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1. Introduction
2. The Internet
3. The Power Grid
4. Bundling Data
5. Homestretch
6. Interference
7. More Information
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- 5. THE HOMESTRETCH -
After the data has been transmitted along the power lines, it will be ready to be sent into the home (see Figure 5). There are several options for this, and it is not surprising then that this is the point at which BPL technologies differ most.
Figure 5. Schematic of a full BPL network [8]. 
A major headache for BPL operators in the past had been the fact it was notoriously difficult to transmit data signals through transformers, in this case, the ones that convert electricity from medium volts to the low volts that are sent into buildings. Two methods allow the data to bypass the transformer drum. One is achieved by attaching a modem/coupler that provides a data detour around and past the transformer and back onto the power lines, continuing into the home. Another method requires attaching a wireless connectivity device to the power line, which can then emit a radio signal containing the data to a receiver located in the home. The wireless method bypasses both the transformer and low voltage wires altogether [4, 8]. Some devices are capable of both wired and wireless in-home transmissions.
Once inside the building's power distribution grid, it is only a matter of plugging in a BPL-enabled device into any electrical socket. The BPL-modem in your computer, as you can guess, converts the RF energy back into readable computer language, so that the user's computer or a BPL-enabled refrigerator, for instance, can interpret the data and display a webpage (see Figures 6, 7). This may or may not be stating the obvious, but this data stream is bidirectional. That is, data is also transmitted back to through the power lines to the electrical substation, where it is then transported back onto the Internet via the backbone . Moreover, the stream is symmetric, meaning both downloading and uploading speed capabilities are the same.
Figure 6. Detailed in-home view of BPL networking possibilities [4]. 
Figure 7. Power line networking network card. Note the plug! 
<< 4. Bundling Data | 6. Interference >>
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