1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0900101.2013 SYNCHRONIZATION INTERFACE STANDARD As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing business priorities. Through ATIS committee
2、s and forums, nearly 200 companies address cloud services, device solutions, emergency services, M2M communications, cyber security, ehealth, network evolution, quality of service, billing support, operations, and more. These priorities follow a fast-track development lifecycle from design and innov
3、ation through solutions that include standards, specifications, requirements, business use cases, software toolkits, and interoperability testing. ATIS is accredited by the American National Standards Institute (ANSI). ATIS is the North American Organizational Partner for the 3rd Generation Partners
4、hip Project (3GPP), a founding Partner of oneM2M, a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications sectors, and a member of the Inter-American Telecommunication Commission (CITEL). For more information, visit . AMERICAN NATIONAL STAN
5、DARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreeme
6、nt has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made towards their resolution. The use of Ame
7、rican National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Stand
8、ards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute.
9、 Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that act
10、ion be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer holdover characteristics for stratum 2, 3, and 3E
11、 clocks; and second-generation Synchronization Status Message quality levels. ATIS-0900101.2013 ii Foreword The information contained in this Foreword is not part of this American National Standard (ANS) and has not been processed in accordance with ANSIs requirements for an ANS. As such, this Forew
12、ord may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard. As a leading technology and solutions development organization, the Alliance for Telecommunications Industry Solution
13、s (ATIS) brings together the top global information and communications technology (ICT) companies to advance the industrys most-pressing business priorities. ATIS serves the public through improved understanding between carriers, customers, and manufacturers. The Copper/Optical Access, Synchronizati
14、on, and Transport (COAST) Committee - formerly the Optical Transport and Synchronization Committee (OPTXS) - engages industry expertise to develop and recommend standards and technical reports for home, access and transport network and synchronization technologies over copper and optical mediums. CO
15、AST is committed to proactive engagement with national, regional and international standards development organizations and forums that share its scope of work. The technical requirements, measurement techniques, metrics, and operational practices documented in COASTs work products encompass copper a
16、nd optical network interfaces and transceiver functionality required for access to, and transport through, telecommunications networks. ANSI guidelines specify two categories of requirements: mandatory and recommendation. The mandatory requirements are designated by the word shall and recommendation
17、s by the word should. Where both a mandatory requirement and a recommendation are specified for the same criterion, the recommendation represents a goal currently identifiable as having distinct compatibility or performance advantages. Suggestions for improvement of this document are welcome. They s
18、hould be sent to the Alliance for Telecommunications Industry Solutions, COAST,1200 G Street NW, Suite 500, Washington, DC 20005. At the time it approved this document, COAST, which is responsible for the development of this Standard, had the following members: K. Biholar, Alcatel-Lucent, COAST Chai
19、r B. Szeto, Xtera, COAST Vice-Chair L. Cosart, Microsemi COAST SYNC Chair and Technical Editor D. Overdorf, AT in clock the offrequency the f frequency. ideal the if 3.1.3 clock fast mode: An operating condition of a clock in which it is locked to an external reference and is using time constants th
20、at are reduced to quickly bring the local oscillators frequency into approximate agreement with the synchronization reference frequency. 3.1.4 clock free-run mode: An operating condition of a clock whose output signals are internally controlled. The clock has never had, or has lost, external referen
21、ce input and has no access to stored data that was 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 the transition from it. Free-run ends when the clock output is influenced by an ex
22、ternal reference or the process to achieve lock to an external reference. Free-run may provide needed stability when external reference has been lost and stored holdover data has been contaminated or deemed disruptive. 8This document is available from the Alliance for Telecommunications Industry Sol
23、utions. 9This document is available from the Alliance for Telecommunications Industry Solutions. 10This document is available from the International Telecommunication Union (ITU), Place des Nations, 1211 Geneva 20, Switzerland. 11Traditionally, a building contains a single service provider. ATIS-090
24、0101.2013 3 3.1.5 clock holdover mode: An operating condition of a clock that has lost its controlling input and is using stored data, acquired while in normal operation, to control its output. The stored data is averaged to minimize the effects of short-term variations, allowing the normal conditio
25、ns to be simulated within specifications. Holdover terminates when the output of the clock is no longer controlled by the data stored from a previously connected reference. 3.1.6 clock normal mode: An operating condition of a clock in which the output signals are controlled by an external input refe
26、rence. It is the expected mode of operation and is the state that permits each clock, within a chain of clocks, to have the same long-term average frequency. Only autonomous stratum 1 sources of timing require no input and, therefore, have a unique status of “normal“ operation being equivalent to “f
27、ree-run“. 3.1.7 digital signal, level n (DSn): See ATIS-0900102. 3.1.8 digital signal cross-connect, level n (DSX-n): See ATIS-0900102. 3.1.9 fractional frequency offset: A measure of the deviation of the frequency of a signal from the reference, expressed as a ratio. rfrf - foffset frequency Fracti
28、onal where: signal; of output frequency actual f frequency. reference the rf 3.1.10 hold-in range: The largest offset between a slave clocks reference frequency and a specified nominal frequency, within which the slave clock maintains lock as the reference frequency varies arbitrarily slowly over th
29、e frequency range. 3.1.11 jitter: The short term variations of the significant instants (e.g., zero level crossings) of a digital signal from their ideal positions in time. Here, short term implies phase variations of frequency greater than or equal to 10 Hz. Jitter may lead to crosstalk and/or dist
30、ortion of the original analog signal and is a potential source of bit errors at the input ports of digital equipment. 3.1.12 maximum time interval error (MTIE): For a sequence of time delay samples xi, MTIE at observation time (S) is: )x(min)x(maxmax)S(MTIEijnjiijnjinNj1111where: N = Number of sampl
31、es in the sequence;= Sample period; 1 + = oSn Annex C illustrates MTIE terminology. 3.1.13 node or digital node: A geographic location at which there is one or more interconnected synchronous digital equipment. 3.1.14 optical carrier level N (OC-N): See ATIS-0900105. 3.1.15 phase: Phase is usually q
32、uantified in units of degrees or radians in scientific literature. In this standard, phase is described broadly in units of time. (See also 3.1.27, time delay.) 3.1.16 phase transients: Perturbations in phase of limited duration seen at synchronization interfaces. Typical duration is several time co
33、nstants of the slave clock that produces it. ATIS-0900101.2013 4 3.1.17 plesiochronous12: Two signals are plesiochronous if their corresponding significant instants (e.g., zero level crossings) occur at nominally the same rate, with any variation in rate being constrained within specified limits. In
34、 this standard, two networks are said to be operating plesiochronously if they are both PRS traceable, but to different PRSs. 3.1.18 pointer justification: Technique for accommodating timing differences within SONET. See ATIS-0900105. 3.1.19 primary reference source (PRS): Equipment that provides a
35、timing signal whose long term accuracy is maintained at 1 x 10-11or better with verification to coordinated universal time (UTC) - that is, time and frequency standard maintained by the US National Institute of Standards and Technology and whose timing signal may be used as the basis of reference fo
36、r the control of other clocks within a network. The primary reference source may generate a timing signal completely autonomous of other references, for example, by use of cesium beam technology. Alternatively, the primary reference source may not be a completely autonomous implementation: in which
37、case, it may employ direct control from UTC derived frequency and time services. In this standard, PRS is synonymous with stratum 1. 3.1.20 pull-in range: The largest offset between a slave clocks reference frequency and a specified nominal frequency, within which the slave clock will achieve lock.
38、3.1.21 separate network: A node or collection of interconnected nodes whose synchronization responsibilities are borne by a single corporate interest. 3.1.22 slip: Generically, a slip is the repetition or deletion of a block of bits in a bit-stream caused by a sufficiently large discrepancy in the r
39、ead and write rates at a receiver buffer. In a synchronized DS1 network, a “controlled slip“ is the repetition or deletion of the 192 data bits of a DS1 frame, without loss of frame bit integrity. An “uncontrolled slip“ is the repetition, or deletion of bits, where framing integrity is not maintaine
40、d. In this standard, a “slip“ always refers to a controlled slip. 3.1.23 SONET (Synchronous Optical Network): See ATIS-0900105. 3.1.24 stratum levels: Based on performances, the clocks in the synchronization network are classified into four levels, called stratum levels. Stratum 1 is the highest and
41、 stratum 4 the lowest level of performance. 3.1.25 synchronous distribution facility: The transmission facilities used to transport the reference signal from one node to another while maintaining the reference signals quality as defined by the Signal Type (I, II, III, or IV; see clause 6.1). 3.1.26
42、synchronous transport signal level N (STS-N): See ATIS-0900105. 3.1.27 time delay: The measured time difference between the significant instants (e.g., zero level crossings) of the signal waveform under test and those of a reference signal. 3.1.28 time interval error (TIE): The variation in time del
43、ay of a given timing signal with respect to an ideal timing signal over a particular time period. Figure 3.1 illustrates the definition of TIE. 12NOTE : The term, Plesiochronous Digital Hierarchy (PDH), is used in some documents to refer to the family of asynchronously multiplexed signals described
44、in ATIS-0900102 and ITU-T Recommendation G.702. This is inconsistent with the above definition of plesiochronous operation. ATIS-0900101.2013 5 TIESt t +S0 0TimeDelayxtx t +Sx t ( )( )00)t(x)St(x)S,t(000TIE Figure 3.1: Time interval error (TIE) 3.1.29 time deviation TDEV or x: The square root of the
45、 time variance. Time deviation is expressed in units of time, usually nanoseconds. Annex D contains additional information on TDEV. 3.1.30 time variance TVAR or x2: A measure of the expected time variation of a signal as a function of integration time. TVAR can also provide information about the spe
46、ctral content of the phase (or time) noise of a signal. TVAR is in units of time squared. For this standard, TVAR is defined as the following calculation on a time series, such as samples of time delay: )1n3N(6nx2xxTVAR21+3n-N1=j21-n0=kk+jk+n+jk+2n+j2xwhere: are samples of time delay data; is the to
47、tal number of time delay data points; 0is the time interval between neighboring samples; is the integration time, the independent variable of TVAR; is the number of data points in the integration time. Thus, the integration time is0 n . Note that the value of TVAR is independent of 0; Annex D contai
48、ns additional information on the parameter TVAR. 3.1.31 transit node: A node that interfaces with other nodes and does not directly interface with customer equipment. 3.1.32 wander: The long term variations of the significant instants (e.g., zero level crossings) of a digital signal from their ideal
49、 positions in time. Long-term implies that these variations are of low frequency (less than 10 Hz). Wander is mainly generated by the variation in transmission characteristics of the media and equipment, which includes disruptions in synchronization reference distribution. Wander is a potential source of slips in synchronous networks. 3.1.33 quality level (QL): Quality level (QL) is a label assigned to a signal generated by a clock that is used to provide a
