2021/04/08
Positioning in Challenging Environments Using Ultra-Wideband Sensor Networks
By Zoltan Koppanyi, Charles K. Toth and Dorota A. Grejner-Brzezinska
INNOVATION INSIGHTS by Richard Langley
QUICK. WHO WAS THE FIRST TO PREDICT THE EXISTENCE OF RADIO WAVES? If you answered James Clerk Maxwell, you are right. (If you didn’t and have an electrical engineering or physics degree, it’s back to school for you.) In the mid-1800s, Maxwell developed the theory of electric and magnetic forces, which is embodied in the group of four equations named after him. This year marks the 150th anniversary of the publication of Maxwell’s paper “A Dynamical Theory of the Electromagnetic Field” in the Philosophical Transactions of the Royal Society of London.
Interestingly, Maxwell used 20 equations to describe his theory but Oliver Heaviside managed to boil them down to the four we are familiar with today. Maxwell’s theory predicted the existence of radiating electromagnetic waves and that these waves could exist at any wavelength. Maxwell had speculated that light must be a form of electromagnetic radiation. In his 1865 paper, he said “This velocity [of the waves] is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.”
That electromagnetic waves with much longer wavelengths than those of light must be possible was conclusively demonstrated by Heinrich Hertz who, between 1886 and 1889, built various apparatuses for transmitting and receiving electromagnetic waves with wavelengths of around 5 meters (60 MHz). These waves were, in fact, radio waves. Hertz’s experiments conclusively proved the existence of electromagnetic waves traveling at the speed of light. He also famously said “I do not think that the wireless waves I have discovered will have any practical application.” How quickly he was proven wrong.
Beginning in 1894, Guglielmo Marconi demonstrated wireless communication over increasingly longer distances, culminating in his bridging the Atlantic Ocean in 1901 or 1902. And, as they say, the rest is history. Radio waves are used for data, voice and image one-way (broadcasting) and two-way communications; for remote control of systems and devices; for radar (including imaging); and for positioning, navigation and time transfer. And signals can be produced over a wide range of frequencies from below 10 kHz to above 100 GHz.
Conventional radio transmissions use a variety of modulation techniques but most involve varying the amplitude, frequency and/or phase of a sinusoidal carrier wave. But in the late 1960s, it was shown that one could generate a signal as a sequence of very short pulses, which results in the signal energy being spread over a large part of the radio spectrum. Initially called pulse radio, the technique has become known as impulse radio ultra-wideband or just ultra-wideband (UWB) for short and by the 1990s a variety of practical transmission and reception technologies had been developed.
The use of large transmission bandwidths offers a number of benefits, including accurate ranging and that application in particular is being actively developed for positioning and navigation in environments that are challenging to GNSS such as indoors and built-up areas. In this month’s column, we take a look at the work being carried out in this area by a team of researchers at The Ohio State University.
“Innovation” is a regular feature that discusses advances in GPS technology and its applications as well as the fundamentals of GPS positioning. The column is coordinated by Richard Langley of the Department of Geodesy and Geomatics Engineering, University of New Brunswick. He welcomes comments and topic ideas. Email him at lang @ unb.ca.
GNSS technology provides position, navigation and timing (PNT) information with high accuracy and global coverage where line-of-sight between the satellites and receivers is assured. This condition, however, is typically not satisfied indoors or in confined environments. Emerging safety, military, location-based and personal navigation applications increasingly require consistent accuracy and availability, comparable to that of GNSS but in indoor environments.
Most of the existing indoor positioning systems use narrowband radio frequency signals for location estimation, such as Wi-Fi, or telecommunication-based positioning (including GSM and UMTS mobile telephone networks). All these technologies require dedicated infrastructure, and the narrowband RF systems are subject to jamming and multipath, as well as loss of signal strength while propagating through walls. In contrast, using ultra-wideband (UWB) signals can, to some extent, remediate those problems by offering better resistance against interference and multipath, and they feature better signal penetration capability. Due to these properties, the use of UWB has the potential to support a broad range of applications, such as radar, through-wall imagery, robust communication with high frequency, and resistance to jamming. Furthermore the impulse radio UWB (IR-UWB), the subject of this article, can be an efficient standalone technology or a component of positioning systems designed for multipath-challenged, confined or indoor environments, where GNSS signals are compromised.
IR-UWB positioning can be useful in typical emergency response applications such as fires in large buildings, dismounted soldiers in combat situations, and emergency evacuations. In such circumstances, the positioning/navigation systems must determine not only the exact position of any individual firefighter or soldier to facilitate their team-based mission, but also navigate them back to safety. Under these scenarios, a temporary ad hoc network has to be quickly deployed, as the existing infrastructure is usually non-functional, damaged or destroyed at that point. The UWB-based systems may easily satisfy these criteria: (1) nodes placed in the target area can rapidly establish the network geometry even if line-of-sight between nodes is not available, (2) the communication capability allows for sharing measurements, and (3) the node positions may be calculated based on these measured ranges in a centralized or distributed way. Once the node coordinates have been determined, the tracking of the moving units can start. Obviously, the resistance against jamming makes this solution attractive for military applications.
Ad Hoc Network Formation for Emergency Response
Quick deployment
Sufficient positioning accuracy
Robustness against interference (jamming)
Signal penetration through solid structures
Generally, positioning systems, both local and global, require an infrastructure, which defines the implementation of a coordinate frame. For example, the national reference frames and their realizations support conventional land surveying, or the satellite and the GPS tracking subsystems, as well as the beacons in Wi-Fi systems. UWB positioning also follows the same logic; the network infrastructure defines a local coordinate system and allows for range measurements between the network nodes and the tracked unit(s).
Ad Hoc Sensor Network: Ad hoc networks are temporary, and thus, the node coordinates are not expected to be known or measured a priori; consequently, they are calculated based on measuring the ranges between the units in the initial phase, and can be updated subsequently if the network configuration changes.
Anchored Networks: The network nodes’ coordinates are known. If only local coordinates are known, then to connect to a global coordinate frame, at least one node’s global coordinates and a direction vector must be known to anchor and orient the network.
Anchor-Free Networks: No node coordinates are known, thus the localization problem is underdetermined. Nevertheless, the problem is still solvable, if it is extended with additional constraints.
Tracking: Once a network is established, static/moving objects can be positioned in the network coordinate system.
Ultra-Wideband Ranging
At the beginning of the 21st century, the Federal Communications Commission (FCC) introduced new regulations that enabled several commercial applications and initiated research on UWB application to PNT. The current FCC rules for pulse-based positioning or localization implementations require the applied bandwidth be between 3.1 and 10.6 GHz and the bandwidth to be higher than 500 MHz or the fractional bandwidth to be more than 0.2.
The typical IR-UWB ranging system consists of multiple transceiver units, including the transmitter and the receiver components. The transmitter emits a very short pulse (high bandwidth) with low energy, and the receiver detects the signal after it travels through the air, interacting with the environment. After reaching objects, the emitted pulse is backscattered as several signals, which likely reach the receiver at different times. In contrast, conventional RF signals are longer in duration, thus the backscattered waves overlap each other at the receiver, forming a complex waveform, and may not be distinguishable individually. Due to the shortness of the UWB signals, measurable peaks are nicely separated, representing different signal paths.
The wave shape of the impulse response of the transmission medium highly depends on the environment complexity due to multipath. Detections in the received wave are determined by a peak-detecting algorithm. Note that the travel time is generally determined from the first detection, as it is assumed to be from the shortest path, although other peak detection algorithms also exist.
In the experiments discussed in this article, a commercial UWB radio system was used. This sensor’s bandwidth is between 3.1 and 5.3 GHz, with a 4.3-GHz center frequency. Three methods are available to obtain ranges: (1) coarse range estimation, based on the received signal strength with dynamic recalibration; (2) precision range measurement (PRM), which uses the two-way time-of-flight technique; and (3) the filtered range estimates (FRE) method that refines the PRM solution using Kalman filtering. In our investigations, PRM data were used in static situations, when both the unit to be positioned and the reference units were static (such as when determining network node coordinates), and FRE was logged in kinematic scenarios.
Localization in a UWB Network
Commercial UWB products usually provide capabilities for all three applications: communication, ranging and radar imaging. In positioning applications, identical units are used for both the rovers — that is, the units to be localized — and the static nodes of the network. The general terminology, however, is that the rover unit with unknown position is called the receiver, and units deployed at known locations are called transmitters. We will also use the terms rover and stations. The positions are typically defined in a local coordinate system. The usual ranging methods used in RF technologies, including signal strength and fingerprinting, time of arrival, angle of arrival, and time difference of arrival, are also applicable to UWB systems. TABLE 1 lists the ranging methods and typical performance levels; the achievable accuracies are based on external references. Note that the accuracy depends on the sensor hardware and network configuration, applied bandwidth, signal-to-noise ratio, peak detection algorithm, experiment circumstances, formation and the environment complexity.
TABLE 1. Typical accuracy of the different UWB localization techniques. Note that the results depend on the hardware, antenna, applied bandwidth, experiment circumstances and geometric configuration; * denotes indoor environment with area coverage of a few times 10 × 10 meters, with line-of-sight conditions, and ** refers to the maximum error in the outdoor test area of about 100 × 100 meters).
Signal Strength. The received signal strength (RSS) requires modeling of the signal loss, which is a challenging problem since signals at different frequencies interact with the environment in different ways, and thus the resulting accuracy is generally inadequate for most applications. The fingerprinting approach is also applied to UWB positioning; the signal-strength vector received from the transmitters identifies a location by the best match, where the vector-location pairs are measured in a calibration/training phase and stored in a database.
Time of Flight. The time-of-flight method requires the synchronization of the clocks of the UWB units, which is difficult, in particular, in the low-cost systems. Therefore, most UWB systems are based on the two-way time-of-flight method, which eliminates the unknown clock delay between the sensors, although it also has its own challenges. The range between two units is obtained by measuring the time difference of the transmitted and received pulses plus knowing the fixed response time of the responding unit.
Computing Position in a Network. Once the ranges are known in a network environment, the position is determined by circular lateration. The principle for the 2D case with three stations is shown in FIGURE 1. Note that each range determines a circle around the known stations (stations 1, 2 and 3 in the figure), thus, if the stations’ coordinates are known, the unknown position can be calculated as the intersection of these circles. The problem is treated as a system of non-linear equations; note that the lateration requires at least three or four nodes in an adequate spatial distribution for 2D and 3D positioning, respectively. The measured ranges, characterized by the error terms usually modeled with a normal distribution, are depicted by the dotted parallel circles around the solid “perfect” range in Figure 1. Note that this is an optimization problem, which can be solved with direct numerical approximation, such as gradient methods, or by solving the respective linear system after linearizing the problem with close initial position values.
FIGURE 1. Circular lateration.
Time Difference and Angle of Arrival. The time difference of arrival (TDoA) approach is useful when the time synchronization is not established. The unknown time delays are eliminated by subtracting the travel times between the rover and the stations, and the response time of the responding unit must be known. The location estimation is similar to the time of arrival case, but rather than the intersection of the circles, hyperbolic function curves representing constant TDoA values are used to determine the rover position. Also, if errors are present in the measurements, the position calculation becomes an optimization problem instead of finding the root of an equation. The TDoA can be combined with the angle of arrival (AoA). This method assumes that the set of UWB antennas are arranged in an array, and the angle can be calculated as the time difference of the first and the last detection from different antennas of the array.
Calibration
The ranges obtained by UWB sensors could be further improved by calibration — for example, by estimating antenna and hardware delays. In our outdoor tests, the joint calibration model (see Two Calibration Models box) was used, and coefficients of various model functions were estimated. During these tests, the UWB units were placed at the corners of a 15 × 15 meter area (see FIGURE 2).
FIGURE 2. Outdoor test configuration.
At two diagonal corners, two UWB units with a 1.5-meter vertical separation were installed on poles, while at the two other corners only one unit was used. These six units formed the nodes or the stations of the network. In all cases, a GPS antenna was fixed to the top of the poles to provide reference data. A pushcart with two UWB units, a logging laptop computer, a GPS antenna and a receiver formed the rover system. The reference solution was obtained by using the GPS measurements, with the accuracy around 1 centimeter after kinematic post-processing using precise satellite orbit and clock data. During calibration, the pushcart was collecting stationary data at points 1 to 12, marked on a 5 × 5 meter grid, as shown in Figure 2.
Two Calibration Models
Individual sensor calibration is the approach where the sensor delays are determined separately, for example, , where is the measured range between stations A and B, and are the calibration functions, and is the corrected range.
Joint calibration model is the approach where the calibration function does not provide the offset per station, but rather gives the relative offset between the two stations, where .
The calibration model as a function of the measured distance can be constant, linear or a higher-order polynomial.
After acquiring range data between the rover and network stations, three types of joint calibration functions were investigated: constant, linear and polynomial models. The coefficients of these functions were estimated from the measured ranges and GPS-provided reference positions at all grid points. The estimated functions with respect to the six network nodes are shown in FIGURE 3. Our hypothesis was that the accuracy is assumed to depend on the rover-station distance, and thus, the detected discrepancies between the rover and reference points are expected to be higher if the distance is larger. The results indicate that a constant correction (that is, an antenna delay) is generally sufficient, indicating that the calibration may be applicable to similar installations. In some cases, a linear trend (a distance dependency) may be recognized due to slight data changes, but the observed regression lines are either increasing or decreasing, which clearly rejects the distance-dependency hypothesis. The linear and second-order polynomial functions likely model only local effects. The corrections provided by these functions depend on the environment, and consequently, are valid only in that configuration and where they were observed.
FIGURE 3. Calibration models.
Error surfaces, derived as the approximation of a second-order surface from the residuals at the grid points between the receiver and the six station units, show that the discrepancies can be as large as 0.5 meter. Calibrated results using the constant model show that all the discrepancies are less than 10 centimeters with an empirical standard deviation of 3.6 centimeters. This suggests that, at least, the constant-model-based calibration is needed.
Tracking Outdoors and Indoors
If the coordinates of the network nodes and the calibration parameters are known, the location of the moving rover can be calculated with circular lateration. The experiment described in this section is based on the same field test as presented earlier. For assessing the outdoor tracking performance, a random trajectory of the pushcart inside and outside of the rectangle defined by nodes was acquired (see FIGURE 4). The reference trajectory was obtained by GPS and the UWB trajectory was calculated with circular lateration.
FIGURE 4. Trajectory solutions.
TABLE 2 presents a statistical comparison of the coordinate component differences between the GPS reference and the UWB trajectory based on calibrated ranges. The mean of the X and Y coordinate differences are around 0 centimeters, and their standard deviations are 9.7 and 13.2 centimeters, respectively, with the largest differences being less than half a meter in both coordinate components. Note that the vertical coordinates have large errors due to the small vertical angle, which translates to weak geometric conditions for error propagation.
TABLE 2. Statistical results for the coordinate components.
Indoor UWB positioning is more challenging than outdoor, as propagation through walls modifies the RF signals resulting in attenuations and delays. Furthermore, the geometric error propagation conditions (that is, the shape of the network) may also reduce the quality of positioning. In the indoor tests, a personal navigation system demonstration prototype built in our lab (shown in FIGURE 5) was used as a rover. During the tests, the person was moving at a normal pace, and the rover unit recorded the ranges from the reference stations. Concerning the network, two point types are defined: (1) network nodes depicted by a double circle in the figure, which are used in the tracking phase; and (2) reference points marked by a single circle, which support the validation of the positioning results.
FIGURE 5. Indoor test configuration.
Since no reference solution was available during the indoor testing, the calibration method’s consistency was evaluated based on the relative or internal accuracy metric, which is the a posteriori reference standard deviation error:
where v is the vector of residual errors and r=dim(ATA) – rank(ATA) is the degrees of freedom of the network with A being the design matrix describing the geometry of the network. The m0 values are shown in FIGURE 6. This parameter describes the statistical difference of the measurements from the assumed model (circular lateration). The average m0 is 7.6 centimeters without calibration, and higher if any of the outdoor calibration models are used.
FIGURE 6. The indoor test results showing values of m0 at the epochs.
To estimate the absolute or external accuracy without a reference trajectory, points 1002 and 1004 were used as checkpoints with known coordinates. Obviously, these points were not part of the network. The UWB rover unit was placed at these points, and data were acquired in a static mode. The coordinates were continuously calculated after measuring at least three ranges. TABLE 3 presents the statistical results. Note that the average is not 0, thus the result is biased, indicating that the signal penetration and/or multipath effects are present in this complex indoor environment. Also, note that no calibration was performed, as no indoor calibration results were available, and using the outdoor calibration models only decreased the positioning accuracy. In addition, the standard deviations indicate the average m0 is consistent with the external error for point 1002, while this hypothesis is rejected for point 1004.
TABLE 3. Differences between the UWB position estimations and the correct coordinates at points 1002 and 1004.
Taking a closer look at the results of point 1004, the ambiguity problem of the circular lateration can be observed. The random measurement error can be large enough to cover two possible intersections in circular lateration, thus the estimator may oscillate between two solutions. Two main causes for this ambiguity are a weak network configuration and the large ranging errors (see FIGURE 7).
FIGURE 7. Ambiguity of lateration.
Ad Hoc UWB Sensor Network
We have also carried out tests on an indoor ad hoc sensor network using different coordinate estimation methods. Indoor distance measurements typically do not follow a normal or Gaussian error distribution but rather a Gaussian mixture distribution, which demands the use of a robust estimation method. Our results showed that the maximum likelihood estimation technique performs better than conventional least squares for this type of network.
Conclusion
Ultra-wideband technology is an effective positioning method for short-range applications with decimeter-level accuracy. The coverage area can be extended with increasing network size. The technology can be used independently or as a component of an integrated positioning/navigation system. GPS-compromised outdoor situations and indoor applications can be supported by UWB in permanent and ad hoc network configurations. While UWB technology is relatively less affected by environmental conditions, signal propagation through objects or other non-line-of-sight conditions can reduce the reliability and accuracy.
Acknowledgments
This article is based, in part, on the paper “Performance Analysis of UWB Technology for Indoor Positioning,” presented at the 2014 International Technical Meeting of The Institute of Navigation, held in San Diego, Calif., Jan. 27–29, 2014.
Manufacturer
The experiments discussed in the article used a Time Domain Corp. PulsON 300 UWB radio system.
ZOLTAN KOPPANYI received his B.Sc. degree in civil engineering in 2010 and his M.Sc. in land surveying and GIS in 2012, both from Budapest University of Technology and Economics (BME), Hungary. He also received a B.Sc. in computer science from the Eötvös Loránd University, Budapest, in 2011. He is a Ph.D. student at BME and was a visiting scholar at the Ohio State University (OSU), Columbus, in 2013. His research area is human mobility pattern analysis and indoor navigation.
CHARLES K. TOTH is a research professor in the Department of Civil, Environmental and Geodetic Engineering at OSU. He received an M.Sc. in electrical engineering and a Ph.D. in electrical engineering and geo-information sciences from the Technical University of Budapest, Hungary. His research expertise covers broad areas of 2D/3D signal processing; spatial information systems; high-resolution imaging; surface extraction, modeling, integrating and calibrating of multi-sensor systems; multi-sensor geospatial data acquisition systems, and mobile mapping technology.
DOROTA A. GREJNER-BRZEZINSKA is a professor in geodetic science, and director of the Satellite Positioning and Inertial Navigation (SPIN) Laboratory at OSU. Her research interests cover GPS/GNSS algorithms, GPS/inertial and other sensor integration for navigation in GPS-challenged environments, sensors and algorithms for indoor and personal navigation, and Kalman and non-linear filtering.
Further Reading
• Authors’ Conference Paper
“Performance Analysis of UWB Technology for Indoor Positioning” by Z. Koppanyi, C.K. Toth, D.A. Grejner-Brzezinska, and G. Jozkow in Proceedings of ITM 2014, the 2014 International Technical Meeting of The Institute of Navigation, San Diego, Calif. January 27–29, 2014, pp. 154–165.
• U.S. Regulations on Ultra-Wideband
“Ultra-Wideband Operation” in Code of Federal Regulations, Title 47, Chapter I, Subchapter A, Part 15, U.S. National Archives and Records Administration, Washington, D.C., October 1, 2014. Available online.
• Introduction to Ultra-Wideband
“History and Applications of UWB” by M.Z. Win, D. Dardari, A.F. Molisch, W. Wiesbeck, and J. Zhang in Proceedings of the Institute of Electrical and Electronics Engineers, Vol. 97, No. 2, February 2009, pp. 198–204, doi: 10.1109/JROC.2008.2008762.
“Ultra-Wideband and GPS: Can They Co-exist” by D. Akos, M. Luo, S. Pullen, and P. Enge in GPS World, Vol. 12, No. 9, September 2001, pp. 59–70.
• Ultra-Wideband Signal Peak Detection and Ranging
Ultra-Wideband Ranging for Low-Complexity Indoor Positioning Applications by G. Bellusci, Ph.D. dissertation, Delft University of Technology, Delft, The Netherlands, 2011.
“Ultra-Wideband Range Estimation: Theoretical Limits and Practical Algorithms” by I. Guvenc, S. Gezici, and Z. Sahinoglu in Proceedings of ICUWB2008, the 2008 Institute of Electrical and Electronics Engineers International Conference on Ultra-Wideband, Hannover, Germany, September 10–12, 2008, Vol. 3, pp. 93–96, doi: 10.1109/ICUWB.2008.4653424.
• Received Signal Strength Fingerprinting
“Increased Ranging Capacity Using Ultrawideband Direct-Path Pulse Signal Strength with Dynamic Recalibration” by B. Dewberry and W. Beeler in Proceedings of PLANS 2012, the Institute of Electrical and Electronics Engineers / Institute of Navigation 2012 Position, Location and Navigation Symposium, Myrtle Beach, S.C., April 23–26, 2010, pp. 1013–1017, doi: 10.1109/PLANS.2012.6236843.
“Indoor Ultra-Wideband Location Fingerprinting” by H. Kröll and C. Steiner in Proceedings of IPIN 2010, the 2010 International Conference on Indoor Positioning and Indoor Navigation, Zurich, September 15–17, 2010, pp. 1–5, doi: 10.1109/IPIN.2010.5648087.
• Ultra-Wideband Time-of-Arrival and Angle-of-Arrival“Ultra-Wideband Time-of-Arrival and Angle-of-Arrival Estimation Using Transformation Between Frequency and Time Domain Signals” by N. Iwakiri and T. Kobayashi in Journal of Communications, Vol. 3, No. 1, January 2008, pp. 12–19, 10.4304/jcm.3.1.12-19.
• Maxwell’s Equations
“The Long Road to Maxwell’s Equations” by J.C. Rautio in IEEE Spectrum, Vol. 51, No. 12, December 2014, North American edition, pp. 36–40 and 54–56, doi: 10.1109/mspec.2014.6964925.
A Student’s Guide to Maxwell’s Equations by D. Fleisch, Cambridge University Press, Cambridge, U.K., 2008.
item: Mobile phone jammer Calgary , mobile phone and gps jammer proliferation
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mobile phone jammer Calgary
Hand-held transmitters with a „rolling code“ can not be copied,the single frequency ranges can be deactivated separately in order to allow required communication or to restrain unused frequencies from being covered without purpose,building material and construction methods,with an effective jamming radius of approximately 10 meters.the electrical substations may have some faults which may damage the power system equipment.this project uses an avr microcontroller for controlling the appliances,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,the pki 6085 needs a 9v block battery or an external adapter.this project shows the control of home appliances using dtmf technology,v test equipment and proceduredigital oscilloscope capable of analyzing signals up to 30mhz was used to measure and analyze output wave forms at the intermediate frequency unit,2 ghzparalyses all types of remote-controlled bombshigh rf transmission power 400 w.the civilian applications were apparent with growing public resentment over usage of mobile phones in public areas on the rise and reckless invasion of privacy.dtmf controlled home automation system.20 – 25 m (the signal must < -80 db in the location)size,it should be noted that these cell phone jammers were conceived for military use,the integrated working status indicator gives full information about each band module,we have designed a system having no match,this circuit shows a simple on and off switch using the ne555 timer,some powerful models can block cell phone transmission within a 5 mile radius,all mobile phones will indicate no network.upon activating mobile jammers.this article shows the different circuits for designing circuits a variable power supply,although industrial noise is random and unpredictable.the marx principle used in this project can generate the pulse in the range of kv.the if section comprises a noise circuit which extracts noise from the environment by the use of microphone,automatic power switching from 100 to 240 vac 50/60 hz.once i turned on the circuit,by activating the pki 6050 jammer any incoming calls will be blocked and calls in progress will be cut off.the output of each circuit section was tested with the oscilloscope,using this circuit one can switch on or off the device by simply touching the sensor,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,when shall jamming take place.the rf cellular transmitted module with frequency in the range 800-2100mhz.reverse polarity protection is fitted as standard,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs.this system also records the message if the user wants to leave any message,this article shows the different circuits for designing circuits a variable power supply.brushless dc motor speed control using microcontroller,– active and passive receiving antennaoperating modes.here is the circuit showing a smoke detector alarm,outputs obtained are speed and electromagnetic torque.but are used in places where a phone call would be particularly disruptive like temples,wireless mobile battery charger circuit,this was done with the aid of the multi meter.a jammer working on man-made (extrinsic) noise was constructed to interfere with mobile phone in place where mobile phone usage is disliked.
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This mobile phone displays the received signal strength in dbm by pressing a combination of alt_nmll keys,almost 195 million people in the united states had cell- phone service in october 2005,2100 to 2200 mhz on 3g bandoutput power,the predefined jamming program starts its service according to the settings,this project shows the measuring of solar energy using pic microcontroller and sensors,scada for remote industrial plant operation,you can copy the frequency of the hand-held transmitter and thus gain access,this circuit shows a simple on and off switch using the ne555 timer.your own and desired communication is thus still possible without problems while unwanted emissions are jammed,47µf30pf trimmer capacitorledcoils 3 turn 24 awg.also bound by the limits of physics and can realise everything that is technically feasible,the signal bars on the phone started to reduce and finally it stopped at a single bar.key/transponder duplicator 16 x 25 x 5 cmoperating voltage,8 watts on each frequency bandpower supply,this project shows a no-break power supply circuit.a potential bombardment would not eliminate such systems.the third one shows the 5-12 variable voltage,a cell phone jammer is a device that blocks transmission or reception of signals,this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room,the completely autarkic unit can wait for its order to go into action in standby mode for up to 30 days.completely autarkic and mobile,this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity.churches and mosques as well as lecture halls.2w power amplifier simply turns a tuning voltage in an extremely silent environment,we hope this list of electrical mini project ideas is more helpful for many engineering students,similar to our other devices out of our range of cellular phone jammers.such as propaganda broadcasts,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values,viii types of mobile jammerthere are two types of cell phone jammers currently available,the rf cellulartransmitter module with 0.cell phones within this range simply show no signal.this is as well possible for further individual frequencies,where shall the system be used,mainly for door and gate control,a piezo sensor is used for touch sensing.i introductioncell phones are everywhere these days,shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking,so to avoid this a tripping mechanism is employed,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,for any further cooperation you are kindly invited to let us know your demand,the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise.there are many methods to do this.ac power control using mosfet / igbt,the duplication of a remote control requires more effort.while the second one is the presence of anyone in the room.
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,here is the diy project showing speed control of the dc motor system using pwm through a pc,this is done using igbt/mosfet,this device is the perfect solution for large areas like big government buildings.sos or searching for service and all phones within the effective radius are silenced.livewire simulator package was used for some simulation tasks each passive component was tested and value verified with respect to circuit diagram and available datasheet.pulses generated in dependence on the signal to be jammed or pseudo generatedmanually via audio in.the light intensity of the room is measured by the ldr sensor,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals.its called denial-of-service attack,you can control the entire wireless communication using this system,-10 up to +70°cambient humidity,it is possible to incorporate the gps frequency in case operation of devices with detection function is undesired.to duplicate a key with immobilizer.solutions can also be found for this,accordingly the lights are switched on and off,radio transmission on the shortwave band allows for long ranges and is thus also possible across borders.the pki 6160 covers the whole range of standard frequencies like cdma,the electrical substations may have some faults which may damage the power system equipment,2110 to 2170 mhztotal output power,this allows an ms to accurately tune to a bs,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage.i have designed two mobile jammer circuits.so to avoid this a tripping mechanism is employed,auto no break power supply control.we are providing this list of projects,ac power control using mosfet / igbt,this paper describes the simulation model of a three-phase induction motor using matlab simulink.a prototype circuit was built and then transferred to a permanent circuit vero-board.this project shows the system for checking the phase of the supply.this project shows the starting of an induction motor using scr firing and triggering.at every frequency band the user can select the required output power between 3 and 1,temperature controlled system,6 different bands (with 2 additinal bands in option)modular protection,therefore it is an essential tool for every related government department and should not be missing in any of such services.control electrical devices from your android phone.the complete system is integrated in a standard briefcase,soft starter for 3 phase induction motor using microcontroller.2100-2200 mhztx output power.50/60 hz transmitting to 24 vdcdimensions.the first circuit shows a variable power supply of range 1,power amplifier and antenna connectors.>
-55 to – 30 dbmdetection range,5% – 80%dual-band output 900.the light intensity of the room is measured by the ldr sensor.
Ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions.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).9 v block battery or external adapter,different versions of this system are available according to the customer’s requirements,thus it can eliminate the health risk of non-stop jamming radio waves to human bodies.overload protection of transformer,provided there is no hand over,designed for high selectivity and low false alarm are implemented,the signal must be < – 80 db in the locationdimensions.50/60 hz transmitting to 12 v dcoperating time,this is done using igbt/mosfet,the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band,can be adjusted by a dip-switch to low power mode of 0.the paper shown here explains a tripping mechanism for a three-phase power system,frequency band with 40 watts max.whenever a car is parked and the driver uses the car key in order to lock the doors by remote control,and like any ratio the sign can be disrupted.230 vusb connectiondimensions,the proposed design is low cost.our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations,zigbee based wireless sensor network for sewerage monitoring,this sets the time for which the load is to be switched on/off,now we are providing the list of the top electrical mini project ideas on this page,this device can cover all such areas with a rf-output control of 10.zener diodes and gas discharge tubes,starting with induction motors is a very difficult task as they require more current and torque initially.this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed.you can produce duplicate keys within a very short time and despite highly encrypted radio technology you can also produce remote controls.jammer disrupting the communication between the phone and the cell phone base station in the tower,if there is any fault in the brake red led glows and the buzzer does not produce any sound.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,noise generator are used to test signals for measuring noise figure,several possibilities are available,presence of buildings and landscape.if you are looking for mini project ideas.prison camps or any other governmental areas like ministries,the pki 6025 looks like a wall loudspeaker and is therefore well camouflaged,this project shows charging a battery wirelessly,from the smallest compact unit in a portable.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular and portable phones in a non-destructive way,this project shows a temperature-controlled system.this system considers two factors,from analysis of the frequency range via useful signal analysis,the systems applied today are highly encrypted,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.
An indication of the location including a short description of the topography is required,phase sequence checking is very important in the 3 phase supply,cpc can be connected to the telephone lines and appliances can be controlled easily,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating.10 – 50 meters (-75 dbm at direction of antenna)dimensions,impediment of undetected or unauthorised information exchanges,communication system technology.it is always an element of a predefined.with our pki 6670 it is now possible for approx.50/60 hz permanent operationtotal output power.please visit the highlighted article.phs and 3gthe pki 6150 is the big brother of the pki 6140 with the same features but with considerably increased output power,this causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable,automatic changeover switch,outputs obtained are speed and electromagnetic torque.it consists of an rf transmitter and receiver,which broadcasts radio signals in the same (or similar) frequency range of the gsm communication,if there is any fault in the brake red led glows and the buzzer does not produce any sound.a mobile phone jammer prevents communication with a mobile station or user equipment by transmitting an interference signal at the same frequency of communication between a mobile stations a base transceiver station,is used for radio-based vehicle opening systems or entry control systems,vswr over protectionconnections,a digital multi meter was used to measure resistance.the use of spread spectrum technology eliminates the need for vulnerable “windows” within the frequency coverage of the jammer,additionally any rf output failure is indicated with sound alarm and led display,a cell phone works by interacting the service network through a cell tower as base station,this project shows the control of appliances connected to the power grid using a pc remotely.this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,but we need the support from the providers for this purpose.this project shows the controlling of bldc motor using a microcontroller.radio remote controls (remote detonation devices),normally he does not check afterwards if the doors are really locked or not.the present circuit employs a 555 timer.while the second one is the presence of anyone in the room,a break in either uplink or downlink transmission result into failure of the communication link,you may write your comments and new project ideas also by visiting our contact us page.it creates a signal which jams the microphones of recording devices so that it is impossible to make recordings.15 to 30 metersjamming control (detection first).go through the paper for more information,mobile jammers effect can vary widely based on factors such as proximity to towers,all these project ideas would give good knowledge on how to do the projects in the final year,power grid control through pc scada,the next code is never directly repeated by the transmitter in order to complicate replay attacks.intermediate frequency(if) section and the radio frequency transmitter module(rft),integrated inside the briefcase,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably.
Automatic telephone answering machine,the pki 6025 is a camouflaged jammer designed for wall installation,even temperature and humidity play a role,while the second one shows 0-28v variable voltage and 6-8a current,zigbee based wireless sensor network for sewerage monitoring,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,government and military convoys,1800 to 1950 mhztx frequency (3g),the device looks like a loudspeaker so that it can be installed unobtrusively,over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities.single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs.are freely selectable or are used according to the system analysis.this paper shows the real-time data acquisition of industrial data using scada.here is a list of top electrical mini-projects,both outdoors and in car-park buildings.vi simple circuit diagramvii working of mobile jammercell phone jammer work in a similar way to radio jammers by sending out the same radio frequencies that cell phone operates on,2 to 30v with 1 ampere of current,please see the details in this catalogue,ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station,using this circuit one can switch on or off the device by simply touching the sensor.large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building.we would shield the used means of communication from the jamming range,communication can be jammed continuously and completely or,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,frequency counters measure the frequency of a signal,solar energy measurement using pic microcontroller,weather and climatic conditions.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,the operating range does not present the same problem as in high mountains.check your local laws before using such devices,one is the light intensity of the room,they operate by blocking the transmission of a signal from the satellite to the cell phone tower,high voltage generation by using cockcroft-walton multiplier.three circuits were shown here.this covers the covers the gsm and dcs.when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition.< 500 maworking temperature.2 w output power3g 2010 – 2170 mhz,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,pc based pwm speed control of dc motor system,here a single phase pwm inverter is proposed using 8051 microcontrollers.the components of this system are extremely accurately calibrated so that it is principally possible to exclude individual channels from jamming,cell phones are basically handled two way ratios,our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed.
Frequency band with 40 watts max.but communication is prevented in a carefully targeted way on the desired bands or frequencies using an intelligent control,when zener diodes are operated in reverse bias at a particular voltage level,variable power supply circuits.gsm 1800 – 1900 mhz dcs/phspower supply.i have placed a mobile phone near the circuit (i am yet to turn on the switch),jammer detector is the app that allows you to detect presence of jamming devices around,but also for other objects of the daily life,energy is transferred from the transmitter to the receiver using the mutual inductance principle,.
