1G Advanced Mobile Phone System (AMPS)
The Advanced Mobile Phone System (AMPS) was developed in 1978, and released to the public in 1983 by Bell Laboratories to cater for increased demand of mobile voice services.
FSKFrequency-Shift Keying signalling was used to connect mobile customers to the base station to place voice calls, this data was transmitted at 10 kbit/sKilobits per second (kbps). Voice data was transmitted over NFMNarrowband Frequency Modulation analog modulation.
As the number of subscribers increased, some 30 kHzKiloHertz (kHz) 10^3 Hz analog voice channels were converted to D-AMPS channels which could service more users using TDMATime Division Multiple Access, at the cost of reduced voice quality.
The technology saw use in many other countries such as Australia, Canada, New Zealand, Pakistan and Spain. However many other countries had created their own systems (Nordic Mobile Telephone (NMT) for example).
In the 1990s, telecommunications companies worldwide started phasing out AMPS services in favour of the improved GSM standard, which provided encryption and data services.
The FCC had originally allocated 40 MHzMegaHertz (MHz) 10^6 Hz of spectrum between 830 MHzMegaHertz (MHz) 10^6 Hz and 870 Mhz, which allowed for 666 voice channel pairs spaced 30 kHzKiloHertz (kHz) 10^3 Hz apart.
This range was expanded to 824-894 MHzMegaHertz (MHz) 10^6 Hz to accommodate more voice channels. The frequencies were previously used for UHFUltra High Frequency (300-3000 MHz) analog TV broadcasting.
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Voice channel and Control channel: