Technolog’s ‘Cello’ calls the tune in GSM-based AMR


Based in the rolling Derbyshire Dales in the very heart of England, Technolog Ltd was founded in 1981 to develop specialised electronic instruments for utility applications. Throughout the 1980s and 1990s Technolog supplied tens of thousands of innovative data logging products to gas and water utilities for monitoring distribution networks. Technolog is now a leading supplier of such devices in the UK and several other countries.

Since 2000, Technolog has significantly expanded operations to encompass remote metering solutions through a family of products known as ‘Cello’ and has become expert in the use of low-power GSM (Global System for Mobile communications) technology for retrieval of metered data. The Company operates an international meter data collection service and has created a specialist service division to install and maintain its products. The Technolog group employs some 200 staff in the UK and France and is a division of Roper Industries Inc.

From an original focus on automatic meter reading (AMR) for larger commercial and industrial (C&I) meters, the company’s activities now encompass products suitable for smaller C&I and residential consumers. Technolog is co-operating with a number of leading international suppliers of electricity meters to integrate its intelligent Cello GSM/GPRS/SMS technology into singlephase and poly-phase meters. The company also has short range RF technology that is used in multi-utility metering and for relay of consumption data to home display units.


GSM is the technology that underpins most of the world’s mobile phone network. The GSM platform is a hugely successful wireless technology and has become the world’s fastest growing communications technology. It was a natural communications medium for Technolog’s ‘Cello’ AMR technology as it provides coverage at most potential meter locations worldwide and offers cost-effective tariffs that have reduced year on year. GSM demands no reliance on meter density to be economic.

An important innovative development by Technolog was to use GSM technology in such a way that the typical battery life of a ‘mobile phone’ in an AMR device could be extended to 10 years with a single cell.

Technolog offers very low airtime tariffs from several GSM operators. This allows Cello users to purchase the products fully tested and ready to use with factory-fitted SIM cards. Technolog Cello products incorporate a proprietary means of compressing metered data that ensures minimal use of GPRS or SMS thereby reducing operating cost. Technolog airtime is compatible with most GSM networks in the world due to international ‘roaming’ arrangements. Unlike much customer-purchased airtime from local GSM operators, which is often fixed to a single network, the Technolog roaming SIM will simply use any GSM network that is present at the meter location. This simplifies commissioning of the Cello by avoiding SIM swaps and ultimately improves the system reliability, as the Cello will also roam onto an alternative GSM network (if available) should the original one be temporarily unavailable.


Historically, any electrical equipment (eg a data logger or an energy management system) connected to gas meters has been through the use of safety barriers. The electrical equipment and safety barrier have to be located well away from the gas meter in what is known as the safe area (ie an area where there is no possibility of an explosive atmosphere). Due to the relatively high cost of safety barriers and associated on-going maintenance, remote reading of gas meters has generally only been cost effective at very large (high consuming) gas meter sites.

The Cello6 is certified intrinsically safe (IS) for use in the most hazardous locations (zone 0). This means that the Cello6 can be connected directly to the gas meter and located in the hazardous area (close to the gas meter) without the need for a safety barrier. This eliminates the risk of an installer incorrectly determining the level of hazard present at the meter site.

The Cello6 connects directly to gas meters and gas volume converters and incorporates replicated pulse outputs, thereby allowing other equipment, such as the consumer’s own energy management systems, to be connected. (The Cello6 can also accept pulses from other pulse output devices, including water meters.)

Technolog is currently undertaking large-scale gas AMR projects with major gas suppliers and utilities in a number of countries.


Larger water meters are often located in underground chambers that can be prone to flooding and poor GSM signal. Technolog have perfected Cello4 specifically to deal with these issues. The Cello4 is waterproof and every product is pressure tested before leaving the factory. Even in good GSM coverage areas, the signal strength in underground chambers is often poor due to the metal chamber cover. Over 85% of all Cello4s are located in underground chambers where reliable operation has been achieved through the use of a special design of antenna and the use of the Short Message Service (SMS text message).



The Cello4 data logger employed
world-wide in water metering.

Technolog has developed versions of the Cello product for polyphase and single phase meters. The product range comprises the Cello EM which connects to the serial port of a wide range of electricity meters, bespoke versions of the Cello EM designed for specific meters and a reference design that allows meter manufacturers to easily incorporate GSM technology into a meter at low development and product cost. The technology will support traditional outbound data calls (‘dial-up’) plus lower cost inbound operation using GPRS or SMS.

Traditionally, meters have been set up by a technician prior to leaving the workshop and are labelled for a particular site, which is impractical, expensive and prone to error. In addition to designing GSM based AMR devices, Technolog provides a low-cost, highly reliable meter programming and meter reading service. The meter programming service allows a smart meter to be programmed with the correct tariff structure at the time of installation without manual intervention.


An electricity meter
incorporating a custom
GSM modern from


The backbone of Technolog’s meter reading service is its Utility Data Network (UDN), which supports SMS and GPRS methods of communication. The UDN has duplicated high-speed connections to the GSM operators and no single point of failure. The data can be routed directly to the customer or securely stored in an Oracle database. The metering database stores site information, meter asset information and photographs, Cello details, meter readings and profile data. As new data is received, it is validated and exported to customers in either an industry standard or bespoke format. In addition, customers receive daily performance reports for their AMR system.

Technolog also hosts metering websites where the data is conveniently presented to end consumers. These websites are designed to be easily customised to the corporate style of the utility or local meter service provider. The websites are able to provide information matching the consumer’s need, ranging from detailed energy analysis to simple trends and meter readings.