Total Access Communication System

Total Access Communication System (TACS) and ETACS are mostly-obsolete variants of AMPS which were used in some European countries (including the UK & Ireland in 1983). TACS was also used in Japan under the name Japanese Total Access Communication (JTAC).[1][1][2][2] It was also used in Hong Kong.[3] ETACS was an extended version of TACS with more channels.

TACS and ETACS are now obsolete in Europe, having been replaced by the GSM system. In the United Kingdom, the last ETACS service operated by Vodafone was discontinued on 31 May 2001, after sixteen years of service. The competing service in the UK operated by Cellnet (latterly BTCellnet) was closed on Sunday 1st October 2000.

Eircell (now Vodafone Ireland) closed its TACS network on 26 January 2001. This followed a long period during which customers were encouraged to switch to GSM services. When the network was closed, there were very few, if any, active TACS customers left. Customers who switched network were able to keep their phone number, but the (088) prefix was changed to either 087 (Eircell) GSM or 086 (Esat Digifone, now O2 Ireland) GSM. At the time, full mobile number portability was not available to TACS customers and the (088) prefix was closed. An automatic voice message was left in place for 12 months advising callers of the customer's new prefix.

ETACS is however still in use in a handful of countries elsewhere in the world. NMT is another analog cellular standard that was widely used in Europe, mainly in the Nordic countries, which has now been fully replaced by GSM except for limited use in rural areas due to its superior range.

Frequency bands used by ETACS in the UK

Channel Cell TX (MHz) Mobile TX (MHz) Notes ..............
1 935.0125 890.0125 25 kHz spaced channels
23 935.5625 890.5625 1st of 21 dedicated vodafone control channels
24 935.5650 890.5650 2nd of 21 dedicated vodafone control channels
300 942.4875 898.0625 9.5 kHz peak speech fm deviation
323 943.0625 898.0625 1st of 21 dedicated cellnet control channels
600 949.9875 904.9875 last TACS channel, ETACS extended this to 1320 later
0

TACS BAND Summary

Base TX Start End (MHz) Mobile start End (MHz) BAND
935 950 890 905 TACS 600 Channels
935 960 890 915 TACS 1000 Channels
917 950 872 905 E-TACS 1320 Channels

UK ETACS and USA AMPS compared

Feature TACS AMPS Notes ..............
Channel Spacing 25 kHz 30 kHz
Speech peak Freq Dev 9.5 kHz 12 kHz
Signalling FSK peak Freq Dev 6.4 kHz 8 kHz
Signalling rate 8 kbit/s 10 kbit/s
SAT 0 5970 Hz 5970 Hz
SAT 1 6000 Hz 6000 Hz
SAT 2 6030 Hz 6030 Hz
ST 8000 Hz
Mobile TX pwr MAC 0 2.82 W
Mobile TX pwr MAC 1 1.12 W
Mobile TX pwr MAC 2 447 mW
Mobile TX pwr MAC 3 178 mW
Mobile TX pwr MAC 4 70.8 mW
Mobile TX pwr MAC 5 28.2 mW
Mobile TX pwr MAC 6 11.2 mW
Mobile TX pwr MAC 7 4.5 mW

References

  1. ^ a b GSM Terma, volny.cz. Article retrieved 2006-01-19.
  2. ^ a b Japanese Total Access Communication (JTAC), mobiledia.com. Article retrieved 2007-01-19.
  3. ^ Cellular Networks QuickStart: Getting up to Speed on Cellular, from 1G to 3G, devx.com. Article dated 2003-03-17, retrieved 2007-01-19.

BT Engineering Journal Vol 4 July 1985

Smith Myers ART 775 User Manual