Data Acquisition and Validation Flashcards

Which error source causes all channels in a multiplexed DAS to have a slight timing difference between their samples?

Answer: Skew error

Skew error arises because time-division multiplexing samples channels sequentially rather than simultaneously, introducing a time offset between channels.

In telemetry data validation, a 'gap' in the data record most commonly indicates:

Answer: A loss of RF link or recorder dropout during acquisition

Data gaps typically result from a temporary RF link outage or recording medium dropout causing missing frames in the time history.

The term 'bit error rate' (BER) in a telemetry system measures:

Answer: The ratio of incorrectly received bits to total transmitted bits

BER is the fraction of bits received in error compared to the total number of bits sent, indicating link quality.

What is the function of a signal conditioner in a data acquisition chain?

Answer: Amplify, filter, and convert raw sensor output to a range suitable for the ADC

Signal conditioning adapts raw transducer outputs—through amplification, filtering, and excitation—to match the ADC's input requirements.

A zero-order hold (ZOH) artifact in sampled data appears as:

Answer: A staircase-like distortion of the reconstructed waveform

ZOH reconstruction holds each sample value constant until the next sample, producing a staircase approximation of the original continuous signal.

During post-flight data review, a parameter shows a constant value for an extended period that is physically implausible. This most likely indicates:

Answer: Sensor saturation or a 'stuck' reading from sensor or recorder failure

A physically implausible constant value typically signals sensor saturation, a failed sensor outputting a rail value, or a frozen data channel.

Which IRIG standard is most commonly referenced for time code formats used in flight test data acquisition?

Answer: IRIG-B

IRIG-B is the most widely used time code format in flight test, providing a modulated or DC-level shifted signal with 1-second frame resolution.