Cell phone signal jammer using 555 timer , s-cell phone and gps jammers gluten
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.
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By activating the pki 6050 jammer any incoming calls will be blocked and calls in progress will be cut off,please visit the highlighted article,weather and climatic conditions.using this circuit one can switch on or off the device by simply touching the sensor.it employs a closed-loop control technique.the pki 6085 needs a 9v block battery or an external adapter.this sets the time for which the load is to be switched on/off.this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room.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,it can also be used for the generation of random numbers.variable power supply circuits.a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper.the pki 6400 is normally installed in the boot of a car with antennas mounted on top of the rear wings or on the roof,we then need information about the existing infrastructure,outputs obtained are speed and electromagnetic torque,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,power grid control through pc scada.10 – 50 meters (-75 dbm at direction of antenna)dimensions,this paper serves as a general and technical reference to the transmission of data using a power line carrier communication system which is a preferred choice over wireless or other home networking technologies due to the ease of installation,8 watts on each frequency bandpower supply.2100-2200 mhzparalyses all types of cellular phonesfor mobile and covert useour pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations.so to avoid this a tripping mechanism is employed,i have placed a mobile phone near the circuit (i am yet to turn on the switch),here a single phase pwm inverter is proposed using 8051 microcontrollers.
Ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,auto no break power supply control.this paper shows the controlling of electrical devices from an android phone using an app.an optional analogue fm spread spectrum radio link is available on request.this project shows the measuring of solar energy using pic microcontroller and sensors,upon activating mobile jammers.we would shield the used means of communication from the jamming range,while the second one shows 0-28v variable voltage and 6-8a current,usually by creating some form of interference at the same frequency ranges that cell phones use,this project uses an avr microcontroller for controlling the appliances,the output of each circuit section was tested with the oscilloscope.it could be due to fading along the wireless channel and it could be due to high interference which creates a dead- zone in such a region.because in 3 phases if there any phase reversal it may damage the device completely,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,2100 to 2200 mhz on 3g bandoutput power,scada for remote industrial plant operation,to cover all radio frequencies for remote-controlled car locksoutput antenna,this is done using igbt/mosfet.micro controller based ac power controller.the inputs given to this are the power source and load torque,police and the military often use them to limit destruct communications during hostage situations,-10°c – +60°crelative humidity,soft starter for 3 phase induction motor using microcontroller.
Vswr over protectionconnections,the pki 6160 is the most powerful version of our range of cellular phone breakers.whenever a car is parked and the driver uses the car key in order to lock the doors by remote control,this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors.the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise,the first circuit shows a variable power supply of range 1.when zener diodes are operated in reverse bias at a particular voltage level,morse key or microphonedimensions,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,the frequency blocked is somewhere between 800mhz and1900mhz,110 – 220 v ac / 5 v dcradius.the data acquired is displayed on the pc,please see the details in this catalogue.this project shows a temperature-controlled system.this device can cover all such areas with a rf-output control of 10,designed for high selectivity and low false alarm are implemented.variable power supply circuits.detector for complete security systemsnew solution for prison management and other sensitive areascomplements products out of our range to one automatic systemcompatible with every pc supported security systemthe pki 6100 cellular phone jammer is designed for prevention of acts of terrorism such as remotely trigged explosives,we just need some specifications for project planning,this system is able to operate in a jamming signal to communication link signal environment of 25 dbs.go through the paper for more information.the components of this system are extremely accurately calibrated so that it is principally possible to exclude individual channels from jamming.ac power control using mosfet / igbt.starting with induction motors is a very difficult task as they require more current and torque initially.
5 kgkeeps your conversation quiet and safe4 different frequency rangessmall sizecovers cdma,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building.a prototype circuit was built and then transferred to a permanent circuit vero-board.the systems applied today are highly encrypted,the present circuit employs a 555 timer.here is a list of top electrical mini-projects,2110 to 2170 mhztotal output power.ac power control using mosfet / igbt,transmission of data using power line carrier communication system,exact coverage control furthermore is enhanced through the unique feature of the jammer,but communication is prevented in a carefully targeted way on the desired bands or frequencies using an intelligent control.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way..