Who Invented the Cell Phone?
Martin Cooper shows the first cell phone, Motorola's DynaTAC.
The first public cell phone call was made from a New York City sidewalk on April 3, 1973, by engineer Martin Cooper. On his way to a press conference to introduce Motorola's DynaTAC “portable radio telephone,” Cooper called a rival engineer, Jeff Engel at AT&T's Bell Laboratories, to gloat that he had a truly mobile phone.
'Calling all cars'
The quest for a portable phone had begun soon after Alexander Graham Bell invented the telephone. Radiotelephony, in which audio signals are carried over high radio frequencies (between 3 kHz to 300 GHz) on the electromagnetic spectrum, was invented in the late 1800s.
All cell phones, even smartphones, are handheld radiotelephones. Police adopted the technology early. The Detroit Police Department installed a one-way radiotelephone system in its patrol cars in 1928. Police started using two-way systems in the 1930s. By 1948, wireless radiotelephone systems were available in 100 cities and often used by police, fleet operators and reporters.
Car phones had limited popularity, and by the 1970s, they posed several problems. First, they cost from $2,000 to $4,000. Second, they were bulky and needed a car to lug around the batteries and equipment. But more importantly, networks, which at most, had 24 channels available, were often clogged.
In 1968, Joel Engel and his colleagues at Bell Laboratories proposed a solution to the overcrowded mobile phone systems. Divide a metropolitan area into zones, or cells — hence the name cellular phone.
Instead of crowding one radio tower in a city, each cell would have its own low-powered tower called a base station. The base station works as both a transmitter and receiver. When someone makes a call from a cell phone, the nearest base station confirms their carrier, and sends a signal to the mobile telephone switching office (MTSO), which tracks the location of the phone and open frequencies available to the call. If the person moves out of range of the first base station into another cell, the MTSO switches the call to an open channel on the base station in the next cell. This network allowed for a large volume of calls and frees callers to move across a city without losing a signal.
So, for many people in 1973, the future of wireless mobile phones meant car phones. But not to Martin Cooper. Cooper, born in Chicago in 1928, earned an engineering degree from the Illinois Institute of Technology in 1950. After a stint in the Navy Reserves, he joined Chicago-based Motorola in 1954 and was assigned to an engineering team that developed the first portable, handheld police radios. He spent nearly 30 years at Motorola, earning his master's degree and eventually becoming a visionary behind the cell phone.
Cooper's hand-held, portable phone, the DynaTAC, was 10 inches long and weighed just under 3 pounds. On the day that Cooper called Engel to brag about his achievement, Motorola announced that the phone would be available for public use by 1976 — if the Federal Communications Commission opened up new radio frequencies.
Radio spectrum fell under the control of the FCC. Both AT&T and Motorola applied for spectrum to develop a cellular mobile phone business, whether for cars or handheld phones. In the meantime, Japan debuted a commercial cell phone system in 1979, and several Nordic countries followed after.
In 1982, the FCC announced which frequencies it would allot to commercial cellular phones and formally opened up competition in the mobile phone industry. Motorola's DynaTAC hit markets the following year. In all, Motorola spent $100 million and 15 years to develop the product. The phone cost nearly $4,000, had one hour of talk time and an eight-hour battery life. It took another decade of engineering advances to make the handheld cell phone more appealing.
Car phones outsold handheld mobile phones until the mid-1990s, when cell phones became smaller and included better batteries. Early models had a briefcase-sized charger. The switch from analog to digital service improved call quality. Organizations such as the Institute of Electrical and Electronics Engineers (IEEE) and systems such as Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA) began to develop international standards for cell phone hardware and networks, allowing for more innovation and competition.
Looking to the future
Martin Cooper left Motorola in 1983 to found his own company called Cellular Business Systems. He moved again in 1992 to ArrayComm Inc., which was working on wireless Internet applications. Again, Cooper correctly predicted the direction of cell phones. Soon calendars, cameras, alarms, calculators and other aspects of personal digital assistants (PDAs) became essential to new models. While phones packed more features, engineers worked to cram as much information over cellular networks as possible with each new generation – 3G, LTE or 4G.