INTEGRATION OF SIMULINK ADS-B (IN/OUT) MODEL IN SDR
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! !"#$%"&$%' $) *+,-."/.0,1 23#,11,1 *'4&,35 6"7.8"9$: ":1 ;7.$:.-4 <!;**26;#$ %&'( Department of Electrical Engineering LASSENA (Laboratory of Specialized Embedded System, Navigation and Avionics) INTEGRATION OF SIMULINK ADS-B (IN/OUT) MODEL IN SDR <=3+/,3,:&"9$: ":1 $+,%"9$:"/ >4, $) ;?*@AB Joe Zambrano [email protected] Omar Yeste [email protected] René Jr. Landry [email protected] In an effort to increase the safety, efficiency and capacity of air transport operations, the FAA proposes a comprehensive reform of the surveillance radar (NextGen). For this, the FAA deploys a relatively new technology called Automatic Dependent Surveillance-Broadcast (ADS-B). This technology allows aircraft equipped with a GPS to periodically send their position and other information to ground stations and other aircraft equipped with ADS-B that are present in the area. Although the FAA expects to keep the primary radar for defense, many of today’s secondary surveillance radars will not be used in the future [1]. A comparison of current surveillance (radar and Mode S) and ADS- B attributes are summarized in Table 1. ADS-B is primarily a means of air traffic management to know the position of the aircraft. Because the accuracy of Global Navigation Satellite Systems (GNSS) is better than that of Air Traffic Control (ATC) radars, modern aircraft know their position much more precisely than ground control [3]. Ground based radar system ADS-B system • Ground based infrastructure only, requires challenge and response and pilot-to- controller voice comm. • Aircraft, ground and space based infrastructure, provides constant flow of more precise position data, reduces required voice comm. • Coverage gaps exist in some areas • ADS-B ground stations can be placed virtually anywhere • Position updates every 12 seconds • Position updates every second • Costly to install and maintain • Significantly less costly to install and maintain • Air Traffic Control • Air Traffic Management To build a system like this, the laboratory of Specialized Embedded System, Navigation and Avionics (LASSENA) of the École de Technologie Supérieure has chosen to take a relatively new approach in the field. This approach, Software Defined Radio (SDR), is mainly used in various communication systems for its flexibility and high performance, so we will use for the implementation of our system the SDRs USRP N210 and B100 manufactured by Ettus Research. RESEARCH PROBLEM ADS-B The idea is therefore that the aircraft calculates its own position (longitude, latitude and altitude) and sends it regularly by radio (1090 MHz) to ground-based receivers and other aircraft. The ADS-B message, contains 56 bits that will determine the ADS-B message type and will occupy a place between the 256 data registers (BDS) in the transponder. The registers are identified by two hexadecimal digits, e.g. BDS 05h (or BDS 0.5) is the squitter used for transmitting the aircraft position [6]. Registers commonly used for ADS-B are shown in Table 2. CONTROL 8 BITS ICAO ADDRESS 24 BITS ADS-B MESSAGE 56 BITS PARITY 24 BITS Table 1: Current surveillance (Radar and Modes S) vs. ADS-B [2] Figure 1: ADS-B (IN/OUT) System [5] ADS-B Message Generator ADS-B TX (GRC) USRP N-210 WBX Simulink Model ADS-B Message Data display ADS-B Message Data display GR-AIR-MODES USRP B100 SBX 1090 MHz ubuntu python Tx Rx ADS-B OUT ADS-B IN SIMULATION REGISTER MESSAGE ADS-B BDS 05h Airborne Position Message BDS 06h Surface Position Message BDS 08h Aircraft Identification (ID) and Category Message BDS 09h Airborne Velocity Message BDS 61h Emergency/Priority Status Message BDS 62h Target State and Status Message BDS 65h Aircraft Operational Status Message Table 2: Content of some BDS registers [7] SIMULATION ARCHITECTURE The simulation and prototype testing architecture is shown in Figure 2. The ADS-B OUT subsystem is plotted on the top. After the message ADS-B is generated, it is sent to the ADS-B TX block, and then, it is sent to the USRP (N210) for transmission at 1090 MHz. On the reception side (in the bottom), the message is received and downconverted to baseband by another USRP (B100) whose file GR-AIR-MODES [8] will decode the ADS-B message for display on Google-earth or simply on the Terminal window. Figure 2: ADS-B (IN/OUT) environment flowchart SIMULINK SIMULATION MODEL: Figure 3.a presents the three stages proposed to simulate an ADS-B system. The block “ADS- B message generator” is linked to block “ADS-B message”. This block allows building any ADS-B message type by manually entering data in hexadecimal format (4bits) from the ADS-B data entry graphical interface. Figure 3: a)Full ADS-B (IN/OUT) Simulink model. b) Waveform of outputs ADS-B OUT and Transmission channel. c) Waveforms of decoding block. Modulation ChannelTx Decodification Demodulation Acquisition Envelope Detector by Squaring the signal and LPF Data Noise Delay ADS-B detector Message Detector From work space ADS-B Modulator 1090Mhz ADS-B message ADS-B message generator |u| 2 sqrt Digital Filter AND XOR 2 x[1n] ADS-B OUT ADS-B IN TRANSMISSION CHANNEL a. b. c. PROTOTYPE We implement a message generator for BDS 05h, BDS 06h and BDS 08h in Matlab. We use Simulink environment for signal processing simulation and GNU Radio Companion (GRC) to transmit the message to a frequency of 1090 MHz by software radio using GRC (Figure 4). The method used was inspired by D. Magazu III. [9] The time of ADS-B messages is 120 μs, where 8 μs correspond to the preamble and 112 μs correspond to the data block modulated in PPM; we also remind that the pulse duration must be reduced by 50 % (to 0.5 μs) to obtain a PPM modulation. Therefore, the sampling rate of the ADS-B transmitter must be at least 2 MHz. RESULTS Figure 4: transmitter GRC GR-AIR-MODES can be used as an ADS-B IN module. Thus, it can be used for real-time validation of the messages generated and emitted by our ADS-OUT component. The message generated by our block ADS-B OUT contains the ICAO address CAB001, the ID “LASSENA” and a ground track of 146°. In addition, the simulated aircraft is a small plane located at altitude 30150 feet, latitude 52.519283°, and longitude 13.402617°. Figure 5: Decoding of ADS-B messages sent from the ADS-B OUT In Figure 6, we can observe messages received and decoded by GR-AIR-MODES. Therefore we can say that the message generator and the transmitter for block ADS-B OUT (Matlab-GRC) work correctly. Figure 6: Real-time display of ADS-B messages sent from the ADS-B OUT block CONCLUSION The advantage of SDRs is the ability to reconfigure by software the parameters required (reduced costs) for the desired applications e.g. in case of an ADS-B reconfiguration due to standard modifications to address ADS-B security issues. We believe that in the medium term, SDRs will become the dominant technology in radio because it is the road that leads to cognitive radio. To conclude, we have worked with these two technologies (ADS-B and SDR) that will dominate the future; demonstrating at first the benefits and opportunities of services offered by ADS-B technology, and in a second time the integration and performance of radio software in the aerospace field. REFERENCES [1] Aircraft Owners and Pilots Association - AOPA. N.D. « Air Traffic Services Brief: Automatic Dependent Surveillance - Broadcast (ADS-B)». < http://www.aopa.org/whatsnew/air_traffic/ads-b. html >. [2] McCallie, L. Donald. 2011. « Exploring Potential ADS-B Vulnerabilities in the FAA’s NextGen Air Transportation System ». Graduate Research Projet presented in Partial Fulfillment of the Requirements for the Degree of Master of Cyber Warfare. Air Force institute Of technology, Wright-Patterson Air Force Base, 46. p p. [3] Defense Electronic. 2005. « Understanding Mode S technology ».<http://rfdesign.com/military_defense_electronics/ radio_understanding_mode_technology>. [4] Civil Aviation Safety Authority. 2012. « ADS-B Automatic Dependent Surveillance-Broadcast ». <http://www.casa.gov.au/wcmswr/ _assets/ main/pilots/download/ads-b. pdf>. [5] Air Traffic Atlanta. 2008. Air Traffic Management and Air Traffic Control Articles. «Automatic Dependent Surveillance-Broadcast (ADS-B). A Primer and Arguments Why the FAA Should Maintain Airport Surveillance Radar ». <http://airtrafficatlanta.com/ads- b_explained_primer .html>. [6] Wolff, Christian, 2012. « Les principes du Radar ». <http://www.radartutorial.eu/index. fr. html>. [7] EUROCONTROL. 2012a. « ADS-B for Dummies ». <http://www.ssd.dhmi.gov.tr/getBinaryFile.aspx?Type=3&dosyaID=123>. [8] Foster, Nick. 2012. « GR-AIR-MODES ». <https://github.com/bistromath/gr-air-modes>. [9] Magazu Domenic. 2012. « Exploiting the Automatic Dependent Surveillance-Broadcast System via False Target ». Graduate Research Projet presented in Partial Fulfillment of the Requirements for the Degree of Master of Science. Air Force institute Of technology, Wright-Patterson Air Force Base, 46. p p. Global Navigation Satellite System ADS-B (IN/OUT) 1090 MHz Traffic Collision Avoidance System (TCAS) ADS-B 1090MHz Radar MODE S ADS-B Receiver Air Traffic Management Cockpit Display of Traffic Information (CDTI) MODE S EXTENDED SQUITTER (112 BITS) ADS-B IN: concerns the reception of ADS-B messages transmitted by other aircraft. In this case, the aircraft is also equipped with a Cockpit Display of Traffic Information (CDTI) to display ADS-B OUT messages from other airplanes and information sent from ground stations [4]. ADS-B OUT: concerns transmission of ADS-B messages by aircraft. The ADS-B signal is broadcast from the aircraft approximately twice per second, and in the event the aircraft is within the coverage radius of an ADS-B ground station, data is transmitted to Air Traffic Management (ATM) facilities [4]. ADS-B 1090MHz Interrogation 1030 MHz Response 1090 MHz
Transcript of INTEGRATION OF SIMULINK ADS-B (IN/OUT) MODEL IN SDR
!"!"#$%"&$%'($)(*+,-."/.0,1(23#,11,1(*'4&,35(6"7.8"9$:(":1(;7.$:.-4(<!;**26;#$"%&'("
Department of Electrical Engineering LASSENA (Laboratory of Specialized Embedded System, Navigation and Avionics)
INTEGRATION OF SIMULINK ADS-B (IN/OUT) MODEL IN SDR <=3+/,3,:&"9$:(":1($+,%"9$:"/(>4,($)(;?*@AB(
Joe Zambrano [email protected]
Omar Yeste [email protected]
René Jr. Landry [email protected]
In an effort to increase the safety, efficiency and capacity of air transport operations, the FAA proposes a comprehensive reform of the surveillance radar (NextGen). For this, the FAA deploys a relatively new technology called Automatic Dependent Surveillance-Broadcast (ADS-B). This technology allows aircraft equipped with a GPS to periodically send their position and other information to ground stations and other aircraft equipped with ADS-B that are present in the area. Although the FAA expects to keep the primary radar for defense, many of today’s secondary surveillance radars will not be used in the future [1]. A comparison of current surveillance (radar and Mode S) and ADS-B attributes are summarized in Table 1.
ADS-B is primarily a means of air traffic management to know the position of the aircraft. Because the accuracy of Global Navigation Satellite Systems (GNSS) is better than that of Air Traffic Control (ATC) radars, modern aircraft know their position much more precisely than ground control [3].
Ground based radar system ADS-B system
• Ground based infrastructure only, requires challenge and response and pilot-to- controller voice comm.
• Aircraft, ground and space based infrastructure, provides constant flow of more precise position data, reduces required voice comm.
• Coverage gaps exist in some areas • ADS-B ground stations can be placed virtually anywhere
• Position updates every 12 seconds • Position updates every second
• Costly to install and maintain • Significantly less costly to install and maintain
• Air Traffic Control • Air Traffic Management
To build a system like this, the laboratory of Specialized Embedded System, Navigation and Avionics (LASSENA) of the École de Technologie Supérieure has chosen to take a relatively new approach in the field. This approach, Software Defined Radio (SDR), is mainly used in various communication systems for its flexibility and high performance, so we will use for the implementation of our system the SDRs USRP N210 and B100 manufactured by Ettus Research.
RESEARCH PROBLEM
ADS-B
The idea is therefore that the aircraft calculates its own position (longitude, latitude and altitude) and sends it regularly by radio (1090 MHz) to ground-based receivers and other aircraft. The ADS-B message, contains 56 bits that will determine the ADS-B message type and will occupy a place between the 256 data registers (BDS) in the transponder. The registers are identified by two hexadecimal digits, e.g. BDS 05h (or BDS 0.5) is the squitter used for transmitting the aircraft position [6]. Registers commonly used for ADS-B are shown in Table 2.
CONTROL!8 BITS! ICAO
ADDRESS!24 BITS! ADS-B
MESSAGE!56 BITS! PARITY!
24 BITS!
Table 1: Current surveillance (Radar and Modes S) vs. ADS-B [2]
Figure 1: ADS-B (IN/OUT) System [5]
ADS-B Message Generator( ADS-B TX(
(GRC)( USRP N-210(WBX(
((
((
Simulink Model( ADS-B Message(Data display(((
ADS-B Message(Data display( GR-AIR-MODES( USRP B100(
SBX(((
(( ((
1090 MHz!((
ubuntu!
((
python!
Tx!
Rx!
ADS-B OUT(
ADS-B IN(
SIMULATION(
REGISTER MESSAGE ADS-B BDS 05h Airborne Position Message BDS 06h Surface Position Message BDS 08h Aircraft Identification (ID) and Category Message BDS 09h Airborne Velocity Message BDS 61h Emergency/Priority Status Message BDS 62h Target State and Status Message BDS 65h Aircraft Operational Status Message
Table 2: Content of some BDS registers [7]
SIMULATION ARCHITECTURE
The simulation and prototype testing architecture is shown in Figure 2. The ADS-B OUT subsystem is plotted on the top. After the message ADS-B is generated, it is sent to the ADS-B TX block, and then, it is sent to the USRP (N210) for transmission at 1090 MHz. On the reception side (in the bottom), the message is received and downconverted to baseband by another USRP (B100) whose file GR-AIR-MODES [8] will decode the ADS-B message for display on Google-earth or simply on the Terminal window.
Figure 2: ADS-B (IN/OUT) environment flowchart
SIMULINK SIMULATION MODEL: Figure 3.a presents the three stages proposed to simulate an ADS-B system. The block “ADS-B message generator” is linked to block “ADS-B message”. This block allows building any ADS-B message type by manually entering data in hexadecimal format (4bits) from the ADS-B data entry graphical interface.
Figure 3: a)Full ADS-B (IN/OUT) Simulink model. b) Waveform of outputs ADS-B OUT and Transmission channel. c) Waveforms of decoding block.
Modulation ChannelTx DecodificationDemodulation Acquisition
Env elope Detector by Squaring the signal and LPF
DataNoise
Delay
ADS-B detector
Message Detector
Fromwork space
ADS-B
Modulator1090Mhz
ADS-B message
ADS-B message generator
|u|2 sqrtDigitalFilter
ANDXOR
2 x[1n]
ADS-B OUT! ADS-B IN!TRANSMISSION!CHANNEL!
a.
b. c.
PROTOTYPE
We implement a message generator for BDS 05h, BDS 06h and BDS 08h in Matlab. We use Simulink environment for signal processing simulation and GNU Radio Companion (GRC) to transmit the message to a frequency of 1090 MHz by software radio using GRC (Figure 4). The method used was inspired by D. Magazu III. [9] The time of ADS-B messages is 120 µs, where 8 µs correspond to the preamble and 112 µs correspond to the data block modulated in PPM; we also remind that the pulse duration must be reduced by 50 % (to 0.5 µs) to obtain a PPM modulation. Therefore, the sampling rate of the ADS-B transmitter must be at least 2 MHz.
RESULTS
Figure 4: transmitter GRC
GR-AIR-MODES can be used as an ADS-B IN module. Thus, it can be used for real-time validation of the messages generated and emitted by our ADS-OUT component. The message generated by our block ADS-B OUT contains the ICAO address CAB001, the ID “LASSENA” and a ground track of 146°. In addition, the simulated aircraft is a small plane located at altitude 30150 feet, latitude 52.519283°, and longitude 13.402617°.
Figure 5: Decoding of ADS-B messages sent from the ADS-B OUT
In Figure 6, we can observe messages received and decoded by GR-AIR-MODES. Therefore we can say that the message generator and the transmitter for block ADS-B OUT (Matlab-GRC) work correctly.
Figure 6: Real-time display of ADS-B messages sent from the ADS-B OUT block
CONCLUSION
The advantage of SDRs is the ability to reconfigure by software the parameters required (reduced costs) for the desired applications e.g. in case of an ADS-B reconfiguration due to standard modifications to address ADS-B security issues. We believe that in the medium term, SDRs will become the dominant technology in radio because it is the road that leads to cognitive radio. To conclude, we have worked with these two technologies (ADS-B and SDR) that will dominate the future; demonstrating at first the benefits and opportunities of services offered by ADS-B technology, and in a second time the integration and performance of radio software in the aerospace field.
REFERENCES [1] Aircraft Owners and Pilots Association - AOPA. N.D. « Air Traffic Services Brief: Automatic Dependent Surveillance - Broadcast (ADS-B)». < http://www.aopa.org/whatsnew/air_traffic/ads-b. html >.
[2] McCallie, L. Donald. 2011. « Exploring Potential ADS-B Vulnerabilities in the FAA’s NextGen Air Transportation System ». Graduate Research Projet presented in Partial Fulfillment of the Requirements for the Degree of Master of Cyber Warfare. Air Force institute Of technology, Wright-Patterson Air Force Base, 46. p p.
[3] Defense Electronic. 2005. « Understanding Mode S technology ».<http://rfdesign.com/military_defense_electronics/radio_understanding_mode_technology>.
[4] Civil Aviation Safety Authority. 2012. « ADS-B Automatic Dependent Surveillance-Broadcast ». <http://www.casa.gov.au/wcmswr/_assets/ main/pilots/download/ads-b. pdf>.
[5] Air Traffic Atlanta. 2008. Air Traffic Management and Air Traffic Control Articles. «Automatic Dependent Surveillance-Broadcast (ADS-B). A Primer and Arguments Why the FAA Should Maintain Airport Surveillance Radar ». <http://airtrafficatlanta.com/ads-b_explained_primer .html>.
[6] Wolff, Christian, 2012. « Les principes du Radar ». <http://www.radartutorial.eu/index. fr. html>.
[7] EUROCONTROL. 2012a. « ADS-B for Dummies ». <http://www.ssd.dhmi.gov.tr/getBinaryFile.aspx?Type=3&dosyaID=123>.
[8] Foster, Nick. 2012. « GR-AIR-MODES ». <https://github.com/bistromath/gr-air-modes>.
[9] Magazu Domenic. 2012. « Exploiting the Automatic Dependent Surveillance-Broadcast System via False Target ». Graduate Research Projet presented in Partial Fulfillment of the Requirements for the Degree of Master of Science. Air Force institute Of technology, Wright-Patterson Air Force Base, 46. p p.
((
Global Navigation Satellite System!
ADS-B (IN/OUT) 1090 MHz!
Traffic Collision!Avoidance!
System (TCAS)!
ADS-B 1090MHz!
(( (((( !
Radar!MODE S!ADS-B!
Receiver! Air Traffic!Management!
Cockpit Display of Traffic Information
(CDTI)!
MODE S!EXTENDED SQUITTER (112 BITS)!
ADS-B IN: concerns the reception of ADS-B messages transmitted by other aircraft. In this case, the aircraft is also equipped with a Cockpit Display of Traffic Information (CDTI) to display ADS-B OUT messages from other airplanes and information sent from ground stations [4].
ADS-B OUT: concerns transmission of ADS-B messages by aircraft. The ADS-B signal is broadcast from the aircraft approximately twice per second, and in the event the aircraft is within the coverage radius of an ADS-B ground station, data is transmitted to Air Traffic Management (ATM) facilities [4].
ADS-B 1090MHz!
Interrogation 1030 MHz
Response 1090 MHz
(( ((
