Refactor

ADSB_Encoder.py

@@ -64,5 +64,6 @@ if __name__ == "__main__":
     samples_array = hackrf.hackrf_raw_IQ_format(df17_array)
 
     SamplesFile = open("Samples.iq8s", "wb") # TODO make this a function and take the file name. Also have the option to run dd on it.
+    # TODO make it empty the file first.
     SamplesFile.write(samples_array)
     os.system("dd if=Samples.iq8s of=Samples_256K.iq8s bs=4k seek=63") # TODO make this a flag, also make it take the file name

ModeS.py

@@ -1,5 +1,5 @@
 from location import *
-from conversions import *
+
 class ModeS:
     """This class handles the ModeS ADSB manipulation
     """
@@ -38,7 +38,7 @@ class ModeS:
 
         df17_str = "{0:02x}{1:02x}{2:02x}{3:02x}{4:02x}{5:02x}{6:02x}{7:02x}{8:02x}{9:02x}{10:02x}".format(*df17_even_bytes[0:11])
         #print df17_str , "%X" % bin2int(crc(df17_str+"000000", encode=True)) , "%X" % get_parity(hex2bin(df17_str+"000000"), extended=True)
-        df17_crc = bin2int(crc(df17_str+"000000", encode=True))
+        df17_crc = self.bin2int(self.modes_crc(df17_str+"000000", encode=True))
 
         df17_even_bytes.append((df17_crc>>16) & 0xff)
         df17_even_bytes.append((df17_crc>> 8) & 0xff)
@@ -60,10 +60,72 @@ class ModeS:
         df17_odd_bytes.append((oddenclon   ) & 0xff)
 
         df17_str = "{0:02x}{1:02x}{2:02x}{3:02x}{4:02x}{5:02x}{6:02x}{7:02x}{8:02x}{9:02x}{10:02x}".format(*df17_odd_bytes[0:11])
-        df17_crc = bin2int(crc(df17_str+"000000", encode=True))
+        df17_crc = self.bin2int(self.modes_crc(df17_str+"000000", encode=True))
 
         df17_odd_bytes.append((df17_crc>>16) & 0xff)
         df17_odd_bytes.append((df17_crc>> 8) & 0xff)
         df17_odd_bytes.append((df17_crc    ) & 0xff)    
         
         return (df17_even_bytes, df17_odd_bytes)
+
+###############################################################
+
+# 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/>.
+
+# the polynominal generattor code for CRC
+
+        
+    def modes_crc(self, msg, encode=False):
+        """Mode-S Cyclic Redundancy Check
+        Detect if bit error occurs in the Mode-S message
+        Args:
+            msg (string): 28 bytes hexadecimal message string
+            encode (bool): True to encode the date only and return the checksum
+        Returns:
+            string: message checksum, or partity bits (encoder)
+        """
+
+        GENERATOR = "1111111111111010000001001" # Currently don't know what is magic about this number
+
+        msgbin = list(self.hex2bin(msg))
+
+        if encode:
+            msgbin[-24:] = ['0'] * 24
+
+        # loop all bits, except last 24 piraty bits
+        for i in range(len(msgbin)-24):
+            # if 1, perform modulo 2 multiplication,
+            if msgbin[i] == '1':
+                for j in range(len(GENERATOR)):
+                    # modulo 2 multiplication = XOR
+                    msgbin[i+j] = str((int(msgbin[i+j]) ^ int(GENERATOR[j])))
+
+        # last 24 bits
+        reminder = ''.join(msgbin[-24:])
+        return reminder
+    
+            
+        
+    def hex2bin(self, hexstr):
+        """Convert a hexdecimal string to binary string, with zero fillings. """
+        scale = 16
+        num_of_bits = len(hexstr) * math.log(scale, 2)
+        binstr = bin(int(hexstr, scale))[2:].zfill(int(num_of_bits))
+        return binstr
+
+    def bin2int(self, binstr):
+        """Convert a binary string to integer. """
+        return int(binstr, 2)

conversions.py

@@ -1,59 +1,6 @@
-###############################################################
 
-# 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/>.
-
-# the polynominal generattor code for CRC
 import math
 
-GENERATOR = "1111111111111010000001001"
 
-def hex2bin(hexstr):
-    """Convert a hexdecimal string to binary string, with zero fillings. """
-    scale = 16
-    num_of_bits = len(hexstr) * math.log(scale, 2)
-    binstr = bin(int(hexstr, scale))[2:].zfill(int(num_of_bits))
-    return binstr
 
-def bin2int(binstr):
-    """Convert a binary string to integer. """
-    return int(binstr, 2)
 
-def crc(msg, encode=False):
-    """Mode-S Cyclic Redundancy Check
-    Detect if bit error occurs in the Mode-S message
-    Args:
-        msg (string): 28 bytes hexadecimal message string
-        encode (bool): True to encode the date only and return the checksum
-    Returns:
-        string: message checksum, or partity bits (encoder)
-    """
-
-    msgbin = list(hex2bin(msg))
-
-    if encode:
-        msgbin[-24:] = ['0'] * 24
-
-    # loop all bits, except last 24 piraty bits
-    for i in range(len(msgbin)-24):
-        # if 1, perform modulo 2 multiplication,
-        if msgbin[i] == '1':
-            for j in range(len(GENERATOR)):
-                # modulo 2 multiplication = XOR
-                msgbin[i+j] = str((int(msgbin[i+j]) ^ int(GENERATOR[j])))
-
-    # last 24 bits
-    reminder = ''.join(msgbin[-24:])
-    return reminder