9.6. Spectral Compatibility of the DSL Systems
This section describes the spectral compatibility of the echo canceled (EC) transmission DSL systems relative to other DSLs deployed in the loop plant. The transmission DSLs included are ISDN, HDSL, and SDSL. For all spectral compatibility studies done in this chapter, only 50-pair cables with 26-gauge wire are assumed in each case.
The transmit spectrum of ISDN is shown in Figure 9.5. Because ISDN is an echo-canceled symmetric transport system, we need to consider the effects of SNEXT. Because the SNEXT spectrum completely overlaps the ISDN transmit spectra, we expect this disturber to dominate over other disturbers whose spectra only partially overlap. Although the HDSL spectrum may ...