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 interfacesBSISO/IEC 7480:1991 This British Standard, having been prepared under the direction
2、of the Information Systems Technology StandardsPolicy Committee, waspublished under the authorityof the Standards Boardand comes intoeffect on 1April 1992 BSI 08-1999 The following BSI references relateto the work of this standard: Committee reference IST/6 Draft for comment 91/61646 DC ISBN 0 580 2
3、0792 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/6, upon which the following bodies were represented: British Computer Society British Rai
4、lways Board British Telecommunications plc Department of Trade and Industry (IT Standards Unit) Digital Equipment Co Ltd. HM Treasury (Central Computer and Telecommunications Agency) IBM United Kingdom Ltd. Information Systems Committee of the Universities Funding Council International Computers Lim
5、ited Logica UK Ltd. Ministry of Defence Swift Project Consortium Amendments issued since publication Amd. No. Date CommentsBSISO/IEC 7480:1991 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO/IEC 7480 1BSISO/IEC 7480:1991 ii BSI 08-1
6、999 National foreword This British Standard reproduces verbatim ISO/IEC7480:1991and implements it as the UK national standard. It supersedes BS6638-1which is withdrawn. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committee whose Techn
7、ical Committee IST/6has 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 European developments and promulgate the
8、m in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from BSI Sales Department, BSI, Linford Wood, Milton Keynes, MK146LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsi
9、ble 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, theISO/IEC title page, pages ii to iv, pages1 to 11 and a back cover. This s
10、tandard 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.ISO/IEC 7480:1991(E) ii BSI 08-1999 Contents Page Foreword iii Introduction 1 1 Scope 1 2 Normative references 2 3 Definitions 2 4 Signal qu
11、ality from the transmitting DTE 4 5 Margin of the receiving DTE 4 6 Measurements at the interchange point 6 Annex A (informative) Signal quality at asynchronous transmission interfaces Mathematical relationship between signalqualityparameters 11 Figure 1 Test arrangement for V.28 generators 7 Figure
12、 2 Test arrangement for V.28 loads 7 Figure 3 Test arrangement for V.10 generators and values of C w 8 Figure 4 Test arrangement for V.10 loads 9 Figure 5 Test arrangement for V.11 generators 9 Figure 6 Test arrangement for V.11 loads 10 Table 1 Signal quality characteristics 5ISO/IEC7480:1991(E) BS
13、I 08-1999 iii 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 development of International Standards
14、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-governmental, in liaison with ISO and IEC,
15、also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard re
16、quires approval by at least75% of the national bodies casting a vote. International Standard ISO/IEC7480was prepared by Joint Technical Committee ISO/IEC JTC1,Information technology: This second edition cancels and replaces the first edition (ISO7480:1984), of which it constitutes a technical revisi
17、on. Annex A of this International Standard is for information only.iv blankISO/IEC7480:1991(E) BSI 08-1999 1 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 transm
18、ission signal quality characteristics 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 tra
19、nsmission equipment, timing was derived 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 t
20、he receiving equipment, start-stop equipment 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 bo
21、th types of application, the signal quality specification in this International Standard is given separately for four performance categories, two of which (P1 and P2) are intended for DTEs using mechanical timing 1)and two for DTEs using electronic timing. By having two mechanical categories, early
22、start-stop transmission equipment with 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
23、 V.14. For each of the four categories defined for the transmitting elements of DTEs (I, II, P1and 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
24、 receiving equipment may operate with 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
25、and receiving equipments are furnished 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 Termin
26、al Equipment (DTE) and Data Circuit-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
27、ter, V.32, V.32bis, X.20, X.20 bis together with V.28 electrical characteristics: X.20together with V.10and/or V.11electrical characteristics. The signal quality requirement is limited to start-stop transmission at the interface with asynchronous DCEs, or with synchronous DCEs operating in asynchron
28、ous mode in accordance with CCITT Recommendations V.14or 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
29、 provided at the ISDN Reference point R as defined in CCITT Recommendation1.411and as specified in CCITT Recommendations V.110, V.120and 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 e
30、quipment and no signal regeneration 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
31、does not specify the speed 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
32、electronic timing definition by replacing “a signal” in the first line by “an isochronous signal” and amending the other definitions accordingly.ISO/IEC 7480:1991(E) 2 BSI 08-1999 2 Normative references The following standards contain provisions which, through reference in this text, constitute prov
33、isions 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 to investigate the possibility of applying the most recent editions of the standa
34、rds indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. CCITT Recommendation1.411:1988, ISDN user network interfaces Reference configurations. CCITT Recommendation V.10 (= X.26):1988, Electrical characteristics for unbalanced double-current intercha
35、nge 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 for general use with integrated circuit equipment in the field of data communicatio
36、ns. CCITT Recommendation V.14:1988, Transmission of start-stop characters over synchronous bearer channels. CCITT RecommendationV.21:1988, 300 bits per second duplex modem standardized for use in the general switched telephone network. CCITT RecommendationV.22:1988, 1200 bits per second duplex modem
37、 standardized for use in the general switched telephone network and on point-to-point2-wire leased telephone-type circuits. CCITT Recommendation V.22 bis:1988, 2400 bits per second duplex modem using the frequency division technique standardized for use on the general switched telephone network and
38、on point-to-point2-wire leased telephone-type circuits. CCITT Recommendation V.23:1988, 600/1200 baud modem standardized for use in the general switched telephone network. CCITT RecommendationV.24:1988, List of definitions for interchange circuits between data terminal equipment and data circuit-ter
39、minating equipment. CCITT RecommendationV.26 ter:1988, 2400 bits per second duplex modem using the echo cancellation technique standardized for use on the general switched telephone network and on point-to-point 2-wire leased telephone-type circuits. CCITT RecommendationV.28:1988, Electrical charact
40、eristics for unbalanced double-current interchange circuits. CCITT RecommendationV.32:1988, A family of 2-wire, duplex modems operating at data signalling rates of up to 9600 bit/s for use on the general switched telephone network and on leased telephone-type circuits. CCITT RecommendationV.32 bis:1
41、990, A duplex modem operating at data signalling rates of up to14400bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits. CCITT RecommendationV.42:1988, Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion. C
42、CITT Recommendation V.110:1988, Support of data terminal equipments (DTEs) with V-series type interfaces by an integrated services digital network (ISDN). CCITT RecommendationV.120:1988, Support by an ISDN of data terminal equipment with V-series type interfaces with provision for statistical multip
43、lexing. CCITT RecommendationX.20:1988, Interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) for start-stop transmission services on public data networks. CCITT RecommendationX.20 bis:1988, Use on public data networks of data terminal equipment (DTE) which is d
44、esigned for interfacing to asynchronous duplex V-series modems. CCITT RecommendationX.24:1988, List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) on public data networks. CCITT RecommendationX.30:1988, Support ofX.21, X.21b
45、is andX.20bis based data terminal equipments (DTEs) by an integrated services digital network (ISDN). 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 electronic timing an implementation in which a signal serves to determine the duration of signal e
46、lements and to achieve synchronization within a transmission system, and is derived from an electronic circuitISO/IEC7480:1991(E) BSI 08-1999 3 3.2 mechanical timing an implementation in which a signal serves to determine the duration of signal elements and to achieve synchronization within a transm
47、ission system, and is generally derived from the angular velocity of an electric motor (power frequency used as timing source is also included in this category) 3.3 start-stop system data transmission system in which each signal representing a character is preceded by a start signal which serves to
48、prepare the receiving device for the reception of a character signal and registration of a character, and is followed by a stop signal which serves to prepare the receiving device for the reception of a subsequent start signal 3.4 start-stop transmission asynchronous transmission such that each grou
49、p of signals representing a character is preceded by a start signal and is followed by a stop signal 3.5 continuous start-stop operation method of operation in start-stop transmission in which the signals representing a series of characters follow one another contiguously 3.6 signal element each of the parts constituting a telegraph or data signal and distinguished from the others by its nature, magnitude, duration and relative position (or by one or some of these features only) 3.7 unit interval in a system using an equal length code, or in a sys
