Large Channel Count Coherent Data Acquisition Systems

Jet engine
chicoplusmainimage
delfinmainimage

Example Jet Engine

ChicoPlus: Early DAQ Card

Delfin: 32 channel 200ksps 24 bit Capture Card

Related Products
Skills Used
  • Digital Signal Processing algorithms
  • Microsoft C++ under Windows
  • TI Code Composer Studio
  • VHDL design

In at the Start

When Dr Jim Hone and Dr Andrew Law started HGL Dynamics around 2000, they needed a COTS data acquisition solution for their systems to record engine vibration data from jet engines. I remember delivering and installing the first development system at their office, then demonstrating how to use the compile and debugging tool, Code Composer by GoDSP. From the beginning they could see the potential of designing in a flexible and comprehensive data acquisition solution and product line.

Early FPGA Based DAQ

At that time the FPGA was finding its way into streaming data acquisition and PCI solutions. Innovative Integration had just released Chico and ChicoPlus, a control and streaming engine for their Omnibus range of A/D and D/A boards. This was ideal for HGL Dynamic’s requirements to stream samples at around 200ksps from multiple channels to performance PC’s for analysis and display. At the same time, Intel had released their Native Signal Processing library for FFT’s etc which later became known as the Intel Performance Primitives. This enabled open fast loop signal processing to be done on PC’s without the need to write assembly language code.

Delfin’s Everywhere

Sigma-Delta (more precisely Delta-Sigma) Adc’s were becoming popular because of their inherent linearity and low cost. Innovative Integration produced a full length PCI card with 32 channels of these 24 bit converters together with a floating point DSP and a full bus master PCI interface. This enabled a single PCI slot to provide 32 channels, paving the way to easily building upto 1024 channel systems. The Delfin included the clock and trigger synchronisation signals to lock cards together, an essential requirement for the mathematical analysis that HGL Dynamics provide. Entegra wrote custom code for HGL Dynamics to use the Delfin.

XMC and Portable PC’s

When XMC cards were introduced in the data acquisition line up, Entegra developed a single XMC based host so that the Analogue to Digital converters were placed as close to the sensors as possible. Prior to this, the rack mount PC’s were situated in air conditioned computing rooms away from the engine under test, which required long cable runs between sensors and converters. Long cables had the disadvantage of large amounts of noise pickup and crosstalk! The XMC based hosts were physically small, rugged and could therefore be placed very close to the engine itself, resulting in very short cables and a much lower noise floor. We made use of X3-SD, X3-SD16 and X3-10M‘s for these applications. Again, Entegra provided code specific to HGL’s requirements to make integration of the card into their Hawk acquisition software.

Digital Acquisition

As well as providing high channel count, simultaneous and coherent analogue to digital conversion, HGL Dynamics needed to record digital data streams at both 10Mbps and 80Mbps from aircraft sensors. Entegra developed both the digital hardware in FPGA’s and software drivers to make the integration for these interfaces seamless into the Hawk system.