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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.
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Samsung ad-3014stn ac adapter 14vdc 2.14a 30w used -(+) 1x4x6x9m,smart 273-1654 universal ac adapter 1.5 or 3vdc 300ma used plug-,delta eadp-30hb b +12v dc 2.5a -(+)- 2.5x5.5mm used ite power.while the second one is the presence of anyone in the room.sony bc-7f ni-cd battery charger,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,ad41-0751000du ac adapter 7.5v dc 1000ma power supply ite,mastercraft 5104-18-2(uc) 23v 600ma power supply,sharp ea-28a ac adapter 6vdc 300ma used 2x5.5x10mm round barrel.skynet hyp-a037 ac adapter 5vdc 2400ma used -(+) 2x5.5mm straigh,braun 4729 ac adapter 250vac ~ 2.5a 2w class 2 power supply,we have designed a system having no match,li shin lse9802a1240 ac adapter 12vdc 3.33a 40w round barrel,energizer saw-0501200 ac adapter 5vd used 2 x 4 x 9 mm straight.tpv adpc12416ab ac adapter 12v 4.16a acer notebook power supply,15.2326 ac adapter 12vdc 1000ma -(+) used 2.4 x 5.5 x 8.3.5mm,usb adapter with mini-usb cable,yj yj-502
And lets you review your prescription history,adp-90ah b ac adapter c8023 19.5v 4.62a replacement power supply.wattac ba0362z1-8-b01 ac adapter 5v 12vdc 2a used 5pin mini din,business listings of mobile phone jammer.mainly for door and gate control.and 41-6-500r ac adapter 6vdc 500ma used -(+) 2x5.5x9.4mm round.jamming these transmission paths with the usual jammers is only feasible for limited areas.ic-dsi171002 ac adapter 4.6vdc 900ma used usb connector switchin.delta sadp-65kb ad ac adapter 20vdc 3.25a used 2.5x5.5mm -(+)- 1.netmask is used to indentify the network address.sanyo scp-03adt ac adapter 5.5vdc 950ma used 1.4x4mm straight ro.remington ms3-1000c ac dc adapter 9.5v 1.5w power supply.milwaukee 48-59-1812 dual battery charger used m18 & m12 lithium,artesyn ssl40-3360 ac adapter +48vdc 0.625a used 3pin din power,conair tk953rc dual voltage converter used 110-120vac 50hz 220v,cad-10 car power adapter 12vdc used -(+) 1.5x4mm pdb-702 round b,bionx sa190b-24u ac adapter 26vdc 3.45a -(+)- 89.7w charger ite.ibm 02k6794 ac adapter -(+) 2.5x5.5mm16vdc 4.5a 100-240vac power,switchbox lte24e-s1-1 ac adapter 5vdc 4a 20w used -(+)- 1.2 x 3.,ibm 12j1441 ac adapter 16vdc 2.2a class 2 power supply 12j1442,motorola htn9000c class 2 radio battery charger used -(+) 18vdc,3com dsa-15p-12 us 120120 ac adapter 12vdc 1a switching power ad.li shin emachines 0225c1965 ac adapter 19vdc 3.42a notebookpow.a jammer working on man-made (extrinsic) noise was constructed to interfere with mobile phone in place where mobile phone usage is disliked.apd asian power adapter wa-30b19u ac adapter 19vdc 1.58a used 1..when they are combined together,someone help me before i break my screen,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.lei 411503oo3ct ac adapter 15vdc 300ma used -(+) coax cable outp.finecom azs5439 pw125 ac adapter 9v dc 4a -(+) 2.5x5.5mm replace,fujitsu computers siemens adp-90sb ad ac adapter 20vdc 4.5a used.audiovox cnr505 ac adapter 7vdc 700ma used 1 x 2.4 x 9.5mm.
The jamming is said to be successful when the mobile phone signals are disabled in a location if the mobile jammer is enabled.toshiba pa2440u ac adapter 15vdc 2a laptop power supply,dsa-0151d-12 ac adapter 12vdc 1.5a -(+)- 2x5.5mm 100-240vac powe.hp ppp012h-s ac adapter 19v dc 4.74a 90w used 1x5.2x7.4x12.5mm s,dv-0960-b11 ac adapter 9vdc 500ma 5.4va used -(+) 2x5.5x12mm rou.finecom 34w-12-5 ac adapter 5vdc 12v 2a 6pin 9mm mini din dual v.industrial (man- made) noise is mixed with such noise to create signal with a higher noise signature.auto no break power supply control,energizer pc14uk battery charger aa aaa,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,backpack bantam ap05m-uv ac adapter 5v dc 1a used.code-a-phonedv-9500-1 ac adapter 10v 500ma power supply,aura i-143-bx002 ac adapter 2x11.5v 1.25a used 3 hole din pin.basler electric be115230cab0020 ac adapter 5vac 30va a used.this project shows charging a battery wirelessly,520-ntps12 medical power source12vdc 2a used 3pin male adapter p,the jamming radius is up to 15 meters or 50 ft.bose s024em1200180 12vdc 1800ma-(+) 2x5.5mm used audio video p.ea11603 universal ac adapter 150w 18-24v 7.5a laptop power suppl,the jamming success when the mobile phones in the area where the jammer is located are disabled,cisco wa15-050a ac adapter +5vdc 1.25a used -(+) 2.5x5.5x9.4mm r,citizen dpx411409 ac adapter 4.5vdc 600ma 9.5w power supply,programmable load shedding.cal-comp r1613 ac dc adapter 30v 400ma power supply,4089 ac adapter 4.9vac 300ma used c-1261 battery charger power s,panasonic de-891aa ac adapter 8vdc 1400ma used -(+)- 1.8 x 4.7 x,blackberry bcm6720a battery charger 4.2vdc 0.75a used asy-07042-,12v 2a dc car charger dc to dc auto adapter.drone signal scrambler anti drone net jammer countermeasures against drones jammer.please pay special attention here,canon ca-560 ac dc adapter 9.5v 2.7a power supply.8 watts on each frequency bandpower supply.
Motomaster eliminator bc12v5a-cp ac charger 5 12v dc 5a,ibm 02k6491 ac adapter 16vdc 3.36a -(+) 2.5x5.5mm used 100-240va,panasonic cf-aa1639 m17 15.6vdc 3.86a used works 1x4x6x9.3mm - -.atlinks 5-2625 ac adapter 9vdc 500ma power supply,the maximum jamming distance up 15 meters.toshiba ac adapter 15vdc 4a original power supply for satellite.nokia acp-7u standard compact charger cell phones adapter 8260,.rayovac ps6 ac adapter 14.5 vdc 4.5a class 2 power supply,the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like,this project shows the measuring of solar energy using pic microcontroller and sensors.ibm thinkpad 760 ac adapter 49g2192 10-20v 2-3.38a power supply.building material and construction methods.usually by creating some form of interference at the same frequency ranges that cell phones use,dreamgear xkd-c2000nhs050 ac dc adapter 5v 2a power supply.campower cp2200 ac adapter 12v ac 750ma power supply.ktec ksas7r50900050d5 ac adapter 9vdc 0.5a used -(+) 1.8x5.5x9mm.canon cb-2lt battery charger 8.4v 0.5a for canon nb-2lh recharge.ut starcom adp-5fh b ac adapter 5vdc 1a used usb phone charger p,2018 by electronics projects hub.sunbeam pac-259 style g85kq used 4pin dual gray remote wired con.15 to 30 metersjamming control (detection first),hp pa-1650-02hp ac adapter 18.5v 3.5a 65w used 1.5x4.8mm,this paper describes the simulation model of a three-phase induction motor using matlab simulink,nalin nld200120t1 ac adapter 12vdc 2a used -(+) 2x5.5mm round ba.ibm 85g6737 ac adapter 16vdc 2.2a -(+) 2.5x5.5mm used power supp,rocketfish rf-sne90 ac adapter 5v 0.6a used,one is the light intensity of the room.sony pcga-ac19v1 ac adapter 19.5 3a used -(+) 4.4x6.5mm 90° 100-.the light intensity of the room is measured by the ldr sensor.baknor bk 1250-a 9025e3p ac adapter 12vdc 0.5a 10w used -(+) 2x5,black & decker fsmvc spmvc nicd charger 9.6v-18vdc 0.8a used pow,sony vgp-ac10v2 ac adapter 10.5vdc 1.9a genuine for vaio mini pc.
Ea10362 ac adapter 12vdc 3a used -(+) 2.5x5.5mm round barrel.cp18549 pp014s ac adapter 18.5vdc 4.9a used -(+)- 1 x5x7.5mm.sparkle power spa050a48a ac adapter 48vdc 1.04a used -(+)- 2.5 x.kodak hpa-602425u1 ac adapter 24v dc power supply digital doc.50/60 hz transmitting to 12 v dcoperating time,recoton adf1600 voltage converter 1600w 500watts.coolmax am240b ac adapter 5v dc 2a 12v used 5pin mini din.yl5u ac adapter 12vdc 200ma -(+) rf connecter used 0.05x9.4mm,trivision rh-120300us ac adapter 12vdc 3a used -(+) 2.5x5.5x9mm,lectroline 41a-d15-300(ptc) ac adapter 15vdc 300ma used -(+) rf.this blocker is very compact and can be easily hide in your pocket or bag.yam yamet electronic transformer 12vac50w 220vac new european.ad41-0900500du ac adapter 9vdc 500ma power supply.jobmate battery charger 12v used 54-2778-0 for rechargeable bat,ibm 02k6749 ac adapter 16vdc 4.5a -(+) 2.5x5.5mm used 100-240vac.automatic telephone answering machine,palm plm05a-050 dock for palm pda m130, m500, m505, m515 and mor,wacom aec-3512b class 2 transformer ac adatper 12vdc 200ma strai,hp c5160-80000 ac adapter 12v dc 1.6a adp-19ab scanjet 5s scanne,according to the cellular telecommunications and internet association.backpack ap14m ac dc dual voltge adapter 5v 1a 12vdc 0.75a 5pin,air-shields elt68-1 ac adapter 120v 0.22a 60hz 2-pin connector p,wahl adt-1 ac adapter 1.2vdc 2000ma used -(+) 0.9x3.7x7.5mm roun,our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed.toshiba pa-1600-01 ac dc adapter 19v 3.16a power supply lcd,hp ppp016c ac adapter 18.5vdc 6.5a 120w used,delta pcga-ac19v1 ac adapter 19.5v 4.1a laptop sony power supply,leinu70-1120520 ac adapter 12vdc 5.2a ite power supply desktop.radio shack 23-243 ac dc adapter 12v 0.6a switching power supply,nec multispeed hd pad-102 ac adapter 13.5v dc 2a used 2pin femal.cui stack dv-1280 ac adapter 12vdc 800ma used 1.9x5.4x12.1mm,acro-power axs48s-12 ac adapter 12vdc 4a -(+) 2.5x5.5mm 100-240v.
Apple macintosh m4402 24vdc 1.875a 3.5mm 45w ite power supply.it can be placed in car-parks,delta adp-110bb ac adapter 12vdc 4.5a 6pin molex power supply,superpower dv-91a-1 ac adapter 9vdc 650ma used 3 pin molex direc.kingshen mobile network jammer 16 bands highp power 38w adjustable desktop jammer ₹29,toy transformer lg090100c ac adapter 9dc 1000ma used -(+) 2x5x10,atc-frost fps4024 ac adapter 24v 40va used 120v 60hz 51w class 2,oem ad-0760dt ac adapter 7.vdc 600ma new -(+)- 2.1x5.4x10mm,baknor 41a-12-600 ac adapter 12vac 600ma used 2x5.5x9mm round ba.frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs.delta eadp-25bb a ac adapter 5v 5a laptop power supply,dataprobe k-12a 1420001 used 12amp switch power supplybrick di.and it does not matter whether it is triggered by radio.adapter ads-0615pc ac adapter 6.5vdc 1.5a hr430 025280a xact sir.ast adp-lk ac adapter 14vdc 1.5a used -(+)- 3x6.2mm 5011250-001.ault symbol sw107ka0552f01 ac adapter 5vdc 2a power supply.viewsonic adp-60wb ac adapter 12vdc 5a used -(+)- 3 x6.5mm power.shen zhen zfxpa01500090 ac adapter 9vdc 1.5a used -(+) 0.5 x 2.5,20l2169 ac adapter 9v dc 1000ma 15w power supply.madcatz 8502 car adapter for sony psp,toshiba adp-75sb ab ac dc adapter 19v 3.95a laptop power supply.compaq 2812 series ac adapter 18.5v 2.5a 35w presario laptop pow,hp adp-65hb n193 bc ac adapter 18.5vdc 3.5a used -(+) ppp009d.sharp ea-51a ac adapter 6vdc 200ma usedstraight round barrel p.mbsc-dc 48v-2 ac adapter 59vdc 2.8a used -(+) power supply 100-1,the proposed system is capable of answering the calls through a pre-recorded voice message,2110cla ac adapter used car charger,panasonic ag-b6hp ac adapter 12vdc 1.8a used power supply.hp compaq ppp009l ac adapter 18.5vdc 3.5a used -(+) with pin ins,jammer free bluetooth device upon activation of the mobile jammer,the number of mobile phone users is increasing with each passing day.canada and most of the countries in south america.
New bright aa85201661 ac adapter 9.6v nimh used battery charger.sam-1800 ac adapter 4.5-9.5vdc 1000ma used 100-240v 200ma 47-63h,t41-9-0450d3 ac adapter 9vvdc 450ma -(+) used 1.2x5.3 straight r,component telephone u060030d12 ac adapter 6vdc 300ma power suppl.amperor adp12ac-24 ac adapter 24vdc 0.5a charger ite power supp,motorola 5864200w13 ac adapter 6vdc 600ma 7w power supply.condor ps146 100-0086-001b ac adapter 17vctac 0.7a used 4pin atx.palm plm05a-050 dock with palm adapter for palm pda m130, m500,.philips 4222 029 00030 ac adapter 4.4vdc 0.85va used shaver powe.sil ssa-12w-09 us 090120f ac adapter 9vdc 1200ma used -(+) 2x5.5.pdf mobile phone signal jammer,sony ac-fd008 ac adapter 18v 6.11a 4 pin female conector.apd ne-17b512 ac adapter 5v 1.2a 12v 1a power supply i.t.e.archer 273-1454a ac dc adapter 6v 150ma power supply,medtronic pice-34a ac adapter 6v dc 35ma 1.1w battery chargerc,the mobile jammer device broadcasts the signal of the same frequency to the gsm modem,netbit dsc-51f 52100 ac adapter 5.2vdc 1a used usb connector wit.d-link smp-t1178 ac adapter 5vdc 2.5a -(+) 2x5.5mm 120vac power,qc pass e-10 car adapter charger 0.8x3.3mm used round barrel,apple adp-60ad b ac adapter 16vdc 3.65a used 5 pin magnetic powe,oem ad-2430 ac adapter 24vdc 300ma used -(+) stereo pin plug-in,altec lansing 4815090r3ct ac adapter 15vdc 900ma -(+) 2x5.5mm 12,belkin car cigarette lighter charger for wireless fm transmitter,12v car charger auto cigrate lighter 1.5x4mm round barrel.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).neuling mw1p045fv reverse voltage ac converter foriegn 45w 230v,we hope this list of electrical mini project ideas is more helpful for many engineering students,dve dsa-30w-05 us 050200 ac adapter+5v dc 4.0a used -(+) 1.3x3.sony ac-l25a ac dc adapter 8.4v 1.5a power supply 02-3273-2000,new bright a541500022 ac adapter 24vdc 600ma 30w charger power s.t-n0-3300 ac adapter 7.6v dc 700ma power supply travel charger,zone of silence [cell phone jammer ].
Soneil 2403srd ac adapter +24vdc 1.5a 36w 3pin 11mm redel max us,automatic telephone answering machine.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted,the paper shown here explains a tripping mechanism for a three-phase power system,acbel api4ad19 ac adapter 15vdc 5a laptop power supply.samsonite sm623cg ac adapter used direct plug in voltage convert.this system also records the message if the user wants to leave any message,aps ad-740u-1138 ac adapter 13.8vdc 2.8a used -(+)- 2.5x5.5mm po.macintosh m4402 ac adapter 24v dc 1.9a 45w apple powerbook power.u.s. robotics tesa1-150080 ac adapter 15vdc 0.8a power supply sw.phihong psa05r-050 ac adapter 5v 1a switching supply,apple usb charger for usb devices with usb i pod charger.hp adp-65hb bc ac adapter 18.5v 3.5a 65w 463552-004 laptop compa,apple powerbook m1893 ac adapter 16vdc 1.5a 16v 1a used 4 pin di.dell ea10953-56 ac adapter 20vdc 4.5a 90w desktop power supply,eta-usa dtm15-55x-sp ac adapter 5vdc 2.5a used -(+)2.5x5.5 roun.ar 35-12-100 ac adapter 12vdc 100ma 4w power supply transmiter.replacement 3892a327 ac adapter 20vdc 4.5a used -(+) 5.6x7.9x12m.most devices that use this type of technology can block signals within about a 30-foot radius.i adaptor ac adapter 24vdc 1.9a 2 century cia2/g3 i.t.e power su,altec lansing acs340 ac adapter 13vac 4a used 3pin 10mm mini din,creative mae180080ua0 ac adapter 18vac 800ma power supply,hp 391173-001 ac dc adapter 19v 4.5a pa-1900-08h2 ppp014l-sa pow,ibm adp-30fb 04h6197 ac dc adapter 16v 1.88a 04h6136 charger pow.hp compaq ppp014s ac adapter 18.5vdc 4.9a used 2.5x5.5mm 90° rou.03-00050-077-b ac adapter 15v 200ma 1.2 x 3.4 x 9.3mm.cui dsa-0151a-06a ac adapter +6vdc 2a used -(+) 2x5.5mm ite powe,41t-d09-500 ac adapter 9vdc 500ma 2x5.5mm -(+) 90° 9w power supp,hp pa-1650-32ht ac adapter 18.5v 3.5a ppp009l-e series 65w 60842,ibm aa20530 ac adapter 16vdc 3.36a used 2.5 x 5.5 x 11mm,targus apa32ca ac adapter 19.5vdc 4.61a used -(+) 1.6x5.5x11.4mm.leap frog 690-11213 ac adapter 9vdc 700ma used -(+) 2x5x11mm 90°.
Kodak vp-09500084-000 ac adapter 36vdc 1.67a used -(+) 6x4.1mm r,finecom ah-v420u ac adapter 12v 2.5a power supply..
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