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Development of a gas smart meter system

Tokyo Gas is developing gas smart meter systems comprising U-Bus equipped Ultrasonic Meters, wide-area wireless networks, U-Bus Air networks, and center systems.
Eight other companies collaborated with Tokyo Gas to evaluate technical specifications, creating industry standards within Japan. Work is also being done to standardize internationally through measures such as proposing IEEE802.15.4g/e as a communications specification for U-Bus Air and incorporating this proposal in a planning document (in April 2012).


In 1989 Tokyo Gas began a service of "Gas Care System" that utilizes telephone lines to perform security monitoring, remote shutoff, and automatic meter reading. It has provided this service to more than 400,000 customers.
However, the spread of cellular phones and the Internet has resulted in a more diverse communications infrastructure in the general household with a shorter lifespan, making a means of communication that does not rely on a telephone line necessary. Furthermore, heightened home security means that there are more residences such as self-locking apartment buildings, that do not provide any access for personnel reading meters. This has rapidly increased the need for remote meter reading, and in the future may heighten the requirement for services that provide safety, peace of mind, and oversight, and which conserve energy.
In order to respond to these needs, Tokyo Gas is collaborating with other manufacturers and gas businesses to develop next-generation gas smart meters.
Gas smart meter systems contiguration image
Gas smart meter systems contiguration image
U-Bus-equipped Gas Meters, wide-area wireless, U-Bus Air networks, and center systems


U-Bus is a new communications interface that utilizes a packet transmission method with a higher transmission speed than the existing city gas meter transmission specification (A line). Tokyo Gas has evaluated specifications together with LP Gas businesses, and is standardizing these specifications, along with the U-Bus Air (detailed below), with the NPO Japan Utility Telemetering Association (JUTA). Information on the U-Bus next-generation gas meter for residential use is listed here: This gas meter is being developed in conjunction with U-Bus communications terminal devices.
U-Bus specification
Layer Main specifications Characteristics
Bus connection method
  • Shared use with devices of different kinds possible
Increased baud rate (9,600bps)
  • High speed transmission (30x faster than currently in use) allows for use in a wider variety of fields, and improves service levels.
Data link
Packet transmission
  • Improved intercommunication with terminals with different baud rates
  • Improved line use efficiency
  • Improved resistance to damage
Fixed packet length (104characters/packet)
  • Improved processing efficiency of terminal devices
  • Improved responsiveness
Meter gateway function
  • Implementation of addressing that is compatible with wide area and relay wireless networks
Easy addressing
  • Less restriction on construction when installing terminals
Security Use of standard encryption
  • Improved authorization and confidentiality

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The Pu-NCU is a wide-area wireless terminal fitted with a U-Bus communications interface. Extremely low power consumption levels allow it to operate for 10 years. Much easier to install and with a significantly improved appearance, the Pu-NCU has a simple configuration that allows it to be fitted to ultrasonic gas meters used in the home.
Installation of these terminals for use with the "Gas Care System" service began in December 2012.
System configuration image
System configuration image


U-Bus Air

U-Bus Air is a short-distance wireless radio communication system with extremely low power consumption which utilizes the 920 MHz band to provide relays between gas meters via multi-hop transmission. U-Bus Air utilizes the IEEE802.15.4g/e standard and is used in accordance with standard NPOJapan Utility Telemetering Association (JUTA) specifications. U-Bus Air devices are able to operate for 10 years on battery power, and can connect to meters outside the area of wide-area wireless coverage.
U-Bus Air specification summary 
Frequency 920MHz band(ARIB STD-T108 standard)
Output 20mW、10mW、1mW
Baud rate 100kbps
Network topology Mesh. 50 units per network
Multistage 5 stages on average, with a maximum of 15 stages

U-Bus Air terminal characteristics
U-Bus Air terminal characteristics

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