• A Discussion About a Distributed DAU Standard

      Eccles, Lee H.; Ellerbrock, Philip J.; Boeing Test & Evaluation (International Foundation for Telemetering, 2013-10)
      Modern aircraft are both bigger in some dimensions and smaller in others than previous generations of aircraft. With earlier airplanes we were able to centrally locate a data acquisition system and bring wires from all of the transducers to a central location. With more recent airplanes two factors have combined to make this impossible. First, each new program requires more transducers and thus more cables: it is no longer possible to bring that many wires to a single location. The other problem is that airplane wings and control surfaces have become thinner leaving less room for cables. To date we have been able to get around the problem by using physically small Data Acquisition Units (DAUs) that are distributed around the aircraft. However, it is now reaching the point where the space available in the airplane to run wires is becoming so limited that we need to use DAUs that have a small number of channels as well. What is being proposed is that the test community develop or adopt a standard that will allow systems to be built that look to the higher level elements of the system as a single DAU but in reality are composed of several small nodes that are distributed around the airplane and connected by some communications medium.
    • Network-Based Data Acquisition System for Flight Test

      Eccles, Lee H.; Malchodi, Larry; Wilhelm, Kenneth A.; Boeing Test & Evaluation (International Foundation for Telemetering, 2013-10)
      The Boeing Test and Evaluation flight test organization tests many airplanes each year. Most of these tests involve 50 to 100 parameters and one or two flights. Airplane certifications may require up to 250,000 parameters and last for months. For the last 20 years we have wanted a modular system that would allow us to use the minimum acquisition hardware required to do the job. At the same time we wanted to train the Instrumentation engineers for a single system. We have achieved both goals with a network-based data acquisition system. We solved the lack of determinism with Ethernet by time-tagging all data in the Data Acquisition Units (DAU) using IEEE Std 1588 Precision Time Protocol. The DAUs themselves are small modules which allow us to install just the DAUs that we need for a given program. This has allowed us to implement the full range of systems yet have all of them operate with the same hardware and software. This paper discusses the architecture that we implemented and our successes with this system.