94 lines
2.9 KiB
Python
94 lines
2.9 KiB
Python
"""Cross-check the ApsisRS exact slant path against ITU-R P.676-12.
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Reads the values written by ``cargo run -p apsis-rs --features rf --example
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dump_gas_exact`` and recomputes each one with the ``itur`` package, which
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implements the exact method of the recommendation directly. The exact method
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integrates the specific attenuation through a layered standard atmosphere and
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traces the refracted ray, so it is the form to use at low elevation.
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The script needs no network access.
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Usage:
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pixi run python validation/python/atmosphere/check_gas_exact.py [path]
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Exit status is zero when every value agrees within tolerance and one
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otherwise.
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"""
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from __future__ import annotations
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import csv
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import sys
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from pathlib import Path
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from itur.models.itu676 import _ITU676_12_
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# The reference atmosphere, matching the Rust side.
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PRESSURE_HPA = 1013.25
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WATER_VAPOUR_DENSITY = 7.5
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TEMPERATURE_K = 288.15
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# The implementation reproduces the reference to about nine significant
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# digits, so this allows for the rounding of the recorded values.
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RELATIVE_TOLERANCE = 1e-7
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DEFAULT_INPUT = Path("validation/data/expected/rust_gas_exact.csv")
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def read_rows(path: Path) -> list[dict[str, str]]:
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"""Reads the CSV rows."""
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with path.open(newline="") as handle:
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reader = csv.DictReader(handle)
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return [row for row in reader if row.get("frequency_ghz")]
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def main(argv: list[str]) -> int:
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path = Path(argv[1]) if len(argv) > 1 else DEFAULT_INPUT
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if not path.exists():
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print(f"missing input file: {path}", file=sys.stderr)
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print(
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"generate it with: cargo run -p apsis-rs --features rf "
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"--example dump_gas_exact > " + str(path),
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file=sys.stderr,
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)
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return 2
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rows = read_rows(path)
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if not rows:
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print("input file has no data rows", file=sys.stderr)
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return 2
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model = _ITU676_12_()
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worst = 0.0
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worst_at = None
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for row in rows:
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frequency = float(row["frequency_ghz"])
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elevation = float(row["elevation_deg"])
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reference = model.gaseous_attenuation_slant_path(
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frequency, elevation, WATER_VAPOUR_DENSITY, PRESSURE_HPA, TEMPERATURE_K,
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mode="exact",
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)
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reference = float(reference.value if hasattr(reference, "value") else reference)
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actual = float(row["attenuation_db"])
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relative = abs(actual - reference) / max(abs(reference), 1e-12)
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if relative > worst:
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worst = relative
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worst_at = (frequency, elevation)
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print(f"scenarios compared: {len(rows)}")
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print(f"worst relative: {worst:.3e} at {worst_at}")
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print(f"tolerance: {RELATIVE_TOLERANCE:.3e} relative")
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if worst <= RELATIVE_TOLERANCE:
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print("result: pass")
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return 0
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print("result: FAIL")
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return 1
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if __name__ == "__main__":
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raise SystemExit(main(sys.argv))
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