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STEP 03 / 06 · ABOUT 5 MIN

Read the waterfall

Identify frequency, time and relative signal strength before moving a control.

A spectrum shows signal distribution across frequency at one moment. A waterfall stacks successive measurements over time. In our lab frequency increases to the right; new rows appear at the top and older rows move down. Colour represents relative level.

Here, a continuous vertical trace means energy stays at the same frequency over time. A wider trace occupies a larger frequency range. That alone identifies neither the transmitter nor its content. Strong interference can also look bright. Without calibration, colours are not an absolute power measurement.

Your turn.

Open the SDR lab. Start the waterfall if paused. Compare the narrow, interrupted CW trace with the wide FM trace. Then pause and locate the frequency axis. All signals are synthetic.

Try it: simulated waterfall →Read more: waterfall and spectrum →
UNDERSTAND & APPLY

Check your understanding

What does a continuous vertical trace show in this waterfall?

Sources & further documentation

Your learning path— / 6
  1. Understand the receive chain
  2. Connect frequency and wavelength
  3. Read the waterfall
  4. Match mode and filter
  5. Use gain deliberately
  6. Tune your own signal

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