RadioPropagationApi/api/app/services/link.py

from sqlalchemy.orm import Session

from app.config import get_settings
from app.core.atmosphere import atmospheric_loss_between
from app.core.diffraction import deygout
from app.core.fresnel import LosSample, los_analysis
from app.core.geo import GeoPoint, sample_path
from app.core.propagation import itm_loss, manual_link_budget, p452_loss
from app.core.raster_sampling import raster_files
from app.models.common import DataSources
from app.models.link import LinkBudgetRequest, LinkBudgetResponse
from app.models.terrain import Obstruction
from app.services.terrain import surface_profile_from_points
from app.services.vegetation import vegetation_loss_along


def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBudgetResponse:
    tx = GeoPoint(lat=request.tx.lat, lon=request.tx.lon)
    rx = GeoPoint(lat=request.rx.lat, lon=request.rx.lon)
    points = sample_path(tx, rx, 256)
    freq_hz = request.frequency_mhz * 1_000_000
    settings = get_settings()
    surface_profile = surface_profile_from_points(
        points,
        include_buildings=request.include_buildings,
        include_canopy=request.include_canopy,
        db=db,
    )
    elevation_profile = [sample.ground_m for sample in surface_profile.samples]
    los_result = los_analysis(
        surface_profile,
        tx_height_agl=request.tx.height_agl,
        rx_height_agl=request.rx.height_agl,
        freq_hz=freq_hz,
        k=request.k_factor,
    )
    diffraction_db = deygout(
        surface_profile,
        tx_height_agl=request.tx.height_agl,
        rx_height_agl=request.rx.height_agl,
        freq_hz=freq_hz,
    )
    vegetation_db = vegetation_loss_along(
        points,
        freq_hz=freq_hz,
        include_vegetation=request.include_vegetation,
    )
    atmospheric_db = atmospheric_loss_between(tx, rx, freq_hz)

    if request.model == "manual":
        propagation_db = 0.0
    elif request.model == "itm":
        propagation_db = (
            itm_loss(
                tx,
                rx,
                tx_height_agl=request.tx.height_agl,
                rx_height_agl=request.rx.height_agl,
                freq_mhz=request.frequency_mhz,
                elevation_profile_m=elevation_profile,
                dem_path=str(settings.dem_path),
            )
            - manual_link_budget(
                tx,
                rx,
                request.tx.power_dbm,
                request.tx.gain_dbi,
                request.rx.gain_dbi,
                request.rx.sensitivity_dbm,
                request.frequency_mhz,
            ).fspl_db
        )
    elif request.model == "p452":
        propagation_db = (
            p452_loss(
                tx,
                rx,
                tx_height_agl=request.tx.height_agl,
                rx_height_agl=request.rx.height_agl,
                freq_mhz=request.frequency_mhz,
                elevation_profile_m=elevation_profile,
                dem_path=str(settings.dem_path),
            )
            - manual_link_budget(
                tx,
                rx,
                request.tx.power_dbm,
                request.tx.gain_dbi,
                request.rx.gain_dbi,
                request.rx.sensitivity_dbm,
                request.frequency_mhz,
            ).fspl_db
        )
    else:
        raise NotImplementedError(f"{request.model} link model is not supported")

    budget = manual_link_budget(
        tx=tx,
        rx=rx,
        tx_power_dbm=request.tx.power_dbm,
        tx_gain_dbi=request.tx.gain_dbi,
        rx_gain_dbi=request.rx.gain_dbi,
        sensitivity_dbm=request.rx.sensitivity_dbm,
        frequency_mhz=request.frequency_mhz,
        diffraction_db=diffraction_db + propagation_db,
        vegetation_db=vegetation_db,
        atmospheric_db=atmospheric_db,
        fresnel_clear=los_result.los_clear,
    )
    geometric_obstructions = [
        sample for sample in los_result.obstructions if sample.clearance_m < 0
    ]
    building_obstructions = [
        sample
        for sample in geometric_obstructions
        if sample.obstruction_type == "building"
    ]
    return LinkBudgetResponse(
        **budget.__dict__,
        fresnel_quality=_fresnel_quality(los_result.los_clear, los_result.geometric_los),
        los_clear=los_result.los_clear,
        geometric_los=los_result.geometric_los,
        first_fresnel_clearance_pct=los_result.first_fresnel_clearance_pct,
        fresnel_violations_count=len(los_result.obstructions),
        geometric_obstructions_count=len(geometric_obstructions),
        building_obstructions_count=len(building_obstructions),
        worst_obstruction=_convert_obstruction(los_result.worst_sample),
        data_sources=DataSources(
            dem=bool(raster_files(settings.dem_path)),
            buildings=request.include_buildings and db is not None,
            landcover=request.include_vegetation
            and bool(raster_files(settings.landcover_path)),
            canopy=request.include_canopy and bool(raster_files(settings.canopy_path)),
        ),
    )


def _fresnel_quality(los_clear: bool, geometric_los: bool) -> str:
    if los_clear:
        return "clear"
    if geometric_los:
        return "partial"
    return "blocked"


def _convert_obstruction(sample: LosSample | None) -> Obstruction | None:
    if sample is None:
        return None
    return Obstruction(
        distance_m=sample.distance_m,
        clearance_m=sample.clearance_m,
        fresnel_radius_m=sample.fresnel_radius_m,
        required_clearance_m=sample.required_clearance_m,
        type=sample.obstruction_type,
    )