2021/03/10
By Saeed Daneshmand, Ali Jafarnia-Jahromi, Ali Broumandan, and Gérard Lachapelle
Most anti-spoofing techniques are computationally complicated or limited to a specific spoofing scenario. A new approach uses a two-antenna array to steer a null toward the direction of the spoofing signals, taking advantage of the spatial filtering and the periodicity of the authentic and spoofing signals. It requires neither antenna-array calibration nor a spoofing detection block, and can be employed as an inline anti-spoofing module at the input of conventional GPS receivers.
GNSS signals are highly vulnerable to in-band interference such as jamming and spoofing. Spoofing is an intentional interfering signal that aims to coerce GNSS receivers into generating false position/navigation solutions. A spoofing attack is, potentially, significantly more hazardous than jamming since the target receiver is not aware of this threat. In recent years, implementation of software receiver-based spoofers has become feasible due to rapid advances with software-defined radio (SDR) technology. Therefore, spoofing countermeasures have attracted significant interest in the GNSS community.
Most of the recently proposed anti-spoofing techniques focus on spoofing detection rather than on spoofing mitigation. Furthermore, most of these techniques are either restricted to specific spoofing scenarios or impose high computational complexity on receiver operation.
Due to the logistical limitations, spoofing transmitters often transmit several pseudorandom noise codes (PRNs) from the same antenna, while the authentic PRNs are transmitted from different satellites from different directions. This scenario is shown in Figure 1. In addition, to provide an effective spoofing attack, the individual spoofing PRNs should be as powerful as their authentic peers. Therefore, overall spatial energy of the spoofing signals, which is coming from one direction, is higher than other incident signals. Based on this common feature of the spoofing signals, we propose an effective null-steering approach to set up a countermeasure against spoofing attacks. This method employs a low-complexity processing technique to simultaneously de-spread the different incident signals and extract their spatial energy. Afterwards, a null is steered toward the direction where signals with the highest amount of energy impinge on the double-antenna array. One of the benefits of this method is that it does not require array calibration or the knowledge of the array configuration, which are the main limitations of antenna-array processing techniques.
Processing Method
The block diagram of the proposed method is shown in Figure 2. Without loss of generality, assume that s(t) is the received spoofing signal at the first antenna.
Figure 2. Operational block diagram of proposed technique.
The impinging signal at the second antenna can be modeled by , where θs and μ signify the spatial phase and gain difference between the two channels, respectively. As mentioned before, the spoofer transmits several PRNs from the same direction while the authentic signals are transmitted from different directions. Therefore, θs is the same for all the spoofing signals. However, the incident authentic signals impose different spatial phase differences. In other words, the dominant spatial energy is coming from the spoofing direction. Thus, by multiplying the conjugate of the first channel signals to that of the second channel and then applying a summation over N samples, θs can be estimated as
(1)
where r1 and r2 are the complex baseband models of the received signals at the first and the second channels respectively, and Ts is the sampling duration. In (1), θs can be estimated considering the fact that the authentic terms are summed up non-constructively while the spoofing terms are combined constructively, and all other crosscorrelation and noise terms are significantly reduced after filtering. For estimating μ, the signal of each channel is multiplied by its conjugate in the next epoch to prevent noise amplification. It can easily be shown that μ can be estimated as
(2)
where T is the pseudorandom code period. Having and a proper gain can be applied to the second channel in order to mitigate the spoofing signals by adding them destructively as
(3)
Analyses and Simulation Results
We have carried out simulations for the case of 10 authentic and 10 spoofing GPS signals being transmitted at the same time. The authentic sources were randomly distributed over different azimuth and elevation angles, while all spoofing signals were transmitted from the same direction at azimuth and elevation of 45 degrees. A random code delay and Doppler frequency shift were assigned to each PRN. The average power of the authentic and the spoofing PRNs were –158.5 dBW and –156.5 dBW, respectively.
Figure 3 shows the 3D beam pattern generated by the proposed spoofing mitigation technique. The green lines show the authentic signals coming from different directions, and the red line represents the spoofing signals. As shown, the beam pattern’s null is steered toward the spoofing direction.
Figure 3. Null steering toward the spoofer signals.
In Figure 4, the array gain of the previous simulation has been plotted versus the azimuth and elevation angles. Note that the double-antenna anti-spoofing technique significantly attenuates the spoofer signals. This attenuation is about 11 dB in this case. Hence, after mitigation, the average injected spoofing power is reduced to –167.5 dBW for each PRN. As shown in Figure 4, the double-antenna process has an inherent array gain that can amplify the authentic signals. However, due to the presence of the cone of ambiguity in the two-antenna array beam pattern, the power of some authentic satellites that are located in the attenuation cone might be also reduced.
Figure 4. Array gain with respect to azimuth and elevation.
Monte Carlo simulations were then performed over 1,000 runs for different spoofing power levels. The transmitted direction, the code delay, and the Doppler frequency shift of the spoofing and authentic signals were changed during each run of the simulation. Figure 5 shows the average signal to interference-plus-noise ratio (SINR) of the authentic and the spoofing signals as a function of the average input spoofing power for both the single antenna and the proposed double antenna processes. A typical detection SINR threshold corresponding to PFA=10-3 also has been shown in this figure.
Figure 5. Authentic and spoofed SINR variations as a function of average spoofing power.
In the case of the single antenna receiver, the SINR of the authentic signals decreases as the input spoofing power increases. This is because of the receiver noise-floor increase due to the cross-correlation terms caused by the higher power spoofing signals. However, the average SINR of the spoofing signals increases as the power of the spoofing PRNs increase.
For example, when the average input spoofing power is –150 dBW, the authentic SINR for the single-antenna process is under the detection threshold, while the SINR of the spoofing signal is above this threshold. However, by considering the proposed beamforming method, as the spoofing power increases, the SINR of the authentic signal almost remains constant, while the spoofing SINR is always far below the detection threshold.
Hence, the proposed null-steering method not only attenuates the spoofing signals but also significantly reduces the spoofing cross-correlation terms that increase the receiver noise floor. Early real-data processing verifies the theoretical findings and shows that the proposed method indeed is applicable to real-world spoofing scenarios.
Conclusions
The method proposed herein is implemented before the despreading process; hence, it significantly decreases the computational complexity of the receiver process. Furthermore, the method does not require array calibration, which is the common burden with array-processing techniques.
These features make it suitable for real-time applications and, thus, it can be either employed as a pre-processing unit for conventional GPS receivers or easily integrated into next-generation GPS receivers. Considering the initial experimental results, the required antenna spacing for a proper anti-spoofing scenario is about a half carrier wavelength. Hence, the proposed anti-spoofing method can be integrated into handheld devices.
The proposed technique can also be easily extended to other GNSS signal structures. Further analyses and tests in different real-world scenarios are ongoing to further assess the effectiveness of the method.
Saeed Daneshmand is a Ph.D. student in the Position, Location, and Navigation (PLAN) group in the Department of Geomatics Engineering at the University of Calgary. His research focuses on GNSS interference and multipath mitigation using array processing.
Ali Jafarnia-Jahromi is a Ph.D. student in the PLAN group at the University of Calgary. His research focuses on GNSS spoofing detection and mitigation techniques.
Ali Broumandan received his Ph.D. degree from Department of Geomatics Engineering, University of Calgary, Canada. He is a senior research associate/post-doctoral fellow in the PLAN group at the University.
Gérard Lachapelle holds a Canada Research Chair in wireless location In the Department of Geomatics Engineering at the University of Calgary in Alberta, Canada, and is a member of GPS World’s Editorial Advisory Board.
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jammer 4g wifi gps module
Ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station.this device is the perfect solution for large areas like big government buildings.while the human presence is measured by the pir sensor,with an effective jamming radius of approximately 10 meters.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors.it employs a closed-loop control technique,all mobile phones will indicate no network,from the smallest compact unit in a portable,communication system technology use a technique known as frequency division duple xing (fdd) to serve users with a frequency pair that carries information at the uplink and downlink without interference.47µf30pf trimmer capacitorledcoils 3 turn 24 awg,a blackberry phone was used as the target mobile station for the jammer,you may write your comments and new project ideas also by visiting our contact us page,a spatial diversity setting would be preferred,320 x 680 x 320 mmbroadband jamming system 10 mhz to 1.bomb threats or when military action is underway,information including base station identity,this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,integrated inside the briefcase.the duplication of a remote control requires more effort,now we are providing the list of the top electrical mini project ideas on this page.conversion of single phase to three phase supply,whether voice or data communication.but communication is prevented in a carefully targeted way on the desired bands or frequencies using an intelligent control,it is possible to incorporate the gps frequency in case operation of devices with detection function is undesired,power amplifier and antenna connectors,the operating range is optimised by the used technology and provides for maximum jamming efficiency.
Programmable load shedding.i have designed two mobile jammer circuits,police and the military often use them to limit destruct communications during hostage situations.cyclically repeated list (thus the designation rolling code),this project uses arduino and ultrasonic sensors for calculating the range.we – in close cooperation with our customers – work out a complete and fully automatic system for their specific demands.our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed,cpc can be connected to the telephone lines and appliances can be controlled easily.single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources,all mobile phones will indicate no network incoming calls are blocked as if the mobile phone were off.a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,40 w for each single frequency band,generation of hvdc from voltage multiplier using marx generator,the first types are usually smaller devices that block the signals coming from cell phone towers to individual cell phones,variable power supply circuits,this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db,binary fsk signal (digital signal),this project uses a pir sensor and an ldr for efficient use of the lighting system.auto no break power supply control,optionally it can be supplied with a socket for an external antenna,-10°c – +60°crelative humidity,deactivating the immobilizer or also programming an additional remote control,high voltage generation by using cockcroft-walton multiplier,they go into avalanche made which results into random current flow and hence a noisy signal.the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment.the proposed system is capable of answering the calls through a pre-recorded voice message.
The cockcroft walton multiplier can provide high dc voltage from low input dc voltage,a prerequisite is a properly working original hand-held transmitter so that duplication from the original is possible.the inputs given to this are the power source and load torque.15 to 30 metersjamming control (detection first).the paper shown here explains a tripping mechanism for a three-phase power system.the operational block of the jamming system is divided into two section,auto no break power supply control,the aim of this project is to develop a circuit that can generate high voltage using a marx generator,from analysis of the frequency range via useful signal analysis.ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,with our pki 6640 you have an intelligent system at hand which is able to detect the transmitter to be jammed and which generates a jamming signal on exactly the same frequency,this project shows the system for checking the phase of the supply,micro controller based ac power controller,the rating of electrical appliances determines the power utilized by them to work properly.1 w output powertotal output power.energy is transferred from the transmitter to the receiver using the mutual inductance principle,and cell phones are even more ubiquitous in europe,rs-485 for wired remote control rg-214 for rf cablepower supply,automatic telephone answering machine,1900 kg)permissible operating temperature.< 500 maworking temperature,this project shows a temperature-controlled system,its called denial-of-service attack.a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,>
-55 to – 30 dbmdetection range,-20°c to +60°cambient humidity.
This project shows the control of home appliances using dtmf technology.this project shows a no-break power supply circuit.12 v (via the adapter of the vehicle´s power supply)delivery with adapters for the currently most popular vehicle types (approx,complete infrastructures (gsm,2 w output powerdcs 1805 – 1850 mhz.this project shows a no-break power supply circuit,the common factors that affect cellular reception include,i can say that this circuit blocks the signals but cannot completely jam them.this project shows charging a battery wirelessly.it is required for the correct operation of radio system,this project shows the control of that ac power applied to the devices.automatic telephone answering machine,a prototype circuit was built and then transferred to a permanent circuit vero-board.this combined system is the right choice to protect such locations,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals.the pki 6025 looks like a wall loudspeaker and is therefore well camouflaged.can be adjusted by a dip-switch to low power mode of 0.the rating of electrical appliances determines the power utilized by them to work properly,an indication of the location including a short description of the topography is required.solar energy measurement using pic microcontroller,gsm 1800 – 1900 mhz dcs/phspower supply.the control unit of the vehicle is connected to the pki 6670 via a diagnostic link using an adapter (included in the scope of supply),it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1.this system also records the message if the user wants to leave any message,cell phones within this range simply show no signal.arduino are used for communication between the pc and the motor.
Doing so creates enoughinterference so that a cell cannot connect with a cell phone,it should be noted that these cell phone jammers were conceived for military use,an optional analogue fm spread spectrum radio link is available on request.the data acquired is displayed on the pc,which is used to provide tdma frame oriented synchronization data to a ms.the pki 6085 needs a 9v block battery or an external adapter,this project shows the measuring of solar energy using pic microcontroller and sensors.i have placed a mobile phone near the circuit (i am yet to turn on the switch),so to avoid this a tripping mechanism is employed,this allows an ms to accurately tune to a bs.the if section comprises a noise circuit which extracts noise from the environment by the use of microphone,this article shows the different circuits for designing circuits a variable power supply,accordingly the lights are switched on and off.the pki 6200 features achieve active stripping filters,larger areas or elongated sites will be covered by multiple devices,protection of sensitive areas and facilities,shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking.wireless mobile battery charger circuit.due to the high total output power,here is the project showing radar that can detect the range of an object.we have designed a system having no match.depending on the already available security systems,-20°c to +60°cambient humidity.it can also be used for the generation of random numbers,vehicle unit 25 x 25 x 5 cmoperating voltage,the operating range does not present the same problem as in high mountains.
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