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.

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

The IS-54 VSELP standard was published by the Telecommunications Industry Association in 1989.

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.

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.

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

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

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.

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

IS-54 employs the same 30 kHz channel spacing and frequency bands ( 824-849 and 869-894 MHz ) 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-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 also supported authentication, a help in preventing fraud.

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

He was, in fact, showing signs of reviving.

So simple, in fact, that it might even work -- although Pamela, now, in her new frame of mind, was careful not to pretend too much assurance.

The mere fact that the tall figure with the rifle and field glasses had been seen riding that way was enough to frighten three rustling homesteaders out of the Upper Laramie country in a single week.

In fact, I was watching you on that little seventeen-inch screen when you rang my bell.

Her heart, her maternal feeling, in fact her being was too busy expressing itself, as quietly thrilled by this sight of her Nicolas curled asleep under a blanket, in a park like a scene from Poussin.

His advice, his voice saying his poems, the fact that he had not so much as touched her -- on the contrary, he had put his head back and she had stroked his hair -- this was all new.

It was also subtly familiar, for it was the odor of the human body, but multiplied innumerable times because of the fact that the aborigines never bathed.

But though the Southern States, when drafting a constitution to unite themselves, narrowed the difference to this fine point by omitting to assert the right to secede, the fact remained that by seceding from the Union they had already acted on the concept that it was composed primarily of sovereign states.

To my knowledge, Lincoln remains the only Head of State and Commander-in-Chief who, while fighting a fearful war whose issue was in doubt, proved man enough to say this publicly -- to give his foe the benefit of the fact that in all human truth there is some error, and in all our error, some truth.

But he was `` afraid of the future -- he would in fact welcome a way back to social integration, a functional art of some kind ''.

The obvious natural fact to ancient thinkers was the diurnal rotation of the heavens.

It was symbolized ( at least for those of us who recognized ourselves in the image ) by that self-consuming, elegiac candle of Edna St. Vincent Millay's, that candle which from the quatrain where she ensconced it became a beacon to us, but which in point of fact would have had to be as tall as a funeral taper to last even the evening, let alone the night.

To you, for instance, the word innocence, in this connotation, probably retained its Biblical, or should I say technical sense, and therefore I suppose I must make myself quite clear by saying that I lost -- or rather handed over -- what you would have considered to be my innocence two weeks before I was legally entitled, and in fact by oath required, to hand it over along with what other goods and bads I had.

One cause of Schopenhauer's pessimism was the fact that he failed to learn the guitar.

By this time she had learned that it was futile to argue with her young husband, yet the uncomfortable fact remained: the American Congregationalists were sending them as missionaries to the Far East and paying their salaries.

That unused room was large enough for -- well, say an elephant could get into it and, as a matter of fact, an elephant did.

He also disliked Runyon, for no good reason other than the fact that the Demon's talent was so marked as to put him well beyond the Hetman's say-so or his supervision.

His accomplishments, and the fact that he was resident, did much to offset the unkind words travelers used to describe Little Rock after a visit there.

Underneath all the high-sounding phrases of royal and papal letters and behind the more down-to-earth instructions to the envoys was the inescapable fact that Edward would have to desert his Flemish allies and leave them to the vengeance of their indignant suzerain, the king of France, in return for being given an equally free hand with the insubordinate Scots.

It was Plummer, in fact, who coined the much quoted remark: `` Mr. Green indeed writes as if he had been present at the landing of the Saxons and had watched every step of their subsequent progress ''.

But his rancor did not cease, and presently, on March 13, when he preached a sermon on the text, `` And Ben-hadad Was Drunk '', he told his congregation how disappointed he was in Mr. Lewis, how he regretted having had him in his house, and how he should have been warned by the fact that the novelist was drunk all the time that he was working on the book.

the mere fact that he was selected, though as a substitute, to act as interlocutor or moderator for it, or perhaps we should say with Buck as ' father of the act ', is in itself a difficult phase of his development to grasp.