Introduction

In the utility industry today, the only constant is change. Many utilities are already using wireless Automatic Meter Reading (AMR) and other advanced data collection technologies. Most others are considering installing AMR. But with the uncertainty of the changing marketplace and its fluctuating requirements, the issue of which technologies to use, and how to use them, can be confusing. Yet there is no room for confusion in a decision so fundamental and critical for utility system developments. What are the different wireless technologies available to address a world wide market, which one will improve utility services whilst reducing costs?

Geographic diversity

Today wireless utilities need smart and flexible solutions that can be selectively deployed to serve geographically diverse countries. Wireless AMR systems use radio frequencies that are controlled and assigned by the local telecommunication authority. Most of the systems operate in the unlicensed bands, the most well known North America band is 902-928MHz, and the equivalent in Europe is 868-870MHz. Therefore, the technical approach is different according to the marketplace. In North America for example, where the frequency bands are shared between several users with several applications, the frequency hopping spread spectrum (FHSS) can be advantageous. From a project management point of view, this difference significantly influences the time for development, the project cost and the risk. For an AMR provider or manufacturer who wants to address either the North American or European market, a solution must be developed for each region in accordance with the local regulations. So the time for development and the cost will be multiplied by two; and that is in effect for the same final application.

Protocol standardization in AMR industry

Radio-based (fixed or mobile) AMR Networks involve installing a fixed communication network over meter modules installed on electric, gas or water meters. Radio-based networks need to include such functionalities as consumption reads, on-request reads, time of use, demand, and consumption monitoring. Each function can be selectively assigned by the utility customer or for other strategic reasons. Meter modules are read via radio, followed by data processing, storage and then transportation to the host processor as necessary.

One of the main issues in the AMR industry is to allow meter modules to work together as a comprehensive solution. Some standard protocols are emerging, like Konnex, led by deregulation and the need for standard and open protocols. But some proprietary protocols are still used for confidentiality and security.

Infrastructure for Radio-based Networks

Wireless meter reading integrates a portable radio network ID. A module is added to the meter reading software that allows the handheld computer to determine which meters are read by radio versus which are read manually. As a meter reader walks a route (for portable data collection), the collector sends a radio "wake-up" signal to the meter modules that have been installed on electric, gas or water meters. The unit then receives meter readings and data back from the meter modules. Meter modules can be read at scheduled times, such as hourly, several times a day or on any schedule. The cost of this infrastructure must be minimal. For the end-users, the added value for Automatic Meter reading is in services provided by the brokers. Each unit needs to be a cost-effective solution. An electric, gas or water meter has functionalities which differ from a data collector. For the meter reader, battery life and sensor interface are important technical parameters in opposition to a remote data collector, where the battery life is not so critical and where there is no sensor interface.

The Solution from XEMICS

XEMICS develops low power integrated circuits, which can fulfil the technical requirements of the AMR industry. In order to further reduce customer development time, risk and cost XEMICS has recently launched a new series of TrueRF™ products. The Drop-In RF module series based on the wireless transceiver series. The DP1201A, a 433MHz mono-channel module, targets low power/low cost applications. The latest Drop-In module introduced by XEMICS is the DP1203. Available on two frequency bands (868 and 915MHz), it responds to a need for flexibility and performances.

Geographic diversity:
The problem of geographic diversity is avoided when using the Drop-In module in the final application. By having the same pin-out whatever the frequency band, the DP1203 offers a perfect fit with local telecommunication regulations. The AMR manufacturers develop only one host board with the Drop-In module footprint. The development time and the risk of a wireless link on two frequencies will therefore be halved. At production, according to the geographic area where the system will be implemented, the frequency band of the wireless electric, gas or water meter will be defined. The utility meter difference due to the geographic region will be achieved by simply selecting the Drop-In module with the right frequency.

Protocol standardization in AMR industry:
In AMR systems the protocol is packet oriented. The information data (payload) is sent as a packet consisting of a preamble, a header with a unique address or ID, control information, the payload and a tail with error detection/error correction checksum.

However, the battery life of the electric, gas and water meter is an important feature and even more for inaccessible meters. Therefore, the communication protocol needs to be developed in such a way as to reduce the power consumption. XEMICS with the DP1203 facilitates the current consumption reduction thanks to the "pattern detector block" embedded into the XE1203 transceiver. This block compares the incoming data-stream with a predefined pattern stored into a XE1203 register. The pattern output is set to high level when a matching condition is detected, otherwise is set to low level. The number of bits used for comparison is set between 1 byte to 4 bytes and the number of tolerated errors for the pattern recognition is also defined by an internal register.

Therefore, for AMR applications, the pattern detector uses the meter ID, a command sent by the Utility Application will be processed by only one meter. In this condition, the current consumption of the electric, gas or water meter is optimized.

In addition, in wireless communication, the data rate also influences the current consumption. At 153.2kbps (maximum data rate of the DP1203) and for the same command, the transmit time is shorter and so reduces the average current consumption.

In order to also serve AMR industries that are using Konnex, the DP1203 offers operation mode compatibilities. This easily achieved by setting registers in the right configuration, as for example the data rate set to 32.77kbps.

Infrastructure for Radio-based Network
The flexibility needed for the radio-based network infrastructure is provided by the Drop-In module DP1203. The design development of a meter reader and a data collector is different, each with their own constraints. To reduce development time, risk and cost, a good approach is to re-use existing blocks. In a radio-based network, the common factor is the radio, by using a Drop-In module as a standard electronic component these objectives can be achieved. The design engineers will focus on system functionality. XEMICS has also developed an 8-bits microcontroller series which can address most of the unit requirements of the radio-based network. For the utility meter, a microcontroller with a sensor interface can be used for precise measurement due to the embedded "ZoomingADC™". Added to a Drop-In module, this utility meter offers performance, flexibility and cost optimization. A repeater or a data collector will be based on the powerful 8-bits microcontroller, in order to process data and radio communication at the same time. Therefore, XEMICS has introduced the "BitJockey™". This function based on two FIFOs (First In First Out) allows the transmit/receive of bytes automatically without additional CPU resources. The main advantage of this is that it works with bytes instead of bits but also it saves CPU time.

Application Protocol Interfaces are available from the XEMICS web site or from XEMICS partners to drive the DP1203 with any XEMICS 8-bits microcontrollers.

ABOUT XEMICS
XEMICS is a privately owned fabless semiconductor company with headquarters in Switzerland and a worldwide sales and customer support network. XEMICS delivers a range of advanced short-range, customized and standard, wireless connectivity solutions to a global customer base. XEMICS is a leading designer and provider of Wireless RF transceivers and Bluetooth™ applications, data acquisition, communication products, CODECs and GPS receivers. With a focus on high-quality low cost solutions XEMICS provides a combination of ultra-low power technology and innovative IC design.

ZoomingADC™ is a XEMICS trademark. It refers to the Analog to digital converter from the XE8000 series. This can select and zoom in on sections of the input signal. BitJockey™ is a XEMICS trademark. It refers to the technology which enables the XE88LC06A to exploit the full bandwith of the transceiver.

The BitJockey™ converts bits to bytes and bytes to bits leaving the core free to do other things, and speeding up the processing of data.

TrueRF™ is a XEMICS trademark. It refers to the technology behind the new XE1200 series products which have a consistently clean RF signal.