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-terminating Equipment (DCE). The interface referred to in this International Standard conforms to CCITT Recommend ations 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 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 CCITT 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 Reference point R as defined in CCITT Recommendation I.411 and as specified in CCITT Recommendations V.110, V.120 and X.30. 1.2 The signal quality characteristics apply regardless of w hether or not multiplexing equipment is included. They do not apply where there is intermediate equipment 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 does not specify the speed characteristics. The nominal value of the modulation rate and the character interval are application dependent.

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-terminating Equipment (DCE). The interface referred to in this International Standard conforms to CCITT Recommend ations 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 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 CCITT 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 Reference point R as defined in CCITT Recommendation I.411 and as specified in CCITT Recommendations V.110, V.120 and X.30. 1.2 The signal quality characteristics apply regardless of w hether or not multiplexing equipment is included. They do not apply where there is intermediate equipment 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 does not specify the speed characteristics. The nominal value of the modulation rate and the character interval are application dependent.