Wireless wonders

Traditionally, water monitoring has been a challenge. But new developments in digital telemetry and SCADA technology are drastically improving performance.

THE INCREASING regulatory demands on utilities to deliver clean water and safely dispose of wastewater is growing - yet the technical environment in which they work has never been more complex or demanding.

Wireless technology is becoming increasingly important in linking sites in the physical world to utilities' connected networks. It allows improved communication to deliver constant, high quality monitoring of water flow and levels, no matter how remote the location, without incurring high costs across the life of the system.

Wood & Douglas' Sentinel range of digital radio solutions provide the flexibility and reliability to water utilities that need to monitor water flow and water levels.

Traditionally, water monitoring has been challenging due to the limitations of analogue wireless systems, limited security, and maintenance issues varying from failing signal strength to service outages as dormant problems lead to breakdowns.

New developments in digital telemetry and SCADA technology mean that water utilities across the UK and Ireland, now have more effective means to monitor performance and measure flow and level, among a host of other applications.

Analogue radio modems typically operate at 1,200bps over-air data rate while the latest digital radio modems operate at 9,600bps on exactly the same radio channels. This higher data rate is crucial when deploying UHF SCADA radio systems that use a polling, method to measure water flow and water levels.

Key data
The Master radio, usually high up on a hilltop, transmits requests to outstation locations and receives responses containing the current Remote Terminal Unit (RTU) values. The RTU, a monitoring device for various key data, such as water pressure, levels and temperature, interfaces the physical world of the water utility to a distributed control system (DCS).

Digital technology allows the Master station to poll around the water utility's outstations far faster with a reduced polling interval. One at a time each outstation radio is polled. When each outstation has been polled the sequence starts again and runs continuously 24/7.

All the SCADA data is read faster and outstation problems are identified, with no data traffic costs.

Some of the greatest advantages in terms of telemetry and SCADA are in the capability of modern digital radio modems to incorporate Network Management System (NMS).

NMS directly responds to the cost issues incurred from loss of monitoring, and resultant service calls. It allows technicians to monitor the health of every radio in their scheme from their desk rather than having to make regular site visits.

The latest NMS are importantly non-intrusive, so do not impact on the SCADA data traffic flow, but still automatically transmit back to the control room important radio parameters which are constantly monitored and logged on a 'diagnostics' computer server.

The parameters reported from each outstation include: received signal strength; antenna VSWR; forward power; reflected power; DC voltage; radio temperature; frequency drift; and the number of good and bad data packets received.

Signal strengths
As the NMS compares the data from all these parameters it can provide early warning of developing problems before a complete outage renders the monitoring system unusable. Simple issues, such as an antenna being blown off direction, which occasionally happens, or water entering the antenna coaxial cable, causing attenuation of the transmit and received signal strengths, can now be rapidly identified and addressed, to ensure SCADA and telemetry operate at maximum capacity with minimal, targeted maintenance.

That translates into some major cost savings as maintenance crew schedules are made much more efficient and works are addressed before the problems escalate.
The goal of all the water treatment processes is to remove existing contaminants in the water, or reduce the concentration of such contaminants so the water becomes fit for its desired end-use.

New techniques in radio signaling transmissions help to deliver the flow of crucial monitoring data 24/7, ensuring that issues are addressed quickly and at an effective cost with a low cost of ownership to the utility.

www.woodanddouglas.com

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