Chapter 7 - Data Processing

Data requirements are directly dictated by the program and its reporting requirements. After all, the entire purpose of a flight test program is to provide da ta to facilitate system development, evaluation, certification, and ultimately, use. Definition of data requirements is a multiple step process that includes specifying the tests and test conditions, identification of the parameters that must be measured, the rate and accuracy needed, definition of data turn-around time and data reduction and/or analysis methods, and
the data presentation formats required. (See Section 6). In the sequence of events that make up a flight test program data processing comes between data acquisition and data analysis. It typically starts with the receipt of the flight test data, whether recorded on tape or received in realtime by telemetry link, and it ends with the delivery of the processed data to the end user, the data analyst. There are many kinds of "data processing" that occur and the Flight Test Engineer (FTE) must ensure that he/she understands what these various processes are and which data that he/she can expect from each step. Some examples of these data processing steps are:

• Conversion of raw binary data into Engineering Unit (EU) data
• Presentation of EU data as numerical values (tables) or graphical time histories, x-y plots, bar
charts, etc.
• Pictorial presentation of the flight path and aircraft attitude and other flight or aircraft parameters
• Calculations in the frequency domain (Fast Fourier Transform)
• Data analysis with dedicated software for:
• Signal analysis
• Signal filtering
• Determination of transfer functions
• Parameter identification
• "Image processing" of video and radar data

This section will describe the responsibilities and involvement of the FTE in the process of setting-up a data processing facility and obtaining flight test data that is ready for final analysis. It will provide some guidance to the novice engineer on how to proceed in this process and will identify some of the personnel with whom interfaces are required. It will not describe how data processing is done. Table 7-I contains a summary of elements that, together, constitute "Data Processing". Many, if not all, of these elements are subject of discussion between the FTE and the home-base instrumentation and data processing engineers to ensure that the desired/required data is received in time in the format that is acceptable for analysis and reporting. The "How" of data processing is discussed in some detail in Chapter 10 of AGARDograph 160, Volume 1 (Issue 2) "Basic Principles of Flight Test Instrumentation Engineering". [7-1] Additional information can be found in reference 7-2.