06. RF Measurements in SDR

Goal

Understand real RF limitations: signal level, noise, and overload.

Key concepts

Signal level

• too low → buried in noise;
• optimal → good SNR;
• too high → overload.

Noise

• limits sensitivity;
• affects BER.

Overload

Signs:

• distorted spectrum;
• harmonics;
• unstable level;
• signal distortion.

Diagram

flowchart TB
    classDef rf fill:#FFE4E6,color:#0F172A,stroke:#E11D48;
    classDef metric fill:#F1F5F9,color:#0F172A,stroke:#64748B;

    SIG["RF signal"]:::rf
    GAIN["Gain control"]:::rf
    RX["RTL-SDR"]:::rf
    FFT["Spectrum"]:::metric

    SIG --> GAIN --> RX --> FFT

Conclusion

RF limitations affect signal quality as much as DSP.