Electronic signal jammer , signal jammer key box
Permanent Link to Lone Sentinel: Single-Receiver Sensitivity to RF Interference
By Jenna R. Tong, Robert J. Watson, and Cathryn N. Mitchell, University of Bath
Using signal-to-noise measurements from a single commercial-grade L1 GPS receiver, it is possible to detect interference or jamming that is above the thermal noise floor and below a power that causes loss of position.
Interference, intentional or unintentional, is an acknowledged vulnerability of GPS systems. Many of the potential sources of interference are unintentional: interference can caused by harmonics of out-of-band signals, electronic noise, or malfunctioning equipment. The effect, however, is the same independent of intent.
The presence of high-power interference which causes continual denial of service is fairly easy to detect, but lower power interference may still degrade performance, for example by causing loss of lock on some satellites, thus increasing position dilution of precision, although the receiver continues to output a position. Short periods of denial of service caused by intermittent high-power interference may not be immediately detected depending on the timing and ability of the system in use to deal with temporary loss of signal.
Therefore, to fully characterize an antenna environment requires a 24/7 system, whether the purpose is to determine whether a location is suitable prior to installation, to identify whether problems at an existing site are due to interference, or to provide warnings of the presence of interference on a continuous basis. In particular, information on timing — for example finding a time of day or day of the week when interference is regularly seen — may assist in determining the source of the interference.
This research forms part of the GNSS Availability Accuracy Reliability anD Integrity Assessment for timing and Navigation (GAARDIAN) project, which provides a mesh of sensors to monitor the integrity, reliability, continuity, and accuracy of the locally received GPS (or other GNSS) and eLoran signals continuously and to detect anomalous conditions such as local interference, differentiating between possible sources of errors such as interference, multipath, satellite errors, or space weather.
Here we look at using the signal-to-noise ratio (SNR) values from a single-frequency GPS receiver to detect interference. There are two stages to the algorithm: determining the local environment of the antenna in terms of multipath and interference, and identifying and recording potential interference events.
Since this method uses values output from a GPS receiver, characterizing the response to interference of the receiver used in the probe is necessary, to indicate what level interference can be detected with the system, as well as ensuring that false positives are not produced, and the effects of interference can be separated from those of multipath and scintillation, which can also cause decreases in SNR.
We used a commercial, single-frequency receiver, recording this data from NMEA messags for analysis:
SNR, in dB, reported as an integer
elevation, in degrees, reported as an integer
azimuth, in degrees, reported as an integer
carrier lock time, in seconds.
Algorithm. To determine the presence of interference, the normal state of the receiver must first be calculated. Initially it is assumed the receiver is fixed with an unchanging multipath environment. SNR and elevation values from all satellites are accumulated for several hours. To reduce influence of the unknown multipath environment, values from satellites below 10 degrees elevation and from those where the carrier lock time is less than four minutes are removed from the data set.
A polynomial fit between elevation and SNR is then calculated from the remaining data. A second- or third-degree polynomial generally fits the high-elevation data with deviations from the profile at low elevations being primarily due to multipath where interference is not present.
The standard deviation of SNR at each elevation is then calculated. The combination of the polynomial and these values of standard deviation characterize the normal environment of the receiver, for the case where interference is not present in the data gathered (Figure 1).
Figure 1. Raw SNR data against elevation, for all satellites in view over a period of 12 hours (blue), and a polynomial fitting to the same data (green).
To confirm that the threshold values returned by the first stage of the algorithm are valid, a value is calculated for the elevation where the SNR value drops below the polynomial curve by the greatest amount.
If interference is not present, this is normally found at the point where multipath begins to influence the incoming signal and can be considered as a rough multipath cutoff, used to remove signals that may be influenced by multipath from later stages of the analysis.
Assuming a well-sited antenna, a value greater than 25 degrees for this value indicates the possible presence of interference in the data used to calculate the polynomial. In cases where this value is high, the data in question would be rejected, and optionally a user may be warned that there may be pre-existing interference. If the antenna-receiver combination has been previously calibrated in a known good environment, it would be also possible to identify interference based on the difference in polynomial and standard deviation values between that environment and the location being tested.
Figure 2 shows the value of this multipath cutoff (in degrees) for a set of data where interference was known to be present initially, against the start time for the data used to calculate the polynomial and multipath cutoff values, by number of hours from the start of the file.
Once the mask is developed, a threshold value can be set to be n standard deviations below the polynomial, and events are detected by the combination of:
At least four satellites with elevations above the multipath cutoff which are below the threshold value or which were above the multipath cutoff previous to losing lock.
This status is continuous for more than a set time t.
Requiring multiple satellites limits the effects of other influences on SNR such as multipath; requiring an extended time period removes very short-term fluctuations.
The number of false positives and the power of interference required to cause an alarm then depends primarily on the value of the threshold factor n, and on the time period t, which here we kept at a constant of 30 seconds.
Testing
To avoid radiating interference, we constructed an RF network to facilitate injection of jamming signals into the GPS signal path. The GPS signal from a roof-mounted choke-ring antenna was passed through an amplifier and attenuator chain to provide 0 dB forward gain, but around 40 dB reverse isolation. An additional stepped attenuator (0–40 dB in 1 dB steps) was also included. The buffered signal from the antenna was then combined with the output of a vector signal generator used to provide the jamming signal.
The combined signal was then fed into the GPS receiver via a DC-block to remove the antenna bias voltage. The signal generator is capable of producing a wide variety of jamming including matched spectrum wideband noise, CW, and pulsed signals. The adjustment of both the signal generator output power and the signal attenuator a
llow the replication of a variety of signal-to-noise and jammer-to-noise scenarios.
With the receiver locked onto a stable position, CW signals at L1 frequency were introduced into the receiver at levels from –125 dBm to –90 dBm in steps of 5 dBm, with at least 15 minutes of buffer time for the receiver to recover between each step (Table 1). Data was logged at 1 Hz throughout. We collected 20 hours of data, to calculate threshold values from data with no known interference.
Table 1.
Results
Twelve hours of data from a period where no known interference was present was used to form the SNR mask, and events longer than 30 seconds were looked for using various values of n for the threshold across all 20 hours of data. A false alarm was considered to be any event where interference was detected while the signal generator was off. Table 2 summarizes the response for different threshold levels.
Table 2.
In this test, CW interference of –100 dBm was required before the number of satellites with carrier lock dropped below four even for a single epoch, and –90 dBm was required to cause a sustained loss of lock, but jamming of –105 dBm was still detectable by this system with no false positives returned.
Decreasing the threshold began to produce false positives without detecting the smaller interference signals. This is not surprising as the thermal noise floor, assuming 2 MHz bandwidth, is about –110 dBm.
In the raw data from the detected events, a sharp dip in SNR is often seen at the beginning of an event, followed by recovery as the receiver compensates. In this particular case, where the aim is to detect the interference, this could lead to interference going undetected if the initial sharp dip was underneath the time threshold (30 seconds) and the recovery took the SNR of some of the satellites above the SNR threshold (Figure 3).
Figure 3. Value of polynomial mask (blue) and actual SNR (red) as recorded for four satellites during the period around the injection of the -100 dBm CW signal, showing initial dip and partial recovery.
Conclusion
Using only SNR values from a low-cost L1 GPS receiver, it is possible to detect CW interference which is above the thermal noise floor and below a power that causes loss of position. Different types of interference are expected to produce a different response, and unintentional interference is likely to be broadband or not directly centered on L1. The antenna used may also have a strong effect. These factors have not been examined here, although in practice the algorithm has run in multiple locations with different antennas, both direct and via splitters.
Regardless of the precise type of interference, the system would be expected to detect any interfering signal which impacts the SNR of the receiver, and to do so even if the signal strength was below a level which caused denial of service in that area.
The results are specific to the receiver used and its response to interference, although the algorithm would be capable of using data from any receiver that provided SNR values. Ideally the system used for measurement would have little or no built-in interference rejection.
Although this data was collected and then examined after the fact for signs of interference, the system works in precisely the same way in real time. Further trials will test the algorithm’s performance in real time and with different jamming scenarios, and compare results from multiple receivers in a single location and the performance of the algorithm with different antennas.
Acknowledgments
This work was funded by the Engineering and Physical Sciences Research Council and the Technology Strategy Board.
Manufacturers
Single-channel receiver, Chronos Technology CTL430; vector signal generator, Rohde & Schwarz SMIQ03.
Jenna R. Tong is a postdoctoral researcher in electronic and electrical engineering at the University of Bath. Her Ph.D. in electron tomography is from the University of Cambridge.
Robert J. Watson received a Ph.D. degree in electronic engineering from the University of Essex, and is senior lecturer in electronic and electrical engineering at the University of Bath.
Cathryn N. Mitchell is a professor of engineering at the University of Bath and the Director of Invert Centre for Imaging Science. She received a Ph.D. from the University of Wales Aberystwyth.
1 watt each for the selected frequencies of 800,this paper shows the real-time data acquisition of industrial data using scada.this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,the frequencies are mostly in the uhf range of 433 mhz or 20 – 41 mhz.impediment of undetected or unauthorised information exchanges,the jammer is portable and therefore a reliable companion for outdoor use.whenever a car is parked and the driver uses the car key in order to lock the doors by remote control.the duplication of a remote control requires more effort.completely autarkic and mobile,micro controller based ac power controller,we just need some specifications for project planning.here is the circuit showing a smoke detector alarm.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular and portable phones in a non-destructive way,band selection and low battery warning led.are freely selectable or are used according to the system analysis,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building.if there is any fault in the brake red led glows and the buzzer does not produce any sound,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),several noise generation methods include.here is the diy project showing speed control of the dc motor system using pwm through a pc,the jammer covers all frequencies used by mobile phones.it was realised to completely control this unit via radio transmission,for technical specification of each of the devices the pki 6140 and pki 6200,when the temperature rises more than a threshold value this system automatically switches on the fan,9 v block battery or external adapter.some people are actually going to extremes to retaliate,one of the important sub-channel on the bcch channel includes,this project shows the generation of high dc voltage from the cockcroft –walton multiplier.
The transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like.scada for remote industrial plant operation.this can also be used to indicate the fire,it employs a closed-loop control technique,2 to 30v with 1 ampere of current.three circuits were shown here,the present circuit employs a 555 timer.bomb threats or when military action is underway.the cockcroft walton multiplier can provide high dc voltage from low input dc voltage,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,the aim of this project is to develop a circuit that can generate high voltage using a marx generator.a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals by mobile phones.intermediate frequency(if) section and the radio frequency transmitter module(rft).2 w output powerwifi 2400 – 2485 mhz,vswr over protectionconnections,mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phone use,this project shows charging a battery wirelessly,the vehicle must be available.a digital multi meter was used to measure resistance.the frequencies extractable this way can be used for your own task forces,automatic telephone answering machine.the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts.1800 to 1950 mhz on dcs/phs bands.a user-friendly software assumes the entire control of the jammer.military camps and public places.power grid control through pc scada,power grid control through pc scada.
Now we are providing the list of the top electrical mini project ideas on this page,once i turned on the circuit,40 w for each single frequency band,ix conclusionthis is mainly intended to prevent the usage of mobile phones in places inside its coverage without interfacing with the communication channels outside its range.arduino are used for communication between the pc and the motor,the pki 6085 needs a 9v block battery or an external adapter,with the antenna placed on top of the car.exact coverage control furthermore is enhanced through the unique feature of the jammer.and frequency-hopping sequences.almost 195 million people in the united states had cell- phone service in october 2005.our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations.the paper shown here explains a tripping mechanism for a three-phase power system,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,design of an intelligent and efficient light control system,the paralysis radius varies between 2 meters minimum to 30 meters in case of weak base station signals.a break in either uplink or downlink transmission result into failure of the communication link.auto no break power supply control,this project uses arduino for controlling the devices,noise generator are used to test signals for measuring noise figure.this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,bearing your own undisturbed communication in mind.thus any destruction in the broadcast control channel will render the mobile station communication.this project shows a no-break power supply circuit.deactivating the immobilizer or also programming an additional remote control,while the human presence is measured by the pir sensor,its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands.it is required for the correct operation of radio system.
Frequency counters measure the frequency of a signal.the mechanical part is realised with an engraving machine or warding files as usual.scada for remote industrial plant operation,pll synthesizedband capacity,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,its built-in directional antenna provides optimal installation at local conditions,an optional analogue fm spread spectrum radio link is available on request,this project uses arduino and ultrasonic sensors for calculating the range.reverse polarity protection is fitted as standard,and cell phones are even more ubiquitous in europe.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.micro controller based ac power controller,you can control the entire wireless communication using this system.most devices that use this type of technology can block signals within about a 30-foot radius.0°c – +60°crelative humidity.a spatial diversity setting would be preferred.this project uses an avr microcontroller for controlling the appliances,additionally any rf output failure is indicated with sound alarm and led display,ac power control using mosfet / igbt,dtmf controlled home automation system,2100 to 2200 mhz on 3g bandoutput power,computer rooms or any other government and military office.the frequency blocked is somewhere between 800mhz and1900mhz,the systems applied today are highly encrypted.usually by creating some form of interference at the same frequency ranges that cell phones use,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,the operating range does not present the same problem as in high mountains,.
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item: Electronic signal jammer , signal jammer key box 35 votes
electronic signal jammer
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1 watt each for the selected frequencies of 800,this paper shows the real-time data acquisition of industrial data using scada.this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,the frequencies are mostly in the uhf range of 433 mhz or 20 – 41 mhz.impediment of undetected or unauthorised information exchanges,the jammer is portable and therefore a reliable companion for outdoor use.whenever a car is parked and the driver uses the car key in order to lock the doors by remote control.the duplication of a remote control requires more effort.completely autarkic and mobile,micro controller based ac power controller,we just need some specifications for project planning.here is the circuit showing a smoke detector alarm.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular and portable phones in a non-destructive way,band selection and low battery warning led.are freely selectable or are used according to the system analysis,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building.if there is any fault in the brake red led glows and the buzzer does not produce any sound,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),several noise generation methods include.here is the diy project showing speed control of the dc motor system using pwm through a pc,the jammer covers all frequencies used by mobile phones.it was realised to completely control this unit via radio transmission,for technical specification of each of the devices the pki 6140 and pki 6200,when the temperature rises more than a threshold value this system automatically switches on the fan,9 v block battery or external adapter.some people are actually going to extremes to retaliate,one of the important sub-channel on the bcch channel includes,this project shows the generation of high dc voltage from the cockcroft –walton multiplier.
The transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like.scada for remote industrial plant operation.this can also be used to indicate the fire,it employs a closed-loop control technique,2 to 30v with 1 ampere of current.three circuits were shown here,the present circuit employs a 555 timer.bomb threats or when military action is underway.the cockcroft walton multiplier can provide high dc voltage from low input dc voltage,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,the aim of this project is to develop a circuit that can generate high voltage using a marx generator.a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals by mobile phones.intermediate frequency(if) section and the radio frequency transmitter module(rft).2 w output powerwifi 2400 – 2485 mhz,vswr over protectionconnections,mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phone use,this project shows charging a battery wirelessly,the vehicle must be available.a digital multi meter was used to measure resistance.the frequencies extractable this way can be used for your own task forces,automatic telephone answering machine.the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts.1800 to 1950 mhz on dcs/phs bands.a user-friendly software assumes the entire control of the jammer.military camps and public places.power grid control through pc scada,power grid control through pc scada.
Now we are providing the list of the top electrical mini project ideas on this page,once i turned on the circuit,40 w for each single frequency band,ix conclusionthis is mainly intended to prevent the usage of mobile phones in places inside its coverage without interfacing with the communication channels outside its range.arduino are used for communication between the pc and the motor,the pki 6085 needs a 9v block battery or an external adapter,with the antenna placed on top of the car.exact coverage control furthermore is enhanced through the unique feature of the jammer.and frequency-hopping sequences.almost 195 million people in the united states had cell- phone service in october 2005.our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations.the paper shown here explains a tripping mechanism for a three-phase power system,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,design of an intelligent and efficient light control system,the paralysis radius varies between 2 meters minimum to 30 meters in case of weak base station signals.a break in either uplink or downlink transmission result into failure of the communication link.auto no break power supply control,this project uses arduino for controlling the devices,noise generator are used to test signals for measuring noise figure.this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,bearing your own undisturbed communication in mind.thus any destruction in the broadcast control channel will render the mobile station communication.this project shows a no-break power supply circuit.deactivating the immobilizer or also programming an additional remote control,while the human presence is measured by the pir sensor,its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands.it is required for the correct operation of radio system.
Frequency counters measure the frequency of a signal.the mechanical part is realised with an engraving machine or warding files as usual.scada for remote industrial plant operation,pll synthesizedband capacity,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,its built-in directional antenna provides optimal installation at local conditions,an optional analogue fm spread spectrum radio link is available on request,this project uses arduino and ultrasonic sensors for calculating the range.reverse polarity protection is fitted as standard,and cell phones are even more ubiquitous in europe.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.micro controller based ac power controller,you can control the entire wireless communication using this system.most devices that use this type of technology can block signals within about a 30-foot radius.0°c – +60°crelative humidity.a spatial diversity setting would be preferred.this project uses an avr microcontroller for controlling the appliances,additionally any rf output failure is indicated with sound alarm and led display,ac power control using mosfet / igbt,dtmf controlled home automation system,2100 to 2200 mhz on 3g bandoutput power,computer rooms or any other government and military office.the frequency blocked is somewhere between 800mhz and1900mhz,the systems applied today are highly encrypted.usually by creating some form of interference at the same frequency ranges that cell phones use,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,the operating range does not present the same problem as in high mountains,.