Just as we thought we had figured it all out, we come across Fig. 13.20, a development based on the phantom circuit principle we introduced in Chap. 1. It is a DSL-based idea from 2-Wire Inc. (US Patent Number 7190716, inventors Andrew Norrell and others). Note that an additional phantom-data channel has been created on two twisted pairs. PoE can be injected with a combination of inductor-feeding (as in one-pair PoE) and the usual center-tapping method. This can also be extended to four PoE, providing six (not four) data channels.
FIGURE 13.20 A phantom inside a phantom (and with PoE).
Future innovation will draw on ...