Kosmoksessa suunnittelua: Satelliittiviestintäjärjestelmien toteuttaminen TypeScriptillä

            // Defines the type of orbit for a satellite
export enum OrbitType {
    LEO = 'Low Earth Orbit',
    MEO = 'Medium Earth Orbit',
    GEO = 'Geostationary Orbit',
    HEO = 'Highly Elliptical Orbit',
}

// Represents the key orbital parameters (Keplerian elements)
export interface OrbitalParameters {
    semiMajorAxis_km: number;       // Size of the orbit
    eccentricity: number;           // Shape of the orbit (0 for circular)
    inclination_deg: number;        // Tilt of the orbit relative to the equator
    raan_deg: number;               // Right Ascension of the Ascending Node (orbit's swivel)
    argumentOfPeriapsis_deg: number;// Orientation of the orbit within its plane
    trueAnomaly_deg: number;        // Position of the satellite along the orbit at a given epoch
    epoch: Date;                    // The reference time for these parameters
}

// Defines the health status of a satellite subsystem
export interface SubsystemStatus {
    name: 'Power' | 'Propulsion' | 'Thermal' | 'Communications';
    status: 'Nominal' | 'Warning' | 'Error' | 'Offline';
    voltage_V?: number;
    temperature_C?: number;
    pressure_kPa?: number;
}

// The core satellite model
export interface Satellite {
    id: string;                     // Unique identifier, e.g., 'SAT-001'
    name: string;                   // Common name, e.g., 'GlobalCom-1A'
    orbit: OrbitType;
    parameters: OrbitalParameters;
    subsystems: SubsystemStatus[];
}

            

              
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            export interface GeoLocation {
    latitude_deg: number;
    longitude_deg: number;
    altitude_m: number;
}

// Defines the frequency bands the ground station can operate on
export enum FrequencyBand {
    S_BAND = 'S-Band',
    C_BAND = 'C-Band',
    X_BAND = 'X-Band',
    KU_BAND = 'Ku-Band',
    KA_BAND = 'Ka-Band',
}

export interface GroundStation {
    id: string; // e.g., 'GS-EU-1' (Ground Station, Europe 1)
    name: string; // e.g., 'Fucino Space Centre'
    location: GeoLocation;
    availableBands: FrequencyBand[];
    uplinkRate_bps: number;
    downlinkRate_bps: number;
    status: 'Online' | 'Offline' | 'Maintenance';
}

            

              
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            // Base structure for any packet coming from the satellite
interface BasePacket {
    satelliteId: string;
    timestamp: number; // Unix timestamp in milliseconds
    sequenceNumber: number;
}

// Specific packet for subsystem health status
export interface HealthStatusPacket extends BasePacket {
    packetType: 'HEALTH_STATUS';
    payload: SubsystemStatus[];
}

// Specific packet for scientific data, e.g., from an imaging payload
export interface ScienceDataPacket extends BasePacket {
    packetType: 'SCIENCE_DATA';
    payload: {
        instrumentId: string;
        dataType: 'image/jpeg' | 'application/octet-stream';
        data: Buffer; // Raw binary data
    };
}

// Specific packet for acknowledging a received command
export interface CommandAckPacket extends BasePacket {
    packetType: 'COMMAND_ACK';
    payload: {
        commandSequenceNumber: number;
        status: 'ACK' | 'NACK'; // Acknowledged or Not Acknowledged
        reason?: string; // Optional reason for a NACK
    };
}

// A union of all possible telemetry packet types
export type TelemetryPacket = HealthStatusPacket | ScienceDataPacket | CommandAckPacket;

// A processor function that safely handles different packet types
function processTelemetry(packet: TelemetryPacket): void {
    console.log(`Processing packet #${packet.sequenceNumber} from ${packet.satelliteId}`);

    switch (packet.packetType) {
        case 'HEALTH_STATUS':
            // TypeScript knows `packet` is of type HealthStatusPacket here
            console.log('Received Health Status Update:');
            packet.payload.forEach(subsystem => {
                console.log(`  - ${subsystem.name}: ${subsystem.status}`);
            });
            break;

        case 'SCIENCE_DATA':
            // TypeScript knows `packet` is of type ScienceDataPacket here
            console.log(`Received Science Data from instrument ${packet.payload.instrumentId}.`);
            // Logic to save the data buffer to a file or database
            saveScienceData(packet.payload.data);
            break;

        case 'COMMAND_ACK':
            // TypeScript knows `packet` is of type CommandAckPacket here
            console.log(`Command #${packet.payload.commandSequenceNumber} status: ${packet.payload.status}`);
            if (packet.payload.status === 'NACK') {
                console.error(`Reason: ${packet.payload.reason}`);
            }
            break;

        default:
            // This part is crucial. TypeScript can perform exhaustive checking.
            // If we add a new packet type to the union and forget to handle it here,
            // the compiler will throw an error.
            const _exhaustiveCheck: never = packet;
            console.error(`Unhandled packet type: ${_exhaustiveCheck}`);
            return _exhaustiveCheck;
    }
}

function saveScienceData(data: Buffer) { /* Implementation omitted */ }

            

              
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            // Base structure for any command sent to the satellite
interface BaseCommand {
    commandId: string; // Unique ID for this command instance
    sequenceNumber: number;
    targetSatelliteId: string;
}

// Command to adjust the satellite's attitude (orientation)
export interface SetAttitudeCommand extends BaseCommand {
    commandType: 'SET_ATTITUDE';
    parameters: {
        quaternion: { w: number; x: number; y: number; z: number; };
        slewRate_deg_s: number;
    };
}

// Command to activate or deactivate a specific payload
export interface SetPayloadStateCommand extends BaseCommand {
    commandType: 'SET_PAYLOAD_STATE';
    parameters: {
        instrumentId: string;
        state: 'ACTIVE' | 'STANDBY' | 'OFF';
    };
}

// Command to perform a station-keeping maneuver
export interface ExecuteManeuverCommand extends BaseCommand {
    commandType: 'EXECUTE_MANEUVER';
    parameters: {
        thrusterId: string;
        burnDuration_s: number;
        thrustVector: { x: number; y: number; z: number; };
    };
}

// A union of all possible command types
export type Telecommand = SetAttitudeCommand | SetPayloadStateCommand | ExecuteManeuverCommand;

// A function to serialize a command into a binary format for uplink
function serializeCommand(command: Telecommand): Buffer {
    // The implementation would convert the structured command object
    // into a specific binary protocol understood by the satellite.
    console.log(`Serializing command ${command.commandType} for ${command.targetSatelliteId}...`);
    
    // The 'switch' here ensures each command type is handled correctly.
    // Type safety guarantees that 'command.parameters' will have the right shape.
    switch (command.commandType) {
        case 'SET_ATTITUDE':
            // Logic to pack quaternion and slew rate into a buffer
            break;
        case 'SET_PAYLOAD_STATE':
            // Logic to pack instrument ID and state enum into a buffer
            break;
        case 'EXECUTE_MANEUVER':
            // Logic to pack thruster details into a buffer
            break;
    }
    
    // Placeholder for actual binary data
    return Buffer.from(JSON.stringify(command)); 
}

            

              
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            // A simplified function to calculate one-way light-speed delay
function getSignalLatency_ms(satellite: Satellite, station: GroundStation): number {
    // In a real system, this would involve complex orbital mechanics to calculate
    // the precise distance between the satellite and the ground station.
    const speedOfLight_km_s = 299792.458;
    let distance_km: number;

    switch (satellite.orbit) {
        case OrbitType.LEO: distance_km = 1000; break; // Simplified average
        case OrbitType.MEO: distance_km = 15000; break;
        case OrbitType.GEO: distance_km = 35786; break;
        default: distance_km = 5000;
    }
    
    return (distance_km / speedOfLight_km_s) * 1000; // Return in milliseconds
}

// A utility for creating a delay
const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms));

// A service for sending commands and awaiting acknowledgment
class CommunicationService {
    async sendCommand(command: Telecommand, groundStation: GroundStation, targetSatellite: Satellite): Promise {
        console.log(`[${new Date().toISOString()}] Sending command ${command.commandType} via ${groundStation.name}...`);
        
        const uplinkLatency = getSignalLatency_ms(targetSatellite, groundStation);
        const downlinkLatency = uplinkLatency; // Simplified assumption
        
        // 1. Serialize the command for transmission
        const commandData = serializeCommand(command);

        // 2. Simulate the uplink delay
        await sleep(uplinkLatency);
        console.log(`[${new Date().toISOString()}] Command signal reached ${targetSatellite.name}.`);

        // In a real system, this part would be a network request to the ground station's hardware.
        // Here we simulate the satellite receiving it and immediately sending an ACK.
        const satelliteProcessingTime_ms = 50;
        await sleep(satelliteProcessingTime_ms);

        // 3. Simulate the downlink delay for the acknowledgment
        console.log(`[${new Date().toISOString()}] Satellite sending acknowledgment...`);
        await sleep(downlinkLatency);
        console.log(`[${new Date().toISOString()}] Acknowledgment received at ${groundStation.name}.`);

        // 4. Return a mock acknowledgment packet
        const ackPacket: CommandAckPacket = {
            satelliteId: targetSatellite.id,
            timestamp: Date.now(),
            sequenceNumber: command.sequenceNumber + 1, // Example logic
            packetType: 'COMMAND_ACK',
            payload: {
                commandSequenceNumber: command.sequenceNumber,
                status: 'ACK',
            }
        };
        
        return ackPacket;
    }
}

            

              
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            // Define different types of scientific data payloads
interface SpectrometerData {
    wavelengths_nm: number[];
    intensities: number[];
}

interface ImagingData {
    resolution: { width: number; height: number; };
    format: 'RAW' | 'JPEG';
    imageData: Buffer;
}

// A generic science packet that can hold any payload type
interface GenericSciencePacket extends BasePacket {
    packetType: 'SCIENCE_DATA';
    payload: {
        instrumentId: string;
        data: T;
    };
}

// Create specific packet types using the generic
type SpectrometerPacket = GenericSciencePacket;
type ImagingPacket = GenericSciencePacket;

// A generic processor class
class DataProcessor {
    process(packet: GenericSciencePacket): void {
        console.log(`Processing data from instrument ${packet.payload.instrumentId}`);
        // Generic processing logic here...
        this.saveToDatabase(packet.payload.data);
    }

    private saveToDatabase(data: T) {
        // Type-safe database saving logic for payload of type T
        console.log('Data saved.');
    }
}

// Instantiate processors for specific data types
const imagingProcessor = new DataProcessor();
const spectrometerProcessor = new DataProcessor();

// Example usage
const sampleImagePacket: ImagingPacket = { /* ... */ };
imagingProcessor.process(sampleImagePacket); // This works

// The following line would cause a compile-time error, preventing incorrect processing:
// spectrometerProcessor.process(sampleImagePacket); // Error: Argument of type 'ImagingPacket' is not assignable to parameter of type 'GenericSciencePacket'.

            

              
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            // Define potential error types
interface CommunicationError {
    type: 'Timeout' | 'SignalLost' | 'InvalidChecksum';
    message: string;
}

// A Result type that can be either a success (Ok) or a failure (Err)
type Result = { ok: true; value: T } | { ok: false; error: E };

// Modified sendCommand to return a Result
async function sendCommandSafe(
    command: Telecommand
): Promise> {
    try {
        // ... simulate sending command ...
        const isSuccess = Math.random() > 0.1; // Simulate a 10% failure rate

        if (!isSuccess) {
            return { ok: false, error: { type: 'SignalLost', message: 'Uplink signal lost during transmission.' } };
        }

        const ackPacket: CommandAckPacket = { /* ... */ };
        return { ok: true, value: ackPacket };

    } catch (e) {
        return { ok: false, error: { type: 'Timeout', message: 'No response from satellite.' } };
    }
}

// Calling code must now explicitly handle the failure case
asnyc function runCommandSequence() {
    const command: SetAttitudeCommand = { /* ... */ };
    const result = await sendCommandSafe(command);

    if (result.ok) {
        // TypeScript knows `result.value` is a CommandAckPacket here
        console.log(`Success! Command acknowledged:`, result.value.payload.status);
    } else {
        // TypeScript knows `result.error` is a CommunicationError here
        console.error(`Command failed: [${result.error.type}] ${result.error.message}`);
        // Trigger contingency plans...
    }
}

            

              
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