Stutensee, July 28, 2014 – The market for ultrasonic water meters promises high growth rates in the near future. As a non-invasive method for flow measurement, ultrasonic water measurement is excellently suited for billing monthly drinking water consumption and also for industrial and agricultural applications: for example, for determining volumes consumed, or – with the help of closed loop systems – for optimizing complete processes. With the GP30 from acam, the MCU of the meter is now completely freed from signal processing calculations.
The legal requirements for calibration-obligatory flow measurement (“legal-for-trade”) are defined in detail in the EN 24006 standard and in the directives for measuring instruments 2004/22/EC of the European Union and the Organisation Internationale de Métrologie Légale (OIML).
Advantages of ultrasonic flow measurement:
• No mechanical counters are used: therefore, there is no mechanical wear and measurement remains precise to the end of the instrument’s life.
• Thanks to the very low current consumption and the long-term stability of the measuring accuracy, by using ultrasonic flow measurement, a calibrated measuring unit can be operated over at least two calibration periods.
• The production costs of ultrasonic counters have in the meantime dropped so much, that hybrid counters (electronically sampled mechanical counters) can no longer compete with them. Other high-volume applications of the ultrasonic measurement technique will enhance this price advantage even further.
• Measuring units can be made almost entirely of plastic, depending on the application. Sheeting with brass is no longer necessary.
• Thanks to the absence of mechanical parts, floating particles, dirt or sand do not affect the long-term stability and the accuracy of the measurement.
• The direction of flow is reliably recognized. In the case of reverse-flow, it is possible to measure or react accordingly.
• The modern devices of today have outstanding stability and sensitivity and can measure even the smallest flows. Joint leaks, line leaks and dripping water from taps as well can be simply recognized and immediately signalled.
The new system-on-chip (SoC) TDC-GP30 from acam messelectronic is now available as a Beta prototype and is being tested by some customers as part of a Beta customer program. The sampling stage for the serial version is planned for the fourth quarter of this year.
How the TDC-GP30 calculates
With the GP30 the MCU of the meter is now completely freed from signal processing calculations. The IC performs all required compensation algorithms and linearizations and calculates the calibrated flow. This has a considerable influence on the current draw of the system.
Low current consumption enables two essential requirements to be met.
a. When used over at least two calibration periods, the measuring device can be operated with a cost-effective battery of the size of an AA cell.
b. Water meters can be operated at higher measurement frequencies to become tamper-proof. Acam recommends operating meters of at least 6-8 Hz.
A clear distinction and structuring between the measurement value processing tasks up to the calibrated flow value and temperature (GP30) on the one hand, from the device management (such as various interfaces, data security, etc. done by the external MCU) on the other hand, are also achieved.
The GP30 transmits the calculated measured values to the successive unit via different digital interfaces (UART, pulse or SPI). The entire electronic hardware of a volume measuring unit with a GP30 consists of only a few components and is extremely compact. It can thus be completely integrated, for example, in a standard transducer, which creates further added value over the entire value chain.
The development of volume measuring units or calibrated counters is supported by acam with development/evaluation kits, allowing necessary adaptations to be carried out very quickly. With these tools, the GP30 can be configured and/or programmed. Optionally acam also offers a basic firmware, which can be parameterized to perform the flow and temperature calculation.
The integrated 32-bit microprocessor can be programmed in Assembler. The assembler, debugger, programming tools, etc. are all included in the evaluation software. The GP30 is in-circuit programmable. The programming takes place in only a few milliseconds with a few hundred uA of current, allowing it to be carried out without any difficulties also in battery operation with high-impedance batteries, such as lithium thionyl chloride.
About acam messelectronic
acam messelectronic GmbH, located in Stutensee near Karlsruhe (Germany), is a fabless vendor with a focus on integrated circuits (IC) for measurement technology. Divided into a total of five product lines, acam offers highly innovative ICs on CMOS technology for several measurement applications. Acam was founded in 1996 and is a privately-held company. One of the main lines is the ICs for ultrasonic flow measurement, the so called Ultrasonic Flow Converters (UFCs). Here, acam is the world’s market leader, holding a market share of around 35 percent. Acam has been developing UFCs since the company was founded, and they are used today by leading heat- and water meter manufacturers. The other product lines (TDC, Picostrain, Picocap, Picoturn) supply their respective fields of application with optimal solutions for precise, current-saving and effective measurement and data processing. Many of the acam products are system-on-chip solutions with user-programmable microprocessors and NVMs.
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