Options for remote data acquisition and system control

This Paper outlines two current data transport systems used for remote data acquisition and controls systems at water and wastewater systems, briefly reviewing history and current systems and then focuses forward on consideration and comparison of traditional Very High Frequency (VHF) radio telemetry with cellular based systems.

Data collection is the area observed as being the area of fastest growth as plant owners endeavour to fulfill their obligations under their resource management agreements and government regulations by using increased plant flow monitoring and analytical instrumentation (turbidity for example).

Facility owners also seek to maximise plant value and utilization by logging pump well flows and operation periods as they monitor the adequacy of reticulation systems during such times as heavy rain events. Over time, the logged data represents a mine of information waiting to be sifted for data that quantifies historic plant and infrastructure performance (reticulation, pump stations etc) which assists in planning for upgrades or replacement, and increases the certainty of the information upon which any upgrade or extension is based.

Increased data loads challenge existing data transport systems; in particular, VHF radio telemetry, where the inherent radio bandwidth limitations are rapidly becoming a block to the increased data traffic associated with greater reporting requirements, and which severely limit future growth for such facilities as remote video observations of plant and security.

Cellular technology is providing a quantum leap in data transmission rates and allowing much more comprehensive facility monitoring, without expending large chunks of capital. What are the pros and cons of this technology? Will it supplant or just supplement the vast existing network of dedicated radio telemetry systems presently installed around the country? These existing VHF systems are generally well understood by those who install and service them and, dare we say, loved by existing facility operators, but have they had their day?

Switchbuild of Dunedin has grasped the advantages that the cellular system offers and applied it to some 50 waste and potable water pumping and storage facilities in the Central Otago area for the Central Otago District Council (CODC).