대한민국 해군 마라도함(LPH-6112) 골키퍼 30mm CIWS 듀얼 추적 레이더 다중경로 반사파 제거 및 1,000Hz 0-Alloc C# 종말 요격 사격통제

using System;
using System.Numerics;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Defense.Navy.Ciws
{
    public readonly record struct RawRadarEcho(
        float SumChannelReal,
        float SumChannelImag,
        float DiffChannelReal,
        float DiffChannelImag,
        float RangeMeters,
        float DopplerSpeedMps
    );

    public ref struct CiwsAiringCommand
    {
        public float TrueElevationDeg;
        public float LeadAzimuthDeg;
        public float LeadElevationDeg;
        public float TimeOfFlightSec;
        public bool FirePermitted;
    }

    public static class GoalkeeperCiwsCore
    {
        private const float MuzzleVelocityMps = 1109.0f; // 30mm MPDS 포구초속
        private const float DragCoeff = 0.00015f;        // 탄도 감속 계수
        private const float Gravity = 9.80665f;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void SolveFireControl(
            ref readonly RawRadarEcho echo,
            Vector3 currentGunPointing,
            ref CiwsAiringCommand command)
        {
            // 1. 복소 모노펄스 각도비 계산: z = D / S
            float sumMagSq = echo.SumChannelReal * echo.SumChannelReal + echo.SumChannelImag * echo.SumChannelImag;
            if (sumMagSq < 1e-6f)
            {
                command.FirePermitted = false;
                return;
            }

            // z = (D_r * S_r + D_i * S_i) / |S|^2 + j (D_i * S_r - D_r * S_i) / |S|^2
            float zReal = (echo.DiffChannelReal * echo.SumChannelReal + echo.DiffChannelImag * echo.SumChannelImag) / sumMagSq;
            float zImag = (echo.DiffChannelImag * echo.SumChannelReal - echo.DiffChannelReal * echo.SumChannelImag) / sumMagSq;

            // 2. 다중경로 반사파 분리 (허수 성분을 이용한 위상 보정)
            float correctedErrorAngleDeg = zReal * 1.8f; // 모노펄스 슬로프 스케일
            if (MathF.Abs(zImag) > 0.1f)
            {
                // 해면 반사 허수부 감쇠 필터
                correctedErrorAngleDeg *= (1.0f / (1.0f + MathF.Abs(zImag) * 2.0f));
            }

            float trueElev = currentGunPointing.Z + correctedErrorAngleDeg;
            command.TrueElevationDeg = trueElev;

            // 3. 미래 탄착점 (Lead Point) 계산: 비행시간 ToF 수치적분
            float distance = echo.RangeMeters;
            float avgBulletSpeed = MuzzleVelocityMps - 0.5f * DragCoeff * distance * MuzzleVelocityMps;
            avgBulletSpeed = MathF.Max(avgBulletSpeed, 600.0f);
            float tof = distance / avgBulletSpeed;
            command.TimeOfFlightSec = tof;

            // 접근 표적 미래 이동량 반영
            float targetDropMeters = 0.5f * Gravity * tof * tof;
            float leadElevationRad = (trueElev * (MathF.PI / 180.0f)) + (targetDropMeters / distance);

            command.LeadAzimuthDeg = currentGunPointing.Y; // 방위각 추적 유지
            command.LeadElevationDeg = leadElevationRad * (180.0f / MathF.PI);

            // 유효 사거리(1.5km ~ 300m) 내 발사 승인
            command.FirePermitted = (distance <= 1500.0f && distance >= 200.0f);
        }
    }
}