Лабораторная 6.5 - Калибровка RF-искажений

Lab 6.5 - RF impairment calibration (DC, IQ imbalance, LO leakage)

Goal

Build a reproducible calibration flow for common RF receiver impairments:

• DC offset;
• IQ gain/phase mismatch;
• LO leakage at baseband DC.

Engineering question

Can we quantify impairment metrics before/after calibration and show measurable improvement on spectrum and constellation?

Executable file

File	Purpose
blocks/block_06_rf_frontend_and_ad9363/python/lab_6_5_rf_impairment_calibration.py	impairment synthesis, calibration, metrics, plots

Run from the repository root:

python blocks/block_06_rf_frontend_and_ad9363/python/lab_6_5_rf_impairment_calibration.py

Generated artifacts

docs/assets/lab65_rf_impairment_spectrum_before_after.png
docs/assets/lab65_rf_impairment_constellation_before_after.png
docs/assets/lab65_rf_impairment_calibration_metrics.json

Metrics

Metric	Meaning
dc_offset_rms	complex mean magnitude of IQ samples
iq_gain_mismatch_db	I vs Q RMS mismatch in dB
iq_cross_correlation	residual non-orthogonality between I and Q
image_rejection_db	desired tone power vs image tone power
lo_leakage_dbfs	LO/DC leakage level relative to peak tone

Calibration stages

1. Remove complex DC component.
2. Match I/Q RMS amplitudes.
3. Orthogonalize Q against I (Gram-Schmidt style).
4. Remove residual DC again.

Report checklist

• [ ] Show before/after spectrum and constellation.
• [ ] Report all five metrics before and after calibration.
• [ ] Explain which metric improved the most and why.
• [ ] State limits of this compact calibration method for real hardware.