A well-respected RF engineer and close friend of mine shares his creed with me: design first, then you build. It seems ridiculously simple, but this concept is often overlooked when creating a new SCADA system. I've seen those oversights cause pain in budgets and frustration around scheduled commissioning dates. When it comes to SCADA radio networks, we must design first.

We can't see radio energy with the naked eye. We have to use tools to measure how well our intended RF signals can and will travel, and to look for possible interference sources in and around our intended spectrum.

When those tools are employed to confirm or fine-tune a SCADA radio network design, you can build with a high degree of confidence. The process of verifying a design is called a radio study or propagation study — that's the subject of the next section, and it can be an invaluable resource.

A proper design phase typically includes four things. Path analysis between the master station and every RTU site. An interference survey across the candidate frequencies. Frequency selection based on co-channel and adjacent-channel conditions in your region. And equipment specification matched to your bandwidth, range, and reliability requirements.

If you have questions on a specific project, call Mark Lavallee at 954-961-2642 or email mark.lavallee@advantage-com.com. I enjoy sharing my thirty years of experience. My company is often called upon to subcontract with design-build consultants, assist control system integrators, and work with end users directly. For more on verifying a design before you build, see Radio Study Why?