AMPS (advanced mobile phone service)

Advanced Mobile Phone Service (AMPS) was one of the first cellular telephone systems to be widely used in North America. It was developed in the 1980s and was the first standardized cellular system. AMPS was a popular analog system that allowed users to make and receive calls, send and receive text messages, and access data services. In this article, we will explore the features of AMPS, how it worked, and its impact on the development of cellular telephony.

History of AMPS

The history of AMPS can be traced back to the early 1970s when cellular technology was first introduced. At the time, the Federal Communications Commission (FCC) allocated spectrum for cellular use, but the technology was still in its infancy, and there were no standardized systems. As a result, different companies were developing their own systems, which were not compatible with each other.

In 1979, a group of industry experts came together to develop a standardized cellular system that would be compatible with all equipment. This group was called the Cellular Telecommunications Industry Association (CTIA), and they developed AMPS. In 1982, the FCC approved AMPS as the first standardized cellular system in the United States. AMPS was deployed commercially in 1983 and quickly became popular due to its reliability and widespread coverage.

Features of AMPS

AMPS had several features that made it a popular cellular system in the 1980s and 1990s. One of the most significant features was its analog technology. AMPS used analog signals to transmit voice and data. Analog signals are continuous waveforms that vary in frequency and amplitude. AMPS used frequency modulation (FM) to modulate the voice signal onto a carrier wave. The carrier wave was then transmitted over the airwaves to the cell tower. The tower demodulated the signal and sent it to the Public Switched Telephone Network (PSTN).

AMPS also had a large coverage area. The system used a cell-based architecture that divided the coverage area into cells. Each cell was serviced by a cell tower that transmitted and received signals from mobile phones within its coverage area. The cell towers were connected to a Mobile Telephone Switching Office (MTSO), which controlled the routing of calls and data between cell towers and the PSTN.

Another important feature of AMPS was its ability to support multiple users simultaneously. The system used a frequency division multiple access (FDMA) technique to allocate different frequency bands to each call. FDMA allowed multiple users to make calls at the same time without interference. However, FDMA also limited the number of users that could be supported within a single cell.

How AMPS worked

AMPS was designed to be a reliable and efficient cellular system. When a user placed a call on an AMPS phone, the phone transmitted an analog signal to the nearest cell tower. The cell tower received the signal and transmitted it to the MTSO. The MTSO then routed the call to the destination phone number. The process was reversed for incoming calls.

AMPS used a technique called frequency reuse to increase the capacity of the system. Frequency reuse allowed the same frequency band to be used in different cells without interference. The cells were separated by a certain distance, which prevented signals from overlapping. This technique allowed the system to support more users than it would have been possible otherwise.

Impact of AMPS

AMPS was a groundbreaking cellular system that had a significant impact on the development of mobile telephony. The system was reliable and efficient, which made it a popular choice for consumers. AMPS paved the way for future cellular systems, such as digital systems, which would eventually replace analog systems.

The popularity of AMPS also led to the development of other cellular technologies, such as Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM). CDMA was introduced in the 1990s and offered several advantages over AMPS. CDMA was a digital cellular technology that provided better call quality and increased capacity. It also allowed for more secure communication and reduced interference. CDMA was eventually adopted by many cellular carriers in the United States and around the world.

GSM was another digital cellular technology that was introduced in the 1990s. GSM was developed in Europe and quickly became the dominant cellular system in Europe, Asia, and other parts of the world. GSM used a different modulation scheme than CDMA and allowed for better call quality and increased capacity. It also offered several features that were not available in AMPS, such as text messaging and data services.

The introduction of CDMA and GSM led to the eventual phase-out of AMPS. Many cellular carriers began to transition to digital systems in the late 1990s and early 2000s. The FCC also started to re-allocate spectrum from analog to digital systems, which made it more difficult for carriers to operate AMPS.

Conclusion

AMPS was a significant technological advancement in the field of mobile telephony. It was the first standardized cellular system in the United States and was widely adopted due to its reliability and coverage. AMPS paved the way for future cellular systems, such as CDMA and GSM, which offered several advantages over analog systems. Although AMPS has been phased out, its legacy can still be seen in the modern cellular systems that we use today.