Testing Powerline In Real-World Environments
As with other communications technologies, the testing environment is always a concern. Product specifications typically indicate maximum throughput based on optimal conditions, which are usually achievable only in a lab. Caveats to optimal powerline conditions outside of this environment include the following:
- Wiring: Because electrical wiring is used for transmission, the quality of the wire is important. This means that, in older homes or apartment buildings, the signal could be degraded based on the wiring quality.
- Home/building size: Attenuation is a concern, and the increased size of the home means there's more wire for the signal to traverse. HomePlug AV works better in areas smaller than 8000 square feet (743 square meters), and some vendors specify a maximum distance of 300 meters as the maximum length the powerline signal can travel without suffering signal degradation and/or loss.
- Number of appliances and other "noisy" electronics: Sources of big power draw create noise on the circuit that can impact the powerline adapter's ability to filter for its own communications channels.
- Plugging into a power strip or similar device: Powerline adapters have built-in filters so that the signals hitting the PHY layer can be quickly sifted through for actual HomePlug transmissions. Power strips and uninterruptible power supplies do not have those filters, and thus ultimately slow down the receipt and transfer to the powerline adapter. On the flip side, some vendors recommend plugging appliances into surge protector outlets in an attempt to filter out some of their noise.
- Electromagnetic radiation: We're talking about transmission over electrical wiring using the same frequencies as other home electronics. Large sources of electromagnetic radiation will affect more than just your powerline adapters.
- Certain capacitors on circuit breakers: If you're not familiar with capacitors, there's a great 15-minute YouTube introduction that shows how performance is better when there is no capacitor, the size of the plate influencing the positive flow is larger and the material of the dielectric insulator is more conductive.
Keep in mind that the powerline adapters are not switches, and they do not store MAC addresses. That means you must have at least one Powerline adapter connected to either a switch or the switch ports on a router. This also means that each test requires two powerline adapters.
Although there are several models available that include features like Wi-Fi extension and plug-in pass-through, the products we chose for our initial round-up reviews were selected because they were the fastest entry-level adapters in their class at the time. Also, although single powerline adapters can be purchased, when starting out, you'll need at least two of them, so it's better to search for powerline starter kits.
