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 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.

Another name for IS-54 is United States Digital Cellular ( USDC ).

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 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.

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

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

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

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

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

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

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

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

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

IS-54 employs the same 30 kHz channel spacing and frequency bands ( 824-849 and 869-894 MHz ) as AMPS.

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.

Even the knowledge that she was losing another boy, as a mother always does when a marriage is made, did not prevent her from having the first carefree, dreamless sleep that she had known since they dropped down the canyon and into Bear Valley, way, way back there when they were crossing those other mountains.

And that is the way I first saw her when my Uncle brought her into his antique store.

Why, in the first place, call himself a liberal if he is against laissez-faire and favors an authoritarian central government with womb-to-tomb controls over everybody??

Life is further characterized, in antithesis to Piepsam, as animal: the image of a dog, which appears at several places, is first given as the criterion of amiable, irrelevant interest aroused by life considered simply as a spectacle: a dog in a wagon is `` admirable '', `` a pleasure to contemplate '' ; ;

In the first instance, `` mimesis '' is here used to mean the recalling of experience in terms of vivid images rather than in terms of abstract ideas or conventional designations.

This is the primary function of the imagination operating in the absence of the original experiential stimulus by which the images were first appropriated.

The first half of The Charles Men, ending on the climax of the battle of Poltava in 1709, is more dramatically coherent than the second.

He is, first and foremost, a defender of public morals, a servant of society.

The first of two possible variations on this theme is symbolized by Mickey Spillane's Mike Hammer.

Noting such evidence is the first step ; ;

So it is that we relive his opening statement in the first television address with the dramatic immediacy of the present.

and it is surely clear that the first of these is the result of the way in which the individual's command of language interacts with the other two.

The first thing to do is get her some money by a temporary but definite adjustment pending a final disposition of the case.

When I take over Taliesin, the first thing I'll do is fire you ''.

If `` Jack the Courtier '' is really to be taken as Swift, the following remark is obviously Steele's comment on Swift's change of parties and its effect on their friendship: `` I assure you, dear Jack, when I first found out such an Allay in you, as makes you of so malleable a Constitution, that you may be worked into any Form an Artificer pleases, I foresaw I should not enjoy your Favour much longer ''.

At this point a working definition of idea is in order, although our first definition will have to be qualified somewhat as we proceed.

`` History has this in common with every other science: that the historian is not allowed to claim any single piece of knowledge, except where he can justify his claim by exhibiting to himself in the first place, and secondly to any one else who is both able and willing to follow his demonstration, the grounds upon which it is based.

We saw it frequently afterward, but our suggestion for the very first encounter is near sunset.

Master Gorton, having foully abused high and low at Aquidneck is now bewitching and bemaddening poor Providence, both with his unclean and foul censures of all the ministers of this country ( for which myself have in Christ's name withstood him ), and also denying all visible and external ordinances in depth of Familism: almost all suck in his poison, as at first they did at Aquidneck.