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1、BRITISH STANDARD BS ISO/IEC 7480:1991 Implementation of ISO/IEC 7480:1991 Information technology Telecommunications and information exchange between systems Start-stop transmission signal quality at DTE/DCE interfaces Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Un
2、controlled Copy, (c) BSI BS ISO/IEC 7480:1991 This British Standard, having been prepared under the direction of the Information Systems Technology Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 1 April 1992 BSI 08-1999 The following BSI
3、 references relate to the work of this standard: Committee reference IST/6 Draft for comment 91/61646 DC ISBN 0 580 20792 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-)
4、 to Technical Committee IST/6, upon which the following bodies were represented: British Computer Society British Railways Board British Telecommunications plc Department of Trade and Industry (IT Standards Unit) Digital Equipment Co Ltd. HM Treasury (Central Computer and Telecommunications Agency)
5、IBM United Kingdom Ltd. Information Systems Committee of the Universities Funding Council International Computers Limited Logica UK Ltd. Ministry of Defence Swift Project Consortium Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:
6、30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO/IEC 7480:1991 BSI 08-1999i Contents Page Committees responsibleInside front cover National forewordii Forewordiii Text of ISO/IEC 74801 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS I
7、SO/IEC 7480:1991 ii BSI 08-1999 National foreword This British Standard reproduces verbatim ISO/IEC 7480:1991 and implements it as the UK national standard. It supersedes BS 6638-1 which is withdrawn. This British Standard is published under the direction of the Information Systems Technology Standa
8、rds Policy Committee whose Technical Committee IST/6 has the responsibility to: aid enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and Europea
9、n developments and promulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from BSI Sales Department, BSI, Linford Wood, Milton Keynes, MK14 6LE. A British Standard does not purport to include all the necessary provisions of a contract. Users
10、 of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the ISO/IEC title page, pages ii to iv, pa
11、ges 1 to 11 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c)
12、BSI Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO/IEC 7480:1991(E) ii BSI 08-1999 Contents Page Forewordiii Introduction1 1Scope1 2Normative references2 3Definitions2 4Signal quality from the transmitting DTE4 5Margin of the receiving
13、DTE4 6Measurements at the interchange point6 Annex A (informative) Signal quality at asynchronous transmission interfaces Mathematical relationship between signal quality parameters11 Figure 1 Test arrangement for V.28 generators7 Figure 2 Test arrangement for V.28 loads7 Figure 3 Test arrangement f
14、or V.10 generators and values of Cw8 Figure 4 Test arrangement for V.10 loads9 Figure 5 Test arrangement for V.11 generators9 Figure 6 Test arrangement for V.11 loads10 Table 1 Signal quality characteristics5 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolle
15、d Copy, (c) BSI ISO/IEC 7480:1991(E) BSI 08-1999iii Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the d
16、evelopment of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-gover
17、nmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publ
18、ication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. International Standard ISO/IEC 7480 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology: This second edition cancels and replaces the first edition (ISO 7480:198
19、4 ), of which it constitutes a technical revision. Annex A of this International Standard is for information only. Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+0
20、0:00 2006, Uncontrolled Copy, (c) BSI ISO/IEC 7480:1991(E) BSI 08-19991 Introduction The intent of this International Standard is to complement the electrical characteristics specified in CCITT V-series recommendations, and to provide a measurement for the transmission signal quality characteristics
21、 not covered in those documents. The signal quality requirement that start-stop transmission equipment should meet is in part dependent on the application and in part dependent on the mechanism for timing derivation used by the equipment. For early start-stop transmission equipment, timing was deriv
22、ed or controlled from a mechanical source but nowadays an electronic source is commonplace. An additional factor is that, whereas most start-stop transmission carries the timing information inherently within the signalling between the transmitting equipment and the receiving equipment, start-stop eq
23、uipment may interface to a converter which encodes the information within a synchronous transmission system in which case, the required signal quality at the interface to the converter may need to be more tightly controlled. To cover both types of equipment in both types of application, the signal q
24、uality specification in this International Standard is given separately for four performance categories, two of which (P1 and P2) are intended for DTEs using mechanical timing1) and two for DTEs using electronic timing. By having two mechanical categories, early start-stop transmission equipment wit
25、h very limited signal quality capability is accommodated (Category P1). For the two electronic categories, the more stringent (Category II) is for equipment to be connected to synchronous DCEs operating in asynchronous mode in accordance with CCITT Recommendation V.14. For each of the four categorie
26、s defined for the transmitting elements of DTEs (I, II, P1 and P2), four complementary categories are defined for the receiving elements of DTEs (A, B, PA, PB). Notwithstanding the obvious pairings implied by the complementary categories, the intention is that any receiving equipment may operate wit
27、h any transmitting equipment, the actual selection being dependent on such factors as channel characteristics and economic considerations of the data communication system. The importance of this International Standard is particularly evident when the transmitting and receiving equipments are furnish
28、ed by different organizations as it provides a basis for agreement between the parties involved. 1 Scope 1.1 This International Standard specifies signal quality requirements for serial data transmission at the interface between start-stop transmission Data Terminal Equipment (DTE) and Data Circuit-
29、terminating Equipment (DCE). The interface referred to in this International Standard conforms to CCITT Recommendations V.24 (telephone networks) and X.24 (data networks) as specified in DCEs of the following CCITT Recommendations: V.21, V.22, V.22 bis, V.23, V.26 ter, V.32, V.32 bis, X.20, X.20 bis
30、 together with V.28 electrical characteristics: X.20 together with V.10 and/or V.11 electrical characteristics. The signal quality requirement is limited to start-stop transmission at the interface with asynchronous DCEs, or with synchronous DCEs operating in asynchronous mode in accordance with CCI
31、TT Recommendations V.14 or V.42. Signal quality pertaining to DTEs working in a synchronous mode of operation is not part of this International Standard. This International Standard is also applicable when the interface as specified in the above CCITT Recommendations is provided at the ISDN Referenc
32、e point R as defined in CCITT Recommendation 1.411 and as specified in CCITT Recommendations V.110, V.120 and X.30. 1.2 The signal quality characteristics apply regardless of whether or not multiplexing equipment is included. They do not apply where there is intermediate equipment and no signal rege
33、neration is provided between interconnected sections. 1.3 This International Standard does not describe the signal quality of the DCE or the line associated with it. Neither does it describe any requirement for an acceptable bit error rate. 1.4 This International Standard does not specify the speed
34、characteristics. The nominal value of the modulation rate and the character interval are application dependent. 1) It is intended to delete the mechanical categories at the next revision (see footnote 2 to Table 1. At that time, consideration will be given to amending the electronic timing definitio
35、n by replacing “a signal” in the first line by “an isochronous signal” and amending the other definitions accordingly. Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO/IEC 7480:1991(E) 2 BSI 08-1999 2 Normative references The following st
36、andards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged
37、to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. CCITT Recommendation 1.411:1988, ISDN user network interfaces Reference configurations. CCITT Recommendation V.1
38、0 (= X.26):1988, Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications. CCITT Recommendation V.11 (= X.27):1988, Electrical characteristics for balanced double-current interchange circuits f
39、or general use with integrated circuit equipment in the field of data communications. CCITT Recommendation V.14:1988, Transmission of start-stop characters over synchronous bearer channels. CCITT Recommendation V.21:1988, 300 bits per second duplex modem standardized for use in the general switched
40、telephone network. CCITT Recommendation V.22:1988, 1 200 bits per second duplex modem standardized for use in the general switched telephone network and on point-to-point 2-wire leased telephone-type circuits. CCITT Recommendation V.22 bis:1988, 2 400 bits per second duplex modem using the frequency
41、 division technique standardized for use on the general switched telephone network and on point-to-point 2-wire leased telephone-type circuits. CCITT Recommendation V.23:1988, 600/1 200 baud modem standardized for use in the general switched telephone network. CCITT Recommendation V.24:1988, List of
42、 definitions for interchange circuits between data terminal equipment and data circuit-terminating equipment. CCITT Recommendation V.26 ter:1988, 2 400 bits per second duplex modem using the echo cancellation technique standardized for use on the general switched telephone network and on point-to-po
43、int 2-wire leased telephone-type circuits. CCITT Recommendation V.28:1988, Electrical characteristics for unbalanced double-current interchange circuits. CCITT Recommendation V.32:1988, A family of 2-wire, duplex modems operating at data signalling rates of up to 9 600 bit/s for use on the general s
44、witched telephone network and on leased telephone-type circuits. CCITT Recommendation V.32 bis:1990, A duplex modem operating at data signalling rates of up to 14 400 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits. CCITT Recommenda
45、tion V.42:1988, Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion. CCITT Recommendation V.110:1988, Support of data terminal equipments (DTEs) with V-series type interfaces by an integrated services digital network (ISDN). CCITT Recommendation V.120:1988, Support by a
46、n ISDN of data terminal equipment with V-series type interfaces with provision for statistical multiplexing. CCITT Recommendation X.20:1988, Interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) for start-stop transmission services on public data networks. CCIT
47、T Recommendation X.20 bis:1988, Use on public data networks of data terminal equipment (DTE) which is designed for interfacing to asynchronous duplex V-series modems. CCITT Recommendation X.24:1988, List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-t
48、erminating equipment (DCE) on public data networks. CCITT Recommendation X.30:1988, Support of X.21, X.21 bis and X.20 bis based data terminal equipments (DTEs) by an integrated services digital network (ISDN). 3 Definitions For the purposes of this International Standard, the following definitions
49、apply. 3.1 electronic timing an implementation in which a signal serves to determine the duration of signal elements and to achieve synchronization within a transmission system, and is derived from an electronic circuit Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 23 04:36:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO/IEC 7480:1991(E) BSI 08-19993 3.2 mechanical timing an implementation in which a signal serves to determine the duration of signal elements and to achieve synchronization within a transmission system, and is generally d
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