Telecommunications

Summary

Telecommunications literally means “communications from afar.” In the modern world, this means primarily electrical and electronic communications, including the technologies that make telecommunications possible, the applications that derive from this technology, and the organizations developing and using it.

Definition and Basic Principles

In the information age, data, sound, and video are gathered, stored, disseminated, and manipulated. Senders, receivers, and manipulators are often separated by miles, even continents. The meaning of telecommunications is to transmit data over a distance.

Telecommunication is typically envisioned as taking place between two people, but it is just as likely that information will be transmitted from people to machines, machines to people, or even machines to machines. The first telecommunications were electrical (such as the telegraph) and not electronic. Later, almost all telecommunications came to involve electronics (such as cellular radio, the Internet, and satellite communications systems).

Because telecommunications involves distance, it is important to consider the transmission medium. Early transmissions were carried over copper wire. Then came radio, and still later came coaxial cable and fiber optics. None of these have become obsolete. Consider a video conversation with a colleague in a foreign country. The transmitter is most likely purely electrical. The voice signal is fed to a copper wire, and electronics convert the message to an electronic, digital form and feed it into a fiber-optic cable. The video is probably transmitted through a satellite link. All this lends credence to the idea that every place on Earth is equidistant from every other place, at least from a communications standpoint.

Background and History

The progress in communication technology from smoke signals and semaphores was not without effort; it took the work of hundreds of men and women. In 1835, American Samuel F. B. Morse developed a rudimentary telegraph system, which he improved and demonstrated in 1837. In 1864, Scottish physicist and mathematician James Clerk Maxwell predicted that waves of oscillating electric and magnetic fields could travel through empty space at the speed of light. In 1887, German physicist Heinrich Hertz tested Maxwell's theory and successfully demonstrated the existence of electromagnetic waves. His work demonstrated that radio waves could be generated at one location and transmitted to a nearby spot.

American scientist Alexander Graham Bell received a patent for the first telephone system in 1876. Inventor Thomas Alva Edison developed an electrical telegraph known as the quadruplex telegraph, which allowed four signals to be sent and received on a single wire at the same time. Between 1877 and 1878, he developed the carbon transmitter, a telephone microphone used in telephones until the 1980s. Almon Brown Strowger, an undertaker, invented the first automatic switching system, the Strowger switch, which would allow telephone users to direct their own calls. He received a patent in 1891. In 1901, Guglielmo Marconi transmitted the first trans-Atlantic radio signal, from Poldhu, Cornwall, to St. John's, Newfoundland.

In 1904, English electrical engineer and physicist Sir John Ambrose Fleming developed the first diode vacuum tube. Then, in 1906, American inventor Lee De Forest inserted a grid in the diode vacuum tube and created the first triode vacuum tube. In 1948, Bell Telephone Laboratories employees Walter Brattain and John Bardeen applied for a patent for the point-contact transistor, and William Bradford Shockley, who had earlier worked with Brattain, applied for a patent for the junction transistor. The three are credited with the invention of the transistor, an electronic device that essentially made the vacuum tube obsolete. In 1958, Jack Kilby, an engineer at Texas Instruments, invented the integrated circuit; six months later, Robert Noyce independently developed the integrated circuit; both are credited with its invention. Without these scientific discoveries and technological adaptations, modern telecommunications would not be possible.

How It Works

Communications involves the conveying of information; telecommunications is communication through a transmission media. For decades, the prevalent means of transmitting information was copper wire. Two wires formed a circuit, and millions of miles of copper wire were strung across the country. Unfortunately, this copper wire had limitations; the desired signal could leak out, and undesirable noise could leak in.

One method of correcting these problems was to use coaxial cable. This type of cable has a single strand of copper at its center, surrounded by insulation and a sheath of conductor such as aluminum or copper. The capacity of coaxial cable is extremely high, and its most well-known application is cable television.

The latest land-based means of transmitting information is fiber optics. A hair-thin strand of glass (very pure and very flexible) does not carry electricity—it carries light. That light is a huge extension of the electromagnetic spectrum and can be triggered on and off at gigabit rates.

Wireless communications have become a significant means of transmitting information. The primary tool of wireless communications, the transistor, was small, used little power, lasted a long time, and was inexpensive. Of equal importance was the speed at which it could operate—it, too, could turn on and off at gigabit rates.

The Transmission Scheme. Equally important is the structure of the signal being sent. Broadly speaking, a signal can be either analog or digital. An analog signal is a continuously varying electrical signal that replicates the amplitude or frequency of the originating signal. Thus, the signal being transmitted over a telephone channel is a sine wave that varies in both frequency and amplitude. Unfortunately, such a transmission scheme has inherent problems. A burst of noise (for instance, electromagnetic static caused by a nearby motor starting) will be picked up by the channel. Also, high-frequency signals, which might be used for data, leak out.

The alternative is a digital transmission scheme. An analog signal is sampled, a process that changes a continuous signal into a discrete one. The magnitude of each sample is converted into a binary code—a series of ones and zeros—and transmitted down the line. It is possible to apply error-checking techniques to a group of ones and zeros and make corrections for any noise bursts that have entered the system. At the distant end, the digital signal is converted back to an analog signal. Usually, the communications channel is capable of extremely high-speed operation. If so, many individual voice or data channels can be multiplexed at the transmitting end and separated at the receiving end.

The Network. Digitization and the use of fiber optics had a tremendous impact on telecommunications and enabled the Internet and packet switching. The Internet is a vast worldwide network of computers, and packet switching is the method used for transmitting data.

The transmission of a message from point A to point B can be done by establishing a path, or circuit, through this network. Establishing a circuit and transmitting a message is known as circuit switching. This method, however, is quite inefficient, so scientists developed a faster and more versatile method, packet switching.

In packet switching, a complete data message is broken up into thousands of packets. Each packet, in addition to carrying the requisite intelligence, carries information regarding its importance and its destination. A selected packet is sent toward its destination and is received by the node at the end of this particular link and analyzed. It is then sent over a new link to the next node along the way, and the previously used link is released.

Thus, each packet can take a different path in its trek across the network. It is left to the intelligence of the computers at each node, and especially to the computer at the receiving end of the overall circuit, to reassemble the packets and deliver them to the recipient. Because of the high speed of this transmission, the time the packet spends at each node (called latency) is less than 1 millisecond.

Applications and Products

The telecommunications industry embraces a number of transmission media (twisted-pair copper, coaxial cable, fiber optics, wireless), a highly efficient transmission scheme (digitization), and a huge, evolving network (the Internet). Uses for these technologies have expanded rapidly, and this trend is likely to continue.

Public Switched Telephone Network. The telephone network that serves much of the world is hierarchical in nature. A circuit from a calling party to a receiving party is extended through a series of telephone central offices up and down until a complete circuit has been established. Transmission media most likely will consist of both copper wires and fiber optics. The information communicated starts out as analog and is transmitted over the majority of its path as a digital signal.

The Internet. Data in the public network use the internet—that vast array of nodes consisting of computer-like devices, interconnected by wire and fiber optics, and employing packet switching. There is no set path for an entire message to traverse, and transmission speed is so high that the cost of transmitting a single message (no matter where) approaches zero.

E-mail. In order for someone to receive an e-mail, their computer or device must be connected to the internet. Connection can be made by coaxial cable or a satellite, as would be the case from a cruise ship. In the past, the computer was likly connected to a telephone line, and digital subscriber line (DSL) technology was used. So that the telephone can be used at the same time as the computer, a DSL circuit using high frequencies was used for the computer and low frequencies for the telephone conversation. A filter was inserted in telephone lines to keep the two separated. A modulation scheme was used to combine the voice and data signals at the user's premises and to separate them at the central office.

Another means of connection is the fiber-to-the-home (FTTH) broadband connection, which uses fiber optics to transmit data to the home. Its advantages are faster speeds and greater capacity for data.

Cell Phones. Cell phones are the most widely used telecommunication tool. A cell phone system employs a series of cells, about ten square miles in size. Each cell site, or base station, is equipped with a tower and an antenna and serves subscribers only within its bounds. A cell phone moving from one cell to another will change operating frequencies automatically to conform with the frequencies assigned to the adjacent cell. This scheme makes it possible to reuse frequencies over and over again as the user moves across the country.

The wireless network consists of the wireless (radio) channels connecting the cell phone to the base station. Once a cell phone signal reaches the base station, it travels through copper or fiber to the central office, where it enters the public switched telephone network, or the internet. The frequencies used for this transmission are extremely valuable, and electronic auctions conducted by the Federal Communications Commission bring in millions of dollars to the US Treasury.

Technologies have been created to improve wireless networks. Wi-Fi (802.11 standard networking) allows connectivity between computers and printers. WiMax (based on the 802.15 standard) is a wireless network that tries to capture the benefits of wireless and broadband technologies. Long Term Evolution (LTE), a fourth generation (4G) wireless broadband technology for wireless networks, was introduced in 2010. Fifth generation (5G) wireless technology was introduced in 2019.

Cable Television and Internet Access. For the most part, cable television employs coaxial cable to connect the head end to the subscribers' premises. The system gets its signal from a satellite 22,300 miles (35,888 kilometers) above the Earth's surface, in geosynchronous orbit. Television is also received through satellites, DSL, and fiber optics. In addition to cable television, cable access providers started selling high-speed broadband Internet access in the 1990s. Cable access Internet service is transmitted over the cable television infrastructure.

Global Positioning System.Global Positioning Systems (GPSs) are built into many cell phones and smartphones, come with most new cars and are also available as handheld devices. They simply identify the user's longitude and latitude. Associated components, which are all computer-based, translate the longitude and latitude to a location on an electronic map of the city or the area and generate a route to get from one place to another.

Perhaps the most sophisticated part of this is how the GPS determines the user's location. The GPS unit does not transmit a signal to one of the twenty-four satellites that form a part of this program, nor does a satellite transmit a unique signal to any GPS unit. Instead, each of the very accurate clocks on board the satellites produces a pulse that will not miss a beat in thousands of years. A somewhat less accurate clock in each GPS unit will produce an equivalent pulse. The Earth-bound unit measures the time between the beep received from the satellite and the beep generated by the unit. This time difference is used to determine the distance separating the satellite and the Earth-bound unit. Thus, the Earth-bound unit, with its internal maps, can determine its distance from the satellite (although its location could be anywhere on the surface of a sphere with the satellite at its center). A second satellite repeats the process, narrowing the location to the circle that represents the intersection of the spheres around the two satellites, and a third satellite narrows the location of the GPS unit to two points, the intersection of a sphere around the third satellite and the circle formed by the intersection of the first two spheres. A fourth satellite would pinpoint the user's location, but usually one of the two possibilities given by the intersection of the spheres of the three satellites makes sense and the other is nonsensical.

Radio Frequency Identification. Identification of automobiles, pets, and other items can be made by equipping them with a tag and by using radio frequency identification (RFID). The tags are tiny (hardly larger than a piece of glitter) and cost as little as seven cents. A common use is to enable people to enter toll roads without stopping to pay each time. As an automobile passes through the toll gate, a transmitter mounted on the gate sends out a radio frequency signal that is received by a device in the automobile. The device captures a bit of the electrical power being transmitted and triggers a small transmitter. This transmitter reflects the signal it has received, adding identification.

This technology is also used for asset tracking, retailing, and security and access. The US Department of Defense requires all equipment being shipped overseas to carry a tag. The equipment can be tracked as if it had a bar code, although visual contact is not required. The technology permits up to fifty readings per second. Walmart, Target, and Best Buy are among the retailers tagging their stock in an effort to better track inventory, and some retailers are requiring their vendors to provide the tags. US passports incorporate tags that contain a photograph and all other passport information. They can also track travel information. Identification chips are often implanted under the skin of dogs, cats, and horses, and ear tags are used to identify cattle and other farm animals.

Careers and Course Work

The telecommunications field encompasses many disciplines, including electrical and computer engineering. Knowledge of programming and software is essential, as software drives hardware. Physics and chemistry also play a role in telecommunications. For example, Global Positioning Systems provided inaccurate results until Einstein's special and general theories of relativity were incorporated. Some segments of the telecommunications industry—such as statistical signal processing and antenna design—are so specialized that only a few will understand them.

Anyone interested in the field must begin with science and mathematics courses in high school. Some positions are available for high school graduates or those with associate degrees, often in installing, maintaining, and repairing telecommunications equipment. The more complex the technology, the more likely higher education will be required. At the college level, depending on the area of interest, a major in electrical engineering or computer engineering is a good choice. Because the field is so broad, supplementary course work should be tailored to areas in which the student wants to specialize. To engage in research or to teach at the college level, a master's degree or doctorate is required.

Social Context and Future Prospects

Predicting the future—especially when the present is moving so quickly—is an impossible task. However, as technology progresses, one thing that is for sure is that there is no end in sight to the possibilities of communication.

In 1965, Gordon E. Moore, then director of engineering at Fairchild Semiconductor and later cofounder of Intel, observed that the power of the computer chip was doubling every eighteen months. Industry experts welcomed the rapid advances but thought the pace was unsustainable; however, that doubling of capability continues and has been dubbed Moore's law.

One aspect of telecommunication that has developed throughout the twenty-first century is artificial intelligence (AI). In 2023, the global AI market size and share in the telecommunications industry was valued at 1.82 billion dollars. AI has helped the telecommunications industry mitigate rising operational costs due to high demands for streaming services and broadband use. As demands and expectations for immediate content and communication continue to increase, AI has become critical in assisting companies in developing positive customer experiences.

Telecommunications has been, and will continue to be, a driving force in the growth of nations. The treatment and transmission of intelligence is faster, cheaper, more comprehensive, and more convenient than ever before. People are aware of what is happening as it happens, and as a result, people are better able to deal with it. People are able to stay connected to work, home, and the world twenty-four hours a day.

There are negative aspects to this trend, and one of the most insidious is privacy. The information being gathered and manipulated is often personal and private, and its availability to virtually any enterprising person is of great concern. In spite of this, data of every sort are flooding the world.

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