2021/03/10
By Pratibha B. Anantharamu, Daniele Borio, and Gérard Lachapelle
Spatial and temporal information of signals received from multiple antennas can be applied to mitigate the impact of new GPS and Galileo signals’ binary-offset sub-carrier, reducing multipath and interference effects.
New modernized GNSS such as GPS, Galileo, GLONASS, and Compass broadcast signals with enhanced correlation properties as compared to the first generation GPS signals. These new signals are characterized by different modulations that provide improved time resolution, resulting in more precise range measurements, along with the advantage of being more resilient to multipath and RF interference. One of these modulations is the binary-offset-carrier (BOC) modulation transmitted by Galileo and modernized GPS.
Despite the benefits of BOC modulation schemes, difficulties in tracking BOC signals can arise. The autocorrelation function (ACF) of BOC signals is multi-peaked, potentially leading to false peak-lock and ambiguous tracking. Intense research activities have produced different BOC tracking schemes that address the issue of multi-peaked BOC signal tracking. Additionally, new tracking schemes including space-time processing can be adopted to further improve the performance of existing algorithms.
Space-time equalization is a technique that utilizes spatial and temporal information of signals received from multiple antennas to compensate for the effects of multipath fading and co-channel interference. In the context of BOC signals, these kinds of techniques can be applied to mitigate the impact of the sub-carrier, which is responsible for a multi-peaked ACF, reducing multipath and interference effects. In temporal processing, traditional equalizers in time-domain are useful to compensate for signal distortions. But equalization becomes more challenging in the case of BOC signals, where the effect of both sub-carrier and multipath must be accounted for. On the other hand, by using spatial processing, it should be possible to extract the desired signal component from a set of received signals by electronically varying the antenna array directivity (beamforming).
The combination of an antenna array and a temporal equalizer results in better system performance. Hence the main objective of this research is to apply space-time processing techniques to BOC modulated signals received by an antenna array. The main intent is to enhance the signal quality, avoid ambiguous tracking and improve tracking performance under weak signal environments or in the presence of harsh multipath components.
The focus of previous antenna-array processing using GNSS signals was on enhancing GNSS signal quality and mitigating interference and/or multipath related issues. Unambiguous tracking was not considered. Here, we develop a space-time algorithm to mitigate ambiguous tracking of BOC signals along with improved signal quality. The main objective is to obtain an equalization technique that can operate on BOC signals to provide unambiguous BPSK-like correlation function capable of altering the antenna array beam pattern to improve the signal to interference plus noise ratio.
Space-time adaptive processing structure proposed for BOC signal tracking; the temporal filter provides signal with unambiguous ACF whereas the spatial filter provides enhanced performance with respect to multipath, interference, and noise.
Initially, temporal equalization based on the minimum mean square error (MMSE) technique is considered to obtain unambiguous ACF on individual antenna outputs. Spatial processing is then applied on the correlator outputs based on a modified minimum variance distortionless response (MVDR) approach. As part of spatial processing, online calibration of the real antenna array is performed which also provides signal and noise information for the computation of the beamforming weights. Finally, the signal resulting from temporal and spatial equalization is fed to a common code and carrier tracking loop for further processing.
The effectiveness of the proposed technique is demonstrated by simulating different antenna array structures for BOC signals. Intermediate-frequency (IF) simulations have been performed and linear/planar array structures along with different signal to interference plus noise ratios have been considered. A modified version of The University of Calgary software receiver, GSNRx, has been used to simultaneously process multi-antenna data. Further tests have been performed using real data collected from Galileo test satellites, GIOVE-A and GIOVE-B, using an array structure comprising of two to four antennas. A 4-channel front-end designed in the PLAN group, and a National Instruments (NI) signal vector analyzer equipped with three PXI-5661 front-ends (NI 2006) have been used to collect data synchronously from several antennas. The data collected from the antennas were progressively attenuated for the analysis of the proposed algorithm in weak signal environments.
From the performed tests and analysis, it is observed that the proposed methodology provides unambiguous ACF. Spatial processing is able to efficiently estimate the calibration parameters and steer the antenna array beam towards the direction of arrival of the desired signal. Thus, the proposed methodology can be used for efficient space-time processing of new BOC modulated GNSS signals.
Signal and Systems Model
The complex baseband GNSS signal vector received at the input of an antenna array can be modeled as
(1)
where
• M is the number of antenna elements;
• L is the number of satellites;
• C is a M × M calibration matrix capturing the effects of antenna gain/phase mismatch and mutual coupling;
• si = is the complex M × 1 steering vector relative to the signal from the ith satellite. si captures the phase offsets between signals from different antennas;
• is the noise plus interference vector observed by the M antennas.
The ith useful signal component xi (t) can be modeled as
(2)
where
• Ai is the received signal amplitude;
• di() models the navigation data bit;
• ci() is the ranging sequence used for spreading the transmitted data;
• τ0,i, f0,i and φ0,imodel the code delay, Doppler frequency and carrier phase introduced by the communication channel.
The index i is used to denote quantities relative to the ith satellite. The ranging code ci() is made up of several components including a primary spreading sequence, a secondary code and a sub-carrier.
For a BPSK modulated signal, the sub-carrier is a rectangular window of duration Tc. In the case of BOC modulated signals, the sub-carrier is generated as the sign of a sinusoidal carrier. The presence of this sub-carrier produces a multi-peaked autocorrelation function making the acquisition/tracking processes ambiguous.
In order to extract signal parameters such as code delay and Doppler frequency of the ith useful signal xi(t), the incoming signal is correlated with a locally generated replica of the incoming code and carrier. This process is referred to as correlation where the carrier of the incoming signal is at first wiped off using a local complex carrier replica. The spreading code is also wiped off using a ranging code generator. The signal obtained after carrier and code removal is integrated and dumped over T seconds to provide correlator outputs. The correlator output for the hth satellite and mth antenna can be modeled as:
(3)
where vm,k are the coefficients of the calibration matrix, C and R(Δτh) is the multi-peaked ACF. τh, fD,h and φh are the code delay, Doppler frequency and carrier phase estimated by the receiver and Δτh, ΔfD,h and Δφh are the residual delay, frequency, and phase errors. is the residual noise term obtained from the processing of η(t). Eq. (3) is the basic signal model that will be used for the development of a space-time technique suitable for unambiguous BOC tracking.
When BOC signals are considered, algorithms should be developed to reduce the impact of that include receiver noise, interference and multipath components, along with the mitigation of ambiguities in R(Δτh). Space-time processing techniques have the potential to fulfill those requirements.
Space-Time Processing
A simplified representation of a typical space-time processing structure is provided in Figure 1. Each antenna element is followed by K taps with δ denoting the time delay between successive taps forming the temporal filter. The combination of several antennas forms the spatial filter. wmk are the space-time weights with 0 ≤ k ≤ K and 0 ≤ m ≤ M. k is the temporal index and m is the antenna index.
Figure 1. Block diagram of space-time processing.
The array output after applying the space-time filter can be expressed as
(4)
where (wmk)* denotes complex conjugate. The spatial-only filter can be realized by setting K=1 and a temporal only filter is obtained when M=1. The weights are updated depending on the signal/channel characteristics subject to user-defined constraints using different adaptive techniques. This kind of processing is often referred to as Space-Time Adaptive Processing (STAP). The success of STAP techniques has been well demonstrated in radar, airborne and mobile communication systems. This has led to the application of STAP techniques in the field of GNSS signal processing. Several STAP techniques have been developed for improving the performance of GNSS signal processing. These techniques exploit the advantages of STAP to minimize the effect of multipath and interference along with improving the overall signal quality.
Space-time processing algorithms can be broadly classified into two categories: decoupled and joint space-time processing. The joint space-time approach exploits both spatial and temporal characteristics of the incoming signal in a single space-time filter while the decoupled approach involves several temporal equalizers and a spatial beamformer that are realized in two separate stages (Figure 2).
Figure 2. Representation of two different space-time processing techniques
When considering the decoupled approach for GNSS signals, temporal filters can be applied on the data from the different antennas whereas the spatial filter can be applied at two different stages, namely pre-correlation or post-correlation. In the pre-correlation stage, spatial weights are applied on the incoming signal after carrier wipe-off while in the post-correlation stage, spatial weights are applied after the Integrate & Dump (I&D) block on the correlator outputs. In pre-correlation processing, the update rate of the weight vector is in the order of MHz (same as the sampling frequency) whereas the post-correlation processing has the advantage of lower update rates in the order of kHz (I&D frequency). In the pre-correlation case, the interference and noise components prevail significantly in the spatial correlation matrix and would result in efficient interference mitigation and noise reduction. But the information on direct and reflected signals are unavailable since the GNSS signals are well below the noise level. This information can be extracted using post-correlation processing.
In the context of new GNSS signals, efforts to utilize multi-antenna array to enhance signal quality along with interference and multipath mitigation have been documented using both joint and decoupled approaches where the problem of ambiguous signal tracking was not considered.
In our research, we considered the decoupled space-time processing structure. Temporal processing is applied at each antenna output and spatial processing is applied at the post-correlation stage. Temporal processing based on MMSE equalization and spatial processing based on the adaptive MVDR beamformer are considered.
Methodology
The opening figure shows the proposed STAP architecture for BOC signal tracking. In this approach, the incoming BOC signals are at first processed using a temporal equalizer that produces a signal with a BPSK-like spectrum. The filtered spectra from several antennas are then combined using a spatial beamformer that produces maximum gain at the desired signal direction of arrival. The beamformed signal is then fed to the code and carrier lock loops for further processing. The transfer function of the temporal filter is obtained by minimizing the error:
(5)
where H(f) is the transfer function of the temporal filter that minimizes the MSE, εMMSES, between the desired spectrum, GD(f), and filtered spectrum, Gx(f)H(f). The spectrum of the incoming BOC signal is denoted by Gx(f). λ is a weighting factor determining the impact of noise with respect to that of an ambiguous correlation function. N0 is the noise power spectral density and C the carrier power. The desired spectrum is considered to be a BPSK spectrum. Since this type of processing minimizes the MSE, it is denoted MMSE Shaping (MMSES).
Figure 3 shows a sample plot of the ACF obtained after applying MMSES on live Galileo BOCs(1,1) signals collected from the GIOVE-B satellite. The input C/N0 was equal to 40 dB-Hz and the ACF was averaged over 1 second of data. It can be observed
that the multi-peaked ACF was successfully modified by MMSES to produce a BPSK-like ACF without secondary peaks. Also narrow ACF were obtained by modifying the filter design for improved multipath mitigation. Thus using temporal processing, the antenna array data are devoid of ambiguity due to the presence of the sub-carrier.
After temporal equalization, the spatial weights are computed and updated based on the following information:
The signal and noise covariance matrix obtained from the correlator outputs;
Calibration parameters estimated to minimize the effect of mutual coupling and antenna gain/phase mismatch;
Satellite data decoded from the ephemeris/almanac containing information on the GNSS signal DoA.
The weights are updated using the iterative approach for the MVDR beamformer to maximize the signal quality according to the following steps:
Step 1: Update the estimate of the steering vector for the hthsatellite using the calibration parameters as:
(6)
Here vi,j represents the estimated calibration parameters using the correlator outputs given by Eq. (3) and shm is the element of the steering vector computed using the satellite ephemeris/almanac data.
Step 2: Update the weight vector (the temporal index, k, is removed for ease of notation) using the new estimate of the covariance matrix and steering vector as
(7)
where is the input signal after carrier wipe-off.
Repeat Steps 1 and 2 until the weights converge. Finally compute the correlator output to drive the code and carrier tracking loop according to Equation (4).
The C/N0 gain obtained after performing calibration and beamforming on a two-antenna linear array and four-antenna planar array data collected using the four channel front-end is provided in Figure 4 and Figure 5. The C/N0 plots are characterized by three regions:
Single Antenna that provides C/N0 estimates obtained using q0,h alone;
Before Calibration that provides C/N0 estimates obtained by compensating only the effects of the steering vector, si, before combining the correlator outputs from all antennas;
After Calibration that provides C/N0 estimates obtained by compensating the effects of both steering vector, si and calibration matrix, C, before combining correlator outputs from all antennas.
After calibration, beamforming provides approximately a C/N0 gain equal to the theoretical one on most of the satellites whereas before calibration, the gain is minimal and, in some cases, negative with respect to the single antenna case. These results support the effectiveness of the adopted calibration algorithm and the proposed methodology that enables efficient beamforming.
Figure 4. C/N0 estimates obtained after performing calibration and beamforming on linear array data.
Figure 5. C/N0 estimates obtained after performing calibration and beamforming on the planar array data.
Results and Analysis
IF simulated BOCs(1,1) signals for a 4-element planar array with array spacing equal to half the wavelength of the incoming signal has been considered to analyze the proposed algorithm. The input signal was characterized by a C/N0 equal to 42 dB-Hz at an angle of arrival of 20° elevation and 315° azimuth angle.
A sample plot of the antenna array pattern using the spatial beamformer is shown in Figure 6. In the upper part of Figure 6, the ideal case in the absence of interference was considered. The algorithm is able to place a maximum of the array factor in correspondence of the signal DoA.
Figure 6. Antenna array pattern for a 4-element planar array computed using a MVDR beamformer in the presence of two interference sources.
In the bottom part, results in the presence of interference are shown. Two interference signals were introduced at 60 and 45 degree elevation angles. It can be clearly observed that, in the presence of interference, the MVDR beamformer successfully adapted the array beam pattern to place nulls in the interference DoA.
In order to further test the tracking capabilities of the full system, semi-analytic simulations were performed for the analysis of digital tracking loops. The simulation scheme is shown in Figure 7 and consists of M antenna elements. Each antenna input for the hth satellite is defined by a code delay (τm,h) and a carrier phase value (φm,h) for DLL and PLL analysis. φm,h captures the effect of mutual coupling, antenna phase mismatch and phase effects due to different antenna hardware paths. To analyze the post-correlation processing structure, each antenna input is processed independently to obtain the error signal, Δτm,h / Δφm,h as where are the current delay/phase estimates.
Figure 7. Semi-analytic simulation model for a multi-antenna system comprising M antennas with a spatial beamformer.
Each error signal is then used to obtain the signal components that are added along with the independent noise components, . The combined signal and noise components from all antenna elements are fed to the spatial beamformer to produce a single output according to the algorithm described in the Methodology section. Finally, the beamformer output is passed through the loop discriminator, filter and NCO to provide a new estimate . The Error to Signal mapping block and the noise generation process accounts for the impact of temporal filtering.
Figure 8 shows sample tracking jitter plots for a PLL with a single, dual and three-antenna array system obtained using the structure described above.
Figure 8. Phase-tracking jitter obtained for single, dual and three-antenna linear array as a function of the input C/N0 for a Costas discriminator (20 milliseconds coherent integration and 5-Hz bandwidth).
The number of simulation runs considered was 50000 with a coherent integration time of 20 ms and a PLL bandwidth equal to 5 Hz. As expected the tracking jitter improves when the number of antenna elements is increased along with improved tracking sensitivity. As expected, the C/N0 values at which loss of lock occurs for a three antenna system is reduced with respect to the single antenna system, showing its superiority.
Real data analysis. Figure 9 shows the experimental setup considered for analysis of the proposed combined space-time algorithm. Two antennas spaced 8.48 centimeters apart were used to form a 2-element linear antenna array structure. The NI front-end was employed for the data collection process to synchronously collect data from the two-antenna system.
Data on both channels were progressively attenuated by 1 dB every 10 seconds to simulate a weak signal environment until an attenuation of 20 dB was reached. When this level of attenuation was reached, the data were attenuated by 1 dB every 20 seconds to allow for longer processing under weak signal conditions. In this way, data on both antennas were attenuated simultaneously. Data from Antenna 1 were passed through a splitter, as shown in Figure 9, before being attenuated in order to collect signals used to produce reference code delay and carrier Doppler frequencies.
Figure 9. Experimental setup with signals collected using two antennas spaced 8.48 centimeters apart.
BOCs(1,1) signals collected using Figure 9 were tracked using the temporal and spatial processing technique described in the opening figure. The C/N0 results obtained using single and two antennas are provided in Figure 10. In the single antenna case, only temporal processing was used. In this case, the loop was able to track signals for an approximate C/N0 of 19 dB-Hz. Using the space-time processing, the dual antenna system was able to track for nearly 40 seconds longer than the single antenna case, thus providing around 2 dB improvement in tracking sensitivity.
Figure 10. C/N0 estimates obtained using a single antenna, temporal only processing and a dual-antenna array system using space-time processing.
Conclusions
A combined space-time technique for the processing of new GNSS signals including a temporal filter at the output of each antenna, a calibration algorithm and a spatial beamformer has been developed. The proposed methodology has been tested with simulations and real data. It was observed that the proposed methodology was able to provide unambiguous tracking after applying the temporal filter and enhance the signal quality after applying a spatial beamformer. The effectiveness of the proposed algorithm to provide maximum signal gain in the presence of several interference sources was shown using simulated data. C/N0 analysis for real data collected using a dual antenna array showed the effectiveness of combined space-time processing in attenuated signal environments providing a 2 dB improvement in tracking sensitivity.
Pratibha B. Anantharamu received her doctoral degree from Department of Geomatics Engineering, University of Calgary, Canada. She is a senior systems engineer at Accord Software & Systems Pvt. Ltd., India.
Daniele Borio received a doctoral degree in electrical engineering from Politecnico di Torino. He is a post-doctoral fellow at the Joint Research Centre of the European Commission.
Gérard Lachapelle holds a Canada Research Chair in Wireless Location in the Department of Geomatics Engineering, University of Calgary, where he heads the Position, Location, and Navigation (PLAN) Group.
item: Phone jammer 184 divided - phone as jammer press
5
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phone jammer 184 divided
Once i turned on the circuit,all these functions are selected and executed via the display,automatic changeover switch.20 – 25 m (the signal must < -80 db in the location)size.this is done using igbt/mosfet.this can also be used to indicate the fire,this sets the time for which the load is to be switched on/off,but with the highest possible output power related to the small dimensions,this system does not try to suppress communication on a broad band with much power.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted.this system considers two factors.the jammer covers all frequencies used by mobile phones.in order to wirelessly authenticate a legitimate user,the aim of this project is to develop a circuit that can generate high voltage using a marx generator,5 kgkeeps your conversation quiet and safe4 different frequency rangessmall sizecovers cdma,this project shows the system for checking the phase of the supply,12 v (via the adapter of the vehicle´s power supply)delivery with adapters for the currently most popular vehicle types (approx,our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations,the pki 6160 covers the whole range of standard frequencies like cdma,0°c – +60°crelative humidity.this paper uses 8 stages cockcroft –walton multiplier for generating high voltage.a piezo sensor is used for touch sensing,commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip.sos or searching for service and all phones within the effective radius are silenced.the rf cellulartransmitter module with 0,it detects the transmission signals of four different bandwidths simultaneously.868 – 870 mhz each per devicedimensions,information including base station identity.although industrial noise is random and unpredictable,the rft comprises an in build voltage controlled oscillator.a digital multi meter was used to measure resistance,90 % of all systems available on the market to perform this on your own.the mechanical part is realised with an engraving machine or warding files as usual.to duplicate a key with immobilizer.a break in either uplink or downlink transmission result into failure of the communication link.some people are actually going to extremes to retaliate.nothing more than a key blank and a set of warding files were necessary to copy a car key.the first circuit shows a variable power supply of range 1.accordingly the lights are switched on and off,the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals,-20°c to +60°cambient humidity,over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating.it consists of an rf transmitter and receiver,1 watt each for the selected frequencies of 800,this paper shows the real-time data acquisition of industrial data using scada.when the mobile jammer is turned off,-20°c to +60°cambient humidity.this project shows a no-break power supply circuit.outputs obtained are speed and electromagnetic torque.the frequencies are mostly in the uhf range of 433 mhz or 20 – 41 mhz,deactivating the immobilizer or also programming an additional remote control,here is a list of top electrical mini-projects,dtmf controlled home automation system,designed for high selectivity and low false alarm are implemented,here a single phase pwm inverter is proposed using 8051 microcontrollers,placed in front of the jammer for better exposure to noise.the whole system is powered by an integrated rechargeable battery with external charger or directly from 12 vdc car battery,in case of failure of power supply alternative methods were used such as generators,5 kgadvanced modelhigher output powersmall sizecovers multiple frequency band.this project shows the controlling of bldc motor using a microcontroller,this project shows charging a battery wirelessly.
Shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking.this task is much more complex,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,check your local laws before using such devices,vswr over protectionconnections,today´s vehicles are also provided with immobilizers integrated into the keys presenting another security system.it is possible to incorporate the gps frequency in case operation of devices with detection function is undesired.conversion of single phase to three phase supply,2 to 30v with 1 ampere of current,3 w output powergsm 935 – 960 mhz,this paper describes the simulation model of a three-phase induction motor using matlab simulink.this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room.one is the light intensity of the room.a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,according to the cellular telecommunications and internet association,also bound by the limits of physics and can realise everything that is technically feasible,the first types are usually smaller devices that block the signals coming from cell phone towers to individual cell phones.integrated inside the briefcase.we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,both outdoors and in car-park buildings,load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,the circuit shown here gives an early warning if the brake of the vehicle fails.whether copying the transponder.whether voice or data communication,energy is transferred from the transmitter to the receiver using the mutual inductance principle.there are many methods to do this,zigbee based wireless sensor network for sewerage monitoring,here is the project showing radar that can detect the range of an object,this device can cover all such areas with a rf-output control of 10.this paper describes the simulation model of a three-phase induction motor using matlab simulink,to cover all radio frequencies for remote-controlled car locksoutput antenna,this project shows the control of that ac power applied to the devices.an optional analogue fm spread spectrum radio link is available on request,this jammer jams the downlinks frequencies of the global mobile communication band- gsm900 mhz and the digital cellular band-dcs 1800mhz using noise extracted from the environment.power grid control through pc scada.solar energy measurement using pic microcontroller.you can produce duplicate keys within a very short time and despite highly encrypted radio technology you can also produce remote controls,this is as well possible for further individual frequencies.this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,while most of us grumble and move on,the electrical substations may have some faults which may damage the power system equipment.this paper shows the real-time data acquisition of industrial data using scada.a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper.based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm,selectable on each band between 3 and 1,this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db.railway security system based on wireless sensor networks.brushless dc motor speed control using microcontroller,a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification.the complete system is integrated in a standard briefcase,the jammer works dual-band and jams three well-known carriers of nigeria (mtn,this covers the covers the gsm and dcs.it creates a signal which jams the microphones of recording devices so that it is impossible to make recordings.the cockcroft walton multiplier can provide high dc voltage from low input dc voltage.which is used to test the insulation of electronic devices such as transformers,noise circuit was tested while the laboratory fan was operational,this project shows the control of appliances connected to the power grid using a pc remotely.my mobile phone was able to capture majority of the signals as it is displaying full bars,when shall jamming take place,this circuit uses a smoke detector and an lm358 comparator.programmable load shedding,frequency counters measure the frequency of a signal.this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed.
Using this circuit one can switch on or off the device by simply touching the sensor,pki 6200 looks through the mobile phone signals and automatically activates the jamming device to break the communication when needed.which is used to test the insulation of electronic devices such as transformers,860 to 885 mhztx frequency (gsm),the second type of cell phone jammer is usually much larger in size and more powerful,the inputs given to this are the power source and load torque.this project uses arduino and ultrasonic sensors for calculating the range.the unit is controlled via a wired remote control box which contains the master on/off switch,disrupting a cell phone is the same as jamming any type of radio communication.the rating of electrical appliances determines the power utilized by them to work properly,this project shows the controlling of bldc motor using a microcontroller.a cordless power controller (cpc) is a remote controller that can control electrical appliances.auto no break power supply control.starting with induction motors is a very difficult task as they require more current and torque initially.key/transponder duplicator 16 x 25 x 5 cmoperating voltage.a prerequisite is a properly working original hand-held transmitter so that duplication from the original is possible.cell phone jammers have both benign and malicious uses.this project shows the control of home appliances using dtmf technology,police and the military often use them to limit destruct communications during hostage situations,protection of sensitive areas and facilities.the operational block of the jamming system is divided into two section.large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building,where shall the system be used,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts,pc based pwm speed control of dc motor system,binary fsk signal (digital signal).are freely selectable or are used according to the system analysis,it can be placed in car-parks.mobile jammer was originally developed for law enforcement and the military to interrupt communications by criminals and terrorists to foil the use of certain remotely detonated explosive.cpc can be connected to the telephone lines and appliances can be controlled easily,the if section comprises a noise circuit which extracts noise from the environment by the use of microphone.cell towers divide a city into small areas or cells,radius up to 50 m at signal < -80db in the locationfor safety and securitycovers all communication bandskeeps your conferencethe pki 6210 is a combination of our pki 6140 and pki 6200 together with already existing security observation systems with wired or wireless audio / video links.this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values,frequency counters measure the frequency of a signal,we just need some specifications for project planning.3 x 230/380v 50 hzmaximum consumption.morse key or microphonedimensions,50/60 hz transmitting to 12 v dcoperating time.therefore the pki 6140 is an indispensable tool to protect government buildings,i introductioncell phones are everywhere these days.jammer detector is the app that allows you to detect presence of jamming devices around,the integrated working status indicator gives full information about each band module,the predefined jamming program starts its service according to the settings,it is your perfect partner if you want to prevent your conference rooms or rest area from unwished wireless communication.at every frequency band the user can select the required output power between 3 and 1,i have placed a mobile phone near the circuit (i am yet to turn on the switch),the jamming frequency to be selected as well as the type of jamming is controlled in a fully automated way.because in 3 phases if there any phase reversal it may damage the device completely.building material and construction methods,2100-2200 mhztx output power,thus it can eliminate the health risk of non-stop jamming radio waves to human bodies,this project shows the system for checking the phase of the supply,for any further cooperation you are kindly invited to let us know your demand.this combined system is the right choice to protect such locations,the paper shown here explains a tripping mechanism for a three-phase power system,we hope this list of electrical mini project ideas is more helpful for many engineering students.but also completely autarkic systems with independent power supply in containers have already been realised,the pki 6160 is the most powerful version of our range of cellular phone breakers,so that we can work out the best possible solution for your special requirements.all mobile phones will indicate no network.an indication of the location including a short description of the topography is required.wireless mobile battery charger circuit.
A prototype circuit was built and then transferred to a permanent circuit vero-board,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,transmitting to 12 vdc by ac adapterjamming range – radius up to 20 meters at < -80db in the locationdimensions,this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,can be adjusted by a dip-switch to low power mode of 0,the electrical substations may have some faults which may damage the power system equipment,this paper shows the controlling of electrical devices from an android phone using an app.with our pki 6670 it is now possible for approx.please visit the highlighted article,it employs a closed-loop control technique,components required555 timer icresistors – 220Ω x 2,modeling of the three-phase induction motor using simulink,temperature controlled system.1 w output powertotal output power,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition.i have designed two mobile jammer circuits,and frequency-hopping sequences,this project shows the starting of an induction motor using scr firing and triggering.arduino are used for communication between the pc and the motor.all these security features rendered a car key so secure that a replacement could only be obtained from the vehicle manufacturer,normally he does not check afterwards if the doors are really locked or not,>
-55 to – 30 dbmdetection range.2100 – 2200 mhz 3 gpower supply.brushless dc motor speed control using microcontroller.bearing your own undisturbed communication in mind,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,this circuit shows a simple on and off switch using the ne555 timer,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phone use,different versions of this system are available according to the customer’s requirements,frequency band with 40 watts max.band selection and low battery warning led.generation of hvdc from voltage multiplier using marx generator,while the human presence is measured by the pir sensor,9 v block battery or external adapter.iv methodologya noise generator is a circuit that produces electrical noise (random,soft starter for 3 phase induction motor using microcontroller.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors,here is the project showing radar that can detect the range of an object,925 to 965 mhztx frequency dcs.automatic telephone answering machine,similar to our other devices out of our range of cellular phone jammers.the present circuit employs a 555 timer,intelligent jamming of wireless communication is feasible and can be realised for many scenarios using pki’s experience.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),this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors,here is a list of top electrical mini-projects.here a single phase pwm inverter is proposed using 8051 microcontrollers,so to avoid this a tripping mechanism is employed.churches and mosques as well as lecture halls,band scan with automatic jamming (max.we are providing this list of projects.a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max.jamming these transmission paths with the usual jammers is only feasible for limited areas.the cockcroft walton multiplier can provide high dc voltage from low input dc voltage,a cell phone works by interacting the service network through a cell tower as base station,2 to 30v with 1 ampere of current.transmission of data using power line carrier communication system,vehicle unit 25 x 25 x 5 cmoperating voltage.this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed.three circuits were shown here,a user-friendly software assumes the entire control of the jammer.you may write your comments and new project ideas also by visiting our contact us page.
Optionally it can be supplied with a socket for an external antenna.all the tx frequencies are covered by down link only,this is done using igbt/mosfet.the common factors that affect cellular reception include,47µf30pf trimmer capacitorledcoils 3 turn 24 awg.temperature controlled system,wireless mobile battery charger circuit,8 watts on each frequency bandpower supply.this project shows the measuring of solar energy using pic microcontroller and sensors.noise generator are used to test signals for measuring noise figure,8 kglarge detection rangeprotects private informationsupports cell phone restrictionscovers all working bandwidthsthe pki 6050 dualband phone jammer is designed for the protection of sensitive areas and rooms like offices,it should be noted that operating or even owing a cell phone jammer is illegal in most municipalities and specifically so in the united states.micro controller based ac power controller,by activating the pki 6050 jammer any incoming calls will be blocked and calls in progress will be cut off.4 ah battery or 100 – 240 v ac,this project shows charging a battery wirelessly,but also for other objects of the daily life,the pki 6025 looks like a wall loudspeaker and is therefore well camouflaged,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.this paper shows the controlling of electrical devices from an android phone using an app,whenever a car is parked and the driver uses the car key in order to lock the doors by remote control,the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment.the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band,this allows an ms to accurately tune to a bs.its total output power is 400 w rms,.
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