The man who gave radio its voice

By Mike Smyth, specialist technical writer
Thursday, 27 June, 2013


A largely forgotten Canadian was once the world’s most famous radio inventor, responsible for the first audio broadcasts.

Many inventors and scientists were involved with the early days of radio, but only a few have gone on to become household names. One who is certainly not in that category is Reginald Fessenden, a Canadian inventor who should probably be more widely known, as it was he who theorised and developed the heterodyne principle of radio and insisted that the only way to transmit legible information was by using a sine wave.

Born in Quebec in 1866, Fessenden was a student with exceptional abilities and by the age of 14 held a mastership in mathematics from a school in Quebec. He began teaching younger students while simultaneously studying at Bishop’s University.

Wanting to improve his knowledge of electricity, he moved to New York, hoping to be employed by Thomas Edison. Although his first applications were rejected, eventually he was accepted as an assistant tester and quickly rose through the ranks to work for Edison himself on chemical, metallurgical and electrical problems. But in 1890, with Edison’s business facing financial difficulties, Fessenden and many others were laid off.

By 1893, Fessenden had become head of the electrical engineering department at the Western University of Pennsylvania (now the University of Pittsburgh), where he started investigating wireless telephones. By 1899 he had a wireless communication system in operation between Pittsburgh and Allegheny City.

Meanwhile, news of Marconi’s experiments inspired Fessenden to the conclusion that he could develop a much more efficient radio detector than the spark gap and coherer duo. But there the matter rested until in 1900 he went to work for the US Weather Bureau to prove the viability of using a network of coastal radio stations, which would eliminate the telegraph. His deal with the Bureau was that it could use any innovations he came up with, but he would retain ownership of the concepts.

His first achievement for the Bureau was the barretter detector, followed closely by the electrolytic detector. This was a fine wire dipped in nitric acid and so successful was it that it became the standard for sensitivity in radio reception.

First audio transmissions

About this time he began looking into the heterodyne principle, where two signals are combined to produce a third, audible tone. Although the theory was sound enough, a workable heterodyne had to wait for a stable local oscillator, and this was not possible until the thermionic valve had become established.

At Rock Point, Maryland, in 1900, Fessenden, using an HF spark transmitter, sent distorted speech signals over 1.6 km. This is believed to have been the first audio radio transmission. Following this success more stations were built along the Atlantic coast, but the venture became marred by a dispute with the Weather Bureau - Fessenden claimed the Bureau had tried to gain a half share of his patents and he refused to sign over the rights, which ended his association with the Bureau.

The next step was the formation of the National Electric Signalling Co (NESCO) with money from two Pittsburgh businessmen investors, with Fessenden as an employee. Its aim was to further Fessenden’s work - it resulted in the development of a high-power rotary spark transmitter for long-distance radio telegraph work and a low-power continuous wave alternator-transmitter for audio and telegraphic transmissions.

Fessenden and his staff at Brant Rock

Fessenden (seated) and his staff at Brant Rock.

Fessenden became even more convinced that a continuous wave transmitter producing a pure sine wave would be the most efficient method of sending quality audio by radio. To bring this about, General Electric was brought in to help develop a series of HF alternator-transmitters.

In January 1906, the decision was taken to attempt to establish a transatlantic radio telegraph service between Brant Rock, Massachusetts and Scotland. Two-way Morse signals were successfully sent; however, it was found that signals could not span the distance during daylight or in summer, and experiments were postponed until the end of the year. Tragedy then struck - a contractor at the Scottish site made an error when moving an antenna support cable and the whole tower collapsed, bringing an end to the venture.

Loud and clear

Fessenden stuck to his idea of a sine wave. His starting point was a basic electric alternator that normally produced AC at a few hundred hertz. He reasoned that by speeding this up he could produce tens of kilohertz, which would produce a signal that would be suitable for connection to an antenna. He then thought that by putting a carbon microphone in the transmission line the strength of the signal could be varied, the genesis of what later came to be known as amplitude modulation. While this was the theory, it would take a few years for a workable prototype to be available.

Various HF alternator-transmitters were produced in conjunction with GE but the inability to amplify the signals was a major drawback. But Fessenden kept the pressure up, and in 1906 Ernst Alexanderson came up with an improved alternator-transmitter that operated at around 50 kHz and was suitable for Fessenden’s purposes. With it, he made the first short-distance audio transmissions.

Ever the entrepreneur, Fessenden is credited with making the very first entertainment broadcast to a general audience. On Christmas Eve 1906, broadcasting from Brant Rock, Fessenden made a short speech, played a phonograph recording of Handle’s Largo, and followed up by grabbing his violin and playing O Holy Night. The broadcast ended with a reading from the Bible by his wife and his secretary. Although the broadcast was heard hundred kilometres away, the signal was marred by noise caused by irregularities in the spark gap transmitter.

The broadcast was repeated only days later on New Year’s Eve, this time aimed at ships of the United Fruit Company out in the Atlantic Ocean and the Caribbean Sea.

Later life

Technical success may have brought recognition but it didn’t bring riches. The two principals of NESCO wanted to sell the company but no buyers were forthcoming. In the meantime, the Fessenden Wireless Company of Canada had been formed in Montreal and this probably raised suspicions that Fessenden was trying to eliminate NESCO from the scene.

The matter came to a head in 1911 when Fessenden was dismissed by NESCO. He immediately sued for breach of contract and a drawn-out legal battle followed. NESCO went into receivership and was then reborn as the International Radio Telegraph Company, before being bought by Westinghouse and then the Radio Corporation of America (RCA). It was March 1928 before the matter was settled and Fessenden received a large cash payout from RCA.

Work on the alternator-transmitter continued at GE and by 1916 a high-powered Alexanderson alternator was produced that could transmit across the Atlantic. A few years later, with the development of valves and amplifiers, audio radio broadcasting had become well established.

Fessenden with a sonar device he invented

In later life, Fessenden moved from radio to sonar. He is shown here with an oscillator used for underwater signalling and obstruction detection. Courtesy NOAA.

By the end of his life Fessenden held more than 500 patents and had received numerous awards. Although he gave up radio after his dismissal from NESCO, he went on to work on a type of sonar system that allowed submarines to communicate with each other, and also developed a radar-like system of detecting icebergs to help prevent Titanic-like disasters.

At the beginning of the First World War he developed a device for detecting enemy artillery. He also founded the principle of reflective seismology and invented a fathometer, a sonar device that measured the depth of a submerged object.

As with many inventors he had his idiosyncrasies: he liked to float on his back in a river or lake while he pondered some new project; he also enjoyed lying on his back on the carpet at home with a cat on his chest. Who can begrudge him these oddities when he gave so much to radio?

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