Operating the right frequency
The Telecommunications Advisory Committee helps to maintain reliable scanning telemetry systems in the water sector. David Tripp, chairman of Spectrum Management Group, reports
The group originally operated under the umbrella of Water Services Association but with the formation of Water UK and its focus on core business, the committee has become independent.
The committee is chaired by Mr Mike Halliwell of the Environment Agency and is supported by the Spectrum Management Group (SMG). This group develops the detailed technical and strategic issues ready for consideration by the full committee. The day to day management of the spectrum and all round support to the committee and water industry is provided by CSS Spectrum Management Services through a management and support contract. CSS also provides the necessary liaison and representation on a number of RA and DTI committees along with radio frequency planning and the engineering required to manage the radio spectrum on behalf of the industry.objectives of TAC
One of the key objectives of TAC is to provide an established common point of contact for the industry in relation to mobile communications and scanning telemetry, both within the industry and with external bodies and organisations. This presence ensures the interests of the industry are always well represented and safeguarded.
The arrangement that TAC has, through CSS Spectrum Management Services, with the RA is unique as the industry not only manages the spectrum allocated to it on a national basis but it also pays a single license fee. This arrangement, along with other proactive arrangements, has saved the industry in excess of £500,000 over the last five years.
In order to ensure members of the industry can make informed judgements on their communications solutions, the committee has developed and published a mobile communications strategy. This raised a considerable number of issues which have subsequently been researched and a second phase strategy report is due to be published shortly.
In order to keep water industry members up-to-date with emerging and evolving technology and equipment CSS Spectrum Management Services with a number of TAC members has jointly organised three international communications conferences focused on the UK utilities. These have been held every two years and have been considered a great success with 200 delegates attending each conference. The next conference will be held in June 2004.Scanning Telemetry
The growth of scanning telemetry has been considerable with a doubling in the number of outstations within the last five years. Although there are other means of transmitting telemetry data, such as telephone lines, private circuits, satellite and cellular telephones it is considered that radio can be the most cost-effective bearer for medium to heavy use and places least reliance on public operators. With increases in labour costs and tighter limits for plant output, remote control and monitoring by telemetry has enabled quality standards to be monitored and maintained while helping to reduce costs.
Radio telemetry links are engineered to provide 99.9% availability. As these units operate in a licensed band and are on channels primarily used by the water sector, interference from other users is virtually unknown. In certain parts of the country some systems can suffer from continental interference, however, in most cases this can be removed by the use of special cancellation equipment. The RA is currently considering realigning this band of frequencies, which should remove this interference. The equipment used is designed and manufactured to a European Telecommunications Standards Institute (ETSI) standard. A single base station will communicate with a large number of outstations enabling considerable volumes of data to be collected on a regular basis with alarm conditions being given priority response. The spectrum used is allocated through a national cellular distribution plan.
The way in which telemetry is used varies from organisation to organisation and depends how closely the system is integrated into the operation of the plant. The trend is to use intelligent outstations which also provide on-site process control or to integrate closely with free-standing programmable logical controllers. However there are many situations which only require a relatively simple outstation in a purely passive role where information on flows, levels, plant status and alarm conditions are passed directly to the control centre or are archived on site and down loaded at pre-set times to the central telemetry computer for display, processing or bulk storage.
An alternative approach is for outstations to monitor the plant status and to generate an alarm condition if a pre-programmed parameter is exceeded, under one or a number of conditions.
In many instances site security and intruder alarm information is transmitted over telemetry to ensure the control centre staff can take the appropriate action. In some instances this is augmented by low resolution CCTV images.
A considerable amount of radio-based telemetry has been installed by many different users, including some of the utilities, on the de-regulated and unlicensed block of radio spectrum. As this band is de-regulated there is no limit or control of the numbers using this spectrum or their location. The band has been a victim of its own success and in some areas it is becoming very congested and at times unusable. We have seen a recent trend for organisations to move away from de-regulated spectrum to the water industry licensed scanning telemetry band. It is fortuitous that some of the equipment used in the de-regulated band can be configured to operate in the licensed band.Future Role of TAC
TAC has a proven track record of safeguarding and managing the radio spectrum required by the water industry, while negotiating reductions in the license fees. It has also recently developed a new water industry telecommunications license with the DTI in order to ensure the industry retains its code powers in relation to telecommunications systems when the new EU licensing legislation comes into force in July 2003.
One of the latest challenges to the organisation is the growth in wind farm planning applications and the effect these farms might have on existing radio based systems. The members recognise the change within the industry and the scope of their overall telecommunications requirements and to this end they are currently reviewing the scope of the tasks and services that should be provided to ensure the long-term communications needs of the industry can be met.