Lesson 4 – Signal and Noise

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Course:  Integrated Science, Physics, Biotechnology and/or STEM courses

Unit:  Measurement, Scientific Process, and Instrumentation Design


See Standards Addressed for all NGSS, WA State (Science, Math and Literacy), and NOAA Ocean Literacy Education Standards Connections.  In addition to the aligned objectives linked above, for this lesson, here is a breakdown of:

What Students Learn:

  • Signal is the meaningful information you are trying to receive or observe.
  • Noise is unwanted random data without meaning that can corrupt or interfere with a signal.
  • Scientists must evaluate signal & noise to interpret observations.
  • Voltage can be used as a proxy variable.
  • An Operational Amplifier can be used to amplify a voltage signal.
  • Transducers transform one type of energy input to a differing type of energy output.
  • Electronic devices have noise originating from thermal effect, EM interference, and quantum mechanical interactions.

What Students Do:

  • Generate operational definitions for signal and noise from common everyday experiences.
  • Quantify Signal, Noise, and Signal to Noise ratio for a graphed radio transmission example.
  • Use semiphore (hand signals) to send and receive a message where noise generally becomes an issue in the reception (see ‘extensions’ below).
  • Analyze the trade-offs in amplifying a signal for measurements.

NOTE:  for advanced (physics) students, the following activities offer an alternative to the semiphore activity.

  • Build an Operational Amplifier circuit on a bread board to amplify the signal from an iPod to a speaker.
  • Collect & Analyze Signal & Noise data for the built speaker circuit using voltage probes and real time graphing software such as LoggerPro from Vernier