ommunicating by facsimile can be extended Br. Telecom Technol J. 9, (1), January. to operation with the computer in the briefcase. Transmission di- McConnell, Bodson, Schaphorst (1992) Fax, 2nd. ed., Artech rectly from the keyboard (actually from memory) and soft copy House, ISBN 0-89006-310-9. reception without printing are easily possible with existing fax Payton and Qureshi (1985) Trellis encoding, Data Communication- standards over the PSTN. S, May. Customer requirements dominate facsimile developments and the Pugh, A. (1991) Facsimile Today, Electronics & Communication increase in use of the G3 interface in non-fax products is expected Engineering Journal, October. to continue although the replacement of documents in the briefcase Reardon, R.(Ed.) (1990) Facsimile Networks for the 1990s, Online by facsimile files in the laptop/notebook PC seems remote. Publications, ISBN 0-86353-131-8. This page intentionally left blank Telecommunication system measurements Hugh Walker BA (Cantab) MSc Hewlett-Packard Ltd (Sections 61.1-61.3) Gary Law BSc PhD Andersen Consulting (Section 61.4) A C Keene BSc CEng MIEE Trend Communications Ltd (Section 61.5) J P Russell Trend Communications Ltd (Section 61.5) David Green Rohde & Schwarz (Sections 61.6-61-11) Contents 61.1 Digital circuit testing 61/3 61.9 The OSI Model and GSM 61/24 61.2 Interface measurements 61/3 61.10 The radio path or Physical Layer (Layer 1) 61/25 61.3 Error performance measurements 61/7 61.11 Data Link Layer (Layer 2) 61/30 61.4 Data communications network measurement 61/12 61.12 Network Layer (layer 3) 61/30 61.5 ISDN test equipment 61/16 61.13 A.F. and speech codec measurements 61/30 61.6 Introduction to cellular radio 61/21 61.14 Test set up configurations 61/30 61.7 Analogue cellular test equipment 61/22 61.15 References 61/32 61.8 Digital cellular test equipment 61/23 This page intentionally left blank Digital circuit testing 61/3 Digital circuit testing ment (A-D and D-A) as specified in G.714. Compliance with half channel specifications ensures int