SDR FAQ

Straight answers for common SDR lab problems: overload, unstable decodes, drift, and poor baselines.

Why is my waterfall bright everywhere?

Often front-end overload from high gain or strong nearby out-of-band transmitters. Lower gain, add filtering/attenuation, and retest.

What sample rate should I choose?

Use the lowest rate that fully covers your target bandwidth while avoiding dropped samples.

Why do signal peaks move during startup?

Oscillator warm-up drift is normal on many devices. Warm up and apply PPM correction.

How do I know if my baseline is healthy?

1. Tune a known strong local reference signal.
2. Confirm repeatability across multiple runs.
3. Log gain/sample-rate settings with each test.
4. Change one variable at a time.

What causes decoder instability most often?

• Front-end overload
• Undersampled bandwidth
• Drift not corrected
• Noisy environment and poor antenna choices