Data Acquisition and Validation Flashcards

What distinguishes a Type K thermocouple from a Type J thermocouple in flight test instrumentation?

Answer: Type K has a wider temperature range and uses chromel-alumel alloys

Type K thermocouples use chromel-alumel junctions and cover roughly −200 °C to +1350 °C, giving a broader range than the iron-constantan Type J.

In a wheatstone bridge strain gauge circuit, the 'bridge balance' condition is important because:

Answer: It sets the output voltage to zero when no load is applied, enabling small strain signals to be detected

A balanced bridge outputs zero volts under no-load conditions so that small resistance changes from strain produce measurable differential voltages.

What does a sample-and-hold circuit do in a data acquisition system?

Answer: Captures and freezes an analog voltage at the moment of sampling so the ADC can convert it accurately

A sample-and-hold circuit captures the instantaneous analog voltage and holds it stable for the duration of the ADC conversion.

Which validation method detects an out-of-range sensor reading by checking it against predetermined physical limits?

Answer: Limit checking

Limit checking flags data values that exceed predefined minimum or maximum thresholds that the physical parameter cannot plausibly exceed.

The purpose of multiplexing in a data acquisition system is to:

Answer: Allow multiple signal channels to share a single transmission or recording path

Multiplexing routes multiple sensor channels sequentially through one ADC or transmission link, reducing hardware complexity and bandwidth requirements.

In flight test data reduction, applying engineering unit (EU) conversion means:

Answer: Translating raw digital counts or voltages into physically meaningful units using calibration coefficients

EU conversion applies calibration coefficients (slope and offset) to convert raw ADC counts or voltage readings into engineering units such as Newtons, degrees, or knots.

A ground station antenna tracking system uses angle data to follow an aircraft. If the tracking data has excessive lag, this most likely results from:

Answer: High latency in the data acquisition and servo control loop

Lag in the tracking control loop causes the antenna to point at where the aircraft was rather than where it is, degrading received signal strength.