Case study: low power metering communications
Background
Our client is a global leader in the automation and controls industry, providing innovative solutions and services to customers, with an increasing focus on software, networks and electronics. Their products and services range from sophisticated control systems for automating industrial plants, to electronic devices and controls for homes and offices. A key feature of future products in these markets will be their ability to communicate information such as billing data, system status reports and control instructions. Consequently, development of these communications-enabled products is a cornerstone of our client's company strategy.
The problem
A vital part of many of these communications-enabled products will be a very low power short-range radio link. This low cost link has to be able to transport modest amounts of data, operating from a battery power source for many years. None of the commercially available designs met all these requirements and so our client undertook the development of a new link, which involved acquiring the necessary R.F. hardware development expertise and acquiring over-air protocol and networking software. The first option chosen - of licencing appropriate software - proved unsuitable, which left the project without the necessary software. A range of products were dependent on a timely solution to the software problem, so Sentec were asked to develop the software from scratch and to an aggressive timetable.
Sentec's approach
The solution was needed quickly. The link hardware required the protocol and network software to run on very low-power embedded microprocessors used to control the R.F. section. Burst frequency hopping spread spectrum FSK was used for over-the-air communication, with coding, locking and error detection chosen to minimise the implementation loss of the link. We focussed our efforts on very early demonstration of the critical software features and we were thus able to demonstrate first working code very early in the project. We then carried out sophisticated computer modelling to optimise the link, modifying and refining the code as the results of the modelling became known.
The solution
The completed software was delivered early and under budget. It functioned correctly on its first trial on the client's target hardware and exhibited near theoretical performance, minimal implementation loss and thus optimum transmission distance for given transmit powers. The feared-for delays in product development were avoided.
