo written by two AT&T engineers, J. F. Bratney and H. C. Lauderback, outlined the establishment of a national radio network, financially supported by advertising. General Electric, Westinghouse and RCA responded by forming their own radio network, however, unable to match AT&T’s progress, in 1926 they bought out AT&T’s network operations, which were reorganized to form the National Broadcasting Company.
Financing Radio Broadcasting (1898-1927) – Soon after Marconi‘s groundbreaking demonstrations, there was speculation about transmitting radio signals to paying customers. However, there was no practical way to limit broadcasts to specific receivers, so for a couple decades broadcasting activities were largely limited to experiments, plus a limited number of public service transmissions by government stations. During the 1922 “broadcasting boom”, most programming was commercial-free, and entertainers, caught up in the excitement of this revolutionary new invention, performed for free. Meanwhile, a few people wondered how to pay for all this. In early 1922, the American Telephone & Telegraph Company began promoting the controversial idea of using advertising to finance programming. Initially AT&T claimed that its patent rights gave it a monopoly over U.S. radio advertising, but a 1923 industry settlement paved the way for other stations to begin to sell time. And eventually advertising-supported private stations became the standard for U.S. broadcasting stations.
Fakes, Frauds, and Cranks (1866-1922) – Unfortunately, some “misunderstood geniuses” are actually crazy, or dishonest, or both.
Word Origins – Reviews of the history of the words “radio”, “broadcast” and “ham”.
Early Government Regulation (1903-1927) – Compared to most other nations, the United States was slow to regulate radio communication. International issues were dealt with by conferences held in Berlin, Germany in 1903 and 1906, followed by a London convention in 1912. The U.S. issued limited shipboard regulations in 1910, but did not implement comprehensive regulations and station licencing until 1912. The development of broadcasting in the early 1920s brought significant challenges and changes, which resulted in passage of the Radio Act of 1927, and the formation of the Federal Radio Commission.
Simply put, broadcast radio is the method of transmitting electromagnetic waves through space; the waves are detected by a conductor that emits alternate electromagnetic fields. The results of these oscillating sets of waves that are working against each other can be turned into sounds or other informational signals.
Radio signals have two kinds of waves. “Audio” waves are the actual sounds that an audience hears when listening to, for instance, music or someone talking. Radio frequency waves travel with the sound in order to “carry” it to home, portable and car radio receivers. Sound waves are broken into three parts; amplitude, frequency and phase, or a “wavelength.”
AM Radio Frequencies
AM radio uses “amplitude modulation” for broadcasting, thus the initials “A” and “M.” The AM receiver detects waves at a specific frequency, amplifying the changes in the signal that you hear in speakers and headphones. AM radio waves are susceptible to forms of interference such as lightning or electrical static. Although many cities still have music-format stations which use AM frequencies, AM broadcasting attracts mainly news, sports, religious and talk-radio programming.
AM radio antenna transmitting-power varies; commercial stations may be broadcasting with anywhere from 250 to 50,000 watts, depending on their Federal Communications Commission (FCC) license agreement. During the sunlit hours of the day, AM waves travel by what is known as “groundwave;” bouncing around the earth’s curve over a specific distance from the signal transmitter.
At night, AM signals travel by “skywave,” created by changes in the ionosphere. The “skywave” lets the stations be heard far from their normal listening area. The FCC requires “daytimers” to reduce their broadcasting power or use directional antennas after sunset. Some stations are only allowed to broadcast during the day.
(Here’s something fun to do: Scan your AM radio at night to see what stations you can pick up and where they are. Cloudy days are best because the signals are bouncing then, but clear days are good too. You may be surprised at what your receiver picks up!)
FM Radio Frequencies
FM radio uses “frequency modulation” to transmit a combination of waves that reproduce the audio signal for broadcasting, thus the initials “F” and “M.” Frequency Modulation transmits information over a carrier wave that varies (unlike AM, where the frequency wave remains steady). The FM band, which transmits between 87.5 and 108 megahertz, is calculated to millions of cycles per second.
Commercial FM broadcasting actually began in 1939; for years FM was used to air classical music and educational programming. FM became popular in the late 1960s for broadcasting “alternative” music, such as “Album-Oriented-Rock” formats (AOR). By the late 1970s, the number of FM stations exceeded AM for airing music formats.
HD Radio allows radio stations to broadcast their programming digitally; allowing for more stations on the frequency band and clearer “CD quality” reception without audio distortion. The term “HD” is mistakenly thought to stand for High Definition or Hybrid Digital, but actually it is just a trademark brand name for the product. HD radio works much like conventional radio with a signal being transmitted to a receiver. The digital signal is compressed with an analog signal; it bounces off objects to create “multipath distortions.”
HD radio receivers clean up the signals by reducing static and noise. HD2 is a term used for multicasting on FM; the primary signal (called HD1) is duplicated and broadcast on HD radio receivers. Like commercial and publically-funded radio stations, HD radio broadcasts are free to listen to but you must have an HD radio receiver to pick them up.
In Band On Channel (IBOC) is the digital broadcasting standard in the United States; IBOC signals use the same FM and AM bandwidths as the stations’ analog signals. As the use of HD radio grows, more stations in the United States are increasing their audiences’ listening choices with multiple programming signals.
Satellite radio is a digital or analog signal that travels through one or more structurally developed satellites that are launched into space. Listening to music and other types of programming from a Satellite radio station is kind of like listening to a CD; high quality with uninterrupted sound. The numbers of stations are varied and can be somewhat unlimited; they can include many formats such as classic rock, soul, love songs, oldies, hip-hop, country, talk shows, news and much more.
Many car models are now installed with satellite radio receivers. Portable receivers are also available at some electronics stores and to purchase online. Satellite radio users must subscribe to use the service, for which there is monthly fee.
Internet Radio, also called webcasting, streaming, net-radio and e-radio, is a method that allows music and other programming to be transmitted through the Internet. Streaming media is somewhat like traditional broadcast radio in that it cannot be stopped or replayed and it is not available “on demand.”
However, unlike broadcast radio (which is limited to listening-area boundaries), web streaming allows the listener to access programming content from Internet radio stations around the world. Many local broadcast stations now bring their programming to the world-wide-web so that it is accessible through computers as well as through traditional radios.
Podcasting is not an immediate broadcast of a program; it is a delayed webcast that is available for the listener to download onto his or her computer or portable device, to listen to when it is convenient to do so. Digital media files are combined into a series that is fed into a server and caught by specially designed software called a “podcatcher.” The series of files are updated with new segments that are sent automatically. The “podcatcher” stores audio files on the user’s computer or portable device, such as an MP3 player or cell phone.
Two-way radios (also called “walkie-talkies” and “handheld receivers”) can both receive and transmit audio communication between two or more users, typically for purposes of business, military, public safety, outdoor recreation and personal activities. In today’s market, along with children’s toys that have limited range, there are two types of two-way radios; FRS (Family Service Radio) and GMRS (General Mobile Radio Service).
FRS units have low power; ranging approximately from a half-watt to two watts which transmit on a total of 14 Channels. GMRS units are higher powered two-way models — typically one to two watts — that transmit on a total of 22 channels and require the users to have an FCC license to use them. The range of coverage of all two-ways varies depending on the radios’ usage locations.
Other Radio Types
Low Power Radio Service (LPRS) is one-way, private, short-distance communication meant for stations to send voice data to people with disabilities as well as for language translation and educational purposes. LPRS is also used for health care and law enforcement activities.
Multi-Use Radio Service (MURS) is a private, short-distance service that is used mostly for business or personal activities. MURS operates with up to two watts on “Very High Frequency” (VHF) channels.
Citizens Band Radio (CB) allows for private two-way radio communication. Mostly used for private or business purposes, CB radios are often found in vehicles but they can be in a stable location as well. The distance between CB radio transmitting and receiving stations must not exceed 155.3 miles (250 km). CB radios used in the United States must be certified by the FCC and have the commission’s label placed directly on the unit by the manufacturer. There are 40 CB service channels in the United States.
Whether as a hobby or for public service, Amateur Radio (also called “ham” radio) operators use different types of transmissions to communicate voice and sounds, such as, for example, Morse Code. Amateur radio operators must undergo training and become specially licensed by the FCC before they can hit the airwaves.