IGITAL EXCHANGE Telephone Set Figure 30.9 Sidetone influences Summary of interactions 30/11 to tolerate the output jitter and wander from the output of the previous equipment then errors may be introduced. Table 30.2 Main analogue transmission parameters Jitter and wander guidance is given in Recommendation G.823 (CCITT, 1989d). The network structure is important in determining Telephone Local line Digital Digital Exchange end to end performance but the structure and operation of the switch line card network synchronisation system can also have an effect on end to end performance. Timing inaccuracies may result in slips within the SLR/RLR Delay Delay network which appear as error bursts on end to end performance. Loss/frequenc Noise Errors Noise Digital transmission and switching systems are considered in more detail in other sections of this book. It should be appreciated Impedance Impedance Impedance that the interaction of these digital network systems and the resul- tant effect on end to end performance is not straightforward. The Noise Balance Impedance best available guidance on the issues is included in the CCITT G about Earth balance series. Recommendations in particular: about Earth Quantising G.821 Error performance. distortion 2. G.822 Slip rate objectives. 3. G.823 Control of jitter and wander within digital networks. 4. G.811 Timing requirements at the outputs of reference clocks and network nodes. ameters. The use of the term 'all' is intended to cover those network Summary of interactions components where the parameter is relevant. For example loss/fre- quency distortion would not be relevant to a digital line system. The previous section has shown that adequate control of end to end Table 30.3 is the basis of a transmission plan as it identifies the performance requires controlling the performance of many of the network component parameters that determine end to end perfor- mance. network elements. In many cases the performance of a single ele- ment can influence several end to end performance par