1、STD.ETS1 ETS 300 462-3-ENGL 3993 3400855 0389600 654 EUROPEAN T 1 ELECOMMUNICATION STANDARD ETS 300 462-1 April 1997 Source: ETSI TC-TM Reference: DETTM-03017-1 ICs: 33.020 Key words: Transmission, synchronization, network, SDH, vocabulary Transmission and Multiplexing (TM); Generic requirements for
2、 synchronization networks; Part 1 : Definitions and terminology for synchronization networks ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.4
3、00: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat?etsi.fr Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 _ Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media, O
4、 European Telecommunications Standards Institute 1997. All rights resewed. STD=ETSI ETS 300 4b2-1-ENGL 1777 3400855 O187bO1 570 9 Page 2 ETS 300 462-1 : April 1997 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may
5、 occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. STD-ETSI ETS 300 462-L-ENGL I1997 3400855 OLB9b02 427 Page 3 ETS 300 462-1 : April 1997 Contents Foreword . 5 1 Scope 7 2 Normative references 7 3
6、Definitions and abbreviations 7 3.1 Definitions 7 General definitions 7 Definitions related to clock equipments . 8 Definitions related to synchronization networks 9 Definitions related to clock modes of operation (applicable to slave clocks) . 9 Definitions related to clock characterization 10 3.2
7、Abbreviations . 12 3.1 . 1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 Synchronous Digital Hierarchy (SDH) specific definitions . 12 4 Measurement configurations . 13 Synchronized clock measurement configuration . 13 4.1 4.2 Independent clock measurement configuration . 14 Annex A (normative): Mathematical models
8、 of timing signals . 16 A.l Total instantaneous phase model of an ideal timing signal . 16 A.2 Total instantaneous phase model of actual timing signals 16 A.3 Time error model . 16 Annex B (informative): Definitions and properties of frequency and time stability quantities 17 6.1 Allan deviation (AD
9、EV) 17 6.2 Modified Allan deviation (MDEV) . 19 6.3 Time deviation (TDEV) 20 6.4 Root mean square Time Interval Error (TIErms) . 22 6.5 Maximum Time Interval Error (MTIE) 23 Annex C (informative): Bibliography 25 History 26 STDOETSI ETS 300 462-L-ENGL 1997 3400855 OL89b03 3b3 = Page 5 ETS 300 462-1
10、: April 1997 Foreword This part one of European Telecommunication Standard (ETS) has been produced by the Transmission and Multiplexing (TM) Technical Committee of the European Telecommunications Standards Institute (ET SI). This ETS has been produced to provide requirements for synchronization netw
11、orks that are compatible with the performance requirements of digital networks. It is one of a family of ETSs covering various aspects of synchronization networks: Part 1: “Definitions and terminology for synchronization networks“ (ETS 300 462-1 2); Part 2: “Synchronization network architecture“ (ET
12、S 300 462-2 3); Part 3: Part 4: Part 5: “The control of jitter and wander within synchronization networks“ (ETS 300 462-3 4); “Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment“ (ETS
13、300 462-4); “Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment“ (ETS 300 462-5); Part 6: “Timing characteristics of primary reference clocks“ (ETS 300 462-6 6). Transposition dates Date of adoption: 4 April 1997 Date of latest announcement
14、 of this ETS (doa): Date of latest publication of new National Standard or endorsement of this ETS (dop/e): 31 July 1997 31 January 1998 Date of withdrawal of any conflicting National Standard (dow): 31 January 1998 Previous page is blaiik 1 Scope This part one of European Telecommunication Standard
15、 (ETS) 300 462 specifies the definitions and abbreviations, used in the other parts of the ETS 300 462 family of ETSs. 2 Normative references This ETS incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the
16、 text of the ETS and the publications are listed hereafter. For dated references, subsequent amendments to, or revisions of, any of these publications apply to this ETS only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to ap
17、plies. I11 Pl 31 41 151 161 171 Pl 3 3.1 ITU-R Recommendation 686 (1 990): “Standard frequencies and time signals -Glossary“. ETS 300 147 (1 996): “Transmission and Multiplexing (TM); Synchronous Digital Hierarchy (SDH) Multiplexing Structure“. prETS 300 462-4: “Transmission and Multiplexing (TM); G
18、eneric requirements for synchronization networks; Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment“. ETS 300 462-5: “Transmission and Multiplexing (TM); Generic requirements for sync
19、hronization networks; Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment“. prETS 300 462-6: “Transmission and Multiplexing (TM); Generic requirements for synchronization networks: Timing characteristics of primary reference clocks“. ITU-T R
20、ecommendation G.701 (1 993): “Vocabulary of digital transmission and multiplexing, and pulse code modulation (PCM) terms“. ITU-T Recommendation G.704 (1 995): “Synchronous frame structures used at 1 544, 6 312, 2 048, 8 488 and 44 736 kbits hierarchical levels“. ITU-T Recommendation G.832 (1995): “T
21、ransport of SDH elements on PDH networks: Frame and multiplexing structures“. Definitions and abbreviations Definitions For the purposes of this family of ETS, the following definitions apply: 3.1.1 General definitions bilateral: A synchronization link where the corrective action to maintain locking
22、 is active at both ends of the link. jitter: Short term variations of the significant instants of a digital signal from their reference positions in time. network synchronization: A generic concept that depicts the way of distributing a common time and/or frequency to all elements in a network. sing
23、le ended synchronization: A method of synchronizing a specified synchronization node with respect to another synchronization node in which synchronization information at the specified node is derived from the phase difference between the local clock and the incoming digital signal from the other nod
24、e. Previous page is blank STDmETSI ETS 300 Yb2-1-ENGL 1997 3400855 0189605 136 Page 8 ETS 300 462-1 : April 1997 slip: The repetition or deletion of a block of bits in a synchronous or plesiochronous bit stream due to a discrepancy in the read and write rates at a buffer. synchronization chain: An a
25、ctive interconnection of synchronization nodes and links. synchronization reference chain: A specific synchronization chain defined in this family of ETSs to form the basis for simulations of jitter and wander in the synchronization network. synchronization status message: A coding of the reference
26、level of the timing source as specified in ETS 300 147 2 for STM-N, ITU-T Recommendation G.704 7 for 2 048 kbiffs, ITU-T Recommendation G.832 8 for synchronous 34 and 140 Mbiffs. time: Is used to specify an instant (time of the day) or as a measure of time interval. NOTE 1: The words time or timing,
27、 when used to describe synchronization networks, usually refer to the frequency signals used for synchronization or measurement. time scale: A system of unambiguous ordering of events. NOTE 2: This could be a succession of equal time intervals, with accurate references of the limits of these time in
28、tervals, which follow each other without any interruption since a well defined origin. A time scale allows to date any event. For example, calendars are time scales. A frequency signal is not a time scale (every period is not marked and dated). For this reason “Universal Time Coordinated (UTC) frequ
29、ency“ should be used instead of “UTC. unilateral: A synchronization link where the corrective action to maintain locking is only active at one end of the link. Universal Time Coordinated (UTC): The time scale, maintained by the Bureau International des Poids et Mesures (BIPM) and the International E
30、arth Rotation Service (IERS), which forms the basis of a coordinated dissemination of standard frequencies and time signal. NOTE 3: The reference frequency for network synchronization is the frequency which generates the UTC time scale. It is therefore preferable to use the words “UTC frequency“ ins
31、tead of “UTC“. wander: The long term variations of the significant instances of a digital signal from their ideal positions in time (where long term implies that these variations are of frequencies less than 10 Hz). NOTE 4: For the purposes of this family of ETSs, this definition of wander does not
32、include integrated frequency departure. 3.1.2 Definitions related to clock equipments clock: A device which provides a reference timing signal. frequency standard: A generator, the output of which is used as a measurement reference timing signal. local node: A synchronous network node which interfac
33、es directly with customer equipment. master clock: A clock providing a reference timing signal to other clocks, behaving as slave clocks. node clock: Clock distributing synchronization reference timing signals within a node. Primary Reference Clock (PRC): A reference clock that provides a reference
34、timing signal compliant with ETS 300 462-6 5, in order to synchronize all or a large part of a network. slave clock: A clock which is locked to a reference timing signal. NOTE 1: When a slave clock loses all its reference timing signals and goes holdover, it can be considered as being a master clock
35、 under these conditions. STD-ETSI ETS 300 462-L-ENGL 3997 3400855 0389606 072 Page 9 ETS 300 462-1 : April 1997 NOTE 2: In locked mode, the slave clock is synchronized to a reference timing signal. The output frequency of the clock is the same as the frequency of the reference timing signal over the
36、 long term, and the phase difference between the input and the output is bounded. Stand Alone Synchronization Equipment (SASE): The stand alone implementation of the logical SSU function, which incorporates its own management function. Synchronization Supply Unit (SSU): A logical function for refere
37、nce timing signal selection, processing and distribution, having the frequency characteristics given in ETS 300 462-4 3. transit node: A synchronous network node which interfaces with other nodes and does not directly interface with customer equipment. 3.1.3 Definitions related to synchronization ne
38、tworks asynchronous mode: A mode where clocks are intended to operate in free running mode. NOTE: This definition applies to clocks. However a more general definition applying to data network is in ITU-T Recommendation G.701 6. master slave mode: A mode where a designated master clock provides refer
39、ence timing signals which are disseminated to all other clocks which are slaved to the master clock. mutually synchronized mode: A mode where all clocks exert a degree of control of each other. plesiochronous mode: A mode where the essential characteristic of time scales or signals such that their c
40、orresponding significant instants occur at nominally the same rate, any variation in rate being constrained within specified limits. pseudo-synchronous mode: A mode where all clocks have a long term frequency accuracy compliant with a primary reference clock as specified in ETS 300 462-6 5 under nor
41、mal operating conditions. Not all clocks in the network will have timing traceable to the same PRC. synchronization link: A link between two synchronization nodes over which a reference timing signal is transmitted. synchronization network: A network to provide reference timing signals. In general,
42、the structure of a synchronization network comprises synchronization nodes connected by synchronization links. synchronization trail: The logical representation of one or several synchronization links. synchronous network: Where all clocks have the same long term accuracy under normal operating cond
43、itions. 3.1.4 Definitions related to clock modes of operation (applicable to slave clocks) free running mode: An operating condition of a clock, the output signal of which is strongly influenced by the oscillating element and not controlled by servo phase-locking techniques. In this mode, the clock
44、has never had a network reference input, or the clock has lost external reference and has no access to stored data, that could be acquired from a previously connected external reference. Free-run begins when the clock output no longer reflects the influence of a connected external reference, or tran
45、sition from it. Free run terminates when the clock output has achieved lock to an external reference. STDIETS1 ETS 300 462-L-ENGL 1997 W 3400855 0389607 TO9 m Page 10 ETS 300 462-1 : April 1997 holdover mode: An operating condition of a clock which has lost its controlling input and is using stored
46、data, acquired while in locked operation, to control its output. The stored data are used to control phase and frequency variations, allowing the locked condition to be reproduced within specifications. Holdover begins when the clock output no longer reflects the influence of a connected external re
47、ference, or transition from it. Holdover terminates when the output of the clock reverts to locked mode condition. locked mode: An operating condition of a clock in which the output signal is controlled by an external input reference. It is the expected mode of operation of a slave clock and the sta
48、te in which each clock within a chain of clocks has the same long term average frequency. 3.1.5 Definitions related to clock characterization ageing: lhe systematic change in frequency of an oscillator with time. NOTE 1: It is the frequency drift when factors external to the oscillator (environment,
49、 power supply, temperature, etc.) are kept constant. An ageing value should always be specified together with the corresponding duration. fractional frequency deviation: The difference between the actual frequency of a signal and a specified nominal frequency, divided by the nominal frequency. Mathematically, the fractional frequency deviation y(t) can be expressed as: frequency accuracy: The maximum magnitude of the fractional frequency deviation for a specified time period. NOTE 2: The frequency accuracy includes the initial frequency offset and any ag
