| Analog Service is similar to FM radio in | | | | spectrum technology this technology was |
| that modulating radio signals carry | | | | restricted to military use and top |
| information such as voice or data. The | | | | secret during World War 2. In the 1980's |
| receiver and transmitter must be tuned | | | | the commercial use of this technology |
| to the same frequency within a small | | | | was realized after a 1976 publication of |
| band width for the receiver to rebuild | | | | Spread Spectrum Systems by Robert Dixon |
| the signal, amplify it, and send it to | | | | was published. Previous publications |
| the speaker. There are limitations on | | | | were classified military reports or |
| the number of channels that can be used | | | | narrow subtopics on academic papers. By |
| making this technology soon to be | | | | 1993 CDMA was accepted as a standard and |
| outlived. Effective February 2008, many | | | | went into operation in 1996. CDMA also |
| wireless providers will be discontinuing | | | | exists at both the 800 MHz and 1900 MHz |
| support of this service. | | | | band, and is used by the major carriers. |
| Digital Service is a method similar to | | | | GSM (Global System for Mobile |
| computers, in that it uses binary code | | | | Communications) is based upon an |
| of Os and 1s. Most new wireless phones | | | | improved version of TDMA technology. In |
| and networks use digital technology. The | | | | 1982, a conference in Europe created a |
| analog signal in Digital is converted | | | | digital standard to allow users to roam |
| into binary code and transmitted as a | | | | from country to country in Europe. By |
| series of on and off transmissions. | | | | 1987, the GSM standard was created based |
| There are three digital wireless | | | | upon both analog and TDMA digital |
| technologies, CDMA, TDMA and GSM and I | | | | technologies. Using wider 200 kHz |
| will explain these three as phones that | | | | channels instead of the 30 kHz channels |
| work with one may not work on another. | | | | TDMA used along with other modifications |
| TDMA (Time Division Multiple Access) was | | | | they were able to speed up the bit rate |
| released in 1994; it uses the frequency | | | | with a more natural sounding |
| bands available to the wireless network | | | | voice-compression algorithm. This also |
| and divided them into time slots with | | | | enabled GSM to provide such other data |
| each phone user having access to one | | | | services as email, fax, internet |
| time slot at regular intervals. In North | | | | browsing, and internet/LAN wireless |
| America TDMA uses both 800 MHz and 1900 | | | | access. The GSM standard was accepted in |
| MHz bands. Most of the major wireless | | | | the United States in 1995 and is the |
| carriers use TDMA. | | | | only phone that can be used around the |
| CDMA (Code Division Multiple Access) | | | | world. This technology will be the bases |
| technology dates back to the 1940's, | | | | of future growth in the wireless phone |
| when it was developed for military use | | | | industry as it offers the multifunction |
| because it was resistant to interference | | | | capabilities today's users require. |
| from enemy signals. Known as spread | | | | |