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First radio transmission of voice
On Dec 24 this year the entire global community will join hands to commemorate an amazing event that took place exactly 100 years ago and which changed forever the shape of communications. At 9pm on that chilly December night, the first extended broadcast of the human voice was transmitted through the air.
Despite geographical differences, weather extremes and cultural, linguistic and racial diversities among various peoples, it was this achievement which paved the way for mankind to form a single community. In fact, it won’t be wrong to suggest that it was this event which laid the foundations of a global village.
The brain behind the seemingly miraculous event was the Canadian scientist and engineer Reginald Fessenden, who was later recognised as the Father of Broadcasting. Fessenden’s 74th death anniversary was widely observed on July 22.
Radio involves the transmission and reception of electromagnetic radiation in the radio frequency range. Radio transmission takes place, through electromagnetic waves, in the approximate frequency range of 10 kilohertz to 300,000 megahertz. This nomenclature is applied also to the devices that are used for radio reception.
There is a great misconception among people about radio, as many of them regard M.G. Marconi as inventor of the broadcasting system as well as of the receiver. Marconi actually invented wireless telegraphy, which involves messaging and is quite different from signalling.
He was Italian by birth but worked mostly in England. On the other hand, Fessenden was a Canadian but was based in the United States.
Many books refer to Marconi as the inventor of radio. However, using the devices that he designed and developed himself, the Italian could transmit telegraphic communication having a range of just one mile. He did so in 1895-96.
In 1893 Prof Reginald A. Fessenden had moved to Pittsburgh in the United States to join Western University, which is known as the University of Pittsburgh today. He did so as the head of the university’s electrical department.
In time, Prof Fessenden came to know of the experiments which Marconi was conducting in England. This motivated him to carry out his own experiments at a laboratory in the Allegheny Observatory.
The success that Marconi’s experiments met involved the transmission and reception of dots and dashes constituting the Morse code. Prof Fessenden had different ideas. His goal was to put the human voice and music on the air.
In his experiments on “voice telephony”, he reached the conclusion that continuous wave transfer was necessary for speech transmission. Because of that he kept on working in line with the work of Nikola Tesla, John Stone-Stone and Elihu Thomson. Furthermore, he sensed that transmission and reception of Morse code could be realised better with the continuous wave method as compared to the spark apparatus that Marconi was using.
As a first step, he put together the theory of the “continuous wave” — which either was emitted or was capable of being emitted continuously and was not pulsed. It’s a source that superimposes sound onto a radio wave and sends out this signal to a receiver where the radio wave would be removed, leaving the listener with the original impressed sound. The continuous wave provides the electronic basis for radio and television transmission.
Ceaseless efforts and research helped him come up with many inventions, one of which was microphotography. This is an invention of great significance even today. Banks, commercial organisations and libraries, besides other professional institutions all over the world, use this system for recording important documents and cheques.
Yet, it was the dream of transmitting speech which motivated Fessenden to scale even greater heights. He toiled round the clock until he was able to make the breakthrough. Into a phonograph cylinder he cut almost microscopic incisions in order that his interrupter would break the circuit 10,000 times each second.
This method, which he used in association with Prof Kintner, provided a fairly adequate means of producing a long train of waves. (To this day this technique is used.)
Following a variety of tests with a Wehnelt interrupter and other devices with which more or less encouraging results were achieved, an induction coil and commutator were settled upon to provide a make and break mechanism for the tuned circuit.
By means of this circuit, and apparatus, 10,000 sparks per second were achieved. Experiments in wireless telephony led to the transmission of speech, which was first successfully accomplished in 1900. Two antennas, each 50 feet high, were installed at Rock Point, Maryland.
In the initial trials, voice signals were rather incomprehensible, but soon his relentlessness was rewarded in the shape of a historical success. Yes, it seemed miraculous to transmit human voice through the air, without the help of wires, though the distance over which the signals travelled was only a mile.
The first radio voice transmission took place on Dec 23, 1900, at Cobb Island, Maryland, at a time when Fessenden was working in close association with the US Weather Bureau. Setting up telegraphic links to furnish remote weather observations was at the centre of his efforts. However, he devoted some of his time to his work on “voice over radio” as well, which he ultimately mastered.
That was the first time that intelligible speech had been transmitted by electromagnetic waves. Therefore, the honour for taking the primary step in the development of what is universally called “radio” today, deservedly belongs to Prof Fessenden.
The first voice message that was successfully transferred and which was intelligible too was: “One, two, three, four. Is it snowing where you are Mr Thiessen? If it is, telegraph back and let me know.”
Between January of 1901 and August of 1902, Fessenden did important experimental work at Manteo and Hatteras, North Carolina. During this period, he developed many new approaches and ideas. However, his most enduring contribution, out of over 500 patents which were granted to him, involves the Heterodyne Principle.
The writer cocographer@yahoo.com is a senior instructor at a technical college in Karachi
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