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Water and Waste Water SCADA Radio Networks; Fundamentals, Best Practices and Choices from the Perspective of a System Owner & Operator
1. Start with First Principals Thinking
a. Water and waste water operations are a mission critical use case
b. High technical standards required for mission critical data transport integrity and reliability
c. The best part is no part, said another way less points of failure is best.
d. In a world of limited resources, the chosen solution must also be affordable.
e. Clearly define the current and future SCADA radio network service area
f. Clearly define the data rate required (often slower is better)
g. Select a radio modem technology that has a future and will be supported well into the future.
2. What does "mission critical" mean in the data communications world
a. If a communications outage can result in public harm, then you are in a mission critical need case. Example is public safety police & fire dispatch also many utility operations such as water production well fields, water distribution or lift station systems.
i. Utility examples; Lift station overflow or operation failure that results in a boil water order.
b. Data communications downtime is measured in minutes per year, vs hours or days. Five nines 99.999% availability = 315 seconds per year of down time, ~ 5 minutes per year.
c. Spare parts must be available and maintained
d. The SCADA radio network is operational before during and after a hurricane or storm event.
3. How do we incorporate best practices and high standards in our SCADA radio networks?
a. Understand, CELLULAR NETWORKS ARE NOT MISSION CRITICAL GRADE
i. Cell sites are vulnerable to power outages, wind damage, cyber-attacks, Cell modems must be replaced every 3-5 years due to evolution in cell tech (think 3G, 4G, LTE, 5G), forced dependence on the cellular carrier to restore communications after an outage event.
b. SCADA radio networks are designed with expertise and tools, then tested before the design is qualified as acceptable. Often referred to as a “In-Field Radio Study”
i. Radio network designs include a "20 dB RF fade margin” for each radio path, data reliability comes from meeting this minimum standard.
ii. In-field radio study is the last step in the design where the radio network is set up temporarily and the RF signal levels in each radio path are measured and confirmed that the computer modeled RF design meets real world performance.
c. Allocate resources wisely, tall antenna towers vs smart towers. Dollars are easy to spend and hard to come by. Large towers require large foundations and have large construction efforts, steel and concrete costs. Our goal is to build the mission critical SCADA radio network with the lowest antenna towers possible.
d. When defining the service area consider future needs / expansion.
e. Select the best SCADA radio modem technology for the system requirements.
i. 150 MHz, 220 MHz, 460 MHz, 800 MHz, 900 MHz Licensed, 900 MHz, 2.4GHz, 3.6 GHz, 4.9 GHz, 5.1 GHz, 5.8 GHz Unlicensed, Mesh, Microwave, Etc.
f. Build all SCADA antenna systems to survive 150 – 200 MPH wind storms, yes this can be done with a robust design.
4. SCADA Radio Networks Maintenance
a. Antennas only last 10 years, plan to replace them all at year 9
b. Perform preventative maintenance on all master and high importance RTU sites at least once per year.
c. Not all antennas are created equal they; vary in construction quality, cost, gain and wind survival ratings.
d. Surge protectors, know their failure modes and how to test them.
e. Radios can degrade over time, have a plan to replace the ones that are under performing, especially the master or sub master radios.
f. Know if radio modem obsolesce will become an issue and have a plan.
g. Create a master RTU radio station log / spreadsheet; record every station’s RF strength, signal to noise level, data quality metrics annually and draw attention to any changes over the life of the network.
User owned SCADA communications networks can achieve minimal down time measured in minutes per year vs. weeks after a severe weather event, power failures, cable cuts, etc. The user owned SCADA radio networks are completely controlled by the owner and their maintenance organization, Vs. telco, cable, or cellular communications carriers. Private secure and autonomous data radio networks are not vulnerable to cyber-attack / terrorism or hackers, Article from Wired Magazine on Cyber War. Proper planning and control of your spare parts program can make a return to service as simple as replacing a broken part. Tornados, hurricanes, fires, and power outages often cause cellular networks outages, as site backup power is usually a small number of minutes, cell sites rely on wired telco infrastructure to create the cellular network backhaul connections that are required for operation. Commercial power availability is required for both wireless and wired connectivity as their (telco & cellular) backup power access is typically minimal.
The industry standard for designing SCADA radio links (both FCC licensed and unlicensed) is 20 dB of RF fade margin. This defines the additional radio signal that is designed into each radio link to insure reliability. What the 20 dB fade margin really means is that there is 100 times more signal than the minimum amount of RF carrier signal needed to reliably operate the radio link and transport your mission critical SCADA data on it. Decibels are logarithmic numbers and a little goes a long way to provide data reliability.
There are countless SCADA radio networks throughout the United States and abroad monitoring and controlling municipal water, waste water, flood water, oil & gas production, power grids, automatic meter reading, and much more. These mission critical radio technology based communications systems have ranges from yards to hundreds of miles. Selecting the right technology, defining the projects requirements, and creating a robust SCADA communications network is what I do as an RF consultant. Having the personal understanding of the pros and cons of each technology can empower the project engineer, owner or operator to make the best business decisions for a system that will have a 10-20 year service lifetime and are often mission critical or high importance factor operation SCADA systems.
Please browse this site, if you have any questions or a specific project you would like to discuss, please feel free to call on me, Mark Lavallee. I truly enjoy sharing my 30 years of specialized experience and knowledge. My company is often called upon assist design build consultants, controls system integrators, and the end users directly. We are highly specialized with tools and talent for auditing existing SCADA systems, selecting the best SCADA radio technology for new systems, and providing qualified radio network designs / in-field radios studies.