Module tec 

Dual-frequency Total Electron Content estimation helpers.

This module starts with the absolute, noisy code-derived slant TEC estimate. It uses the dual-frequency code geometry-free combination P1 - P2 and the dispersive ionospheric group-delay relationship delay_m = 40.308e16 * TECU * (1 / f1^2 - 1 / f2^2), where carrier frequencies are in hertz and one TECU is 1e16 electrons per square meter.

use sidereon_core::constants::{C_M_S, F_L1_HZ, F_L2_HZ};
use sidereon_core::precise_positioning::{
    estimate_tec, DualFrequencyObservation, TecConfig, TecEpoch, TecObservation,
    TEC_GROUP_DELAY_COEFFICIENT,
};

fn observation(_epoch: usize, slant_tec_tecu: f64, phase_bias_tecu: f64) -> DualFrequencyObservation {
    let denominator = TEC_GROUP_DELAY_COEFFICIENT
        * (1.0 / (F_L1_HZ * F_L1_HZ) - 1.0 / (F_L2_HZ * F_L2_HZ));
    let code_geometry_free_m = denominator * slant_tec_tecu;
    let phase_geometry_free_m = -denominator * (slant_tec_tecu + phase_bias_tecu);
    DualFrequencyObservation {
        satellite_id: "G01".to_string(),
        ambiguity_id: "G01".to_string(),
        p1_m: 0.0,
        p2_m: -code_geometry_free_m,
        phi1_cyc: phase_geometry_free_m / (C_M_S / F_L1_HZ),
        phi2_cyc: 0.0,
        f1_hz: F_L1_HZ,
        f2_hz: F_L2_HZ,
        lli1: None,
        lli2: None,
    }
}

let epochs = (0..2)
    .map(|epoch| TecEpoch {
        time_s: epoch as f64 * 30.0,
        receiver_latitude_rad: 0.0,
        receiver_longitude_rad: 0.0,
        observations: vec![TecObservation {
            observation: observation(epoch, 20.0, 5.0),
            elevation_rad: 60.0_f64.to_radians(),
            azimuth_rad: 90.0_f64.to_radians(),
        }],
    })
    .collect::<Vec<_>>();
let tec = estimate_tec(&epochs, TecConfig::default())?;
assert_eq!(tec.arcs.len(), 1);
assert_eq!(tec.arcs[0].samples.len(), 2);

Structs

CodeSlantTecEstimate

Code geometry-free slant TEC estimate for one dual-frequency observation.

IonosphericPiercePoint

Ionospheric pierce point on the configured thin shell.

LeveledTecSample

One leveled TEC sample emitted for a continuous arc.

PhaseSlantTecEstimate

Phase geometry-free slant TEC estimate for one dual-frequency observation.

TecConfig

Configuration for thin-shell TEC estimation.

TecEpoch

One epoch of dual-frequency TEC observations.

TecEstimate

TEC estimates for all continuous satellite arcs in a stream.

TecEstimateSample

One leveled TEC estimate at one epoch for one satellite.

TecLevelingResult

Result of phase-code leveling across one continuous satellite arc.

TecLevelingSample

One dual-frequency slant TEC sample used by phase-code leveling.

TecObservation

One satellite’s dual-frequency TEC observation with topocentric geometry.

TecSatelliteArc

TEC estimates for one satellite continuous arc.

Enums

TecError

Error produced while estimating dual-frequency TEC.

Constants

DEFAULT_IONOSPHERIC_SHELL_HEIGHT_M

Default single-layer ionospheric shell height in meters.

ELECTRONS_PER_TECU_M2

Electrons per square meter represented by one TECU.

TEC_GROUP_DELAY_COEFFICIENT

Ionospheric group-delay coefficient for TECU inputs.

Functions

code_geometry_free_m

Compute the code geometry-free combination P1 - P2, in meters.

estimate_code_slant_tec

Estimate absolute code-derived slant TEC for one dual-frequency observation.

estimate_phase_slant_tec

Estimate biased phase-derived slant TEC for one dual-frequency observation.

estimate_tec

Estimate TEC over a time-ordered stream of dual-frequency epochs.

ionospheric_pierce_point

Compute the ionospheric pierce point for a receiver and satellite look angle.

level_slant_tec_arc

Level a continuous arc of code and phase slant TEC samples.

phase_geometry_free_m

Compute the carrier phase geometry-free combination L1 - L2, in meters.

slant_tec_from_code_geometry_free_m

Convert a code geometry-free delay in meters into slant TEC in TECU.

slant_tec_from_phase_geometry_free_m

Convert a phase geometry-free delay in meters into biased slant TEC in TECU.

thin_shell_mapping_function

Thin-shell obliquity factor mapping vertical TEC to slant TEC.

vertical_tec_from_slant_tec

Convert slant TEC to vertical TEC with the configured thin-shell mapping.