1、INTERNATIONAL STANDARD ISO/IEC 11573 First edition 1994-l 2-15 Information technology - Telecommunications and information exchange between systems - Synchronization methods and technical requirements for Private Integrated Services Networks Technologies de /information - T thetimedifference between
2、these homologous instants is generally limited. 1.2.19 Synchronization The process of adjusting the corresponding significant instants of signals so that a constant phase relationship exists between them. 1.2.20 Time-Interval Error (TIE) Thevariationintimedelayofagiventimingsignal withrespecttoanide
3、altimingsignaloveraparticulartimeperiod. Figure1 illustrates the definition of TIE. 1.2.21 Timing loop An unstable condition in which two or more equipment clocks transfer timing to each other, forming a loop without a designated master timing source. 1.2.22 Time to repair The time by which, with a
4、stated probability, the link is repaired. 1.2.23 Transparent Alinkorgroupoflinksistransparentifthesignalcarriedisnotre-timedfromaclockassociatedwiththelink(s).Thetimingof a signal passing across atransparent link may however be altered due to jitter, wander, filtering, or fault conditions. Figure 2
5、illustrates the definition of transparent and non transparent links. 1.2.24 Wander The long-term variations of the significant instants of a digital signal from their ideal positions in time. Long-term implies that these variations are of low frequency. o ISOAEC ISO/IEC 11573:1994(E) 1.3 Abbreviatio
6、ns and acronyms AIS: BITS : CCITT : CPE : co: Cl: c2 : C3: DCS : DSX : DTE : ESF : FM: GPS : MTIE : MUX : NCTE : NI : PISN : PINX : wm : PSTN : PLL : PRC : PM: SES : SDH : TO : Tl : T2: TIE : UI: UTC: A1 Time gelay with respect tl ideal referent in seconds Alarm Indication signal Building Integrated
7、 Timing Supply International Telegraph and Telephone Consultative Committee Customer Premises Equipment Basic Rate transparent or non transparent links 1,544 Mbits/s transparent or non transparent links 2,048 Mbits/s transparent or non transparent links Non ISDN transparent or non transparent links
8、Digital Cross-connect System Digital Signal Cross-connect Data Terminal Equipment Extended Super Frame Frequency Modulation Global Positioning System Maximum Time Interval Error (see figurel) Multiplexer Network Channel Terminating Equipment Network Interface Private Integrated Services Network. Pri
9、vate Integrated Services Network Exchange (PABX, Key System, . ). parts per million Public Switched Telecommunication Network Phase Locked Loop Primary Reference Clock Phase Modulation Severely Errored Second Synchronous Digital Hierarchy Basic Rate Access to public ISDN 1,544 Mbits/s Access to publ
10、ic ISDN 2,048 Mbits/s Access to public ISDN Time Interval Error (see figurel) Unit Interval (488 ns for T2 and C2,648 ns for Tl and Cl, 5208 ns for TO and CO) Universal Coordinated Time Slope representing long term frequency departure L Observation period Figure 1 - Time Interval Error (TIE) Figure 2 - Links definition 3
