diff --git a/pyModeS/c_decoder/adsb.pyx b/pyModeS/c_decoder/adsb.pyx
new file mode 100644
index 0000000..7f947fc
--- /dev/null
+++ b/pyModeS/c_decoder/adsb.pyx
@@ -0,0 +1,235 @@
+# Copyright (C) 2015 Junzi Sun (TU Delft)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# cython: language_level=3
+
+"""ADS-B Wrapper.
+
+The ADS-B wrapper also imports functions from the following modules:
+
+- pyModeS.decoder.bds.bds05
+    Functions: ``airborne_position``, ``airborne_position_with_ref``, ``altitude``
+- pyModeS.decoder.bds.bds06
+    Functions: ``surface_position``, ``surface_position_with_ref``, ``surface_velocity``
+- pyModeS.decoder.bds.bds08
+    Functions: ``category``, ``callsign``
+- pyModeS.decoder.bds.bds09
+    Functions: ``airborne_velocity``, ``altitude_diff``
+
+"""
+
+from libc.math cimport NAN as nan
+
+# from pyModeS.decoder.bds import bds05, bds06, bds09
+from .common cimport typecode, icao as c_icao, df, hex2bin, bin2int, char_to_int
+
+from .bds.bds05 import (
+    airborne_position,
+    airborne_position_with_ref,
+    altitude,
+)
+from .bds.bds06 import (
+    surface_position,
+    surface_position_with_ref,
+    surface_velocity,
+)
+from .bds.bds08 import category, callsign
+from pyModeS.decoder.bds.bds09 import airborne_velocity, altitude_diff
+
+def icao(bytes msg):
+    return c_icao(msg)
+
+def position(bytes msg0 not None, bytes msg1 not None, int t0, int t1, double lat_ref=nan, double lon_ref=nan):
+    """Decode position from a pair of even and odd position message
+    (works with both airborne and surface position messages)
+
+    Args:
+        msg0 (string): even message (28 bytes hexadecimal string)
+        msg1 (string): odd message (28 bytes hexadecimal string)
+        t0 (int): timestamps for the even message
+        t1 (int): timestamps for the odd message
+
+    Returns:
+        (float, float): (latitude, longitude) of the aircraft
+    """
+    cdef int tc0 = typecode(msg0)
+    cdef int tc1 = typecode(msg1)
+
+    if 5 <= tc0 <= 8 and 5 <= tc1 <= 8:
+        if (lat_ref != lat_ref) or (lon_ref != lon_ref):
+            raise RuntimeError(
+                "Surface position encountered, a reference \
+                               position lat/lon required. Location of \
+                               receiver can be used."
+            )
+        else:
+            return surface_position(msg0, msg1, t0, t1, lat_ref, lon_ref)
+
+    elif 9 <= tc0 <= 18 and 9 <= tc1 <= 18:
+        # Airborne position with barometric height
+        return airborne_position(msg0, msg1, t0, t1)
+
+    elif 20 <= tc0 <= 22 and 20 <= tc1 <= 22:
+        # Airborne position with GNSS height
+        return airborne_position(msg0, msg1, t0, t1)
+
+    else:
+        raise RuntimeError("incorrect or inconsistant message types")
+
+
+def position_with_ref(bytes msg not None, double lat_ref, double lon_ref):
+    """Decode position with only one message,
+    knowing reference nearby location, such as previously
+    calculated location, ground station, or airport location, etc.
+    Works with both airborne and surface position messages.
+    The reference position shall be with in 180NM (airborne) or 45NM (surface)
+    of the true position.
+
+    Args:
+        msg (string): even message (28 bytes hexadecimal string)
+        lat_ref: previous known latitude
+        lon_ref: previous known longitude
+
+    Returns:
+        (float, float): (latitude, longitude) of the aircraft
+    """
+
+    cdef int tc = typecode(msg)
+
+    if 5 <= tc <= 8:
+        return surface_position_with_ref(msg, lat_ref, lon_ref)
+
+    elif 9 <= tc <= 18 or 20 <= tc <= 22:
+        return airborne_position_with_ref(msg, lat_ref, lon_ref)
+
+    else:
+        raise RuntimeError("incorrect or inconsistant message types")
+
+
+def altitude(bytes msg):
+    """Decode aircraft altitude
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+
+    Returns:
+        int: altitude in feet
+    """
+
+    cdef int tc = typecode(msg)
+
+    if tc < 5 or tc == 19 or tc > 22:
+        raise RuntimeError("%s: Not a position message" % msg)
+
+    if tc >= 5 and tc <= 8:
+        # surface position, altitude 0
+        return 0
+
+    cdef bytearray msgbin = hex2bin(msg)
+    cdef int q = char_to_int(msgbin[47])
+    cdef int n
+    cdef double alt
+    if q:
+        n = bin2int(msgbin[40:47] + msgbin[48:52])
+        alt = n * 25 - 1000
+        return alt
+    else:
+        return nan
+
+
+def velocity(bytes msg, bint rtn_sources=False):
+    """Calculate the speed, heading, and vertical rate
+    (handles both airborne or surface message)
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
+
+    Returns:
+        (int, float, int, string, string, string): speed (kt),
+            ground track or heading (degree),
+            rate of climb/descent (ft/min), speed type
+            ('GS' for ground speed, 'AS' for airspeed),
+            direction source ('true_north' for ground track / true north
+            as refrence, 'mag_north' for magnetic north as reference),
+            rate of climb/descent source ('Baro' for barometer, 'GNSS'
+            for GNSS constellation).
+            
+            In the case of surface messages, None will be put in place
+            for vertical rate and its respective sources.
+    """
+    
+    cdef int tc = typecode(msg)
+
+    if 5 <= tc <= 8:
+        return surface_velocity(msg, rtn_sources)
+
+    elif tc == 19:
+        return airborne_velocity(msg, rtn_sources)
+
+    else:
+        raise RuntimeError(
+            "incorrect or inconsistant message types, expecting 4<TC<9 or TC=19"
+        )
+
+
+def speed_heading(bytes msg):
+    """Get speed and ground track (or heading) from the velocity message
+    (handles both airborne or surface message)
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+
+    Returns:
+        (int, float): speed (kt), ground track or heading (degree)
+    """
+    spd, trk_or_hdg, rocd, tag = velocity(msg)
+    return spd, trk_or_hdg
+
+
+def oe_flag(bytes msg):
+    """Check the odd/even flag. Bit 54, 0 for even, 1 for odd.
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+    Returns:
+        int: 0 or 1, for even or odd frame
+    """
+    cdef bytearray msgbin = hex2bin(msg.encode())
+    return char_to_int(msgbin[53])
+
+
+def version(bytes msg):
+    """ADS-B Version
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string, TC = 31
+
+    Returns:
+        int: version number
+    """
+    cdef int tc = typecode(msg)
+
+    if tc != 31:
+        raise RuntimeError(
+            "%s: Not a status operation message, expecting TC = 31" % msg
+        )
+
+    cdef bytearray msgbin = hex2bin(msg)
+    cdef int version = bin2int(msgbin[72:75])
+
+    return version
diff --git a/pyModeS/c_decoder/bds/bds05.pyx b/pyModeS/c_decoder/bds/bds05.pyx
index 5bbff54..4fd4bb4 100644
--- a/pyModeS/c_decoder/bds/bds05.pyx
+++ b/pyModeS/c_decoder/bds/bds05.pyx
@@ -25,7 +25,7 @@
 cimport cython
 
 from .. cimport common
-from libc.math cimport NAN as nan, remainder
+from libc.math cimport NAN as nan
 
 
 @cython.cdivision(True)
diff --git a/pyModeS/c_decoder/bds/bds06.pyx b/pyModeS/c_decoder/bds/bds06.pyx
index eb2d65e..80ffa92 100644
--- a/pyModeS/c_decoder/bds/bds06.pyx
+++ b/pyModeS/c_decoder/bds/bds06.pyx
@@ -26,7 +26,7 @@ cimport cython
 
 from .. cimport common
 from cpython cimport array
-from libc.math cimport NAN as nan, remainder
+from libc.math cimport NAN as nan
 
 import math
 
diff --git a/pyModeS/c_decoder/bds/bds08.pyx b/pyModeS/c_decoder/bds/bds08.pyx
new file mode 100644
index 0000000..804246a
--- /dev/null
+++ b/pyModeS/c_decoder/bds/bds08.pyx
@@ -0,0 +1,61 @@
+# cython: language_level=3
+
+cimport cython
+
+from .. cimport common
+
+
+def category(bytes msg):
+    """Aircraft category number
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+
+    Returns:
+        int: category number
+    """
+
+    cdef int tc = common.typecode(msg)
+    if tc < 1 or tc > 4:
+        raise RuntimeError("%s: Not a identification message" % msg)
+
+    cdef bytearray msgbin = common.hex2bin(msg)
+    mebin = msgbin[32:87]
+    return common.bin2int(mebin[5:8])
+
+
+def callsign(bytes msg):
+    """Aircraft callsign
+
+    Args:
+        msg (string): 28 bytes hexadecimal message string
+
+    Returns:
+        string: callsign
+    """
+
+    cdef int tc = common.typecode(msg)
+    if tc < 1 or tc > 4:
+        raise RuntimeError("%s: Not a identification message" % msg)
+
+    cdef bytearray _chars = bytearray(
+        b"#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######"
+    )
+    cdef unsigned char[:] chars = _chars
+    cdef bytearray msgbin = common.hex2bin(msg)
+    cdef bytearray csbin = msgbin[40:96]
+
+    cdef bytearray _cs = bytearray(8)
+    cdef unsigned char[:] cs = _cs
+    cs[0] = chars[common.bin2int(csbin[0:6])]
+    cs[1] = chars[common.bin2int(csbin[6:12])]
+    cs[2] = chars[common.bin2int(csbin[12:18])]
+    cs[3] = chars[common.bin2int(csbin[18:24])]
+    cs[4] = chars[common.bin2int(csbin[24:30])]
+    cs[5] = chars[common.bin2int(csbin[30:36])]
+    cs[6] = chars[common.bin2int(csbin[36:42])]
+    cs[7] = chars[common.bin2int(csbin[42:48])]
+
+    # clean string, remove spaces and marks, if any.
+    # cs = cs.replace('_', '')
+    return _cs.decode().replace("#", "")
diff --git a/setup.py b/setup.py
index 103b162..ae17fca 100644
--- a/setup.py
+++ b/setup.py
@@ -24,6 +24,7 @@ extensions = [
     Extension("pyModeS.c_decoder.adsb", ["pyModeS/c_decoder/adsb.pyx"]),
     Extension("pyModeS.c_decoder.bds.bds05", ["pyModeS/c_decoder/bds/bds05.pyx"]),
     Extension("pyModeS.c_decoder.bds.bds06", ["pyModeS/c_decoder/bds/bds06.pyx"]),
+    Extension("pyModeS.c_decoder.bds.bds08", ["pyModeS/c_decoder/bds/bds08.pyx"]),
 ]