Principles of Synchronous Digital Hierarchy

74 Principles of Synchronous Digital Hierarchy

has to conne itself to the allotted bandwidth so as not to cause interference

with the adjacent channels.

The line code of Figure 4.5 needs double the bandwidth as compared to the

line code of Figure 4.3. This is because the former uses two pulses for every

symbol, whereas the latter uses only one pulse per symbol. As stated in pre-

ceding sections, for higher bandwidth a penalty has to be paid to achieve the

advantage of more transitions in the signal for better timing extraction. If

bandwidth cannot be increased, some other type of line coding will have to

be adopted which can resolve the prob ...