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Indicating Amplifier

Modular amplifiers for high-end conditioning of cylinder pressure, low pressure, displacement or timing signals for the purpose of combustion analysis.

AVL Solution

Our indicating amplifiers portfolio is suitable for most application fields and test environments. The different form factors of the FI/FlexIFEM and MicroIFEM amplifier families cover stand-alone usage as well as full integration into the test facility.

Your Benefits

  • Quick sensor swap and best traceability due to AVL Sensor Data Management SDMTM
  • Easy integration in various environments due to robustness and signal filtering
  • Compatibility with a large range of sensor types
  • High transient accuracy due to intelligent drift compensation for piezoelectric sensors
  • User-friendly parameterization due to full integration in IndiCom

Indicating amplifiers

The AVL indicating amplifiers perfectly close the gap between our sensor solutions and our data acquisition units. Our amplifiers indeed offer full compatibility with our sensors, especially via our Sensor Data Management SDMTM concept. The integration of our amplifiers in the indicating chain – especially in terms of parameterization and user-friendliness - is guaranteed by the software solutions IndiCom and IndiPar.

Our amplifiers also offer complete stand-alone solutions in terms of basic combustion analysis, and their flexibility furthermore allows integration into a broad variety of testing environments.

Product Family





Well-proven, modular and advanced amplifier concept, best suited for applications directly at the test bed and in vehicle
  • R&D and application of light/heavy-duty, racing, large engines
  • MicroIFEM Piezo
  • MicroIFEM Combi
  • MicroIFEM Multipurpose


Stand-alone and intelligent amplifier concept, furthermore delivering basic combustion characteristics such as peak firing pressure
  • R&D and application for light/heavy-duty, racing, large engines
  • Endurance testing
  • On-board measurement
  • In-vehicle performance testing
  • FI Piezo


High-end scalable amplifier family with increased processor performance for complex cylinder pressure-based computations such as combustion noise, upwards compatible to FlexIFEM Indi via simple software upgrade
  • R&D and application for light/heavy-duty, racing, large engines
  • Endurance testing
  • On-board measurement
  • In-vehicle performance testing
  • Acoustics development
  • FlexIFEM Noise

Key features


Drift   compensation

State-of-the-art drift compensation for highest accuracy

Standard piezoelectric amplifiers are subject to drift, meaning that at constant cylinder pressure the output voltage signal does not remain constant as one would expect, but drifts towards either end of the output range. Such electric drift can have different root causes (e.g. low input isolation) and is inherent to the piezoelectric measurement chain, but can be compensated so that the amplifier delivers a constant voltage at constant cylinder pressure.
All our indicating amplifiers are therefore equipped with a state-of-the-art drift compensation technology, implemented by feeding back to the input of the operation amplifier a compensation current which is as large as the lost current. The feedback current is actualized at the beginning of every cycle, thus ensuring highest accuracy throughout the entire measurement

Peak firing pressure measurement

 More than just an amplifier

Via built-in digitalization of the cylinder pressure signal and LCD display the AVL FI Piezo and FlexIFEM amplifiers optionally offer the possibility to detect engine cycles, display cycle-based pressure curves, and calculate peak firing pressure or engine speed.
DAC and digital outputs transform those devices into real stand-alone pmax measurement or monitoring devices. Further time-based algorithms such as combustion noise are also available in the FlexIFEM family.

SDM Sensor Data Management

 Increasing efficiency due to organized workflow

SDM guarantees end-to-end automated data transfer and thus ensures error free measurements. This solution covers the complete measurement chain running from the sensor to the post-processing software. AVL Sensor Data Management™ SDM consists of several hardware and software components:

  • SID Sensor Identification (see picture top left)
  • SIC Sensor Identification Cable (see picture top right)
  • SDC Sensor Data Connector (see picture bottom left)
  • SDB Sensor Data Base (see picture bottom right)


Indicating amplifiers and signal conditioning

Product Family




Number of channels 4 1 or 2 1 or 2
Power supply 9.5…36 VDC 9.5…36 VDC 9.5…36 VDC
Dimensions WxHxD 9.5’’ x 1HU x 230 mm 86x112x270 mm 86x112x270 mm
Weight 1.5 kg 1.6 kg 1.6 kg
Signal output -11…+11 V -11…+11 V -11…+11 V
Parameterization Remote via RS232 interface Via front-keypad, or remote via RS232 or USB interface Via front-keypad, or remote via RS232 or USB interface
Integrated LCD no yes yes
Sensor Data Management SID & SDC SID(*) & SDC SID(*) & SDC
Peak firing pressure measurement no yes (optional) yes (optional)
Additional time-based measurements no
  • Engine speed
  • Engine speed
  • Combustion noise

Indicating amplifiers and signal conditioning

MicroIFEM Piezo

 Download:Productdescription_MicroIFEM Piezo_E.pdf

FI Piezo

 Download: Productdescription_FI Piezo_E.pdf

FlexIFEM Noise

 Download: Productdescription_FlexIFEM Noise_E.pdf


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General | Februar 2014