Total Access Communication System

analog mobile phone system standard, introduced in the Americas during the early 1980s. Though analog is no longer considered advanced at all, the relatively seamless cellular switching technology AMPS introduced was what made the original mobile radiotelephone practical, and was considered quite advanced at the time.

Technology

It was the first-generation technology, using FDMA, which has inherent problems with capacity and security. Each cell has 416 channels or frequencies in the 824~849MHz range for transmissions from mobile stations, paired with 416 channels in the 869~894MHz range for transmissions from base stations, and must use a different set than neighboring cells to avoid interference. This significantly reduces the number of channels available at each site in real-world systems. Each AMPS channel pair is 30kHz wide. The AMPS band was taken from the same 806~890MHz frequency band which was originally UHF TV channels 70~83. (The remainder went mostly to public safety use, after the few TV stations using those channels were required to move.)

Later, AMPS was upgraded to D-AMPS, a digital, TDMA, based 2G standard. The first version of the D-AMPS standard was known as IS-54. IS-54 and was supplanted by IS-136.

Total Access Communication System or TACS is the European version of AMPS. ETACS was an extended version of TACS with more channels. TACS and ETACS are now obsolete in Europe, having been replaced by the more scalable and all-digital GSM system.

Companies using AMPS

• Telecom New Zealand - Telecom customers are in the process of migrating over to the new CDMA service. The old AMPS/D-AMPS system is due to be phased out in 2007. Since the establishment of the AMPS service in 1987 the network had always had the largest coverage of any network in New Zealand. However in recent times Digital GSM and CDMA coverage has matured enough to match or exceed AMPS coverage in many areas.
• Verizon Wireless - Although most Verizon customers use digital PCS services, the backup AMPS network is the largest in the United States.