|Choosing A SCADA Radio Technology
|FCC License, License Free or Cellular
|Design, Test, Then Build It
|Radio Study Why?
|How to Build it Reliably
and Waste Water SCADA Radio Networks; Fundamentals, Best Practices and Choices
from the Perspective of a System Owner & Operator
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
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
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.
do we incorporate best practices and high standards in our SCADA radio
a. Understand, CELLULAR NETWORKS ARE NOT MISSION
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
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
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
e. Select the best SCADA radio modem technology for the
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,
f. Build all SCADA antenna systems to survive 150 – 200
MPH wind storms, yes this can be done with a robust design.
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
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.