AMPS, TACS, and NMT: Analog Cellular Standards Explained

This page will delve into the differences between AMPS, TACS, and NMT, all of which are analog cellular telephone standards. Let’s break down each one.

• AMPS: Stands for Advanced Mobile Phone System.
• TACS: Stands for Total Access Communication System.
• NMT: Stands for Nordic Mobile Telephone.

AMPS (Advanced Mobile Phone System)

Here are the key features of the AMPS standard, including NAMPS (Narrow Band AMPS):

• Mobile Transmit/Receive Frequency: 824 to 849 MHz (Transmit) and 869 to 894 MHz (Receive)
• Duplex Scheme: FDD (Frequency Division Duplexing)
• Multiple Access Scheme: FDMA (Frequency Division Multiple Access)
• Number of Channels: 832 in AMPS and 2496 in NAMPS
• Number of Users Per Channel: One
• Spacing Between RF Channels: 30 KHz in AMPS and 10 KHz in NAMPS
• Modulation Scheme: FM (Frequency Modulation)

TACS (Total Access Communication System)

The following outlines the characteristics of the TACS standard:

• Mobile Transmit/Receive Frequency:
  • ETACS: 916 to 949 MHz (Receive) and 871 to 904 MHz (Transmit)
  • NTACS: 860 to 870 MHz (Receive) and 915 to 925 MHz (Transmit)
• Duplex Scheme: FDD
• Multiple Access Scheme: FDMA
• Number of Channels: 1240 in ETACS and 400 in NTACS
• Spacing Between RF Channels: 25 KHz in ETACS and 12.5 KHz in NTACS

NMT (Nordic Mobile Telephone)

Below are the features that define the NMT standard:

• Mobile Transmit/Receive Frequency:
  • NMT-450: 463 to 468 MHz (Receive) and 453 to 458 MHz (Transmit)
  • NMT-900: 935 to 960 MHz (Receive) and 890 to 915 MHz (Transmit)
• Duplex Scheme: FDD
• Multiple Access Scheme: FDMA
• Number of Channels: 200 in NMT-450 and 1999 in NMT-900
• Spacing Between RF Channels: 25 KHz in NMT-450 and 12.5 KHz in NMT-900