Maritime Target Tracking System

Build a target tracking system that processes NMEA sentences to monitor and analyze tracked targets from radar or AIS systems.

Requirements

Your system should parse NMEA target tracking data and provide the following capabilities:

1. Parse Target Position Data: Accept NMEA sentences containing target latitude and longitude information and extract the target's position in decimal degrees.

2. Extract Tracked Target Details: Process NMEA sentences with comprehensive tracking information including target number, distance, bearing, speed, and course.

3. Process Own Ship Data: Parse NMEA sentences containing vessel's own heading, course, and speed information.

4. Calculate Closest Point of Approach (CPA): For tracked targets, extract CPA distance and time-to-CPA from the tracking data.

Implement your solution in src/target_tracker.py with the following functions:

• parse_target_position(sentence: str) -> dict: Parse a target position sentence and return a dictionary with keys: target_number, latitude, longitude, timestamp

• parse_tracked_target(sentence: str) -> dict: Parse a tracked target sentence and return a dictionary with keys: target_number, distance, bearing, speed, course, cpa_distance, cpa_time

• parse_own_ship(sentence: str) -> dict: Parse own ship data and return a dictionary with keys: heading, course, speed

• get_closest_target(sentences: list) -> dict: Given a list of NMEA sentence strings, return the target with the smallest CPA distance, or None if no valid tracked targets exist

Dependencies { .dependencies }

pynmea2 { .dependency }

Python library for parsing NMEA 0183 protocol messages.

Tests

Parse Target Position

• Given the sentence "$RATLL,01,5241.123,N,00506.456,E,TARGET1,121505.00,T,*32", the function returns a dictionary with target_number=1, latitude≈52.6854, longitude≈5.1076, and timestamp present @test

Parse Tracked Target

• Given the sentence "$RATTM,01,5.2,135.0,T,2.5,045.0,T,0.8,0.5,N,,T,,*4F", the function returns a dictionary with target_number=1, distance=5.2, bearing=135.0, speed=2.5, course=45.0, cpa_distance=0.8, and cpa_time=0.5 @test

Parse Own Ship Data

• Given the sentence "$RAOSD,125.0,A,235.0,N,12.5,A,*77", the function returns a dictionary with heading=125.0, course=235.0, and speed=12.5 @test

Find Closest Target

• Given a list containing tracked target sentences with CPA distances of 2.5, 0.8, and 1.2, the function returns the target with CPA distance 0.8 @test

@generates

API

def parse_target_position(sentence: str) -> dict:
    """
    Parse a target position NMEA sentence.

    Args:
        sentence: NMEA sentence string containing target position

    Returns:
        Dictionary with keys: target_number, latitude, longitude, timestamp
    """
    pass

def parse_tracked_target(sentence: str) -> dict:
    """
    Parse a tracked target NMEA sentence.

    Args:
        sentence: NMEA sentence string containing tracked target data

    Returns:
        Dictionary with keys: target_number, distance, bearing, speed,
                             course, cpa_distance, cpa_time
    """
    pass

def parse_own_ship(sentence: str) -> dict:
    """
    Parse own ship data NMEA sentence.

    Args:
        sentence: NMEA sentence string containing own ship data

    Returns:
        Dictionary with keys: heading, course, speed
    """
    pass

def get_closest_target(sentences: list) -> dict:
    """
    Find the target with the smallest CPA distance from a list of sentences.

    Args:
        sentences: List of NMEA sentence strings

    Returns:
        Dictionary with target data for closest target, or None if no valid targets
    """
    pass