Features:

- initial support for multiples tracks simulation

Enhancements:
- code profiling and optimization
 - faster lookup table based ppm + IQ generation
 - faster CRC24 computations
 - frame encoding

Bug fixes:
- callsign encoding
- typos

ADSBLowLevelEncoder.py

@@ -1,23 +1,39 @@
+""" This class is responsible for low level encoding of IQ sample
+
+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/>.
+"""
 from CustomDecorators import *
 import numpy
 
 @Singleton
 class ADSBLowLevelEncoder:
-    """
-    Hamming and Manchester Encoding example
-
-    Author: Joel Addison
-    Date: March 2013
-
-    Functions to do (7,4) hamming encoding and decoding, including error detection
-    and correction.
-    Manchester encoding and decoding is also included, and by default will use
-    least bit ordering for the byte that is to be included in the array.
-    """
 
     def __init__(self):
-        self.adsb_frame_preamble = [0xA1,0x40]
-        self.adsb_frame_pause = [0]*70
+        self._adsb_frame_preamble = [0xA1,0x40]
+        self._adsb_frame_pause = [0]*4
+
+        # Build a manchester encoding lookup table
+        self._manchester_lookup = []
+        for i in range(256):
+            me = self.manchester_encode(i)
+            self._manchester_lookup.append([127*val for pair in zip(me, me) for val in pair])
+
+        # Build preamble and pause manchester encoded versions
+        me_bits = numpy.unpackbits(numpy.asarray(self._adsb_frame_preamble, dtype=numpy.uint8))
+        self._adsb_frame_preamble_IQ = [127*val for pair in zip(me_bits, me_bits) for val in pair]
+        self._adsb_frame_pause_IQ = self._adsb_frame_pause*16
+
+        self._len_pre_IQ = len(self._adsb_frame_preamble_IQ)
+        self._len_pause_IQ = len(self._adsb_frame_pause_IQ)
+
 ###############################################################
 # Further work on fork
 # Copyright (C) 2017 David Robinson
@@ -38,65 +54,62 @@ class ADSBLowLevelEncoder:
         # Encode byte
         for i in range(7, -1, -1):
             if self.extract_bit(byte, i):
-                manchester_encoded.extend([0,1])
-            else:
                 manchester_encoded.extend([1,0])
+            else:
+                manchester_encoded.extend([0,1])
 
         return manchester_encoded
 
-    def frame_1090es_ppm_modulate(self, even, odd = []):
+    def frame_1090es_ppm_modulate_IQ(self, even, odd = []):
         """
         Args:
             even and odd: The data frames that need to be converted to PPM
         Returns:
-            The bytearray of the PPM data
+            The bytearray of the IQ samples for PPM modulated data
         """
-        ppm = [ ]
 
         length_even = len(even)
         length_odd  = len(odd)
       
-        if (length_even != 0):
-            ppm.extend(self.adsb_frame_pause)      # pause
-            ppm.extend(self.adsb_frame_preamble)   # preamble
+        if (length_even != 0 and length_odd == 0):
+            IQ = bytearray(32*length_even+2*self._len_pause_IQ+self._len_pre_IQ)
+            pos = self._len_pause_IQ
+            IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
+            pos += self._len_pre_IQ
 
-            for i in range(length_even):
-                word16 = numpy.packbits(self.manchester_encode(~even[i]))
-                ppm.extend(word16[0:2])
+            tmp = []
+            for b in even:
+                tmp.extend(self._manchester_lookup[b])
+            IQ[pos:pos+32*length_even] = tmp
             
-            ppm.extend(self.adsb_frame_pause)  # pause
+            return IQ
 
-        if (length_odd != 0):
-            ppm.extend(self.adsb_frame_pause)        # pause
-            ppm.extend(self.adsb_frame_preamble)     # preamble
+        elif (length_even != 0 and length_odd != 0):
+            IQ = bytearray(32*(length_even+length_odd)+2*self._len_pre_IQ+3*self._len_pause_IQ)
+            pos = self._len_pause_IQ
+            IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
+            pos += self._len_pre_IQ
 
-            for i in range(length_odd):
-                word16 = numpy.packbits(self.manchester_encode(~odd[i]))
-                ppm.extend(word16[0:2])
+            tmp = []
+            for b in even:
+                tmp.extend(self._manchester_lookup[b])
+            length_even_IQ = 32*length_even
+            IQ[pos:pos+length_even_IQ] = tmp
+            pos += length_even_IQ
 
-            ppm.extend(self.adsb_frame_pause)  # pause
+            pos += self._len_pause_IQ
 
-        return bytearray(ppm)
+            IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
+            pos += self._len_pre_IQ
 
-    def hackrf_raw_IQ_format(self, ppm):
-        """
-        Args:
-            ppm: this is some data in ppm (pulse position modulation) which will be converted into
-                 hackRF raw IQ sample format, ready to be broadcasted
+            tmp = []
+            for b in odd:
+                tmp.extend(self._manchester_lookup[b])
+
+            IQ[pos:pos+32*length_odd] = tmp
+        
+            return IQ
 
-        Returns:
-            bytearray: containing the IQ data
-        """
-        signal = []
-        bits = numpy.unpackbits(numpy.asarray(ppm, dtype=numpy.uint8))
-        for bit in bits:
-            if bit == 1:
-                I = 127
-                Q = 127
         else:
-                I = 0
-                Q = 0
-            signal.append(I)
-            signal.append(Q)
 
-        return bytearray(signal)
+            return None

AbstractTrajectorySimulatorBase.py

@@ -21,10 +21,10 @@ You should have received a copy of the GNU General Public License along with
 this program. If not, see <http://www.gnu.org/licenses/>.
 """
 
-import time
+import time, datetime
 import abc
 import threading
-
+from CustomDecorators import *
 from ModeS import ModeS
 
 class AbstractTrajectorySimulatorBase(threading.Thread,abc.ABC):
@@ -38,14 +38,26 @@ class AbstractTrajectorySimulatorBase(threading.Thread,abc.ABC):
 
         self._do_stop = False
     
+        self._position_message_period_us = 150000           # max should be 0.2s
+        self._velocity_message_period_us = 1200000          # max should be 1.3s
+        self._identitification_message_period_us = 10000000 # max should be 15s
+        self._squawk_message_period_us = 800000             # TODO : specs says that interval should be randomized between [0.7s;0.9s] and max is 1.0s
+
+        self._startruntime = None
+        self._simstep = 0
+    
     # Thread core function
     def run(self):
 
-        is_first_step = True
         while not self._do_stop:
+            now = datetime.datetime.now(datetime.timezone.utc)
+            if (not self._startruntime or (now - self._startruntime).total_seconds() >= self._simstep*self.refresh_delay()):
+                self._simstep += 1
                 encoder_changed = False
+
+                #self._broadcast_thread.getMutex().acquire()
                 # check if modeS encoder needs update
-            if self._aircraftinfos.icao_changed or self._aircraftinfos.capability_changed or is_first_step:
+                if self._aircraftinfos.icao_changed or self._aircraftinfos.capability_changed or not self._startruntime:
                     self._modeSencoder.icao = self._aircraftinfos.icao
                     self._modeSencoder.ca = self._aircraftinfos.capability
                     encoder_changed = True
@@ -78,16 +90,21 @@ class AbstractTrajectorySimulatorBase(threading.Thread,abc.ABC):
                     self.df_velocity = self._modeSencoder.df_encode_ground_velocity(self._aircraftinfos.speed_kt, self._aircraftinfos.track_angle_deg, self._aircraftinfos.vspeed_ftpmin) 
                     self._broadcast_thread.replace_message("airborne_velocity",self.df_velocity)
 
-            is_first_step = False
-            self.update_aircraftinfos()         # update_aircraftinfos() : abstract method that need to be implemented i nderived classes
-            time.sleep(self.refresh_delay())    # refresh_delay()        : abstract method that need to be implemented i nderived classes
+                #self._broadcast_thread.getMutex().release()
+                if not self._startruntime:
+                    self._startruntime = now
+                
+                self.update_aircraftinfos()         # update_aircraftinfos() : abstract method that need to be implemented in derived classes
+                
+                #elapsed = (datetime.datetime.now(datetime.timezone.utc) - now).total_seconds()
+                #sleep_time = self.refresh_delay() - elapsed
+                #if sleep_time < 0.0:
+                #    sleep_time = 0.0
+            time.sleep(0.05*self.refresh_delay())    # refresh_delay()        : abstract method that need to be implemented in derived classes
 
         # upon exit, reset _do_stop flag in case there is a new start
         self._do_stop = False
 
-    def stop(self):
-        self._do_stop = True
-
     @abc.abstractmethod
     def refresh_delay(self):
         ...
@@ -95,3 +112,46 @@ class AbstractTrajectorySimulatorBase(threading.Thread,abc.ABC):
     @abc.abstractmethod
     def update_aircraftinfos(self):
         ...
+
+    def stop(self):
+        self._do_stop = True
+
+    @property
+    def elapsed_sim_time(self):
+        return self._simstep*self.refresh_delay()
+
+    @property
+    def aircraftinfos(self):
+        return self._aircraftinfos
+
+    @property
+    def position_message_period_us(self):
+        return self._position_message_period_us
+
+    @position_message_period_us.setter
+    def position_message_period_us(self,value):
+        self._position_message_period_us = value
+
+    @property
+    def velocity_message_period_us(self):
+        return self._velocity_message_period_us
+
+    @velocity_message_period_us.setter
+    def velocity_message_period_us(self,value):
+        self._velocity_message_period_us = value
+
+    @property
+    def identitification_message_period_us(self):
+        return self._identitification_message_period_us
+
+    @identitification_message_period_us.setter
+    def identitification_message_period_us(self,value):
+        self._identitification_message_period_us = value
+
+    @property
+    def squawk_message_period_us(self):
+        return self._squawk_message_period_us
+
+    @squawk_message_period_us.setter
+    def squawk_message_period_us(self,value):
+        self._squawk_message_period_us = value

AircraftInfos.py

@@ -15,8 +15,38 @@ this program. If not, see <http://www.gnu.org/licenses/>.
 """
 
 import math
+import json
 
 class AircraftInfos:
+
+    @classmethod
+    def from_json(cls,filepath):
+        json_file = open(filepath,'r')
+        state_dic = json.load(json_file)
+        json_file.close()
+
+        icao_aa = state_dic["icao_aa"]
+        callsign = state_dic["callsign"]
+        squawk = state_dic["squawk"]
+
+        alt_ft  = state_dic["alt_ft"]
+        lat_deg = state_dic["lat_deg"]
+        lon_deg = state_dic["lon_deg"]
+        speed_kph = state_dic["speed_kph"]
+        vspeed_ftpmin = state_dic["vspeed_ftpmin"]
+        maxloadfactor = state_dic["maxloadfactor"]
+        track_angle_deg = state_dic["track_angle_deg"]
+        capability = state_dic["capability"]
+        type_code = state_dic["type_code"]
+        surveillance_status = state_dic["surveillance_status"]
+        timesync = state_dic["timesync"]
+        nicsup = state_dic["nicsup"]
+        on_surface = state_dic["on_surface"]
+
+        return AircraftInfos(icao_aa,callsign,squawk,
+                                  lat_deg,lon_deg,alt_ft,speed_kph,vspeed_ftpmin,maxloadfactor,track_angle_deg, \
+                                  timesync,capability,type_code,surveillance_status,nicsup,on_surface)
+
     def __init__(self,icao,callsign,squawk,
                       lat_deg,lon_deg,alt_msl_ft,speed_kph,vspeed_ftpmin,maxloadfactor,track_angle_deg,
                       timesync,capability,type_code,surveillance_status,nicsupb,on_surface):

FixedTrajectorySimulator.py

@@ -21,7 +21,7 @@ class FixedTrajectorySimulator(AbstractTrajectorySimulatorBase):
         super().__init__(mutex,broadcast_thread,aircrafinfos)
 
     def refresh_delay(self):
-        return 0.005
+        return 0.05
 
     def update_aircraftinfos(self):
         pass

HackRfBroadcastThread.py

@@ -57,19 +57,14 @@ def hackrfTXCB(hackrf_transfer):
 
 @Singleton
 class HackRfBroadcastThread(threading.Thread):
-    def __init__(self,mutex,airborne_position_refresh_period = 150000):
+    def __init__(self,airborne_position_refresh_period = 150000):
         super().__init__()
-        self._mutex = mutex
+        self._mutex = threading.Lock()
 
         self._lowlevelencoder = ADSBLowLevelEncoder()
 
-        self._messages = {}
-        # key : "name of message" value : ["data to be broadcasted", datetime of last broadcast, delay_between 2 messages of this type]
-        self._messages["identification"] = [None, None, 10000000]    # max should be 15s
-        self._messages["register_6116"] = [None, None, 800000]       # TODO : specs says that interval should be randomized between [0.7s;0.9s] and max is 1.0s
-        self._messages["airborne_position"] = [None, None, airborne_position_refresh_period]   # max should be 0.2s
-        self._messages["surface_position"] = [None, None, 150000]    # max should be 0.2s
-        self._messages["airborne_velocity"] = [None, None, 1200000]  # max should be 1.3s
+        self._messages_feed_threads = {}
+
 
         # Initialize pyHackRF library
         result = HackRF.initialize()
@@ -86,6 +81,8 @@ class HackRfBroadcastThread(threading.Thread):
         if (result != LibHackRfReturnCode.HACKRF_SUCCESS):
             print("Error :",result, ",", HackRF.getHackRfErrorCodeName(result))
 
+        self._hackrf_broadcaster.setCrystalPPM(0)
+            
         result = self._hackrf_broadcaster.setSampleRate(2000000)
         if (result != LibHackRfReturnCode.HACKRF_SUCCESS):
             print("Error :",result, ",", HackRF.getHackRfErrorCodeName(result))
@@ -125,21 +122,45 @@ class HackRfBroadcastThread(threading.Thread):
     def stop(self):
         self._do_stop = True
 
-    # updates the next data to be broadcaster for a given message type
-    def replace_message(self,type,frame_even,frame_odd = []):
-        frame_ppm = self._lowlevelencoder.frame_1090es_ppm_modulate(frame_even, frame_odd)
-        frame_IQ = self._lowlevelencoder.hackrf_raw_IQ_format(frame_ppm)
+    def getMutex(self):
+        return self._mutex
+
+    # updates the next data to be broadcaster for a given message type
+    #@Timed
+    def replace_message(self,type,frame_even,frame_odd = []):
+
+        frame_IQ = self._lowlevelencoder.frame_1090es_ppm_modulate_IQ(frame_even, frame_odd)
+
+          # this will usually be called from another thread, so mutex lock mecanism is used during update
 
-        # this will usuallyy be called from another thread, so mutex lock mecanism is used during update
         self._mutex.acquire()
-        self._messages[type][0] = frame_IQ
+        calling_thread = threading.current_thread()
+        if calling_thread in self._messages_feed_threads:
+            self._messages_feed_threads[calling_thread][type][0] = frame_IQ
         self._mutex.release()
 
-    def broadcast_one_message(self,data): 
+    def register_track_simulation_thread(self,feeder_thread):
+        if feeder_thread in self._messages_feed_threads:
+            print(feeder_thread,"already registred as a feeder")
+        else:
+            self._messages_feed_threads[feeder_thread] = {}
+
+            # key : "name of message" value : ["data to be broadcasted", datetime of last broadcast, delay_between 2 messages of this type]
+            self._messages_feed_threads[feeder_thread]["identification"] = [None, None, feeder_thread.identitification_message_period_us]
+            self._messages_feed_threads[feeder_thread]["register_6116"] = [None, None, feeder_thread.squawk_message_period_us]
+            self._messages_feed_threads[feeder_thread]["airborne_position"] = [None, None, feeder_thread.position_message_period_us]
+            self._messages_feed_threads[feeder_thread]["surface_position"] = [None, None, feeder_thread.position_message_period_us]
+            self._messages_feed_threads[feeder_thread]["airborne_velocity"] = [None, None, feeder_thread.velocity_message_period_us]
+
+    def broadcast_data(self,data):
+        length = len(data)
+        if length != 0:
+            sleep_time = length*0.50e-6*(1.0+1e-6*self._hackrf_broadcaster.getCrystalPPM())
             self._tx_context.last_tx_pos = 0  
             self._mutex.acquire()
-        self._tx_context.buffer_length = len(data)
+            self._tx_context.buffer_length = length
             self._tx_context.buffer = (c_ubyte*self._tx_context.buffer_length).from_buffer_copy(data)
+            
             # TODO : need to evaluate if mutex protection is requiered during full broadcast or
             #        could be reduced to buffer filling (probably can be reduced)
             #        reduced version is when next line mutex.release() is uncommented and
@@ -153,25 +174,61 @@ class HackRfBroadcastThread(threading.Thread):
                 print("Error :",result, ",", HackRF.getHackRfErrorCodeName(result))
 
             while self._hackrf_broadcaster.isStreaming():
-            time.sleep(0.00001)
+                time.sleep(sleep_time)
 
             result = self._hackrf_broadcaster.stopTX()
             if (result != LibHackRfReturnCode.HACKRF_SUCCESS):
                 print("Error :",result, ",", HackRF.getHackRfErrorCodeName(result))
 
-        #self.mutex.release() 
+            #self._mutex.release() 
 
     def run(self):
+
         while not self._do_stop:
-            for k,v in self._messages.items():
+            #self._mutex.acquire()
             now = datetime.datetime.now(datetime.timezone.utc)
+            plane_messages = bytearray()
+            sleep_time = 10.0
+            for thread_broadcast_schedule in self._messages_feed_threads.values():
+                for v in thread_broadcast_schedule.values():
+                    #now = datetime.datetime.now(datetime.timezone.utc)
+                    v2_sec = v[2]*1e-6
+                    if v[1] != None:
+                        remaining = v2_sec - (now - v[1]).total_seconds()
+                    else:
+                        remaining = -float('inf')
+                        sleep_time = 0.0
                     # Time throttling : messages are broadcasted only at provided time intervall
-                # TODO : implement UTC syncing mecanism (requiered that the actual host clock is UTC synced)
-                #        which can be implemented to some accuracy level with ntp or GPS + PPS mecanisms
-                if (v[0] != None and len(v[0]) > 0) and (v[1] == None or (now - v[1]) >= datetime.timedelta(seconds=v[2] // 1000000,microseconds=v[2] % 1000000)):
-                    self.broadcast_one_message(v[0])
+                    # TODO : implement UTC syncing mecanism (requiered that the actual host clock is UTC synced) ?
+                    #        which may be implemented to some accuracy level with ntp or GPS + PPS mecanisms ? in Python ?
+                    if (v[0] != None and len(v[0]) > 0) and remaining <= 0.0:
+                        plane_messages.extend(v[0])
                         v[1] = now
-            time.sleep(0.0001)  # this loop will run at 10 kHz max
+                    elif remaining > 0.0:
+                        remaining = math.fmod(remaining,v2_sec)
+                        if remaining < sleep_time:
+                            sleep_time = remaining
+
+
+            #print("sleep_time1",sleep_time)
+            bc_length = len(plane_messages)
+            if (bc_length > 0):
+                self.broadcast_data(plane_messages)
+
+                elasped = (datetime.datetime.now(datetime.timezone.utc) - now).total_seconds()
+                sleep_time -= elasped
+
+                if sleep_time < 0.0:
+                    sleep_time = 0.0
+                elif sleep_time < 0.5:
+                    sleep_time *= 0.1
+                else:
+                    sleep_time = 0.5
+
+                time.sleep(0.1*sleep_time)
+            else:
+                time.sleep(0.000001)
+            #self._mutex.release()
 
         # upon exit, reset _do_stop flag in case there is a new start
         self._do_stop = False

ModeS.py

@@ -1,6 +1,8 @@
 from ModeSLocation import ModeSLocation
 import math
 import numpy
+from CustomDecorators import *
+
 ###############################################################
 # Further work on fork
 # Copyright (C) 2017 David Robinson
@@ -9,6 +11,9 @@ class ModeS:
     """
     
     def __init__(self,df,icao,ca):
+
+        self._location = ModeSLocation()
+
         self.df = df        # as far as I understand specification, this should be :
                             # 17 if the broadcast source is an aircraft
                             # 18 if the broadcast source is some other ADSB facility (tower)
@@ -17,30 +22,42 @@ class ModeS:
         self.ca = ca        # capability see §3.1.2.5.2.2.1
                             # (will usually be 5 for level 2 transponder and airborne)
 
+        self._charmap = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######"
+        self._crc_poly = 0x01FFF409
+
+        self._crc_lookup_T0 = [0]*256
+
+        crc = 0x1000000
+        i = 1
+        while(i < 256):
+            if crc & 0x1000000:
+                crc <<= 1
+                crc = crc ^ self._crc_poly
+            else:
+                crc <<= 1
+                
+            for j in range(i):
+                self._crc_lookup_T0[i ^ j] = (crc ^ self._crc_lookup_T0[j])
+        
+            i <<= 1
+
     def df_frame_start(self):
         """
-        This will build the usual df frame start
+        This will build the usual df frame start and reserve a full frame with "0" for the reste of message
         """        
-        frame = []
-        frame.append((self.df << 3) | self.ca)
-        frame.append((self.icao >> 16) & 0xff)
-        frame.append((self.icao >> 8) & 0xff)
-        frame.append((self.icao) & 0xff)
+        frame = bytearray(14)
+        frame[0] = (self.df << 3) | self.ca
+        frame[1] = ((self.icao >> 16) & 0xff)
+        frame[2] = ((self.icao >> 8) & 0xff)
+        frame[3] = ((self.icao) & 0xff)
         return frame
 
-    def df_frame_append_crc(self,frame):
-        frame_str = "{0:02x}{1:02x}{2:02x}{3:02x}{4:02x}{5:02x}{6:02x}{7:02x}{8:02x}{9:02x}{10:02x}".format(*frame[0:11])
-        frame_crc = self.bin2int(self.modes_crc(frame_str + "000000", encode=True))
-        frame.append((frame_crc >> 16) & 0xff)
-        frame.append((frame_crc >> 8) & 0xff)
-        frame.append((frame_crc) & 0xff)
-
     # Ref :
     # ICAO Annex 10 : Aeronautical Telecommunications
     # Volume IV : Surveillance and Collision Avoidance Systems
     # Figure C-1. Extended Squitter Airborne Position
     # "Register 05_16"
-
+    #@Timed
     def df_encode_airborne_position(self, lat, lon, alt, tc, ss, nicsb, timesync):
         """
         This will encode even and odd frames from airborne position extended squitter message
@@ -52,38 +69,38 @@ class ModeS:
         nicsb = NIC supplement-B (§C.2.3.2.5)
         """
 
-        location = ModeSLocation()
-        enc_alt =	location.encode_alt_modes(alt, False)
+        #encode height information
+        enc_alt =	self._location.encode_alt_modes(alt, False)
         
         #encode that position
-        (evenenclat, evenenclon) = location.cpr_encode(lat, lon, False, False)
-        (oddenclat, oddenclon)   = location.cpr_encode(lat, lon, True, False)
+        (evenenclat, evenenclon) = self._location.cpr_encode(lat, lon, False, False)
+        (oddenclat, oddenclon)   = self._location.cpr_encode(lat, lon, True, False)
 
         ff = 0
         df_frame_even_bytes = self.df_frame_start()
         # data
-        df_frame_even_bytes.append((tc<<3) | (ss<<1) | nicsb)
-        df_frame_even_bytes.append((enc_alt>>4) & 0xff)
-        df_frame_even_bytes.append((enc_alt & 0xf) << 4 | (timesync<<3) | (ff<<2) | (evenenclat>>15))
-        df_frame_even_bytes.append((evenenclat>>7) & 0xff)
-        df_frame_even_bytes.append(((evenenclat & 0x7f) << 1) | (evenenclon>>16))
-        df_frame_even_bytes.append((evenenclon>>8) & 0xff)
-        df_frame_even_bytes.append((evenenclon   ) & 0xff)
+        df_frame_even_bytes[4]  = (tc<<3) | (ss<<1) | nicsb
+        df_frame_even_bytes[5]  = (enc_alt>>4) & 0xff
+        df_frame_even_bytes[6]  = (enc_alt & 0xf) << 4 | (timesync<<3) | (ff<<2) | (evenenclat>>15)
+        df_frame_even_bytes[7]  = (evenenclat>>7) & 0xff
+        df_frame_even_bytes[8]  = ((evenenclat & 0x7f) << 1) | (evenenclon>>16)
+        df_frame_even_bytes[9]  = (evenenclon>>8) & 0xff
+        df_frame_even_bytes[10] = (evenenclon   ) & 0xff
 
-        self.df_frame_append_crc(df_frame_even_bytes)
+        self.df_frame_write_crc(df_frame_even_bytes)
 
         ff = 1
         df_frame_odd_bytes = self.df_frame_start()
         # data
-        df_frame_odd_bytes.append((tc<<3) | (ss<<1) | nicsb)
-        df_frame_odd_bytes.append((enc_alt>>4) & 0xff)
-        df_frame_odd_bytes.append((enc_alt & 0xf) << 4 | (timesync<<3) | (ff<<2) | (oddenclat>>15))
-        df_frame_odd_bytes.append((oddenclat>>7) & 0xff)
-        df_frame_odd_bytes.append(((oddenclat & 0x7f) << 1) | (oddenclon>>16))
-        df_frame_odd_bytes.append((oddenclon>>8) & 0xff)
-        df_frame_odd_bytes.append((oddenclon   ) & 0xff)
+        df_frame_odd_bytes[4]  = (tc<<3) | (ss<<1) | nicsb
+        df_frame_odd_bytes[5]  = (enc_alt>>4) & 0xff
+        df_frame_odd_bytes[6]  = (enc_alt & 0xf) << 4 | (timesync<<3) | (ff<<2) | (oddenclat>>15)
+        df_frame_odd_bytes[7]  = (oddenclat>>7) & 0xff
+        df_frame_odd_bytes[8]  = ((oddenclat & 0x7f) << 1) | (oddenclon>>16)
+        df_frame_odd_bytes[9]  = (oddenclon>>8) & 0xff
+        df_frame_odd_bytes[10] = (oddenclon   ) & 0xff
 
-        self.df_frame_append_crc(df_frame_odd_bytes)
+        self.df_frame_write_crc(df_frame_odd_bytes)
 
         return (df_frame_even_bytes, df_frame_odd_bytes)
 
@@ -101,16 +118,17 @@ class ModeS:
     # Volume IV : Surveillance and Collision Avoidance Systems
     # Figure C-3. Extended Squitter Status
     # "Register 07_16"
+    #@Timed
     def df_encode_extended_squitter_status(self, trs = 0x0, ats = 0x0):
         df_frame = self.df_frame_start()
 
-        df_frame.append((trs << 6) & 0x3 | (ats << 5) & 0x1)
-        df_frame.extend([0]*6)
+        df_frame[4] = ((trs << 6) & 0x3 | (ats << 5) & 0x1)
 
-        self.df_frame_append_crc(df_frame)
+        self.df_frame_write_crc(df_frame)
         return df_frame
     
     #From https://github.com/jaywilhelm/ADSB-Out_Python on 2019-08-18
+    #@Timed
     def df_encode_ground_velocity(self, ground_velocity_kt, track_angle_deg, vertical_rate):
   
         #1-5    downlink format
@@ -161,15 +179,15 @@ class ModeS:
 
         dfvel = self.df_frame_start()
         # data
-        dfvel.append((tc << 3) | st)
-        dfvel.append((ic << 7) | (resv_a << 6) | (NAC << 3) | (S_EW << 2) | ((V_EW >> 8) & 0x03))
-        dfvel.append(0xFF & V_EW)
-        dfvel.append((S_NS << 7) | ((V_NS >> 3))) #& 0x7F))
-        dfvel.append(((V_NS << 5) & 0xE0) | (VrSrc << 4) | (S_Vr << 3) | ((Vr >> 6) & 0x03))        
-        dfvel.append(((Vr  << 2) & 0xFC) | (RESV_B))
-        dfvel.append((S_Dif << 7) | (Dif))
+        dfvel[4] = ((tc << 3) | st)
+        dfvel[5] = ((ic << 7) | (resv_a << 6) | (NAC << 3) | (S_EW << 2) | ((V_EW >> 8) & 0x03))
+        dfvel[6] = (0xFF & V_EW)
+        dfvel[7] = ((S_NS << 7) | ((V_NS >> 3))) #& 0x7F))
+        dfvel[8] = (((V_NS << 5) & 0xE0) | (VrSrc << 4) | (S_Vr << 3) | ((Vr >> 6) & 0x03))        
+        dfvel[9] = (((Vr  << 2) & 0xFC) | (RESV_B))
+        dfvel[10] = ((S_Dif << 7) | (Dif))
 
-        self.df_frame_append_crc(dfvel)
+        self.df_frame_write_crc(dfvel)
 
         return dfvel
 
@@ -186,19 +204,17 @@ class ModeS:
         tc = 1  # §C.2.3.4
         ec = 1  # §C.2.3.4
 
-        map = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######"
-
         dfname = self.df_frame_start()
         # data
-        dfname.append((tc << 3) | (ec))
-        dfname.append((0xFC & (int(map.find(csname[0])) << 2)) | (0x03 & (int(map.find(csname[1])) >> 6)))
-        dfname.append((0xF0 & (int(map.find(csname[1])) << 4)) | (0x0F & (int(map.find(csname[2])) >> 2)))
-        dfname.append((0xF0 & (int(map.find(csname[2])) << 6)) | (0x3F & (int(map.find(csname[3])) >> 0)))
-        dfname.append((0xFC & (int(map.find(csname[4])) << 2)) | (0x03 & (int(map.find(csname[5])) >> 4)))
-        dfname.append((0xF0 & (int(map.find(csname[5])) << 4)) | (0x0F & (int(map.find(csname[6])) >> 2)))
-        dfname.append((0xF0 & (int(map.find(csname[6])) << 6)) | (0x3F & (int(map.find(csname[7])) >> 0)))
+        dfname[4]  = (tc << 3) | (ec)
+        dfname[5]  = (0xFC & (int(self._charmap.find(csname[0])) << 2)) | (0x03 & (int(self._charmap.find(csname[1])) >> 4))
+        dfname[6]  = (0xF0 & (int(self._charmap.find(csname[1])) << 4)) | (0x0F & (int(self._charmap.find(csname[2])) >> 2))
+        dfname[7]  = (0xF0 & (int(self._charmap.find(csname[2])) << 6)) | (0x3F & (int(self._charmap.find(csname[3])) >> 0))
+        dfname[8]  = (0xFC & (int(self._charmap.find(csname[4])) << 2)) | (0x03 & (int(self._charmap.find(csname[5])) >> 4))
+        dfname[9]  = (0xF0 & (int(self._charmap.find(csname[5])) << 4)) | (0x0F & (int(self._charmap.find(csname[6])) >> 2))
+        dfname[10] = (0xF0 & (int(self._charmap.find(csname[6])) << 6)) | (0x3F & (int(self._charmap.find(csname[7])) >> 0))
 
-        self.df_frame_append_crc(dfname)
+        self.df_frame_write_crc(dfname)
 
         return dfname
 
@@ -208,6 +224,7 @@ class ModeS:
     # Figure C-8a. Extended Squitter Aircraft Status
     # "Register 61_16"
 
+    #@Timed
     def modaA_encode(self,modeA_4096_code = "7000", emergency_state = 0x0):
         frame = self.df_frame_start()
         # data
@@ -216,7 +233,7 @@ class ModeS:
                   # 1 : Emergency/Priority Status and Mode A Code
                   # 2 : TCAS/ACAS RA Broadcast -> Figure C-8b : fields have different meaning
                   # 3-7 : reserved
-        frame.append((format_tc << 3) | st)
+        frame[4] = ((format_tc << 3) | st)
 
         # Encode Squawk
         # ABCD (A:0-7, B:0-7, C:0-7, D:0-7)
@@ -277,67 +294,39 @@ class ModeS:
         elif squawk_str == "7500":
             emergency = 0x5
 
-        frame.append(emergency << 5 | squawk_bits >> 8)
-        frame.append(squawk_bits & 0xFF)
+        frame[5] = (emergency << 5 | squawk_bits >> 8)
+        frame[6] = (squawk_bits & 0xFF)
 
-        frame.extend([0]*4)
-
-        self.df_frame_append_crc(frame)
+        self.df_frame_write_crc(frame)
 
         return frame
 
-###############################################################
-# 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/>.
-###############################################################
+    #@Timed
+    def df_frame_write_crc(self,frame):
+        crc = self.crc24_lu(frame[0:11])
+        frame[11] = crc >> 16
+        frame[12] = (crc >> 8) & 0xFF
+        frame[13] = crc & 0xFF
 
-# the polynominal generattor code for CRC
+    #@Timed
+    # CRC24 without lookup table
+    def crc24(self,msg):
+        crc = 0x0
+        for b in msg:
+            crc ^= (b << 16)
+            for i in range(8):
+                crc <<= 1
+                if crc & 0x1000000: crc ^= self._crc_poly
 
-    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)
-        """
+        return crc & 0xFFFFFF
 
-        GENERATOR = "1111111111111010000001001" # polynomial coefficients
+    #@Timed
+    # CRC24 with lookup table (about 3x faster than non lookup version)
+    def crc24_lu(self,msg):
+        #print("len:",len(msg))
+        crc = 0x0
+        for b in msg:
+            tmp = (crc ^ (b << 16)) >> 16
+            crc = ((crc << 8) ^ self._crc_lookup_T0[tmp & 0xff])
 
-        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)
+        return crc & 0xFFFFFF

ModeSLocation.py

@@ -1,4 +1,5 @@
 import math
+from CustomDecorators import *
 
 class ModeSLocation:
     """This class does ModeS/ADSB Location calulations"""
@@ -89,6 +90,7 @@ class ModeSLocation:
     # encode CPR position
     # https://adsb-decode-guide.readthedocs.io/en/latest/content/cpr.html
     # compact position reporting
+    #@Timed
     def cpr_encode(self, lat, lon, ctype, surface):
         if surface is True:
             scalar = 2.**19

PseudoCircleTrajectorySimulator.py

@@ -20,28 +20,25 @@ from AbstractTrajectorySimulatorBase import AbstractTrajectorySimulatorBase
 class PseudoCircleTrajectorySimulator(AbstractTrajectorySimulatorBase):
     def __init__(self,mutex,broadcast_thread,aircrafinfos):
         super().__init__(mutex,broadcast_thread,aircrafinfos)
-        self._starttime = datetime.datetime.now(datetime.timezone.utc)
-        
-        self._lasttime = self._starttime
 
         self._lat0 = aircrafinfos.lat_deg
         self._lon0 = aircrafinfos.lon_deg
 
     def refresh_delay(self):
-        return 0.005
+        return 0.02
 
     def update_aircraftinfos(self):
-        now = datetime.datetime.now(datetime.timezone.utc)
-        elapsed = (now - self._lasttime).total_seconds()
         turn_rate = self.getTurnRate()
         R = self.getTurnRadius()
         Rlat = (R/6371000.0)*(180.0/math.pi)
-        ta = self._aircraftinfos.track_angle_deg - (turn_rate*elapsed)*(180.0/math.pi)
+        ta = self._aircraftinfos.track_angle_deg - (turn_rate*self.refresh_delay())*(180.0/math.pi)
         ta = math.fmod(ta,360.0)
-        self._aircraftinfos.track_angle_deg = ta
+        self._aircraftinfos.track_angle_deg = ta # intermediate value and single assignment needed at time because of
+                                                 # setter and change detection mecanism in AircraftInfo (somehox shitty)
+                                                 # TODO : implement better mecanism
         self._aircraftinfos.lat_deg = self._lat0 - Rlat*math.sin(self._aircraftinfos.track_angle_deg*math.pi/180.0)
         self._aircraftinfos.lon_deg = self._lon0 + Rlat/math.cos(self._aircraftinfos.lat_deg*math.pi/180.0)*math.cos(self._aircraftinfos.track_angle_deg*math.pi/180.0)
-        self._lasttime = now
+        #self._lasttime = now
 
     def getTurnRate(self):
         tr = (9.81/self._aircraftinfos.speed_mps)*math.sqrt(self._aircraftinfos.maxloadfactor**2.0 - 1.0)

README.md

@@ -53,7 +53,7 @@ The hardware setup I'm using is pictured below. Please note the RF attenuators (
 The extra 1090MHz filter is probably not requiered as the flight aware dongle already features 1090 MHz filtering.
 My HackRF is fitted with a 0.5 ppm TCXO
 
-![test setup image](./test-setup.jpg "test setup")
+![test setup image](./images/test-setup.jpg "test setup")
 
 The default hackrf settings in repo are :
 - 1090 MHz
@@ -72,11 +72,47 @@ Those forged broadcasts may be used to spoof ATC, trigger TCAS or other maliciou
 
 ## Command line examples
 
+####*Command line switches can be displayed with*  
+
+```
+mathieu@devbox:~/Dev/matioupi/realtime-adsb-out$ ./realtime-adsb-out.py -h
+Usage: ./realtime-adsb-out.py [options]
+
+-h | --help              Display help message.
+--scenario <opt>          Scenario mode with a provided scenario filepath
+--icao <opt>             Callsign in hex, Default:0x508035
+--callsign <opt>         Callsign (8 chars max), Default:DEADBEEF
+--squawk <opt>           4-digits 4096 code squawk, Default:7000
+--trajectorytype <opt>   Type of simulated trajectory amongst :
+                           fixed       : steady aircraft
+                           circle      : pseudo circular flight
+                           random      : random positions inside circle area
+                           waypoints   : fly long flight path
+                           Default:fixed
+--lat <opt>              Latitude for the plane in decimal degrees, Default:50.44994
+--long <opt>             Longitude for the place in decimal degrees. Default:30.5211
+--altitude <opt>         Altitude in decimal feet, Default:1500.0
+--speed <opt>            Airspeed in decimal kph, Default:300.0
+--vspeed <opt>           Vertical speed en ft/min, positive up, Default:0
+--maxloadfactor          Specify the max load factor for aircraft simulation. Default:1.45
+--trackangle <opt>       Track angle in decimal degrees. Default:0
+--timesync <opt>         0/1, 0 indicates time not synchronous with UTC, Default:0
+--capability <opt>       Capability, Default:5
+--typecode <opt>         ADS-B message type, Default:11
+--sstatus <opt>          Surveillance status, Default:0
+--nicsupplementb <opt>   NIC supplement-B, Default:0
+--surface                Aircraft located on ground, Default:False
+--waypoints <opt>        Waypoints file for waypoints trajectory
+--posrate <opt>          position frame broadcast period in µs, Default: 150000
+```
+
+####*Single plane scenarii can be achieved with command line switches*  
+
 `./realtime-adsb-out.py --callsign 'FCKPUTIN' --alt 4500 --speed 600 --trajectorytype circle --maxloadfactor 1.03`
 
 will generate a pseudo circular trajectory, flown at 4500 ft, 600 km/h and a load factor of 1.03.
 
-![circle mode example image](./adsb-out-circle.png "circle mode example")
+![circle mode example image](./images/adsb-out-circle.png "circle mode example")
 
 `./realtime-adsb-out.py --callsign 'FCKPUTIN' --alt 4500  --trajectorytype random`
 
@@ -84,13 +120,22 @@ will generate a random trajectory in a ~30s at specified (here default) speed ar
 track angle is randomized, speed is randomized, altitude is randomized. The default position frame broadcast period can be lowered in order to
 produce a large numer of tracks in a given area
 
-![random mode example image](./adsb-out-random.png "random mode example")
+![random mode example image](./images/adsb-out-random.png "random mode example")
+
+####*More complex scenarii with multiple planes can be achieved though json configuration files*  
+
+`./realtime-adsb-out.py --scenario ./examples/scenario3.json`  
+  
+![4 planes scenario example](./images/adsb-out-scenario3.png "4 planes scenario example")
+
+The maximum number of planes that can be simulated has not been evaluated yet. It will depends on the refresh rate of each message type, etc.
+Tests have been performed on a laptop computer, but with not too many tracks, it should be possible to run on lighter platforms such as Raspberry Pi.  
 
 ## Reference documentation
 
 All reference documentation from the repositories mentionned in the foreword.
 
-https://mode-s.org/
+[https://mode-s.org/](https://mode-s.org/)
 
 *ICAO Annex 10, Aeronautical Telecommunications, Volume IV - Surveillance Radar and Collision Avoidance Systems* which at time of writing can be retrieved here:
 - english version https://www.bazl.admin.ch/bazl/en/home/specialists/regulations-and-guidelines/legislation-and-directives/anhaenge-zur-konvention-der-internationalen-zivilluftfahrtorgani.html
@@ -99,5 +144,8 @@ https://mode-s.org/
 *ICAO doc 9871 edition 1* which can be retrieved here (There is an edition 2 of this document but all seems to be behing paywalls):
 - [ICAO doc 9871 edition 1](http://www.aviationchief.com/uploads/9/2/0/9/92098238/icao_doc_9871_-_technical_provisions_for_mode_s_-_advanced_edition_1.pdf)  
   
+Ghost in the Air(Traffic): On insecurity of ADS-B protocol and practical attacks on ADS-B devices (Andrei Costin, Aurélien Francillon):
+[publication PDF hosted at eurocom.fr](https://www.s3.eurecom.fr/docs/bh12us_costin.pdf)
+
 A DEFCON 20 video on Youtube that already highlighted some ADS-B weaknesses (and at this time, there was no HackRF):
 [DEFCON 20 (2012) - RenderMan - Hacker + Airplanes = No Good Can Come Of This](https://www.youtube.com/watch?v=mY2uiLfXmaI)

examples/A400M-094.json

@@ -0,0 +1,18 @@
+{
+    "icao_aa":"4B8214",
+    "callsign":"180094",
+    "squawk" : "7000",
+    "alt_ft": 35000.0,
+    "lat_deg": 50.24994,
+    "lon_deg": 30.0211,
+    "speed_kph": 780.0,
+    "vspeed_ftpmin": 0.0,
+    "maxloadfactor": 1.01,
+    "track_angle_deg": 0.0,
+    "capability": 5,
+    "type_code": 11,
+    "surveillance_status": 0,
+    "timesync": 0,
+    "nicsup": 0,
+    "on_surface": false
+}

examples/A400M-110.json

@@ -0,0 +1,18 @@
+{
+    "icao_aa":"3B7761",
+    "callsign":"FRBAR",
+    "squawk" : "7000",
+    "alt_ft": 15500.0,
+    "lat_deg": 50.24994,
+    "lon_deg": 30.5211,
+    "speed_kph": 750.0,
+    "vspeed_ftpmin": 0.0,
+    "maxloadfactor": 1.06,
+    "track_angle_deg": 0.0,
+    "capability": 5,
+    "type_code": 11,
+    "surveillance_status": 0,
+    "timesync": 0,
+    "nicsup": 0,
+    "on_surface": false
+}

examples/AN-IL78MP.json

@@ -0,0 +1,18 @@
+{
+    "icao_aa":"0x50FF5E",
+    "callsign":"R10002",
+    "squawk" : "7000",
+    "alt_ft": 6500.0,
+    "lat_deg": 50.44994,
+    "lon_deg": 30.8211,
+    "speed_kph": 500.0,
+    "vspeed_ftpmin": 0.0,
+    "maxloadfactor": 1.06,
+    "track_angle_deg": 0.0,
+    "capability": 5,
+    "type_code": 11,
+    "surveillance_status": 0,
+    "timesync": 0,
+    "nicsup": 0,
+    "on_surface": false
+}

examples/MRYIA.json

@@ -0,0 +1,18 @@
+{
+    "icao_aa":"0x508035",
+    "callsign":"MRYIA",
+    "squawk": "7000",
+    "alt_ft": 4500.0,
+    "lat_deg": 50.44994,
+    "lon_deg": 30.5211,
+    "speed_kph": 600.0,
+    "vspeed_ftpmin": 0.0,
+    "maxloadfactor": 1.03,
+    "track_angle_deg": 0.0,
+    "capability": 5,
+    "type_code": 11,
+    "surveillance_status": 0,
+    "timesync": 0,
+    "nicsup": 0,
+    "on_surface": false
+}

examples/scenario.json

@@ -0,0 +1,7 @@
+{
+    "plane1":
+    {
+        "filename":"./examples/MRYIA.json",
+        "trajectory_type":"circle"
+    }
+}

examples/scenario2.json

@@ -0,0 +1,12 @@
+{
+    "plane1":
+    {
+        "filename":"./examples/MRYIA.json",
+        "trajectory_type":"circle"
+    },
+    "plane2":
+    {
+        "filename":"./examples/AN-IL78MP.json",
+        "trajectory_type":"circle"
+    }
+}

examples/scenario3.json

@@ -0,0 +1,22 @@
+{
+    "plane1":
+    {
+        "filename":"./examples/MRYIA.json",
+        "trajectory_type":"circle"
+    },
+    "plane2":
+    {
+        "filename":"./examples/AN-IL78MP.json",
+        "trajectory_type":"circle"
+    },
+    "plane3":
+    {
+        "filename":"./examples/A400M-094.json",
+        "trajectory_type":"circle"
+    },
+    "plane4":
+    {
+        "filename":"./examples/A400M-110.json",
+        "trajectory_type":"circle"
+    }    
+}

realtime-adsb-out.py

@@ -14,8 +14,9 @@ You should have received a copy of the GNU General Public License along with
 this program. If not, see <http://www.gnu.org/licenses/>.
 """
 
-import sys, time, math
-import threading
+import sys, time, math, os
+import threading, json
+import traceback
 
 from AircraftInfos import AircraftInfos
 from FixedTrajectorySimulator import FixedTrajectorySimulator
@@ -30,6 +31,7 @@ def usage(msg=False):
     if msg:print(msg)
     print("Usage: %s [options]\n" % sys.argv[0])
     print("-h | --help              Display help message.")
+    print("--scenario <opt>          Scenario mode with a provided scenario filepath")
     print("--icao <opt>             Callsign in hex, Default:0x508035")
     print("--callsign <opt>         Callsign (8 chars max), Default:DEADBEEF")
     print("--squawk <opt>           4-digits 4096 code squawk, Default:7000")
@@ -59,6 +61,21 @@ def usage(msg=False):
 
     sys.exit(2)
 
+def getTrackSimulationThread(trajectory_type,brodcast_thread,aircraftinfos,waypoints_file = None):
+
+    if trajectory_type == 'fixed':
+        return FixedTrajectorySimulator(brodcast_thread.getMutex(),brodcast_thread,aircraftinfos)
+    elif trajectory_type == 'circle':
+        return PseudoCircleTrajectorySimulator(brodcast_thread.getMutex(),brodcast_thread,aircraftinfos)
+    elif trajectory_type == 'random':
+        return RandomTrajectorySimulator(brodcast_thread.getMutex(),brodcast_thread,aircraftinfos)        
+    elif trajectory_type == 'waypoints':
+        print("WaypointsTrajectorySimulator not implemented yet")
+        exit(-1)
+        return WaypointsTrajectorySimulator(brodcast_thread.getMutex(),brodcast_thread,aircraftinfos,waypoints_file)
+    else:
+        return None
+
 def main():
 
     # Default values
@@ -82,10 +99,10 @@ def main():
     trajectory_type = 'fixed'
     waypoints_file = None
     posrate = 150000
-
+    scenariofile = None
     try:
         (opts, args) = getopt(sys.argv[1:], 'h', \
-            ['help','icao=','callsign=','squawk=','trajectorytype=','lat=','long=','altitude=','speed=','vspeed=','maxloadfactor=','trackangle=',
+            ['help','scenario=','icao=','callsign=','squawk=','trajectorytype=','lat=','long=','altitude=','speed=','vspeed=','maxloadfactor=','trackangle=',
             'timesync=','capability=','typecode=','sstatus=','nicsupplementb=','surface','posrate='
             ])
     except GetoptError as err:
@@ -94,6 +111,7 @@ def main():
     if len(opts) != 0:
         for (opt, arg) in opts:
             if opt in ('-h', '--help'):usage()
+            elif opt in ('--scenario'):scenariofile = arg
             elif opt in ('--icao'):icao_aa = arg
             elif opt in ('--callsign'):callsign = arg
             elif opt in ('--squawk'):squawk = arg
@@ -117,38 +135,64 @@ def main():
             elif opt in ('--posrate'):posrate = int(arg)
             else:usage("Unknown option %s\n" % opt)
 
+    track_simulators = []
+    broadcast_thread = HackRfBroadcastThread(posrate) # posrate would usally be used with random mode to generate load of tracks
+
+    if scenariofile == None:
+        print("Going to run in single plane from command line mode")
         aircraftinfos = AircraftInfos(icao_aa,callsign,squawk, \
                                     lat_deg,lon_deg,alt_ft,speed_kph,vspeed_ftpmin,maxloadfactor,track_angle_deg, \
                                     timesync,capability,type_code,surveillance_status,nicsup,on_surface)
 
-    # TODO : the mutex would better be implemented as an object attribute in broadcast thread
-    mutex = threading.Lock()
+        track_simulation = getTrackSimulationThread(trajectory_type,broadcast_thread,aircraftinfos,waypoints_file)
 
-    brodcast_thread = HackRfBroadcastThread(mutex,posrate) # posrate would usally be used with random mode to generate load of tracks
+        track_simulators.append(track_simulation)
         
-    if trajectory_type == 'fixed':
-        trajectory_simulator = FixedTrajectorySimulator(mutex,brodcast_thread,aircraftinfos)
-    elif trajectory_type == 'circle':
-        trajectory_simulator = PseudoCircleTrajectorySimulator(mutex,brodcast_thread,aircraftinfos)
-    elif trajectory_type == 'random':
-        trajectory_simulator = RandomTrajectorySimulator(mutex,brodcast_thread,aircraftinfos)        
-    elif trajectory_type == 'waypoints':
-        print("WaypointsTrajectorySimulator not implemented yet")
-        exit(-1)
-        trajectory_simulator = WaypointsTrajectorySimulator(mutex,brodcast_thread,aircraftinfos,waypoints_file)
+    else:
+        print("Going to run in json scenario mode from file "+os.path.abspath(scenariofile))
+        with open(scenariofile,'r') as json_file:
+            scenario = json.load(json_file)
+
+        for plane in scenario.values():
+            plane_info = AircraftInfos.from_json(plane["filename"])
+
+            if "waypoints_file" in plane:
+                waypoints_file = plane["waypoints_file"]
+
+            track_simulation = getTrackSimulationThread(plane["trajectory_type"],broadcast_thread,plane_info,waypoints_file)
+
+            track_simulators.append(track_simulation)
+
+        print("scenario contains tracks simulation instructions for "+str(len(track_simulators))+" planes:")
+        for tsim in track_simulators:
+            print("callsign: "+tsim.aircraftinfos.callsign.ljust(9,' ')+"MSL altitude: "+"{:7.1f}".format(tsim.aircraftinfos.alt_msl_ft)+" ft")
+
+    for tsim in track_simulators:
+        broadcast_thread.register_track_simulation_thread(tsim)
 
     while(val:=input("Type \'s + Enter\' to start the adsb-out simulation, and type \'s + Enter\' again to stop it:\n") != 's'):
         time.sleep(0.05)
 
-    trajectory_simulator.start()
-    brodcast_thread.start()
+    # start all threads
+    for tsim in track_simulators:
+        tsim.start()
+
+    broadcast_thread.start()
+
     # user input loop. Todo : implement other commands ? (in that case don't forget to check if mutex protection is needed)
     while(val:=input("") != 's'):
         time.sleep(0.05)
-    trajectory_simulator.stop()
-    brodcast_thread.stop()
-    trajectory_simulator.join()
-    brodcast_thread.join()
+
+    # stop all threads
+    for tsim in track_simulators:
+        tsim.stop()
+        
+    broadcast_thread.stop()
+
+    # wait for all threads to terminate
+    for tsim in track_simulators:
+        tsim.join()
+    broadcast_thread.join()
 
     print("reatime-adsb-out simulation is finished")