BS 6638-2:1989

National foreword
Committees responsible
Guide
1. Scope
2. Normative references
3. Definitions
4. Data signalling rate characteristics
5. Signal quality from the transmitting DTE
6. Signal quality at the receiving DTE
7. Measurements at the interchange point
Annex
A. Classification of timing relationships
Tables
1. Signal quality characteristics
A.1 Directional sense of timing relationships
Figures
1. Test arrangement for V.28 generators
2. Test arrangement for V.28 loads
3. Test arrangement for V.10 generators and values
    of Cw
4. Test arrangement for V.10 loads
5. Test arrangement for V.11 generators
6. Test arrangement for V.11 loads
7. Codirectional timing
8. Contradirectional timing
9. Illustration of signal quality parameters on
    interchange circuits associated with the transmit
    direction
10. Illustration of signal quality parameters on
    interchange circuits associated with the receive
    direction
A.1 Direction of timing and data interchange circuits

Signal quality requirements for serial data transmission.

1.1 This International Standard specifies signal quality requirements for serial data transmission at the interface between synchronous transmission Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE). The interface referred to in this International Standard conforms to CCITT Recommendations V.24 (telephone networks), X.24 (data networks) as specified in DCEs of CCITT Recommendations:

V.22, V.22bis, V.23, V.26. V.26bis, V.26ter, V.27, V.27bis, V.27ter, V.29, V.32, V.33, or

X.21bis together with V.28, electrical characteristics; or

V.35 together with V.28/V.35 electrical characteristics; or

V.36, V.37 or X.21 together with V.10/V.11, electrical characteristics; or

X.22 together with V.11, electrical characteristics.

It is also recognized and considered that during the evolution of ISDN there will exist V.-series and X.-series type interfaces at ISDN Reference point R, as specified in CCITT Recommendations V.110, X.30 and X.31.

The speed limitation is determined by the referenced CCITT DCE Recommendations in the X. (e.g. X.10) and V. (e.g. V.5, V.6) series.

The signal quality requirement is limited to synchronous transmission at the interface with synchronous DCEs. Signal quality pertaining to asynchronous DTEs is not part of this International Standard.

1.2 This International Standard recognizes the need to have performance categories of signal quality depending on the type of interchange circuits used at the interface for signal element timing. Two classes of timing, codirectional timing and contradirectional timing, are considered.

The signal quality is categorized by measurements of timing displacement between data and timing signals, of jitter, duty cycle, and accuracy of the timing signals. Application to ISDN Reference point S/T is excluded.

1.3 This International Standard is of particular importance when the interconnected equipment is furnished by different organizations. It does not attempt to indicate what action, if any, is to be taken if the limits are not met, but it is intended to provide a basis for agreement between parties involved.

1.4 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.

1.5 This International Standard may also be used for DTE to DTE direct connections when the referenced CCITT Interfaces are applied.