diff --git a/lib/aprs/bad_packet.ex b/lib/aprs/bad_packet.ex
index de2bac6..f75cbf0 100644
--- a/lib/aprs/bad_packet.ex
+++ b/lib/aprs/bad_packet.ex
@@ -15,6 +15,7 @@ defmodule Aprs.BadPacket do
   end
 
   @doc false
+  @spec changeset(%Aprs.BadPacket{}, map()) :: Ecto.Changeset.t()
   def changeset(bad_packet, attrs) do
     bad_packet
     |> cast(attrs, [:raw_packet, :error_message, :error_type, :attempted_at])
@@ -24,6 +25,7 @@ defmodule Aprs.BadPacket do
   @doc """
   Returns recent bad packets, ordered by attempted_at descending
   """
+  @spec recent(Ecto.Queryable.t(), pos_integer()) :: Ecto.Query.t()
   def recent(query \\ __MODULE__, limit \\ 100) do
     from(b in query,
       order_by: [desc: b.attempted_at],
@@ -34,6 +36,7 @@ defmodule Aprs.BadPacket do
   @doc """
   Returns bad packets by error type
   """
+  @spec by_error_type(Ecto.Queryable.t(), String.t()) :: Ecto.Query.t()
   def by_error_type(query \\ __MODULE__, error_type) do
     from(b in query,
       where: b.error_type == ^error_type
@@ -43,6 +46,7 @@ defmodule Aprs.BadPacket do
   @doc """
   Returns count of bad packets in the last N hours
   """
+  @spec count_recent(pos_integer()) :: Ecto.Query.t()
   def count_recent(hours \\ 24) do
     cutoff = DateTime.add(DateTime.utc_now(), -hours * 3600, :second)
 
diff --git a/lib/aprs/convert.ex b/lib/aprs/convert.ex
index e90dc37..61fcb87 100644
--- a/lib/aprs/convert.ex
+++ b/lib/aprs/convert.ex
@@ -1,8 +1,12 @@
 defmodule Aprs.Convert do
   @moduledoc false
+
+  @spec wind(number(), :ultimeter, :mph) :: float()
   def wind(speed, :ultimeter, :mph), do: speed * 0.0621371192
 
+  @spec temp(number(), :ultimeter, :f) :: float()
   def temp(value, :ultimeter, :f), do: value * 0.1
 
+  @spec speed(number(), :knots, :mph) :: float()
   def speed(value, :knots, :mph), do: Float.round(value * 1.15077945, 2)
 end
diff --git a/lib/aprs/data_extended.ex b/lib/aprs/data_extended.ex
index 7f32bbc..e662d64 100644
--- a/lib/aprs/data_extended.ex
+++ b/lib/aprs/data_extended.ex
@@ -17,6 +17,7 @@ defmodule Aprs.DataExtended do
   end
 
   @doc false
+  @spec changeset(%Aprs.DataExtended{}, map()) :: Ecto.Changeset.t()
   def changeset(%DataExtended{} = data_extended, attrs) do
     data_extended
     |> cast(attrs, [
diff --git a/lib/aprs/encoding_utils.ex b/lib/aprs/encoding_utils.ex
index 8bf8ae5..852e6c1 100644
--- a/lib/aprs/encoding_utils.ex
+++ b/lib/aprs/encoding_utils.ex
@@ -7,6 +7,8 @@ defmodule Aprs.EncodingUtils do
   to web clients.
   """
 
+  alias Parser.Types.MicE
+
   @doc """
   Sanitizes a binary to ensure it can be safely JSON encoded.
 
@@ -22,6 +24,7 @@ defmodule Aprs.EncodingUtils do
       iex> Aprs.EncodingUtils.sanitize_string(<<72, 101, 108, 108, 111, 211, 87, 111, 114, 108, 100>>)
       "HelloWorld"
   """
+  @spec sanitize_string(binary() | nil | any()) :: binary() | nil | any()
   def sanitize_string(binary) when is_binary(binary) do
     # Always scrub problematic bytes, even from valid UTF-8 strings
     # PostgreSQL rejects null bytes and other control characters even if they're valid UTF-8
@@ -34,6 +37,7 @@ defmodule Aprs.EncodingUtils do
   @doc """
   Sanitizes all string fields in an APRS packet to ensure safe JSON encoding.
   """
+  @spec sanitize_packet(struct() | map()) :: struct() | map()
   def sanitize_packet(%Aprs.Packet{} = packet) do
     %{
       packet
@@ -51,13 +55,14 @@ defmodule Aprs.EncodingUtils do
   @doc """
   Sanitizes string fields in the data_extended structure.
   """
+  @spec sanitize_data_extended(nil | map() | MicE.t() | any()) :: nil | map() | MicE.t() | any()
   def sanitize_data_extended(nil), do: nil
 
   def sanitize_data_extended(%{comment: comment} = data_extended) when is_map(data_extended) do
     %{data_extended | comment: sanitize_string(comment)}
   end
 
-  def sanitize_data_extended(%Parser.Types.MicE{message: message} = mic_e) do
+  def sanitize_data_extended(%MicE{message: message} = mic_e) do
     %{mic_e | message: sanitize_string(message)}
   end
 
@@ -78,6 +83,7 @@ defmodule Aprs.EncodingUtils do
 
   # Private helper functions
 
+  @spec scrub_problematic_bytes(binary()) :: String.t()
   defp scrub_problematic_bytes(binary) do
     # Handle both invalid UTF-8 sequences and problematic control characters
     cleaned =
@@ -101,11 +107,13 @@ defmodule Aprs.EncodingUtils do
   end
 
   # Check if byte should be kept (ASCII printable + safe whitespace)
+  @spec valid_utf8_byte?(integer()) :: boolean()
   defp valid_utf8_byte?(byte) when byte >= 32 and byte <= 126, do: true
   defp valid_utf8_byte?(byte) when byte in [9, 10, 13], do: true
   defp valid_utf8_byte?(_), do: false
 
   # Ensure the final result is valid UTF-8
+  @spec ensure_valid_utf8(binary()) :: binary()
   defp ensure_valid_utf8(binary) do
     if String.valid?(binary) do
       binary
@@ -133,6 +141,7 @@ defmodule Aprs.EncodingUtils do
       iex> Aprs.EncodingUtils.to_hex(<<72, 101, 108, 108, 111>>)
       "48656C6C6F"
   """
+  @spec to_hex(binary()) :: String.t()
   def to_hex(binary) when is_binary(binary) do
     binary
     |> :binary.bin_to_list()
@@ -151,6 +160,7 @@ defmodule Aprs.EncodingUtils do
       iex> Aprs.EncodingUtils.encoding_info(<<72, 101, 211, 108, 111>>)
       %{valid_utf8: false, byte_count: 5, invalid_at: 2}
   """
+  @spec encoding_info(binary()) :: map()
   def encoding_info(binary) when is_binary(binary) do
     valid = String.valid?(binary)
     byte_count = byte_size(binary)
@@ -169,6 +179,7 @@ defmodule Aprs.EncodingUtils do
     end
   end
 
+  @spec find_invalid_byte_position(binary(), non_neg_integer()) :: non_neg_integer() | nil
   defp find_invalid_byte_position(<<>>, _pos), do: nil
 
   defp find_invalid_byte_position(binary, pos) do
diff --git a/lib/aprs/is/is.ex b/lib/aprs/is/is.ex
index 6e0c762..1f7ce29 100644
--- a/lib/aprs/is/is.ex
+++ b/lib/aprs/is/is.ex
@@ -9,6 +9,22 @@ defmodule Aprs.Is do
   @aprs_timeout 60 * 1000
   @keepalive_interval 20 * 1000
 
+  @type state :: %{
+          server: charlist() | String.t(),
+          port: pos_integer(),
+          socket: :ssl.sslsocket() | nil,
+          timer: reference() | nil,
+          keepalive_timer: reference() | nil,
+          connected_at: DateTime.t(),
+          packet_stats: map(),
+          buffer: String.t(),
+          login_params: %{
+            user_id: String.t(),
+            passcode: String.t(),
+            filter: String.t()
+          }
+        }
+
   def start_link(opts \\ []) do
     GenServer.start_link(__MODULE__, opts, name: __MODULE__)
   end
@@ -139,6 +155,7 @@ defmodule Aprs.Is do
 
   # Server methods
 
+  @spec connect_to_aprs_is(String.t() | charlist(), pos_integer()) :: {:ok, :ssl.sslsocket()} | {:error, any()}
   defp connect_to_aprs_is(server, port) do
     # Additional safeguard: prevent connections in test environment
     if Application.get_env(:aprs, :env) == :test or
@@ -152,6 +169,7 @@ defmodule Aprs.Is do
     end
   end
 
+  @spec send_login_string(:ssl.sslsocket(), String.t(), String.t(), String.t()) :: :ok | {:error, any()}
   defp send_login_string(socket, aprs_user_id, aprs_passcode, filter) do
     login_string =
       "user #{aprs_user_id} pass #{aprs_passcode} vers aprs.me 0.1 filter #{filter}\r\n"
@@ -161,10 +179,12 @@ defmodule Aprs.Is do
     :gen_tcp.send(socket, login_string)
   end
 
+  @spec create_timer(non_neg_integer()) :: reference()
   defp create_timer(timeout) do
     Process.send_after(self(), :aprs_no_message_timeout, timeout)
   end
 
+  @spec create_keepalive_timer(non_neg_integer()) :: reference()
   defp create_keepalive_timer(interval) do
     Process.send_after(self(), :send_keepalive, interval)
   end
@@ -216,7 +236,9 @@ defmodule Aprs.Is do
     end
   end
 
-  def handle_info({:tcp, _socket, packet}, state) do
+  @impl true
+  @spec handle_info({:ssl, port(), binary()} | any(), state()) :: {:noreply, state()}
+  def handle_info({:ssl, _socket, data}, state) do
     # Cancel the previous timer
     Process.cancel_timer(state.timer)
 
@@ -225,7 +247,7 @@ defmodule Aprs.Is do
     packet_stats = update_packet_stats(state.packet_stats, current_time)
 
     # Append new packet data to buffer
-    buffer = state.buffer <> packet
+    buffer = state.buffer <> data
 
     # Process complete lines (ending with \r\n or \n)
     {complete_lines, remaining_buffer} = extract_complete_lines(buffer)
@@ -262,6 +284,7 @@ defmodule Aprs.Is do
   end
 
   # Extract complete lines from buffer, returning {complete_lines, remaining_buffer}
+  @spec extract_complete_lines(String.t()) :: {[String.t()], String.t()}
   defp extract_complete_lines(buffer) do
     # Split by both \r\n and \n to handle different line endings
     parts = String.split(buffer, ~r/\r?\n/, parts: :infinity)
@@ -388,6 +411,7 @@ defmodule Aprs.Is do
   end
 
   # Helper to check if a packet has position data worth storing
+  @spec has_position_data?(map()) :: boolean()
   defp has_position_data?(packet) do
     require Logger
 
@@ -425,6 +449,7 @@ defmodule Aprs.Is do
   end
 
   # Helper to validate coordinate values
+  @spec are_valid_coords?(any(), any()) :: boolean()
   defp are_valid_coords?(lat, lon) do
     require Logger
 
@@ -454,6 +479,7 @@ defmodule Aprs.Is do
   end
 
   # Helper to convert various types to float
+  @spec to_float(any()) :: float() | nil
   defp to_float(value) when is_float(value), do: value
   defp to_float(value) when is_integer(value), do: value * 1.0
   defp to_float(%Decimal{} = value), do: Decimal.to_float(value)
@@ -468,6 +494,7 @@ defmodule Aprs.Is do
   defp to_float(_), do: nil
 
   # Normalize data_type to ensure proper storage
+  @spec normalize_data_type(map()) :: map()
   defp normalize_data_type(%{data_type: data_type} = attrs) when is_atom(data_type) do
     %{attrs | data_type: to_string(data_type)}
   end
@@ -478,6 +505,7 @@ defmodule Aprs.Is do
   #   :ets.select_count(:aprs_messages, total_spec)
   # end
 
+  @spec update_packet_stats(map(), integer()) :: map()
   defp update_packet_stats(stats, current_time) do
     new_total = stats.total_packets + 1
 
@@ -503,10 +531,12 @@ defmodule Aprs.Is do
     end
   end
 
+  @spec server_to_string(String.t() | charlist() | any()) :: String.t()
   defp server_to_string(server) when is_list(server), do: List.to_string(server)
   defp server_to_string(server) when is_binary(server), do: server
   defp server_to_string(server), do: to_string(server)
 
+  @spec default_packet_stats() :: map()
   defp default_packet_stats do
     %{
       total_packets: 0,
@@ -519,6 +549,7 @@ defmodule Aprs.Is do
 
   # Helper function to recursively convert structs to maps
   # This handles nested structs that Map.from_struct/1 cannot handle
+  @spec struct_to_map(any()) :: any()
   defp struct_to_map(%{__struct__: struct_type} = struct) do
     converted_map =
       struct
diff --git a/lib/aprs/packet.ex b/lib/aprs/packet.ex
index 0fffad5..f689afc 100644
--- a/lib/aprs/packet.ex
+++ b/lib/aprs/packet.ex
@@ -61,6 +61,7 @@ defmodule Aprs.Packet do
   end
 
   @doc false
+  @spec changeset(%Aprs.Packet{}, map()) :: Ecto.Changeset.t()
   def changeset(packet, attrs) do
     # Convert atom data_type to string
     attrs = normalize_data_type(attrs)
@@ -121,6 +122,7 @@ defmodule Aprs.Packet do
     |> maybe_set_has_position()
   end
 
+  @spec maybe_create_geometry_from_lat_lon(Ecto.Changeset.t()) :: Ecto.Changeset.t()
   defp maybe_create_geometry_from_lat_lon(changeset) do
     lat = get_field(changeset, :lat) || get_change(changeset, :lat)
     lon = get_field(changeset, :lon) || get_change(changeset, :lon)
@@ -207,9 +209,10 @@ defmodule Aprs.Packet do
   defp normalize_data_type(attrs), do: attrs
 
   @doc """
-  Extracts additional data from the parsed packet's data_extended field
+  Extracts additional data from the raw packet and data_extended structure
   and merges it with the packet attributes for storage.
   """
+  @spec extract_additional_data(map(), String.t() | nil) :: map()
   def extract_additional_data(attrs, raw_packet \\ nil) do
     data_extended = attrs[:data_extended] || attrs["data_extended"] || %{}
 
@@ -446,6 +449,7 @@ defmodule Aprs.Packet do
   @doc """
   Create a geometry point from lat/lon coordinates.
   """
+  @spec create_point(number() | nil, number() | nil) :: Geo.Point.t() | nil
   def create_point(lat, lon) when is_number(lat) and is_number(lon) do
     if lat >= -90 and lat <= 90 and lon >= -180 and lon <= 180 do
       %Geo.Point{coordinates: {lon, lat}, srid: 4326}
@@ -457,18 +461,21 @@ defmodule Aprs.Packet do
   @doc """
   Extract lat/lon from a PostGIS geometry point.
   """
+  @spec extract_coordinates(Geo.Point.t() | any()) :: {number() | nil, number() | nil}
   def extract_coordinates(%Geo.Point{coordinates: {lon, lat}}), do: {lat, lon}
   def extract_coordinates(_), do: {nil, nil}
 
   @doc """
   Get latitude from a packet's location geometry.
   """
+  @spec lat(%Aprs.Packet{}) :: number() | nil
   def lat(%__MODULE__{location: %Geo.Point{coordinates: {_lon, lat}}}), do: lat
   def lat(_), do: nil
 
   @doc """
   Get longitude from a packet's location geometry.
   """
+  @spec lon(%Aprs.Packet{}) :: number() | nil
   def lon(%__MODULE__{location: %Geo.Point{coordinates: {lon, _lat}}}), do: lon
   def lon(_), do: nil
 
diff --git a/lib/aprs/packet_replay.ex b/lib/aprs/packet_replay.ex
index 0d5a129..9c55c56 100644
--- a/lib/aprs/packet_replay.ex
+++ b/lib/aprs/packet_replay.ex
@@ -19,6 +19,24 @@ defmodule Aprs.PacketReplay do
   @default_replay_window_minutes 60
   @default_replay_speed 5.0
 
+  @type state :: %{
+          user_id: String.t(),
+          replay_topic: String.t(),
+          replay_speed: float(),
+          start_time: DateTime.t(),
+          end_time: DateTime.t(),
+          region: String.t() | nil,
+          bounds: map(),
+          callsign: String.t() | nil,
+          with_position: boolean(),
+          limit: pos_integer(),
+          paused: boolean(),
+          packets_sent: non_neg_integer(),
+          replay_started_at: DateTime.t(),
+          replay_timer: reference() | nil,
+          last_packet_time: DateTime.t() | nil
+        }
+
   # Client API
 
   @doc """
@@ -34,6 +52,7 @@ defmodule Aprs.PacketReplay do
     * `:limit` - Maximum number of packets to replay (default: 5000)
     * `:with_position` - Only include packets with position data (default: true)
   """
+  @spec start_replay(keyword()) :: {:ok, pid()} | {:error, any()}
   def start_replay(opts) do
     user_id = Keyword.fetch!(opts, :user_id)
 
@@ -53,6 +72,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Stops an active replay session for a user.
   """
+  @spec stop_replay(String.t()) :: :ok
   def stop_replay(user_id) do
     name = via_tuple(user_id)
 
@@ -66,6 +86,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Pauses an active replay session.
   """
+  @spec pause_replay(String.t()) :: :ok | :already_paused
   def pause_replay(user_id) do
     name = via_tuple(user_id)
     GenServer.call(name, :pause)
@@ -74,6 +95,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Resumes a paused replay session.
   """
+  @spec resume_replay(String.t()) :: :ok
   def resume_replay(user_id) do
     name = via_tuple(user_id)
     GenServer.call(name, :resume)
@@ -82,6 +104,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Changes the replay speed.
   """
+  @spec set_replay_speed(String.t(), number()) :: :ok
   def set_replay_speed(user_id, speed) when is_number(speed) and speed > 0 do
     name = via_tuple(user_id)
     GenServer.call(name, {:set_speed, speed})
@@ -90,6 +113,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Updates replay filters (region, bounds, callsign, etc.)
   """
+  @spec update_filters(String.t(), keyword()) :: :ok
   def update_filters(user_id, filters) when is_list(filters) do
     name = via_tuple(user_id)
     GenServer.call(name, {:update_filters, filters})
@@ -98,6 +122,7 @@ defmodule Aprs.PacketReplay do
   @doc """
   Gets information about the current replay session.
   """
+  @spec get_replay_info(String.t()) :: map()
   def get_replay_info(user_id) do
     name = via_tuple(user_id)
     GenServer.call(name, :get_info)
@@ -106,6 +131,7 @@ defmodule Aprs.PacketReplay do
   # Server implementation
 
   @impl true
+  @spec init(keyword()) :: {:ok, state()}
   def init(opts) do
     user_id = Keyword.fetch!(opts, :user_id)
 
@@ -152,6 +178,7 @@ defmodule Aprs.PacketReplay do
   end
 
   @impl true
+  @spec handle_info(any(), state()) :: {:noreply, state()} | {:stop, :normal, state()}
   def handle_info(:start_replay, state) do
     # Fetch historical packets based on filters
     # Always filter by bounds (visible map area) and limit to packets with position
@@ -245,6 +272,7 @@ defmodule Aprs.PacketReplay do
   end
 
   @impl true
+  @spec handle_call(any(), {pid(), any()}, state()) :: {:reply, any(), state()}
   def handle_call(:pause, _from, state) do
     if state.replay_timer do
       Process.cancel_timer(state.replay_timer)
@@ -345,6 +373,7 @@ defmodule Aprs.PacketReplay do
   end
 
   @impl true
+  @spec terminate(any(), state()) :: :ok
   def terminate(_reason, state) do
     # Clean up any timers
     if state.replay_timer do
@@ -362,10 +391,12 @@ defmodule Aprs.PacketReplay do
 
   # Helper functions
 
+  @spec via_tuple(String.t()) :: {:via, Registry, {atom(), String.t()}}
   defp via_tuple(user_id) do
     {:via, Registry, {Aprs.ReplayRegistry, "replay:#{user_id}"}}
   end
 
+  @spec sanitize_packet_for_transport(any()) :: map()
   defp sanitize_packet_for_transport(packet) do
     # Convert to map and ensure all fields are JSON-safe
     packet
@@ -374,6 +405,7 @@ defmodule Aprs.PacketReplay do
     |> sanitize_map_values()
   end
 
+  @spec sanitize_map_values(map()) :: map()
   defp sanitize_map_values(map) when is_map(map) do
     Enum.reduce(map, %{}, fn {k, v}, acc ->
       Map.put(acc, k, sanitize_value(v))
diff --git a/lib/aprs/packets.ex b/lib/aprs/packets.ex
index 48eaa9b..c4bbac7 100644
--- a/lib/aprs/packets.ex
+++ b/lib/aprs/packets.ex
@@ -16,6 +16,7 @@ defmodule Aprs.Packets do
   ## Parameters
     * `packet_data` - Map containing packet data to be stored
   """
+  @spec store_packet(map()) :: {:ok, struct()} | {:error, :validation_error | :storage_exception}
   def store_packet(packet_data) do
     require Logger
 
@@ -114,6 +115,7 @@ defmodule Aprs.Packets do
     * `packet_data` - The original packet data that failed to parse
     * `error` - The error that occurred during parsing
   """
+  @spec store_bad_packet(map() | String.t(), any()) :: {:ok, struct()} | {:error, Ecto.Changeset.t()}
   def store_bad_packet(packet_data, error) do
     error_type =
       case error do
@@ -216,6 +218,7 @@ defmodule Aprs.Packets do
   @doc """
   Gets historical packet count for a map area.
   """
+  @spec get_historical_packet_count(map()) :: non_neg_integer()
   def get_historical_packet_count(opts \\ %{}) do
     base_query = from(p in Packet, select: count(p.id), where: p.has_position == true)
 
@@ -262,9 +265,10 @@ defmodule Aprs.Packets do
   defp filter_by_time(query, _), do: query
 
   @doc """
-  Get packets only from the last hour for current display.
+  Gets recent packets for the map view.
   This is used for initial map loading to show only recent packets.
   """
+  @spec get_recent_packets(map()) :: [struct()]
   def get_recent_packets(opts \\ %{}) do
     # Always limit to the last hour
     one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)
@@ -361,6 +365,7 @@ defmodule Aprs.Packets do
   @doc """
   Gets the total count of stored packets in the database.
   """
+  @spec get_total_packet_count() :: non_neg_integer()
   def get_total_packet_count do
     Repo.one(from p in Packet, select: count(p.id))
   end
@@ -382,17 +387,20 @@ defmodule Aprs.Packets do
   end
 
   @doc """
-  Clean packets older than a specific number of days.
+    Clean packets older than a specific number of days.
 
-  This function allows for more granular cleanup operations by specifying
-  the exact age threshold for packet deletion.
+    This function allows for more granular cleanup operations by specifying
+    the exact age threshold for packet deletion.
+  @doc \"""
+  Removes packets older than the specified number of days.
 
   ## Parameters
-  - `days` - Number of days to retain packets (packets older than this will be deleted)
+  - `days` - Number of days to keep (packets older than this will be deleted)
 
   ## Returns
   - Number of packets deleted
   """
+  @spec clean_packets_older_than(pos_integer()) :: non_neg_integer()
   def clean_packets_older_than(days) when is_integer(days) and days > 0 do
     cutoff_time = DateTime.add(DateTime.utc_now(), -days * 86_400, :second)
 
@@ -481,6 +489,7 @@ defmodule Aprs.Packets do
   end
 
   # Get packets from last hour only - used to initialize the map
+  @spec get_last_hour_packets() :: [struct()]
   def get_last_hour_packets do
     one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)
 
diff --git a/lib/aprs/passcode.ex b/lib/aprs/passcode.ex
index 07d0cb4..b72a775 100644
--- a/lib/aprs/passcode.ex
+++ b/lib/aprs/passcode.ex
@@ -17,6 +17,7 @@ defmodule Aprs.Passcode do
       iex> Aprs.Passcode.generate("W5ISP")
       15748
   """
+  @spec generate(String.t()) :: non_neg_integer()
   def generate(callsign) when is_binary(callsign) do
     # Split on '-' and take first part, uppercase, and limit to 10 chars
     realcall =
diff --git a/lib/aprs/workers/packet_cleanup_worker.ex b/lib/aprs/workers/packet_cleanup_worker.ex
index e2c8097..5a99c17 100644
--- a/lib/aprs/workers/packet_cleanup_worker.ex
+++ b/lib/aprs/workers/packet_cleanup_worker.ex
@@ -25,6 +25,7 @@ defmodule Aprs.Workers.PacketCleanupWorker do
   require Logger
 
   @impl Oban.Worker
+  @spec perform(Oban.Job.t()) :: :ok | {:error, String.t()}
   def perform(%Oban.Job{args: %{"cleanup_days" => days}}) when is_integer(days) do
     Logger.info("Starting scheduled APRS packet cleanup for packets older than #{days} days")
 
@@ -41,6 +42,7 @@ defmodule Aprs.Workers.PacketCleanupWorker do
     :ok
   end
 
+  @spec perform(Oban.Job.t()) :: :ok | {:error, String.t()}
   def perform(%Oban.Job{args: _args}) do
     Logger.info("Starting scheduled APRS packet cleanup")
 
@@ -78,6 +80,7 @@ defmodule Aprs.Workers.PacketCleanupWorker do
   ## Returns
   - Number of packets deleted
   """
+  @spec cleanup_packets_older_than(pos_integer()) :: non_neg_integer()
   def cleanup_packets_older_than(days) when is_integer(days) and days > 0 do
     Logger.info("Starting APRS packet cleanup for packets older than #{days} days")
 
diff --git a/lib/aprs_web/helpers/aprs_symbols.ex b/lib/aprs_web/helpers/aprs_symbols.ex
index b9b35fe..528721d 100644
--- a/lib/aprs_web/helpers/aprs_symbols.ex
+++ b/lib/aprs_web/helpers/aprs_symbols.ex
@@ -22,6 +22,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
       iex> AprsWeb.Helpers.AprsSymbols.get_sprite_filename("\\")
       "aprs-symbols-24-1.png"
   """
+  @spec get_sprite_filename(String.t()) :: String.t()
   def get_sprite_filename(symbol_table_id) do
     case symbol_table_id do
       "/" -> "aprs-symbols-24-0.png"
@@ -34,6 +35,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   @doc """
   Get the high-resolution sprite sheet filename for retina displays.
   """
+  @spec get_sprite_filename_2x(String.t()) :: String.t()
   def get_sprite_filename_2x(symbol_table_id) do
     case symbol_table_id do
       "/" -> "aprs-symbols-24-0@2x.png"
@@ -56,6 +58,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
       iex> AprsWeb.Helpers.AprsSymbols.get_symbol_position("!")
       {-216, 0}   # ASCII 33, position 1 -> column 1, row 0
   """
+  @spec get_symbol_position(String.t() | integer()) :: {integer(), integer()}
   def get_symbol_position(symbol_code) when is_binary(symbol_code) do
     # Get first character if string
     char_code = symbol_code |> String.first() |> String.to_charlist() |> List.first()
@@ -92,6 +95,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
       iex> AprsWeb.Helpers.AprsSymbols.symbol_css_style("/", ">")
       "background-image: url('/aprs-symbols/aprs-symbols-24-0.png'); background-position: -1440px 0px; width: 24px; height: 24px;"
   """
+  @spec symbol_css_style(String.t(), String.t() | integer()) :: String.t()
   def symbol_css_style(symbol_table_id, symbol_code) do
     sprite_file = get_sprite_filename(symbol_table_id)
     {x, y} = get_symbol_position(symbol_code)
@@ -105,6 +109,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   @doc """
   Generate HTML for an APRS symbol with proper sprite positioning.
   """
+  @spec symbol_html(String.t(), String.t() | integer(), keyword()) :: {:safe, String.t()}
   def symbol_html(symbol_table_id, symbol_code, opts \\ []) do
     css_class = Keyword.get(opts, :class, "aprs-symbol")
     extra_style = Keyword.get(opts, :style, "")
@@ -119,6 +124,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   Get a data URL for the symbol that can be used in JavaScript/Leaflet.
   This creates a small canvas with just the symbol extracted from the sprite.
   """
+  @spec get_symbol_data_attributes(String.t(), String.t() | integer()) :: map()
   def get_symbol_data_attributes(symbol_table_id, symbol_code) do
     sprite_file = get_sprite_filename(symbol_table_id)
     sprite_file_2x = get_sprite_filename_2x(symbol_table_id)
@@ -137,6 +143,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   @doc """
   Get the default symbol for unknown or invalid symbols.
   """
+  @spec default_symbol() :: {String.t(), String.t()}
   def default_symbol do
     # Car icon as default
     {"/", ">"}
@@ -145,6 +152,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   @doc """
   Validate if a symbol table ID and code combination is valid.
   """
+  @spec valid_symbol?(any(), any()) :: boolean()
   def valid_symbol?(symbol_table_id, symbol_code) do
     case {symbol_table_id, symbol_code} do
       {table, code} when table in ["/", "\\"] and is_binary(code) and byte_size(code) > 0 ->
@@ -161,6 +169,7 @@ defmodule AprsWeb.Helpers.AprsSymbols do
   This is a subset of common symbols - for a complete list, you'd want to
   reference the official APRS symbol specification.
   """
+  @spec symbol_description(String.t(), String.t()) :: String.t()
   def symbol_description(symbol_table_id, symbol_code) do
     case {symbol_table_id, symbol_code} do
       # Primary Table (/)
diff --git a/lib/aprs_web/live/map_live/index.ex b/lib/aprs_web/live/map_live/index.ex
index 498e148..4a284fb 100644
--- a/lib/aprs_web/live/map_live/index.ex
+++ b/lib/aprs_web/live/map_live/index.ex
@@ -8,6 +8,7 @@ defmodule AprsWeb.MapLive.Index do
   alias AprsWeb.Endpoint
   alias AprsWeb.Helpers.AprsSymbols
   alias Parser.Types.MicE
+  alias Phoenix.LiveView.Socket
 
   @default_center %{lat: 39.8283, lng: -98.5795}
   @default_zoom 5
@@ -30,6 +31,7 @@ defmodule AprsWeb.MapLive.Index do
     {:ok, socket}
   end
 
+  @spec assign_defaults(Socket.t(), DateTime.t()) :: Socket.t()
   defp assign_defaults(socket, one_hour_ago) do
     assign(socket,
       packets: [],
@@ -61,6 +63,7 @@ defmodule AprsWeb.MapLive.Index do
     )
   end
 
+  @spec maybe_start_geolocation(Socket.t()) :: Socket.t()
   defp maybe_start_geolocation(socket) do
     if Application.get_env(:aprs, :disable_aprs_connection, false) != true do
       ip =
@@ -81,6 +84,8 @@ defmodule AprsWeb.MapLive.Index do
         end)
       end
     end
+
+    socket
   end
 
   defp schedule_timers do
@@ -242,6 +247,7 @@ defmodule AprsWeb.MapLive.Index do
     {:noreply, socket}
   end
 
+  @spec handle_bounds_update(map(), Socket.t()) :: {:noreply, Socket.t()}
   defp handle_bounds_update(bounds, socket) do
     # Update the map bounds from the client
     map_bounds = %{
@@ -270,6 +276,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec process_bounds_update(map(), Socket.t()) :: Socket.t()
   defp process_bounds_update(map_bounds, socket) do
     # Filter visible packets to only include those within the new bounds and time threshold
     new_visible_packets =
@@ -709,6 +716,7 @@ defmodule AprsWeb.MapLive.Index do
   end
 
   # Check if a packet is within the time threshold (not too old)
+  @spec packet_within_time_threshold?(map(), DateTime.t()) :: boolean()
   defp packet_within_time_threshold?(packet, threshold) do
     case packet do
       %{received_at: received_at} when not is_nil(received_at) ->
@@ -724,6 +732,7 @@ defmodule AprsWeb.MapLive.Index do
 
   # Fetch historical packets from the database
   # Helper function to start historical replay
+  @spec start_historical_replay(Socket.t()) :: Socket.t()
   defp start_historical_replay(socket) do
     # Get time range for historical data
     now = DateTime.utc_now()
@@ -764,6 +773,7 @@ defmodule AprsWeb.MapLive.Index do
   end
 
   # Fetch historical packets from the database
+  @spec fetch_historical_packets(list(), DateTime.t(), DateTime.t()) :: [struct()]
   defp fetch_historical_packets(bounds, start_time, end_time) do
     # Force start_time to be at most 1 hour ago
     one_hour_ago = DateTime.add(DateTime.utc_now(), -3600, :second)
@@ -790,6 +800,7 @@ defmodule AprsWeb.MapLive.Index do
     Enum.sort_by(packets, fn packet -> packet.received_at end)
   end
 
+  @spec has_position_data?(map() | struct()) :: boolean()
   defp has_position_data?(packet) do
     case packet.data_extended do
       %MicE{} = mic_e ->
@@ -806,6 +817,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec within_bounds?(map() | struct(), map()) :: boolean()
   defp within_bounds?(packet, bounds) do
     {lat, lng} = get_coordinates(packet)
 
@@ -830,6 +842,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec get_coordinates(map() | struct()) :: {number() | nil, number() | nil}
   defp get_coordinates(packet) do
     case packet.data_extended do
       %MicE{} = mic_e ->
@@ -855,6 +868,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec build_packet_data(map() | struct()) :: map() | nil
   defp build_packet_data(packet) do
     data_extended = build_data_extended(packet.data_extended)
     {lat, lng} = get_coordinates(packet)
@@ -865,6 +879,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec build_packet_map(map() | struct(), number(), number(), map() | nil) :: map()
   defp build_packet_map(packet, lat, lng, data_extended) do
     {final_table_id, final_symbol_code} = get_validated_symbol(packet, data_extended)
     callsign = generate_callsign(packet)
@@ -886,6 +901,7 @@ defmodule AprsWeb.MapLive.Index do
     }
   end
 
+  @spec get_validated_symbol(map() | struct(), map() | nil) :: {String.t(), String.t()}
   defp get_validated_symbol(packet, data_extended) do
     symbol_table_id = get_symbol_table_id(packet, data_extended)
     symbol_code = get_symbol_code(packet, data_extended)
@@ -897,14 +913,17 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec get_symbol_table_id(map() | struct(), map() | nil) :: String.t()
   defp get_symbol_table_id(packet, data_extended) do
     get_in(data_extended, ["symbol_table_id"]) || packet.symbol_table_id || "/"
   end
 
+  @spec get_symbol_code(map() | struct(), map() | nil) :: String.t()
   defp get_symbol_code(packet, data_extended) do
     get_in(data_extended, ["symbol_code"]) || packet.symbol_code || ">"
   end
 
+  @spec generate_callsign(map() | struct()) :: String.t()
   defp generate_callsign(packet) do
     if packet.ssid && packet.ssid != "" do
       "#{packet.base_callsign}-#{packet.ssid}"
@@ -916,8 +935,10 @@ defmodule AprsWeb.MapLive.Index do
   # Get IP location from external service
 
   # Get location from IP using ip-api.com
+  @spec get_ip_location(String.t() | nil) :: {float(), float()} | nil
   defp get_ip_location(nil), do: nil
 
+  @spec get_ip_location(String.t()) :: {float(), float()} | nil
   defp get_ip_location(ip) do
     url = "#{@ip_api_url}#{ip}"
 
@@ -966,11 +987,13 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec build_data_extended(nil | MicE.t() | map()) :: nil | map()
   defp build_data_extended(nil), do: nil
 
   defp build_data_extended(%MicE{} = mic_e), do: build_mice_data_extended(mic_e)
   defp build_data_extended(data_extended), do: build_map_data_extended(data_extended)
 
+  @spec build_mice_data_extended(MicE.t()) :: map()
   defp build_mice_data_extended(mic_e) do
     lat = mic_e.lat_degrees + mic_e.lat_minutes / 60.0 + mic_e.lat_fractional / 6000.0
     lat = if mic_e.lat_direction == :south, do: -lat, else: lat
@@ -990,6 +1013,7 @@ defmodule AprsWeb.MapLive.Index do
     end
   end
 
+  @spec build_map_data_extended(map()) :: map()
   defp build_map_data_extended(data_extended) do
     %{
       "latitude" => data_extended[:latitude],
@@ -1002,9 +1026,11 @@ defmodule AprsWeb.MapLive.Index do
   end
 
   # Helper function to convert string or float to float
+  @spec to_float(number() | String.t()) :: float()
   defp to_float(value) when is_float(value), do: value
   defp to_float(value) when is_integer(value), do: value * 1.0
 
+  @spec to_float(String.t()) :: float()
   defp to_float(value) when is_binary(value) do
     case Float.parse(value) do
       {float_val, _} -> float_val
diff --git a/lib/parser.ex b/lib/parser.ex
index ffa516c..41c997c 100644
--- a/lib/parser.ex
+++ b/lib/parser.ex
@@ -9,6 +9,22 @@ defmodule Parser do
 
   require Logger
 
+  @type packet :: %{
+          id: String.t(),
+          sender: String.t(),
+          path: String.t(),
+          destination: String.t(),
+          information_field: String.t(),
+          data_type: atom(),
+          base_callsign: String.t(),
+          ssid: String.t(),
+          data_extended: map() | nil,
+          received_at: DateTime.t()
+        }
+
+  @type parse_result :: {:ok, packet()} | {:error, atom() | String.t()}
+
+  @spec parse(String.t()) :: parse_result()
   def parse(message) do
     with {:ok, [sender, path, data]} <- split_packet(message),
          {:ok, [base_callsign, ssid]} <- parse_callsign(sender),
@@ -50,7 +66,8 @@ defmodule Parser do
   end
 
   # Safely split packet into components
-  defp split_packet(message) do
+  @spec split_packet(String.t()) :: {:ok, [String.t()]} | {:error, String.t()}
+  def split_packet(message) do
     case String.split(message, [">", ":"], parts: 3) do
       [sender, path, data] when byte_size(sender) > 0 and byte_size(path) > 0 ->
         {:ok, [sender, path, data]}
@@ -61,7 +78,8 @@ defmodule Parser do
   end
 
   # Safely split path into destination and digipeater path
-  defp split_path(path) do
+  @spec split_path(String.t()) :: {:ok, [String.t()]} | {:error, String.t()}
+  def split_path(path) do
     case String.split(path, ",", parts: 2) do
       [destination, digi_path] ->
         {:ok, [destination, digi_path]}
@@ -75,13 +93,15 @@ defmodule Parser do
   end
 
   # Safe version of parse_datatype that returns {:ok, type} or {:error, reason}
-  defp parse_datatype_safe(data) do
+  @spec parse_datatype_safe(String.t()) :: {:ok, atom()} | {:error, String.t()}
+  def parse_datatype_safe(data) do
     case String.first(data) do
       nil -> {:error, "Empty data field"}
       first_char -> {:ok, parse_datatype(first_char)}
     end
   end
 
+  @spec parse_callsign(String.t()) :: {:ok, [String.t()]} | {:error, String.t()}
   def parse_callsign(callsign) do
     cond do
       not is_binary(callsign) ->
@@ -107,6 +127,7 @@ defmodule Parser do
   # first 40 characters of the message. I'm not going to deal with that
   # weird case right now. It seems like its for a specific type of old
   # TNC hardware that probably doesn't even exist anymore.
+  @spec parse_datatype(String.t()) :: atom()
   def parse_datatype(datatype) when datatype == ":", do: :message
   def parse_datatype(datatype) when datatype == ">", do: :status
   def parse_datatype(datatype) when datatype == "!", do: :position
@@ -133,6 +154,7 @@ defmodule Parser do
 
   def parse_datatype(_datatype), do: :unknown_datatype
 
+  @spec parse_data(atom(), String.t(), String.t()) :: map() | nil
   def parse_data(:mic_e, destination, data), do: parse_mic_e(destination, data)
   def parse_data(:mic_e_old, destination, data), do: parse_mic_e(destination, data)
 
@@ -172,7 +194,7 @@ defmodule Parser do
         }
 
       _ ->
-        parse_position_with_timestamp(false, data)
+        parse_position_with_timestamp(false, data, :timestamped_position)
     end
   end
 
@@ -226,6 +248,7 @@ defmodule Parser do
 
   def parse_data(_type, _destination, _data), do: nil
 
+  @spec parse_position_with_datetime_and_weather(boolean(), String.t(), String.t()) :: map()
   def parse_position_with_datetime_and_weather(aprs_messaging?, date_time_position_data, weather_report) do
     case date_time_position_data do
       <<time::binary-size(7), latitude::binary-size(8), sym_table_id::binary-size(1), longitude::binary-size(9)>> ->
@@ -260,6 +283,7 @@ defmodule Parser do
     end
   end
 
+  @spec decode_compressed_position(binary()) :: map()
   def decode_compressed_position(
         <<"/", latitude::binary-size(4), longitude::binary-size(4), symbol_code::binary-size(1), _cs::binary-size(2),
           _compression_type::binary-size(2), _rest::binary>>
@@ -274,11 +298,13 @@ defmodule Parser do
     }
   end
 
+  @spec convert_to_base91(binary()) :: integer()
   def convert_to_base91(<<value::binary-size(4)>>) do
     [v1, v2, v3, v4] = to_charlist(value)
     (v1 - 33) * 91 * 91 * 91 + (v2 - 33) * 91 * 91 + (v3 - 33) * 91 + v4
   end
 
+  @spec parse_position_without_timestamp(boolean(), String.t()) :: map()
   def parse_position_without_timestamp(aprs_messaging?, position_data) do
     case position_data do
       <<latitude::binary-size(8), sym_table_id::binary-size(1), longitude::binary-size(9), symbol_code::binary-size(1),
@@ -346,10 +372,12 @@ defmodule Parser do
     end
   end
 
+  @spec parse_position_with_timestamp(boolean(), binary(), atom()) :: map()
   def parse_position_with_timestamp(
         aprs_messaging?,
-        <<_dti::binary-size(1), time::binary-size(7), latitude::binary-size(8), sym_table_id::binary-size(1),
-          longitude::binary-size(9), symbol_code::binary-size(1), comment::binary>>
+        <<time::binary-size(7), latitude::binary-size(8), sym_table_id::binary-size(1), longitude::binary-size(9),
+          symbol_code::binary-size(1), comment::binary>>,
+        _data_type
       ) do
     case validate_position_data(latitude, longitude) do
       {:ok, {lat, lon}} ->
@@ -395,6 +423,7 @@ defmodule Parser do
       }
   end
 
+  @spec parse_position_with_timestamp(boolean(), binary()) :: map()
   def parse_position_with_timestamp(_aprs_messaging?, <<"/", _::binary>>) do
     %{
       data_type: :timestamped_position_error,
@@ -410,6 +439,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_mic_e(String.t(), String.t()) :: MicE.t() | map()
   def parse_mic_e(destination_field, information_field) do
     # Logger.debug("MIC-E: " <> destination_field <> " :: " <> information_field)
     # Mic-E is kind of a nutty compression scheme, APRS packs additional
@@ -443,6 +473,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_mic_e(binary()) :: map()
   def parse_mic_e(data) do
     case data do
       <<dti::binary-size(1), latitude::binary-size(6), longitude::binary-size(7), symbol_code::binary-size(1),
@@ -466,6 +497,7 @@ defmodule Parser do
     end
   end
 
+  @spec parse_mic_e_digit(binary()) :: [integer() | atom() | nil]
   def parse_mic_e_digit(<<c>>) when c in ?0..?9, do: [c - ?0, 0, nil]
   def parse_mic_e_digit(<<c>>) when c in ?A..?J, do: [c - ?A, 1, :custom]
   def parse_mic_e_digit(<<c>>) when c in ?P..?Y, do: [c - ?P, 1, :standard]
@@ -476,6 +508,7 @@ defmodule Parser do
 
   def parse_mic_e_digit(_c), do: [:unknown, :unknown, :unknown]
 
+  @spec parse_mic_e_destination(String.t()) :: map()
   def parse_mic_e_destination(destination_field) do
     digits =
       destination_field
@@ -617,6 +650,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_manufacturer(String.t(), String.t(), String.t()) :: String.t()
   def parse_manufacturer(" ", _s2, _s3), do: "Original MIC-E"
   def parse_manufacturer(">", _s2, "^"), do: "Kenwood TH-D74"
   def parse_manufacturer(">", _s2, _s3), do: "Kenwood TH-D74A"
@@ -643,6 +677,7 @@ defmodule Parser do
   def parse_manufacturer(_s1, "~", _s3), do: "Other"
   def parse_manufacturer(_symbol1, _symbol2, _symbol3), do: "Unknown"
 
+  @spec find_matches(Regex.t(), String.t()) :: [String.t()]
   defp find_matches(regex, text) do
     case Regex.names(regex) do
       [] ->
@@ -657,11 +692,13 @@ defmodule Parser do
     end
   end
 
+  @spec convert_compressed_lat(binary()) :: float()
   def convert_compressed_lat(lat) do
     [l1, l2, l3, l4] = to_charlist(lat)
     90 - ((l1 - 33) * 91 ** 3 + (l2 - 33) * 91 ** 2 + (l3 - 33) * 91 + l4 - 33) / 380_926
   end
 
+  @spec convert_compressed_lon(binary()) :: float()
   def convert_compressed_lon(lon) do
     [l1, l2, l3, l4] = to_charlist(lon)
     -180 + ((l1 - 33) * 91 ** 3 + (l2 - 33) * 91 ** 2 + (l3 - 33) * 91 + l4 - 33) / 190_463
@@ -700,6 +737,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_status(String.t()) :: map()
   def parse_status(data) do
     %{
       status_text: data,
@@ -761,6 +799,7 @@ defmodule Parser do
     )
   end
 
+  @spec parse_object(String.t()) :: map()
   def parse_object(data) do
     %{
       raw_data: data,
@@ -769,6 +808,7 @@ defmodule Parser do
   end
 
   # Item Report parsing
+  @spec parse_item(binary()) :: map()
   def parse_item(<<item_indicator, item_name_and_data::binary>>) when item_indicator in [?%, ?)] do
     # Items can have up to 9 character names, followed by ! for position or _ for killed
     case Regex.run(~r/^(.{1,9})([\!\_])(.*)$/, item_name_and_data) do
@@ -856,6 +896,7 @@ defmodule Parser do
     )
   end
 
+  @spec parse_weather(String.t()) :: map()
   def parse_weather(data) do
     weather_data = parse_weather_data(data)
 
@@ -1065,6 +1106,7 @@ defmodule Parser do
     end
   end
 
+  @spec parse_telemetry(String.t()) :: map()
   def parse_telemetry(data) do
     %{
       raw_data: data,
@@ -1146,6 +1188,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_station_capabilities(String.t()) :: map()
   def parse_station_capabilities(data) do
     %{
       capabilities: data,
@@ -1162,6 +1205,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_query(String.t()) :: map()
   def parse_query(data) do
     %{
       query_data: data,
@@ -1183,6 +1227,7 @@ defmodule Parser do
     )
   end
 
+  @spec parse_user_defined(String.t()) :: map()
   def parse_user_defined(data) do
     %{
       user_data: data,
@@ -1241,6 +1286,7 @@ defmodule Parser do
     end
   end
 
+  @spec parse_third_party_traffic(String.t()) :: map()
   def parse_third_party_traffic(data) do
     %{
       third_party_data: data,
@@ -1281,6 +1327,7 @@ defmodule Parser do
     end
   end
 
+  @spec parse_phg_data(String.t()) :: map()
   def parse_phg_data(data) do
     %{
       phg_data: data,
@@ -1361,6 +1408,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_peet_logging(String.t()) :: map()
   def parse_peet_logging(data) do
     %{
       peet_data: data,
@@ -1376,6 +1424,7 @@ defmodule Parser do
     }
   end
 
+  @spec parse_invalid_test_data(String.t()) :: map()
   def parse_invalid_test_data(data) do
     %{
       test_data: data,
@@ -1408,6 +1457,7 @@ defmodule Parser do
   end
 
   # Validate timestamp format
+  @spec validate_timestamp(String.t()) :: String.t() | nil
   defp validate_timestamp(time) when byte_size(time) == 7 do
     if Regex.match?(~r/^\d{6}[hz\/]$/, time) do
       time
@@ -1416,7 +1466,8 @@ defmodule Parser do
     end
   end
 
-  defp validate_timestamp(time), do: time
+  @spec validate_timestamp(any()) :: nil
+  defp validate_timestamp(_), do: nil
 
   defp extract_timestamp(weather_data) do
     case Regex.run(~r/^(\d{6}[hz\/])/, weather_data) do
diff --git a/lib/types/position.ex b/lib/types/position.ex
index af2dccc..f85286e 100644
--- a/lib/types/position.ex
+++ b/lib/types/position.ex
@@ -4,6 +4,19 @@ defmodule Parser.Types.Position do
   """
   require Logger
 
+  @type direction :: :north | :south | :east | :west | :unknown
+
+  @type t :: %__MODULE__{
+          lat_degrees: non_neg_integer(),
+          lat_minutes: non_neg_integer(),
+          lat_fractional: non_neg_integer(),
+          lat_direction: direction(),
+          lon_direction: direction(),
+          lon_degrees: non_neg_integer(),
+          lon_minutes: non_neg_integer(),
+          lon_fractional: non_neg_integer()
+        }
+
   defstruct lat_degrees: 0,
             lat_minutes: 0,
             lat_fractional: 0,
@@ -13,6 +26,7 @@ defmodule Parser.Types.Position do
             lon_minutes: 0,
             lon_fractional: 0
 
+  @spec from_aprs(String.t(), String.t()) :: %{latitude: float(), longitude: float()}
   def from_aprs(aprs_latitude, aprs_longitude) do
     aprs_latitude = aprs_latitude |> String.replace(" ", "0") |> String.pad_leading(9, "0")
     aprs_longitude = aprs_longitude |> String.replace(" ", "0") |> String.pad_leading(9, "0")
@@ -49,10 +63,12 @@ defmodule Parser.Types.Position do
     end
   end
 
+  @spec from_decimal(number(), number()) :: %{latitude: number(), longitude: number()}
   def from_decimal(latitude, longitude) do
     %{latitude: latitude, longitude: longitude}
   end
 
+  @spec convert_garbage_to_zero(String.t()) :: String.t()
   defp convert_garbage_to_zero(value) do
     _ = String.to_float(value)
     value
@@ -90,6 +106,7 @@ defmodule Parser.Types.Position do
   #     |> Kernel.*(60)
   #     |> Float.round(2)
 
+  @spec convert_fractional(String.t()) :: float()
   defp convert_fractional(fractional),
     do: fractional |> String.trim() |> String.pad_leading(4, "0") |> String.to_float() |> Kernel.*(60)
 end
diff --git a/test/parser/parser_test.exs b/test/parser/parser_test.exs
index 5d07ec3..2abc9f3 100644
--- a/test/parser/parser_test.exs
+++ b/test/parser/parser_test.exs
@@ -164,7 +164,7 @@ defmodule Parser.ParserTest do
       assert result.error == "Compressed position not supported in timestamped position"
 
       # Local time
-      result = Parser.parse_data(:timestamped_position, "APRS", "@092345/4903.50N/07201.75W>")
+      result = Parser.parse_data(:timestamped_position, "APRS", "092345/4903.50N/07201.75W>")
       assert result.data_type == :position
       assert result.time == "092345/"
 
@@ -297,16 +297,16 @@ defmodule Parser.ParserTest do
 
     test "handles various timestamp errors" do
       # Invalid hour (>23)
-      result = Parser.parse_position_with_timestamp(false, "@252345z4903.50N/07201.75W>")
+      result = Parser.parse_position_with_timestamp(false, "252345z4903.50N/07201.75W>", :timestamped_position)
       assert result.data_type == :position
       assert result.time =~ "252345"
 
       # Invalid minute (>59)
-      result = Parser.parse_position_with_timestamp(false, "@096045z4903.50N/07201.75W>")
+      result = Parser.parse_position_with_timestamp(false, "096045z4903.50N/07201.75W>", :timestamped_position)
       assert result.data_type == :position
 
       # Invalid second (>59)
-      result = Parser.parse_position_with_timestamp(false, "@092361z4903.50N/07201.75W>")
+      result = Parser.parse_position_with_timestamp(false, "092361z4903.50N/07201.75W>", :timestamped_position)
       assert result.data_type == :position
 
       # Wrong format/length
@@ -316,7 +316,7 @@ defmodule Parser.ParserTest do
 
     test "handles MDHM timestamp format errors" do
       # Invalid MDHM format
-      result = Parser.parse_position_with_timestamp(false, "@9999999/4903.50N/07201.75W>")
+      result = Parser.parse_position_with_timestamp(false, "9999999/4903.50N/07201.75W>", :timestamped_position)
       assert result.data_type == :position
     end
   end