IS-54 was, in fact, backward compatible with analog cellular and indeed co-exists on the same radio channels as AMPS.

To maintain compatibility with the existing AMPS cellular telephone system, the primary forward and reverse control channels in IS-54 cellular systems use the same signaling techniques and modulation scheme ( binary FSK ) as AMPS.

* Digital AMPS ( IS-54 and IS-136 ), a 2G mobile-phone standard that uses Time division multiple access

IS-54 and IS-136 are second-generation ( 2G ) mobile phone systems, known as Digital AMPS ( D-AMPS ).

IS-54 maintains compatibility with Advanced Mobile Phone System ( AMPS ) in many ways.

The IS-54 standard specifies 84 control channels, 42 of which are shared with AMPS.

An AMPS / IS-54 infrastructure can support use of either analog AMPS phones or D-AMPS phones.

That name is based on the abbreviation for time division multiple access, a common multiple access technique which is used by multiple protocols, including GSM, as well as in IS-54 and IS-136.

IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data ( CSD ), and an improved compression protocol.

IS-54 is the first mobile communication system which had provision for security, and the first to employ TDMA technology.

IS-54 stands for Interim Standard-54, which is a mobile communication standard employing digital technology.

The ANSI designation of IS-54 is ANSI / TIA / EIA-627, but this standard is still popularly referred to as IS-54.

The quest resulted in IS-54, the first American 2G standard.

IS-54, on the other hand, increased capacity by digital means using TDMA protocols.

Using IS-54, a cellular carrier could convert any of its system's analog voice channels to digital.

IS-54 also supported authentication, a help in preventing fraud.

The access method used for IS-54 is Time Division Multiple Access ( TDMA ), which was the first U. S. digital standard to be developed.

Time Division Multiple Access or TDMA was initially defined by the IS-54 standard and is now specified in the IS-13x series of specifications of the EIA / TIA.

The IS-54 system has different synchronization sequences for each of the six time slots making up the frame, thereby allowing each receiver to synchronize to its own preassigned time slots.

The modulation scheme for IS-54 is 7C / 4 differential quaternary phase shift keying ( DQPSK ), otherwise known as differential 7t / 4 4-PSK or π / 4 DQPSK.

IS-54 security features is also a matter of interest as it was the first standard to specify some security measures.

IS-54 uses the CAVE ( Cellular Authentication, Voice Privacy and Encryption ) algorithm for authentication and the CMEA ( Cellular Message Encryption Algorithm ) for encryption.

Variations of this codec have been used in several 2G cellular telephony standards, including IS-54, IS-136 ( D-AMPS ), GSM ( Half Rate speech ) and iDEN.

But even if that other plant employs the same number of workers and makes the same product, there are other facts to consider.

It is taught as part of the undergraduate curriculum of any chemical engineering program, and employs many of the same principles in control engineering.

CDMA employs spread-spectrum technology and a special coding scheme ( where each transmitter is assigned a code ) to allow multiple users to be multiplexed over the same physical channel.

Occasionally a database employs storage redundancy by database objects replication ( with one or more copies ) to increase data availability ( both to improve performance of simultaneous multiple end-user accesses to a same database object, and to provide resiliency in a case of partial failure of a distributed database ).

Occasionally a database employs storage redundancy by database objects replication ( with one or more copies ) to increase data availability ( both to improve performance of simultaneous multiple end-user accesses to a same database object, and to provide resiliency in a case of partial failure of a distributed database ).

It usually has three piston valves and employs the same fingering system as other brass instruments, but four piston valve and rotary valve variants also exist.

Most scholars see chapters 1 – 16 ( the Priestly code ) and chapters 17 – 26 ( the Holiness code ) as the work of two related schools, but while the Holiness material employs the same technical terms as the Priestly code, it broadens their meaning from pure ritual to the theological and moral, turning the ritual of the Priestly code into a model for the relationship of Israel to God: as the tabernacle is made holy by the presence of the Lord and kept apart from uncleanliness, so He will dwell among Israel when Israel is purified ( made holy ) and separated from other peoples.

Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose.

The portamento circuitry employs a fixed slide time, meaning that whatever the interval between notes, the time taken to reach the correct pitch is always the same.

The non-dress uniform ( 2 ) employs the same colour scheme, but less decoration.

Upon returning home, he employs the same tactics on his wife ; beating her senseless when she refuses to make what he wants for dinner.

The financial structure and the nature of the CBC often place it in the same category as other national broadcasters, such as the British broadcaster BBC, although unlike the BBC ( and more like the Irish network RTÉ ), the CBC employs commercial advertising to supplement its federal funding on its television broadcasts.

The game employs the same board and pieces as standard chess, but the starting position of the pieces along the players ' home ranks is randomized.

Porro-prism binoculars will inherently produce a brighter image than roof-prism binoculars of the same magnification, objective size, and optical quality, because the roof-prism design employs silvered surfaces that reduce light transmission by 12 % to 15 %.

Traditional thought employs the prefixes hetero-( opposite ), homo-( same ), bi-( two ) and trans-(' across ').

Star Trek: Armada II employs many of the same features of its predecessor, though with a few improvements.

Vendor-managed inventory ( VMI ) employs the same principles as those of JIT inventory, however, the responsibilities of managing inventory is placed with the vendor in a vendor / customer relationship.

" To Autumn " employs poetical techniques which Keats had perfected in the five poems written in the Spring of the same year, but departs from them in some aspects, dispensing with the narrator and dealing with more concrete concepts.

He employs a wide variety of styles, sometimes even within the same work, but aims to make his work accessible to a relatively large audience.

Indeed, Percy Grainger's incomplete orchestral fragment Train Music employs the same function.

Relayer has the same song format as 1972's Close to the Edge — a long epic on the first side, and two nine-minute pieces on the second — but employs a radically different musical style.

Truly a master is at work, and he invokes the same Mock-heroic style in The Dunciad which also employs the language of heroic poetry to describe menial or trivial subjects.

The threshold it employs is not based on empirical research and is not directly related to the NHS budget, nor is it at the same level as that used by Primary Care Trusts ( PCTs ) in providing treatments not assessed by NICE, which tends to be lower.

There is some dispute about who exactly first developed this operating principle, as the SVT's mechanism ( as implemented in 1935 competition prototype ) closely resembles Dieudonné Saive's design of 1937 ; Saive eventually designed the FN FAL, which employs the same operating principle as the SVT.