The condenser telephone , also known as the Phonopore telephone system, was an invention first patented in 1892 and subsequently introduced in many countries in large numbers, whereby telephone voice communications could be made over existing Morse code telegraph infrastructure at a low installation and running cost.
In the 1830s the first commercial telegraph system was constructed in England. Over time the system was perfected and across the world overhead telegraph lines were built at rapid pace to connected towns and countries. The telegraph system allowed immediate communications by Morse telegraph codes to pass important government, commercial and private messages which up until then were delivered by mail on coaches and horseback.
The Telegraph system operated for many decades until voice communications were experimented with and perfected. Voice communications over telephone equipment was trialed in the 1860s and by the 1870s basic telephone apparatus were being used in small applications. In 1877 the first successful long distance telephone line was constructed in California, USA.
Telegraph lines in rural areas typically used one wire earth return circuits, this is a system whereby one conductor is installed on insulators mounted on telegraph poles. The circuit return current travels back via the earth to the origin battery. One wire on a pole was very economical to build and one wire circuits expanded rapidly to remote rural communities. Telephone circuits as distinct from telegraph circuits ideally use two wires to provide a noise free line. Once telephone communications became more commonplace in big cities there became more interest in voice telephone lines for long distance communications to smaller centers remote from the cities. Voice messages improved the correctness of the information and could allow more messages to be sent including direct person to person communications. Telegraphs typically operated between two telegraph offices and the messages written on a telegraph note and hand delivered to the recipient.
In the 1890s and 1900s the Telegraph authorities were faced with the dilemma of modernising the old telegraph systems, then in use for 40 or more years, to new voice telephone systems. The cost to convert the hundreds of kilometers of overhead 'one wire' systems to 'two wire' for telephone would have been enormous. Extra wire, crossarms, and transposition of wires to reduce crosstalk all added to the conversion cost. Where conversion could be justified by high traffic levels, meaning high income from those busy lines, they were quickly converted to two wire telephone circuits, but in many cases the cost could not be justified. A method was invented whereby a telephone circuit could be established using the one wire and earth return method similar to the telegraph circuit method. The telegraph could be retained as this was still accepted as the basic method for transferring simple data someone similar to SMS text messages versus voice calls today.
One wire circuits were typically called earth return circuits, or sometimes 'non metallic' and two wire were also referred to as 'metallic circuits'. Metallic referring to a total metal (copper or steel) circuit for both legs of the circuit. [1]
This basic telephone circuit was known as a Buzzer, or more commonly, a Condenser Telephone Circuit. [2]
A patent registered by François van Rysselberghe (1846-1893) in 1882 is thought to be the original invention of the basis of the phonopore (condensor) method. The technique was developed and improved by Charles Langdon-Davies in 1890, particularly with the invention of a method to call between phones [3] Patents were lodged for improved versions of instruments for commercial use including one lodged by Ellis F Frost in 1902. [4]
The system worked over a single aerial telegraph wire. Using a coil of wire an inductor was formed that could filter the lower Morse frequency from the much higher voice frequency. The inductor blocked the higher voice frequency but allowed the low Morse frequency to pass. Similarly but opposite to the effect of the inductor, a condenser (capacitor) was installed that passed the higher voice frequency but blocked the low Morse frequency. The two separated frequencies were diverted the respective instruments, either the Morse instrument or the telephone instrument.
The Condenser system equipment was located at each end of a telegraph line in the telegraph equipment rooms. This limited the installation works to easy accessible buildings and avoided work on the aerial lines and poles that may extend for many kilometers, 50 kilometers and longer were not unusual.
A report by the New South Wales Government details a saving of 93% by using the Condenser system as distinct from construction of a second telephone wire to provide a telephone service. [5]
Electrical telegraphs were point-to-point text messaging systems, primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called telegraphs, that were devised to communicate text messages more quickly than physical transportation. Electrical telegraphy can be considered to be the first example of electrical engineering.
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Ancient Greek: τῆλε, romanized: tēle, lit. 'far' and φωνή, together meaning distant voice. A common short form of the term is phone, which came into use early in the telephone's history.
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined, so such systems are thus not true telegraphs.
A teleprinter is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations.
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
A communications system or communication system is a collection of individual telecommunications networks systems, relay stations, tributary stations, and terminal equipment usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union.
A loading coil or load coil is an inductor that is inserted into an electronic circuit to increase its inductance. The term originated in the 19th century for inductors used to prevent signal distortion in long-distance telegraph transmission cables. The term is also used for inductors in radio antennas, or between the antenna and its feedline, to make an electrically short antenna resonant at its operating frequency.
Antonio Santi Giuseppe Meucci was an Italian inventor and an associate of Giuseppe Garibaldi, a major political figure in the history of Italy. Meucci is best known for developing a voice-communication apparatus that several sources credit as the first telephone.
Nathan Beverly Stubblefield was an American inventor best known for his wireless telephone work. Self-described as a "practical farmer, fruit grower and electrician", he received widespread attention in early 1902 when he gave a series of public demonstrations of a battery-operated wireless telephone, which could be transported to different locations and used on mobile platforms such as boats. While this initial design employed conduction, in 1908 he received a U.S. patent for a wireless telephone system that used magnetic induction. However, he was ultimately unsuccessful in commercializing his inventions. He later went into seclusion, and died alone in 1928.
The invention of the telephone was the culmination of work done by more than one individual, and led to an array of lawsuits relating to the patent claims of several individuals and numerous companies. Notable people including in this were Antonio Meucci, Elisha Gray and Alexander Graham Bell.
In telecommunications and electrical engineering in general, an unbalanced line is a pair of conductors intended to carry electrical signals, which have unequal impedances along their lengths and to ground and other circuits. Examples of unbalanced lines are coaxial cable or the historic earth return system invented for the telegraph, but rarely used today. Unbalanced lines are to be contrasted with balanced lines, such as twin-lead or twisted pair which use two identical conductors to maintain impedance balance throughout the line. Balanced and unbalanced lines can be interfaced using a device called a balun.
The history of telecommunication began with the use of smoke signals and drums in Africa, Asia, and the Americas. In the 1790s, the first fixed semaphore systems emerged in Europe. However, it was not until the 1830s that electrical telecommunication systems started to appear. This article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. The history of telecommunication is an important part of the larger history of communication.
The invention of radio communication was preceded by many decades of establishing theoretical underpinnings, discovery and experimental investigation of radio waves, and engineering and technical developments related to their transmission and detection. These developments allowed Guglielmo Marconi to turn radio waves into a wireless communication system.
The arc converter, sometimes called the arc transmitter, or Poulsen arc after Danish engineer Valdemar Poulsen who invented it in 1903, was a variety of spark transmitter used in early wireless telegraphy. The arc converter used an electric arc to convert direct current electricity into radio frequency alternating current. It was used as a radio transmitter from 1903 until the 1920s when it was replaced by vacuum tube transmitters. One of the first transmitters that could generate continuous sinusoidal waves, it was one of the first technologies used to transmit sound by radio. It is on the list of IEEE Milestones as a historic achievement in electrical engineering.
This history of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent was granted to Alexander Graham Bell in 1869.
Acoustic telegraphy was a name for various methods of multiplexing telegraph messages simultaneously over a single telegraph wire by using different audio frequencies or channels for each message. A telegrapher used a conventional Morse key to tap out the message in Morse code. The key pulses were transmitted as pulses of a specific audio frequency. At the receiving end a device tuned to the same frequency resonated to the pulses but not to others on the same wire.
Telecommunications engineering is a subfield of electronics engineering which seeks to design and devise systems of communication at a distance. The work ranges from basic circuit design to strategic mass developments. A telecommunication engineer is responsible for designing and overseeing the installation of telecommunications equipment and facilities, such as complex electronic switching system, and other plain old telephone service facilities, optical fiber cabling, IP networks, and microwave transmission systems. Telecommunications engineering also overlaps with broadcast engineering.
George Ashley Campbell was an American engineer. He was a pioneer in developing and applying quantitative mathematical methods to the problems of long-distance telegraphy and telephony. His most important contributions were to the theory and implementation of the use of loading coils and the first wave filters designed to what was to become known as the image method. Both these areas of work resulted in important economic advantages for the American Telephone and Telegraph Company (AT&T).
Mahlon Loomis was an American dentist and inventor known for proposing a wireless communication and electric power generating system based on his idea that there were electrically charged layers in the Earth's atmosphere.
Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a corresponding saving on the labour required to string it. The benefits of doing this were not immediately noticed by telegraph pioneers, but it rapidly became the norm after the first earth-return telegraph was put into service by Carl August von Steinheil in 1838.