Orbis.Tracker (Orbis v0.8.0)

Real-time satellite position tracker.

A GenServer that continuously propagates a satellite's position and broadcasts updates to subscribers. Multiple trackers can run concurrently for different satellites.

Examples

# Start tracking ISS
{:ok, [tle]} = Orbis.CelesTrak.fetch_tle(25544)
{:ok, tracker} = Orbis.Tracker.start_link(tle, interval_ms: 1000)

# Get current position
state = Orbis.Tracker.get_state(tracker)
state.position  #=> {x, y, z} in km
state.geodetic  #=> %{latitude: ..., longitude: ..., altitude_km: ...}

# Subscribe to updates
Orbis.Tracker.subscribe(tracker)
receive do
  {:orbis_tracker, ^tracker, state} ->
    IO.puts("ISS at #{state.geodetic.latitude}, #{state.geodetic.longitude}")
end

# Stop tracking
Orbis.Tracker.stop(tracker)

Summary

Types

state()

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

get_state(tracker)

Get the current tracking state.

start_link(tle, opts \\ [])

Start tracking a satellite.

stop(tracker)

Stop tracking.

subscribe(tracker)

Subscribe the calling process to position updates.

unsubscribe(tracker)

Unsubscribe the calling process from position updates.

update_tle(tracker, tle)

Update the TLE for a tracked satellite (e.g., after fetching a newer one).

Types

state()

@type state() :: %Orbis.Tracker{
  catalog_number: String.t(),
  geodetic: map() | nil,
  interval_ms: pos_integer(),
  last_update: DateTime.t() | nil,
  monitors: term(),
  position: {float(), float(), float()} | nil,
  pubsub: term(),
  subscribers: MapSet.t(),
  timer_ref: reference() | nil,
  tle: Orbis.Elements.t(),
  velocity: {float(), float(), float()} | nil
}

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

get_state(tracker)

@spec get_state(GenServer.server()) :: map()

Get the current tracking state.

Returns a map with position, velocity, geodetic coordinates, and timestamp.

start_link(tle, opts \\ [])

@spec start_link(
  Orbis.Elements.t(),
  keyword()
) :: GenServer.on_start()

Start tracking a satellite.

Options

:interval_ms - update interval in milliseconds (default: 1000)
:name - optional registered name for the process
:pubsub - {module, pubsub_name, topic} to broadcast via Phoenix.PubSub (or any module implementing broadcast/3). Messages are sent as {:orbis_tracker, tracker_pid, state_map}, the same shape as direct subscriber messages.

Examples

{:ok, tracker} = Orbis.Tracker.start_link(tle)
{:ok, tracker} = Orbis.Tracker.start_link(tle, interval_ms: 5000)

# With Phoenix PubSub
{:ok, tracker} = Orbis.Tracker.start_link(tle,
  pubsub: {Phoenix.PubSub, MyApp.PubSub, "satellite:25544"})

stop(tracker)

@spec stop(GenServer.server()) :: :ok

Stop tracking.

unsubscribe(tracker)

@spec unsubscribe(GenServer.server()) :: :ok

Unsubscribe the calling process from position updates.

update_tle(tracker, tle)

@spec update_tle(GenServer.server(), Orbis.Elements.t()) :: :ok

Update the TLE for a tracked satellite (e.g., after fetching a newer one).