The smart meter industry has developed into a complex marketplace

Smart Metering Systems

 

With an expected rollout of 53 million smart meters by 2020 the smart metering systems market is rapidly reaching maturity.

Within the UK the second version of the Smart Metering Equipment Technical Specifications (SMETS) has been published and countries around the world are consulting on and publishing their own recommendations for communication and usability standards for smart metering systems. Although these standards specify particular communication protocols, there is still flexibility to allow engineers to use the best protocol for the job. This can however leave buyers frustrated, with diminishing economies of scale reducing their buying power.

Read a summary of the smart meter system structure and SMETS implications below or use the button above to skip straight to our range of recommended products including tips on maximising buying power and achieving ultra-low power consumption when designing your device.

Smart Meter System outline

In essence the standard smart metering system or smart grid is composed of one or more smart meters which have the ability to communicate with an in-home hub and a neighbourhood hub, which in turn communicates with a receiver being monitored by a utility company.

Smart meters are composed of three major blocks of circuits which may be integrated into a SoC or incorporated into the device as separate modules. The purposes of these modules are:

  1. Measurement
  2. Communication
  3. User interaction

 

Many smart meter designs are now available with full-scale rollout expected by 2020

Measurement

Measurement is the primary role of a smart meter. Ultimately these devices are created to measure the usage of gas, electric, water or help with temperature control. Various means of measurement are used dependant on the type of fluid being monitored. Viscous fluids may be measured using flow meters, gases may require pressure monitoring, and electricity may be monitored using single, twin or polyphaser metering.

Time-keeping

All smart meters, regardless of the utility they are measuring, require accurate time-keeping in order to allow accurate data analysis and billing. Most importantly time synchronization also ensures reliable transmission of data to the neighbourhood hub and utility receiver in the wide area network as discussed below.

The most recent version of SMETS states that the clock within all types of smart metering equipment must be accurate to within 10 seconds of UTC date and time.

Not only is it important for smart meters to achieve accurate time synchronization, but they must also do so using only a tiny amount of power. Most gas and water meters will be required to maintain power for extended periods of time, reliant solely on battery power. This means every nanoamp of extra power consumption counts and it’s important to specify the lowest energy-consuming peripheral products possible for pairing with communication and measurement chipsets or smart meter SoCs.

 

What does this mean for frequency components?

In practice the requirements of smart meters mean additional specifications standards are required for frequency components: An operating temperature range of -25 to +55°C with a storage temperature range of -30 to +60°C is common within the industry, with ±10ppm stability over the operating temperature range being preferred to ensure radio frequency accuracy.

Ageing is also paramount: ±10ppm over 20 years is the widely accepted figure for ageing of frequency components within the smart metering industry.

 

Communication

Many types of communication protocol are common within smart metering systems including short range wireless standards for home or building networks, such as ZigBee and BLE (Bluetooth low energy). Neighbourhood area networks also make use of 2.4GHz ZigBee and BLE but also commonly use sub 1GHz communications. Finally WAN (wide area networks) may use GSM and 3G or Ethernet and fibre.

SMETS standard stipulates the use of ZigBee in some types of smart meter systems (see below) but for others engineers are free to find a novel solution.

 

Measurement

These short-range networks within a smart meter system allow communication between the smart meter, in-home display (or "home-hub") and smart appliances within the building or home.

This type of communication between the meter, appliances and the home or building hub means the user can see a full picture of their energy usage, including a breakdown of that usage by appliance, great for monitoring peak time activity and energy budget expenditure. Some smart appliances and hub communications also allow for on/off signalling so an appliance can be controlled directly from the home hub.

Home area network devices add extra functionality to the smart metering system

 

For both Gas and Electric Smart Metering Equipment (GSME or ESME) the SMETS standard stipulates:

"The HAN Interface of GSME [or ESME] shall be capable of joining a ZigBee SEP v1.2 Smart Metering Home Area Network which: …operates within the 2400 – 2483.5 MHz harmonised frequency band"

Both electric and gas metering equipment must also be "certified by the ZigBee Alliance as compliant"

The In-Home Display device used within the HAN must also meet both of these functionality requirements.

There are also auxiliary devices which may be included in the HAN section of a smart metering system, including prepayment interface devices and connected auxiliary load control switches.

In addition to the above requirements all smart meters must be registered and conform to DLMS (Device Language Message Specification) standards. DLMS have a conformance checking tool which you can find here.

 

WAN - Wide Area Network

In order to transmit data to a utility company the smart meter will then transfer data through a secure data network outside of the home, usually known as the wide area network.

WANs may consist of data transmission directly to the utility receiver, or depending on the density of meters and level of network coverage within an area, data may first be aggregated at a neighbourhood hub or data aggregation point (DAP) using ZigBee communication. This data is then parcelled into secure data packets and transferred using the WAN communication protocol.

Wide area network communication does not require the fast data rate necessary within HANs but must instead ensure the signal can be carried greater distances than those within the HAN. Protocols common to this level of network include Cellular GSM, LoRa, 3G technology and even Ethernet and fibre.

Lower data transfer rates are typically employed and available channels can be significantly narrower, requiring the use of smaller bandwidths.

 

Recommended frequency products for Smart metering systems

Get the lowest-power consumption for your smart metering device using our ultra-low power, industry standard footprint, low cost products listed here.

Can’t find quite the right frequency or specification? Golledge have a range of over 20,000 product lines so drop us an email at sales@golledge.com and one of our knowledgeable sales engineers will be in touch to help.

 

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Ultra-low power crystals are the mainstay frequency provider for smart metering systems

Part
Number
Frequency Package
mm
Further Information
CM7V SM Crystal

MP07244

Spec SheetPDF Specsheet Quote Me...
32.768kHz 3.2 x 1.5 x 0.65
(3215)

Circuit condition of 6pF makes achieving low current consumption possible.

For more specs see product family CM7V

GSX-315 SM Crystal

MP05348

Spec SheetPDF SpecsheetQuote Me...
32.768kHz 3.2 x 1.5 x 0.65
(3215)

Circuit condition of 12.5pF means MP05348 is perfect for pairing with the majority of industry chips. Its versatile nature means purchasers can combine orders and increase purchasing power.

For more specs see product family GSX-315

GSX-200 SM Crystal

MS07663

Spec SheetPDF SpecsheetQuote Me...
32.768kHz 8.0 x 3.8 x 2.43

Offers the lowest cost option for 6pF requirements whilst remaining low power, however requires larger board space than either MP05348 or MP07244.

For more specs see product family GSX-200

GSX-331 SM Crystal

MP07223

Spec SheetPDF SpecsheetQuote Me...
12.0MHz 3.2 x 2.5 x 0.8
(3225)

Ageing ±1ppm max first year.


Save board space for 18pF applications with the small 3225 package MP07223.

For more specs see product family GSX-331

GSX49-4 SM Crystal

MP06828

Spec SheetPDF SpecsheetQuote Me...
12.0MHz 12.0 x 4.7 x 4.3

Lowest cost, fundamental mode crystal with enhanced frequency stability as standard.

For more specs see product family GSX49-4

GSX-333 SM Crystal

MP03660

Spec SheetPDF SpecsheetQuote Me...
24.0MHz 3.2 x 2.5 x 0.7
(3225)

Ageing ±1ppm max first year.


Tight calibration tolerance and ±15ppm stability over temperature range makes MP03660 a great 9pF solution.

For more specs see product family GSX-333

GSX-331 SM Crystal

MP06247

Spec SheetPDF SpecsheetQuote Me...
24.0MHz 3.2 x 2.5 x 0.8
(3225)

Ageing ±2ppm max first year.


A fundamental mode crystal for circuit conditions of 10pF, operation over -40 to +85°C as standard, guaranteed aging over 20 years.

For more specs see product family GSX-331

GSX-333 SM Crystal

MA05768

Spec SheetPDF SpecsheetQuote Me...
26.0MHz 3.2 x 2.5 x 0.7
(3225)

Ageing ±1ppm max first year.


±9ppm stability over temperature range and -25 to +75°C means MA05768 offers the ideal 26.0MHz option for outdoor metering devices.

For more specs see product family GSX-333

GSX49-4 SM Crystal

MP02810

Spec SheetPDF SpecsheetQuote Me...
30.0MHz 12.0 x 4.7 x 4.3

If board area allows for this lowest cost option, enhanced stability comes as standard.

For more specs see product family GSX49-4

GSX-331 SM Crystal

MP07224

Spec SheetPDF SpecsheetQuote Me...
32.0MHz 3.2 x 2.5 x 0.8
(3225)

Tight calibration and temperature stabilities, combined with an operating temperature range of -25 to +75°C make MP07224 a great option for a wide range of metering devices.

For more specs see product family GSX-331

GSX-331 SM Crystal

MP07243

Spec SheetPDF SpecsheetQuote Me...
32.0MHz 3.2 x 1.5 x 0.8
(3225)

The ideal 32.0MHz part for outdoor meter operation where ageing is paramount.

For more specs see product family GSX-331

 

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TCXO - Temperature compensated oscillators allow for extreme accuracy over a wide range of temperatures, perfect for smart meters that require time accuracy whilst withstanding extreme weathers.

Part
Number
Frequency Package
mm
Further Information
GTXO-253 TCXO

MP07050

Spec SheetPDF SpecsheetQuote Me...
26.0MHz 2.5 x 2.0 x 1.0
(2520)

Ageing ±1ppm max first year.


A tiny surface mount package makes MP07050 the best option for functions where tight stability is a requirement.

For more specs see product family GTXO-253

GTXO-93 TCXO

MP07085

Spec SheetPDF SpecsheetQuote Me...
26.0MHz 3.2 x 2.5 x1.2
(3225)

Ageing ±1ppm max first year.


When accuracy over temperature range is important MP07085, with tight stability of ±2.5ppm over temperature range of -40 to +80°C and lowest cost, is the ideal 26.0MHz solution.

For more specs see product family GTXO-93

GTXO-253 TCXO

MP07215

Spec SheetPDF SpecsheetQuote Me...
31.250MHz 2.5 x 2.0 x 1.0
(2520)

Ageing ±1ppm max first year.


The perfect combination of accuracy and package size, MP07215 is the best 31.250MHz option for accuracy-dependant functions.

For more specs see product family GTXO-253

 

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SAW Filters – providing refined filtering, essential for smart metering systems

Part
Number
Frequency Package
mm
Further Information
GSRF Surface Acoustic Wave device

MP07084

Spec SheetPDF SpecsheetQuote Me...
869.30MHz 3.0 x 3.0 x 1.4

With a bandwidth of 1.3MHz and minimum insertion loss of 3.4dB maximum (excluding loss in matching elements) MP07084 allows tight out of band rejection while minimising loss of sensitivity.

For more specs see product family GSRF

GSRF Surface Acoustic Wave device

MA05253

Spec SheetPDF SpecsheetQuote Me...
2441.80MHz 3.0 x 3.0 x 1.4

Perfect for filtering the ZigBee 2.4GHz band, MA05253 offers typical insertion loss of only 2.1dB, ensuring a strong signal at receiver. This part also offers low in-band distortion with ripple figures of only 0.9dB.

For more specs see product family GSRF

 

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Real Time Clock Modules (RTCs) offer extra functionality and lower power consumption than a standard SoC solution

Part
Number
Frequency Package
mm
Further Information
RV8803C7 Real Time Clock

MP06786

Spec SheetPDF SpecsheetQuote Me...
32.7680kHz 3.2 x 1.5 x 0.8

The world’s highest stability RTC over wider temperature variations (0.26 secs per day over -40 to +85°C) combines with unusually low current consumption for a temperature compensated device (240nA). This product is ideal for outdoor battery-powered metering solutions.

Click here for more RTC module options

RV1805C3 Real Time Clock

MP06292

Spec SheetPDF SpecsheetQuote Me...
32.7680kHz 3.7 x 2.5 x 0.9

The lowest power consumption RTC module (lower than a standard watch crystal internal oscillator combination) at 17nA, MP06292 is a popular solution for applications that rely solely on battery supply such as water metering and gas metering.

Click here for more RTC module options