The Internet Power Line Adapter - University of Queensland

Home Automation, Power Lines and the Internet Quenten Alick
Chapter 7
7.1 Review of the Design
This chapter will be looking at the design of the system, with the benefit of
hindsight, and how the design was carried out. The three main sub-sections of
the system will be examined, the power measurement unit, the Internet
connectivity and the power line communications.
Overall, the biggest problem that was encountered with the design was defining
the topic. Linked with this problem was the original scope of the topic as well.
Initially there was a grand plan as to what could be accomplished and it was not
realized until too late, that the plan was not feasible to implement in the
timeframe available. As a result, time was wasted on areas that have not been
included in the final product. This is a problem with the way that the thesis was
approached by the students, and as (soon-to-be) professional engineers, it is an
area upon which they need to improve.
The areas that were approached ambitiously were that of the Internet
connectivity and the power measurement. Part of the original plan was to use an
embedded web server to connect to the Internet. This was chosen since an
embedded processor is much cheaper than a PC (the option that we took in the
end). Embedding the web server also has the advantage that the device is
dedicated and can devote all its time to servicing requests whereas a PC will
often be used for other applications. Although most homes have PCs these days
it is unlikely that most home automation users would be able to install and use
Linux and Apache. The final advantage of the embedded system is that it is
much more portable than a PC.
The power measurement also started as part of the grand plan that needed to be
cut back. The design of accurate watt-hour meters is a complex topic that can be
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