galileo/docs/configuration.md

Configuration

ReceiverConfig owns RF, acquisition, tracking, front-end, and fixed-point dataclasses. YAML loading is strict: a misspelled field is an error.

Important validation rules include positive sampling/loop rates, a real IF strictly below Nyquist, integer sample counts per integration interval, ordered correlator tap spacing, explicit FFT length when requested, E1B bit-transition protection beyond 4 ms, and E1C secondary-code handling beyond 4 ms. E1B tracking is conservatively limited to 4 ms until navigation-symbol synchronization is implemented.

intermediate_frequency_hz may be nonzero for either real or analytic input. The front end always outputs complex baseband and divides the effective sample rate by the integer decimation factor. Acquisition/tracking must use that output rate.

Acquisition parallelism fields expose future hardware/software scheduling but do not change numerical results. zero_padding_mode: none provides the exact N-sample circular correlation. A longer FFT changes the sampled numerical correlation/edge convention; it is not additional physical delay information.

Default YAML files:

• e1_default.yaml: requested 16.368 MHz nominal defaults.
• acquisition_example.yaml: faster 4.092 MHz executable search.
• tracking_example.yaml: 4.092 MHz tracking defaults.
• e1_cboc.yaml: explicit full-band CBOC selection at 32.736 Msps and a 2.25 MHz analytic low IF.
• navigation_collection.yaml: SignalSim IQ-to-I/NAV regression. Its default tracking.architecture is e1c_pilot_aided_e1b; the CLI can select e1b_only for an A/B replay.

AcquisitionConfig.modulation and TrackingConfig.modulation independently select BOC11 or CBOC. Both default to BOC11, so existing SignalSim and low-bandwidth configurations retain their measured behavior. A CBOC vector must set both fields to CBOC for a matched acquisition/tracking replica.

The BOC lock detector parameters are part of TrackingConfig. The defaults use 25 noncoherent power epochs, three confirmations, and the configured loss_of_lock_epochs for sustained failure. Carrier and BOC central/outer shape thresholds have explicit entry and exit values. lock_signal_loss_power_ratio sets the five-tap power loss test. These parameters affect monitoring and reacquisition only; they do not change discriminator or loop-filter coefficients. boc_side_peak_coherence_enter/exit calibrate the coherent E/L-to-P tap-sign test needed to distinguish the negative half-chip BOC sidelobe from the main peak using more than magnitude-only information.