Track

The track function is the main entry point for processing GNSS signals. It takes an incoming signal and a TrackState, performs downconversion and correlation for all tracked satellites, estimates Doppler frequencies, and returns an updated TrackState.

Function Reference

Tracking.track — Function

track(
    signal,
    track_state,
    sampling_frequency;
    downconvert_and_correlator,
    intermediate_frequency,
    preferred_num_code_blocks_to_integrate
)

Main tracking function that processes a signal and updates the tracking state. Performs downconversion, correlation, and Doppler estimation for all satellites in the track state. Returns an updated TrackState with new phase/Doppler estimates and decoded bits.

source

Optional Parameters

downconvert_and_correlator: The downconversion and correlation implementation to use. Defaults to CPUDownconvertAndCorrelator.
intermediate_frequency: The intermediate frequency of the signal. Defaults to 0.0Hz.
preferred_num_code_blocks_to_integrate: The preferred number of code blocks to integrate. Defaults to 1. Will only integrate more than one block once bit synchronization has been achieved.

Downconversion and Correlation

Tracking.CPUDownconvertAndCorrelator — Type

CPU-based implementation of downconversion and correlation. Uses LoopVectorization for SIMD-optimized processing. The MESF type parameter specifies the maximum expected sampling frequency for buffer allocation.

source

Tracking.AbstractDownconvertAndCorrelator — Type

Abstract downconverter and correlator type. Structs for downconversion and correlation must have this abstract type as a parent.

source

Correlator Sample Shifts

Tracking.get_correlator_sample_shifts — Function

get_correlator_sample_shifts(
    correlator,
    sampling_frequency,
    code_frequency
)

Calculate the replica phase offset required for the correlator with respect to the prompt correlator, expressed in samples. The shifts are ordered from latest to earliest replica.

source

get_correlator_sample_shifts(
    correlator,
    sampling_frequency,
    code_frequency
)

Calculate the replica phase offset required for the correlator with respect to the prompt correlator, expressed in samples. The shifts are ordered from latest to earliest replica.

source

Tracking.get_early_late_sample_spacing — Function

get_early_late_sample_spacing(
    correlator,
    sampling_frequency,
    code_frequency
)

Calculate the total spacing between early and late correlator in samples.

source