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Greater Fidelity Using a 3D Approach By Wei Zhang, Attila Komjathy, Simon Banville, and Richard B. Langley INNOVATION INSIGHTS by Richard Langley MAY YOU LIVE IN INTERESTING TIMES. So goes the purported Chinese proverb and curse. When it comes to the ionosphere, an interesting time might indeed be a curse for most users of GPS. The ionosphere – that region of the upper atmosphere where free electrons exist in sufficient numbers to affect the propagation of radio waves – owes its existence primarily to the extreme ultraviolet (EUV) and x-ray photons emitted by the sun. They ionize atoms and molecules in the upper atmosphere, freeing the outer electrons. Mostly the ionosphere is well behaved but it can get quite interesting when it is disturbed by space weather events such as solar flares or coronal mass ejections. The signals from the GPS satellites are perturbed as they transit the ionosphere. Pseudorange measurements are increased in value (an additional delay) and carrier-phase measurements are decreased (a phase advance). If not fully modeled or otherwise accounted for, the perturbations can decrease the accuracy of GPS positioning, navigation, and timing (PNT). For highest PNT accuracies, observations are made at the two frequencies transmitted by all GPS satellites and because the ionosphere’s effect on radio signals is dispersive, a linear combination of the measurements removes almost all of the ionospheric perturbations. On the other hand, the ionosphere’s effect on single frequency observations must be corrected using a model. Most commonly, the model assumes that all of the electrons in the ionosphere can be compressed into a thin shell at a certain height above the receiver. This permits the computation of an estimate of the vertical ionospheric delay. Then, a mapping function is used to predict the slant delay, the delay contributing to a GPS measurement. The approach works reasonably well, particularly if near-real-time values of vertical delay can be provided to users as is done by the Wide Area Augmentation System and other satellite-based augmentation systems. However, this two-dimensional approach ignores the fact that the electron content of the ionosphere is actually spread out in the vertical direction and so has certain inaccuracies, which can increase when the ionosphere is disturbed. In an effort to improve ionosphere modeling with potential application to single-frequency GNSS users, a couple of my current graduate students together with a former student, have investigated a three-dimensional approach to ionospheric modeling using empirical orthogonal functions or EOFs to describe the vertical structure of the ionosphere. EOFs reduce the dimensionality of a data set or an empirical model consisting of a large number of interrelated variables, while retaining as much of the variance present in the data set as possible. This is achieved by transforming to a new set of variables, the orthogonal functions, which are uncorrelated (orthogonal), and which are ordered so that the first few retain most of the variation present in all of the original variables. Only three functions are required to account for more than 99 percent of the variability in the International Reference Ionosphere – 2007, for example. In this month’s column we look at the performance of this 3D approach to modeling the ionosphere including times when the ionosphere is particularly interesting. “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. Ionospheric modeling plays an important role in improving the accuracies of positioning and navigation, especially for current civil aircraft navigation and mass-market single-frequency users. Measurement-driven models are considered to be among the best candidates for real-time single-frequency positioning owing to their real-time applicability and relatively higher accuracy compared to empirical models, such as the GPS broadcast (also known as Klobuchar) and NeQuick models. A good example of a real-time positioning application is satellite-based augmentation systems (SBAS), including the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), the Japanese MSTAT Satellite-based Augmentation System (MSAS), and the Indian GPS Aided Geo Augmented Navigation system (GAGAN). Because the ionosphere can be the largest error source in single-frequency positioning, the accuracy of ionospheric modeling is critical for single-frequency applications. Several organizations have been routinely providing ionospheric products to correct errors caused by the ionosphere in the form of ionospheric maps — that is, vertical total electron content (vTEC) at grid points (including regional and global products), such as those from WAAS and the International GNSS Service (IGS), with various processing time delays ranging from near real time to a couple of weeks. Among the earliest works of ionosphere modeling, the University of New Brunswick-Ionospheric Modeling Technique (UNB-IMT) was developed in the mid-1990s. This technique was demonstrated to effectively derive both regional and global total electron content (TEC) maps. However, most of the models, including the current version of UNB-IMT, approximate the ionosphere using a single thin-shell approach with an altitude set at, for example 350 km, which may introduce additional modeling errors up to several TEC units (1 TECU = 1016 electrons/m2), corresponding to meter-level errors of measurement delay or advance at the GPS L1 frequency. To overcome any downside of such models, three-dimensional (3D) ionospheric tomographic modeling methods have been proposed and implemented by several groups since the late 1990s. Different from the two-dimensional (2D) single thin-shell ionospheric models, where the parameters to be estimated are associated with TEC, the modeled variables in the tomographic model are related to electron density functions. Therefore, we may expect more complex structures of electron densities (such as those observed during ionospheric storms or in the highly variable equatorial anomaly) to be revealed by the models. A commonly accepted modeling approach is to describe the ionospheric horizontal (longitudinal and latitudinal) variability by a spherical harmonic (SH) expansion up to a specific degree and its vertical dimension modeled by empirical orthogonal functions (EOFs). However, SH models are not ideal for capturing local variability in the ionosphere because each basis function of spherical harmonics exists over the entire geographic region of interest, such as the entire globe in the case of global modeling. In other words, localized measurements will have influence on the estimated state across the whole globe. As alternative approaches,  wavelet, finite element (meshes/pixels), and local-basis-function models have been proposed and implemented to capture the localized information content in the measurements and pass this information on to the end user. On the other hand, the inversion process can occasionally become singular as many of the parameters to be estimated tend to be ineffective and less meaningful. This is especially the case when our goal is to obtain better accuracies with higher order wavelet bases or smaller meshes/pixels. Due to the potential computing and transmitting burden, the two modeling techniques may have more difficulties associated with real-time applications, such as real-time single-frequency positioning, although they have advantages for capturing localized structures in the ionosphere. Aiming for potential real-time applications of 3D tomographic models, we have extended the UNB-IMT from 2D to 3D by modeling the vertical dimension of the ionosphere using EOFs. In this article, we discuss our approach and report on some initial tests including comparing its performance with the 3D SH approach. The 2D UNB-IMT was demonstrated to work with various network sizes: regional, baseline-by-baseline, and even single standalone stations. Therefore, it is expected that this technique will help in capturing localized ionospheric structures above small regional networks or above a single standalone station. Additional benefits may be expected for disturbed ionospheric conditions. For assessing the two modeling techniques, a small regional network was chosen to perform station-by-station and batch processes. The performance of both methods with the two processing scenarios has been compared by analyzing the post-fit residuals and vTECs of the state estimation process, as well as the repeatability of estimates of differential code biases (DCBs) for both quiet and disturbed ionospheric conditions. 3D UNB-IMT Because of the limited number of ionospheric parameters to be estimated, the 2D UNB-IMT was considered suitable for real-time applications, such as real-time single-frequency precise point positioning (PPP) and SBASs. In fact, it can be proven that the modeling method of the current 2D UNB-IMT is identical to the original planar fit of WAAS in nature if the locations of reference stations tend to collocate with WAAS ionospheric grid points (IGPs). Although additional parameters are involved, we believe the 3D UNB-IMT approach with its potential for improved modeling accuracy is still suitable for real-time applications. In this section, we will introduce the 3D UNB-IMT modeling strategy and demonstrate its applicability with a regional network and single standalone stations. Model Description. In order to clearly present the technique demonstrated in our recent work, we first briefly review the 2D UNB-IMT. Linear polynomial functions were initially proposed for describing the spatial variability of the ionosphere. We model the observed slant TEC (sTEC) between a satellite and a receiver from carrier-phase and pseudorange (code) observations at some epoch as the product of a bilinear polynomial representing the vTEC at the thin-shell ionospheric pierce point (IPP) of the signal raypath and a mapping function that projects the vTEC to sTEC plus receiver and satellite instrumental biases (DCBs). The input variables are the geographic longitude of the IPP referenced to the solar-geomagnetic coordinate system (in other words, the difference between the longitude of the IPP and the longitude of the mean sun) and the difference between the geomagnetic latitude of the IPP and the geomagnetic latitude of the station. We consequently have three polynomial coefficients to estimate for each station: a constant term, one to describe the longitude variations, and one for the latitude variations. The mapping function used in the model is the standard geometric mapping function, which computes the secant of the zenith angle of the signal geometric ray path at the IPP at a specified shell height. Because of the dependence of the ionosphere on solar radiation and the geomagnetic field, the solar-geomagnetic reference frame is used to compute the TEC over each station in this technique. Since the ionosphere changes more slowly in the sun-fixed reference frame than in the Earth-fixed one, such a reference frame is ideal for producing more accurate TEC estimates. The initial version of UNB-IMT ignored the non-linear spatial variation of the ionosphere. Non-linear terms are expected to be able to absorb more complex variability of the ionosphere and thus more properly describe the ionosphere in disturbed conditions. Regarding this issue, the drawbacks of some modeling methods based on linear models have been reported: for example, the highly variable ionosphere might be absorbed by the estimated DCBs, making the repeatability of the estimated DCBs (day-to-day variability) correlated with the variability of the ionosphere. To enhance the performance of UNB-IMT, especially under disturbed ionospheric conditions, UNB researchers extended the linear version of UNB-IMT to a quadratic one and assessed it by using a wide-area regional network in North America. This modified approach reduced the post-fit residuals significantly by better modeling the ionospheric variations with the help of the additional second order (non-linear) terms. To better use a priori information in the development of 3D UNB-IMT, we separate the TEC into a background reference or “known” part and a perturbation or to-be-modeled part. The background reference part of TEC could be calculated from an a priori source of electron density, such as any kind of ionospheric model, including empirical and theoretical ionospheric models. The density, as a function of latitude, longitude, height, and time, is integrated along the raypath between the receiver and a satellite. Then, the perturbation part of the electron density is modeled by the inner product of EOFs and polynomial functions with associated estimated coefficients to depict the variability of the ionosphere in the vertical and horizontal directions respectively. And this part is similarly integrated along the raypath and added to the reference part along with the DCBs. Empirical Orthogonal Functions. The EOF method is a method of choice for analyzing the variability of a single field (with only one scalar variable). Variability of the ionosphere with respect to height is needed for the 3D models. The method finds the spatial patterns of variability based on historical data sets (as reflected in empirical or theoretical models). In other words, the modes of variability decomposed by the method are primarily “data modes,” and not necessarily physical or actual real-time models. Due to its noted ability in describing the background ionosphere, the data sets output from the empirical Ionospheric Reference Ionosphere 2007, were utilized to form the EOFs in our technique. Thus, the data sets of electron densities are realized by uniform sampling at the following variant time scale intervals and specific geographic locations: Solar cycle: [1998:1:2008] (year) Season of year: [Dec., Mar., Jun., Sep.] (month) Time of day: [1:1:24] (hour) Day of month: [1:9:28] (day of month) Geographic latitude: [30:5:60] (degree)  Geographic longitude: [280:5:300] (degree), where the numbers separated by colons correspond to minimum:increment:maximum. The data sets cover the whole spatial area of interest. The data sets of a whole solar cycle in typical equinox and solstice months are used to ensure that the EOFs span the range of profile variations that include the variation in solar EUV and x-ray output. Each electron density profile with respect to height at these locations and time points is sampled in the vertical dimension at [100:2:2000] (km). Figure 1 shows the first three third-order normalized EOFs based on the data sets. The first three eigenvalues account for 92.22, 6.69, and 0.78 percent of the total respectively. Provided the solution is nonsingular, the choice of the highest order of EOFs is a trade off between processing time and modeling accuracy as to the specific network and capability of computer(s). In our current work, the highest order of three was chosen. In this case, the neglected vertical variation of the ionosphere corresponding to higher order EOFs is 0.31 percent. FIGURE 1. The normalized first three dominant EOFs extracted from the IRI-2007 empirical model. Once the modeling approach has been constructed, the following task is to estimate the coefficients. Considering the potential real-time applications, a Kalman filter is employed to solve the TEC observation equation. To be specific, the following settings are used. The correlation time is set to five minutes, which correspond to the WAAS update interval for ionospheric grid points. The uncertainty of the dynamic model, 0.008 TECU2/second, is chosen to characterize the potential rapid change of the ionosphere. Finally, the estimated coefficients provided by the Kalman filter are then used to reconstruct the electron density field. Testing the Approach In this section, we report on tests of the 3D UNB-IMT and compare its performance with that of the 3D SH approach. Because of the advantages of sensitivity of 2D UNB-IMT, especially with the single-station processing strategy, it is expected that this technique will help in better capturing localized ionospheric structures above small regional networks or above a single standalone station compared to the 3D SH approach. Additional benefits may be expected for disturbed ionospheric conditions. For assessing the two modeling techniques, a small regional network of four IGS reference stations located from geographic latitude 39.0° N to 48.1° N and longitude 66.7° W to 77.6° W was chosen to perform single-station and multi-station (network) processing. The stations are GODZ in Greenbelt, Maryland; UNBJ and FRDN in Fredericton, New Brunswick; and VALD in Val d’Or, Quebec. Figure 2 shows the locations of the reference stations chosen for the modeling. The dual-frequency GPS data used for the tests was obtained from October 13–25 (day of year (doy) 286–298) in 2011 with the sampling time interval of 30 seconds. The corresponding values of the interplanetary magnetic field Bz component; the planetary geomagnetic index, Kp; the auroral electrojet index, AE; and the disturbance storm-time index, Dst on these days are shown in FIGURE 3. It is seen that a severe ionospheric storm triggered by a coronal mass ejection from the sun occurred late on October 24 (doy 297), 2011, and continued through the entire day of October 25 (doy 298), 2011. The other days seem relatively quiet. Thus, we chose October 16, 2011, as a typical day with quiet ionospheric conditions and October 25, 2011, as a typical day with disturbed ionospheric conditions in the following tests. The performance of both methods (3D UNB-IMT and SH model) with the two processing scenarios will be compared by analyzing the post-fit residuals and TEC of the state estimation process for both quiet and disturbed ionospheric conditions. FIGURE 2. The network of the four stations used in the evaluation procedures. All four reference stations in the small network have the ability to provide both C/A- and P-code pseudorange measurements. In our tests, the P-code observable is used to extract TEC through leveling the corresponding carrier-phase measurements. We used a 15°-elevation-angle cut-off in our study. Single Station Experiment. The estimated parameters of 2D and 3D UNB-IMT have different physical meanings due to the different modeling strategies. In theory, the 3D UNB-IMT can reproduce the electron densities for any location (horizontal and vertical) at any epoch. Figure 4 shows an example of the electron density profile produced by the linear 3D UNB-IMT in the zenith direction of station FRDN at 12:00 UT on October 16 (doy 289), 2011. Therefore, we will have to integrate electron densities into TEC for the 3D UNB-IMT modeling results if we want to compare how the two approaches have modeled the ionosphere side by side. For the purpose of sensitivity comparison, the results from 2D and 3D UNB-IMT are compared in terms of post-fit residuals as well as time series of estimated vTEC in the single-station processing scenario. As discussed above, we use the GPS data from station FRDN only for October 16 and 25, 2011, in this subsection. The post-fit residuals are calculated as the difference between the measured and estimated biased sTEC. FIGURE 4. The electron density profile produced by linear 3D UNB-IMT overhead FRDN at 12:00 (UT) on October 16 (doy 289) in 2011. From the top to bottom panels, Figure 5 shows the estimated vTEC in the zenith direction over the station, post-fit residuals, estimated satellite and receiver DCBs, and unbiased sTEC with respect to local mean solar time series obtained with linear 2D (left-hand panels) and 3D (right-hand panels) UNB-IMT approaches respectively. We use a different color for each satellite to see individual improvement of satellites in terms of post-fit residuals, estimated DCB, and unbiased sTEC. As for the potential improvement of 3D UNB-IMT, we supposed, if the 2D model with single-shell assumption does not depict the variability of the ionosphere quite well (especially the vertical variability of the ionosphere), we should expect to see an improvement from the 3D model in terms of post-fit residuals. As seen in this figure, the 3D UNB-IMT improves the results in terms of post-fit residuals. The means and standard deviations of the residuals with the 2D and 3D UNB-IMT are shown in Table 1. FIGURE 5. Sensitivity test (the panels from the top to the bottom correspond to: estimated vertical TEC, post-fit residuals, satellite and receiver DCB, slant TEC with respect to local time) between linear 2D (the left-hand panels) and 3D (the right-hand panels) models at FRDN on October 16 (doy 289) in 2011. TABLE 1. The means and standard deviations of the residuals under the quiet (Q, October 16, 2011) and disturbed or storm (S, October 25, 2011) ionospheric conditions with linear (L) and quadratic (Q) modeling approaches. Units = TECU. The 3D UNB-IMT with three times as many parameters is allowed to “accommodate” more (vertical) variations of the ionosphere. The benefits are also manifest in the improvement of the estimated vTEC and estimated satellite and receiver DCBs. In terms of estimated vTEC, the smooth variation of TEC may be expected at mid-latitudes during quiet ionospheric conditions without any ionospheric anomaly. The unmodeled variation of TEC in 2D UNB-IMT seen in the post-fit residuals is also manifest as “artificial small jumps” in the vTEC panel. In other words, the 3D UNB-IMT is able to better represent the measurements from low-elevation-angle satellites owing to the EOFs replacing the mapping function. It is the typical case when a satellite comes into or goes out of view of the receiver. The estimated DCBs are relatively constant over the entire day. But it is also found from the estimated DCBs that the results from 2D UNB-IMT have slightly more variability. Both effects seem to be related to the unmodeled errors. The post-fit residuals in the 3D UNB-IMT are closer to the zero mean Gaussian distribution. Then, we further evaluated the performance of 2D and 3D UNB-IMT under significantly disturbed conditions. Figure 6 shows the results with the same modeling strategies as demonstrated in Figure 5 but on October 25, 2011. Similar conclusions can be drawn from Figure 6, where better results in terms of post-fit residuals are obtained with 3D UNB-IMT (Table 1). In terms of estimated vTEC, the results from both strategies under the disturbed conditions look more irregular than those under the quiet conditions and deviate a little from the sine-wave-like daily variation. Some actual variation of the ionosphere during disturbed conditions may be captured and correctly illustrated as the bumps for both approaches. Furthermore, the unmodeled errors may also be explained as artificial small jumps/bumps in vTEC curves (revealed by the magnitude of post-fit residuals). It is seen that 3D linear UNB-IMT explains more variation of the ionosphere than 2D linear UNB-IMT. However, some residual unmodeled errors may still exist with the 3D model. FIGURE 6. Sensitivity test (the panels from the top to the bottom correspond to: estimated vertical TEC, residuals, satellite and receiver DCB, slant TEC with respect to local time) between linear 2D (the left-hand panels) and 3D (the right-hand panels) models at FRDN on October 25 (doy 298) in 2011. As concluded by other investigators, a higher order model could explain more spatial (non-linear) variations of the ionosphere, especially for geomagnetic storm conditions. The results with 2D and 3D quadratic UNB-IMT approaches are shown in Figure 7. In the post-fit residual panels, it can be seen that the residuals with 3D quadratic UNB-IMT are mostly within ±2 TECU except for several small spikes that happened between 0:00 and 4:00 local mean solar time and reflect that not all the electron density variations had been correctly represented by the model used. But it is clear that the 3D quadratic UNB-IMT can significantly improve the modeling precision compared to the 2D quadratic/linear UNB-IMT and 3D linear UNB-IMT. The magnitude of the post-fit residuals shown in this panel is even comparable with the results for the quiet condition shown in Figure 5. In terms of vTEC, a few spurious spikes are occasionally found when processing the data from the four stations with the 3D quadratic model and single-station processing strategy. Other data sources, such as data from incoherent backscatter measurements, may be needed to confirm if the spikes are caused by the instability of the model or actual ionospheric structures. Still, the vTEC curves with 3D quadratic UNB-IMT look smoother than 2D UNB-IMT. In terms of estimated DCBs, it is found that the results with 3D quadratic UNB-IMT approach exhibit relatively fewer perturbations than the other three approaches tested. FIGURE 7. Sensitivity test (the panels from the top to the bottom correspond to: estimated vertical TEC, residuals, satellite and receiver DCB, slant TEC with respect to local time) between quadratic 2D (the left-hand panels) and 3D (the right-hand panels) models at FRDN on October 25 (doy 298) in 2011. As we found for the 2D modeling approaches, the single thin-shell assumption with a fixed ionospheric shell height may introduce additional modeling errors. That is mainly because the layer with highest electron density (F2 layer) is not always located at a fixed height. Especially in disturbed ionospheric conditions, such as the case shown in Figures 6 and 7, the layer height would change significantly. Some methods have been proposed and tested with the help of more reliable “true” heights from other resources, such as ionosondes. However, due to the limited number of the instruments deployed and limited information provided (only information from overhead), the applications with these methods would have to be limited to the specific area covered by stations or networks equipped with the instruments. In addition, as to real-time application, the data processing time delay of ionosondes might be another technical issue these methods have to face. Compared with these methods, one benefit of the 3D UNB-IMT is its potential for real-time application for any size of network. Another benefit is its vertical modeling capability to depict vertical variation of electron density so the improved results would also be expected for disturbed ionospheric conditions. It is clearly seen from Figures 6 and 7 that the lowest vTECs around 4:00 LT reach down to 0 TECU with the 2D linear/quatratic UNB-IMT, which are considered as unphysical results. It is confirmed that small biases still exist in the results with the 2D model likely due to the improper shell height chosen (fixed at 350 km for the results shown in this article). Multi-Station Experiment. When using the modeling scheme for a network solution, we will generally have two possible processing scenarios. One is processing the data of all the stations as a batch, and the other is processing station by station (or baseline by baseline). The advantages and disadvantages of the batch process can be summarized as follows. It has more redundancies in the Kalman filter to estimate a more stable and reliable set of satellite and receiver DCBs. Due to more measurements as an input (state) of the Kalman filter, the convergence time would be shorter in terms of the estimated DCBs. It would be of benefit for real-time applications if we have limited a priori information about the estimated ionospheric parameters and/or DCBs. However, the batch solution seems to be less sensitive to localized information content than the station-by-station solution. The overall effect of the batch solution is smoothing over the network, reducing the size of some small perturbations. Theoretically, localized measurements should not have significant influence on the estimated state across an extended area or even the entire globe. In other words, the batch solution may be beneficial for relatively small local-area networks, but may not be ideally suited for networks as large as wide-area ones. Another straightforward disadvantage of the batch process is its relatively longer processing time, which might be a downside if it is used for real-time applications. In the multi-station experiment, we tested the 3D UNB- IMT with a small regional network of four IGS reference stations (Figure 2) to investigate its performance with localized ionospheric variations. We performed tests with two scenarios: batch and station-by-station. Due to space restrictions, we cannot thoroughly report the results we obtained here. Please see the conference paper listed in Further Reading for the full details. Overall, the results we obtained in terms of post-processing residuals were similar to those in the single station experiment. We also found that the 3D UNB-IMT with EOFs seems to be able to better model the measurements with low elevation angles than the 2D UNB-IMT with a mapping function. Comparing 3D UNB-IMT with SH Model. We have compared the results using the batch processing strategy with those from the SH model. The reason for this approach is that we intended to compare the results of the two processing strategies (UNB-IMT and SH) with identical conditions. That is, both methods processed the data using a batch scheme and estimated both ionospheric parameters and DCBs simultaneously, instead of using some other source or processed results. Therefore, in this case, we can compare the results side by side and evaluate the effectiveness of the estimated ionospheric parameters. Based on the data from the network of the four stations, the sensitivity of the SH models is lower than that of 3D UNB-IMT, although the number of ionospheric parameters of the SH models is comparable or even larger than that of 3D UNB-IMT. In other words, the ionospheric parameters in 3D UNB-IMT to describe the variability of the ionosphere are more effective and meaningful to such a network scale than those in the 3D SH model. Given the nature of its basis functions, the SH model is an excellent tool for global modeling, but it has some shortcomings for localized variability modeling. As to larger regional networks with longer baselines, such as those used for WAAS, which covers North America, the difference of the sensitivities between the batch and the station-by-station solutions should be larger than the results we have obtained. However, we cannot conclude that the sensitivity of 3D UNB-IMT is better than that of the 3D SH model with the batch processing strategy for such large regional networks before more tests are conducted. Still, it is clearly seen in our tests that the 3D SH model is not always ideal for regional networks in terms of sensitivity. We reached similar conclusions for October 25, 2011, where the residuals spread more widely compared with quiet-condition residuals. In the storm conditions, the residuals of the quadratic 3D UNB-IMT spread relatively less than those of other modeling strategies. This is especially the case for the several hours at the beginning of the day, which corresponds to the peak of the Dst and Kp indices shown in Figure 3. The quadratic 3D UNB-IMT seems to have the capacity to handle the ionospheric spatial and temporal variation even during severe storm conditions. FIGURE 3. Interplanetary magnetic field Bz component, Kp index, AE index, and Dst index during October 13–25 (doy 286–298) in 2011; nT = nanoteslas (Data from World Data Center for Geomagnetism, Kyoto and Goddard Space Flight Center Space Physics Data Facility). Repeatability of Estimated DCBs. The DCBs not only have influence on the quality (accuracy) of the vTEC estimation, but their repeatability can also provide information to evaluate ionospheric models. This implies that the ionospheric models that have the capability to estimate/eliminate more accurate DCBs, independent of ionospheric variability, are preferable. We carried out a number of tests to evaluate the repeatability of estimated DCB values using the 2D and 3D UNB-IMT approaches as well as the 3D SH technique under both quiet and disturbed ionospheric conditions. For quiet ionospheric conditions, the performance of all the tested models looks comparable, although the quadratic 3D UNB-IMT performs slightly better than the others. As to the disturbed conditions, the quadratic 2D/3D UNB-IMT seems be able to provide more stable DCBs than the other models. However, the improvement of the extension from 2D to 3D is slight for the quadratic models, although it is significant for the linear models. The performance of the 3D SH model looks fairly poor compared to 3D UNB-IMT for regional modeling. Consult the conference paper for further details. Conclusions and Future Research In the work described in this article, we extended the UNB-IMT from 2D to 3D and compared the performance between them in station-by-station and batch processing scenarios for both quiet and storm ionospheric conditions. We used the data from a small regional network of dual-frequency GPS receivers. The DCBs and ionospheric delays were estimated at the same time by a Kalman filter. The newly developed approach was evaluated by analyzing the post-fit residuals, TEC of the state estimation process, and the repeatability of estimates of DCBs. In the single-station processing, the improvement of 3D UNB-IMT has been demonstrated in both quiet and disturbed ionospheric conditions in terms of post-fit residuals. The 3D UNB-IMT with more parameters allows the depiction of more complex (vertical) variability of the ionosphere. The 3D UNB-IMT is able to better deal with the measurements from low-elevation-angle satellites owing to EOFs replacing the mapping function. The artificial jumps with 2D UNB-IMT when satellites come into or go out of view of the receiver have been properly handled by the 3D UNB-IMT. In addition, the time series of estimated DCBs with 3D UNB-IMT exhibit less perturbation than the results with 2D UNB-IMT. As to the multi-station (network) processing, it is confirmed that the station-by-station solution is more sensitive to localized information than the batch solution. Based on the results from our research, station-by-station processing with 3D UNB-IMT is suggested to increase chances to catch localized ionospheric structures. The repeatability of estimated DCBs was investigated as another indicator to evaluate the viability ofionospheric models. Before the 3D UNB-IMT is tested in the positioning domain for single-frequency positioning, it is worth validating the model with other data sources. In addition, the potential benefits of 3D UNB-IMT during extremely disturbed ionospheric conditions is worth investigating further. Acknowledgments We would like to thank the IGS and the Crustal Dynamics Data Information System for providing the GPS data, and we acknowledge the financial contribution of the Natural Sciences and Engineering Research Council of Canada for supporting the first and last authors. This article is based on the paper “Eliminating Potential Errors Caused by the Thin Shell Assumption: An Extended 3D UNB Ionospheric Modelling Technique” presented at the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation, Nashville, Tennessee, September 16–20, 2013. WEI ZHANG received his M.Sc. degree in space science in 2009 from the School of Earth and Space Science of Peking University, China. He is currently an M.Sc.E. student in the Department of Geodesy and Geomatics Engineering at University of New Brunswick (UNB) under the supervision of Dr. Richard B. Langley. ATTILA KOMJATHY is a principal investigator at the California Institute of Technology Jet Propulsion Laboratory and an adjunct professor at UNB, specializing in remote sensing techniques using GPS. He received his Ph.D. from the Department of Geodesy and Geomatics Engineering of UNB in 1997. SIMON BANVILLE works for the Geodetic Survey Division of Natural Resources Canada on real-time precise point positioning (PPP) using global navigation satellite systems. He is also in the process of completing his Ph.D. degree at UNB under the supervision of Dr. Langley. FURTHER READING • Authors’ Conference Paper “Eliminating Potential Errors Caused by the Thin Shell Approximation: An Extended 3D UNB Ionospheric Modelling Technique” by W. Zhang, R.B. Langley, A. Komjathy, and S. Banville in Proceedings of ION GNSS+ 2013, the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation, Nashville, Tennessee, September 16–20, 2013, pp. 2447–2462. • 2D Ionosphere Modeling “SBAS Ionospheric Modeling with the Quadratic Approach: Reducing the Risks” by H. Rho, R. Langley, and A. Komjathy in Proceedings of ION GNSS 2005, the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, Long Beach, California, September 13–16, 2005, pp. 723–734. Global Ionospheric Total Electron Content Mapping Using the Global Positioning System by A. Komjathy, Ph.D. dissertation, Technical Report No. 188, Department of Geodesy and Geomatics Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada, 1997. “Improvement of a Global Ionospheric Model to Provide Ionospheric Range Error Corrections for Single-frequency GPS Users” by A. Komjathy and R. Langley in Proceedings of the 52nd Annual Meeting of The Institute of Navigation, Cambridge, Massachusetts, January 22–24, 1996, pp. 557–566. • 3D (4D) Ionosphere Modeling “Comparison of 4D Tomographic Mapping Versus Thin-shell Approximation for Ionospheric Delay Corrections for Single-frequency GPS Receivers over North America” by D.J. Allain and C.N. Mitchell in GPS Solutions, Vol. 14, No. 3, 2009, pp. 279–291, doi: 10.1007/s10291-009-0153-0. “Regional 4-D modeling of the Ionospheric Electron Density” by M. Schmidt, D. Bilitza, C. Shum, and C. Zeilhofer in Advances in Space Research, Vol. 42, No. 4, 2008, pp. 782–790, doi: 10.1016/j.asr.2007.02.050. “History, Current State, and Future Directions of Ionospheric Imaging” by G.S. Bust and C.N. Mitchell in Reviews of Geophysics, Vol. 46, No. 1, RG1003, March 2008, doi: 10.1029/2006RG000212. “Development of the Global Assimilative Ionospheric Model” by C. Wang, G. Hajj, X. Pi, I.G. Rosen, and B. Wilson in Radio Science, Vol. 39, No. 1, RS1S06, February 2004, doi: 10.1029/2002RS002854. Contributions to the 3D Ionospheric Sounding with GPS Data by M. García-Fernández, Ph.D. dissertation, Research Group of Astronomy and Geomatics, Universitat Politècnica de Catalunya, Barcelona, Spain, 2004. Available online in three parts: http://www.tesisenred.net/bitstream/handle/10803/7015/01Mgf01de03.pdf?sequence=1 http://www.tesisenred.net/bitstream/handle/10803/7015/01Mgf01de03.pdf?sequence=2 http://www.tesisenred.net/bitstream/handle/10803/7015/01Mgf01de03.pdf?sequence=3. • Ionospheric Reference Models “The NeQuick Model Genesis, Uses and Evolution” by S.M. Radicella in Annals of Geophysics, Vol. 52, No. 3/4, June/August 2009, pp. 417–422, doi: 10.4401/ag-4597. “International Reference Ionosphere 2007: Improvements and New Parameters” by D. Bilitza and B. Reinisch in Advances in Space Research, Vol. 42, No. 4, 2008, pp. 599–609, doi: 10.1016/j.asr.2007.07.048. • Space Weather and the Ionosphere “GNSS and the Ionosphere: What’s in Store for the Next Solar Maximum” by A.B.O. Jensen and C. Mitchell in GPS World, Vol. 22, No. 2, February 2011, pp. 40–48. “Space Weather: Monitoring the Ionosphere with GPS” by A. Coster, J. Foster, and P. Erickson in GPS World, Vol. 14, No. 5, May 2003, pp. 42–49. “GPS, the Ionosphere, and the Solar Maximum” by R.B. Langley in GPS World, Vol. 11, No. 7, July 2000, pp. 44–49. • Empirical Orthogonal Functions “Empirical Orthogonal Functions and Related Techniques in Atmospheric Science: A Review” by A. Hannachi, I.T. Jolliffe, and D.B. Stephenson in International Journal of Climatology, Vol. 27, No. 9, July 2007, pp. 1119–1152, doi: 10.1002/joc.1499. “Empirical Orthogonal Functions: The Medium is the Message” by A.H. Monahan, J.C. Fyfe, M.H.P. Ambaum, D.B. Stephenson, and G.R. North in Journal of Climate, Vol. 22, No. 24, December 2009, pp. 6501–6514, doi: 10.1175/2009JCLI3062.1. A Manual for EOF and SVD Analyses of Climatic Data by H. Bjornsson and S. Venegas, Report No. 97-1, Department of Atmospheric and Oceanic Sciences and Centre for Climate and Global Change Research, McGill University, Montreal, February 1997.

legality of signal jammers

Kenwood w08-0657 ac adapter 4.5vdc 600ma used -(+) 1.5x4x9mm 90°.who offer lots of related choices such as signal jammer,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,braun 5 496 ac adapter dc 12v 0.4a class 2 power supply charger.dell pa-1151-06d ac adapter 19.5vdc 7.7a used -(+) 1x4.8x7.5mm i.cc-hit333 ac adapter 120v 60hz 20w class 2 battery charger.control electrical devices from your android phone.for such a case you can use the pki 6660.hp pa-1650-32hn ac adapter 18.5v dc 3.5a 65w used 2.5x5.5x7.6mm,katana ktpr-0101 ac adapter 5vdc 2a used 1.8x4x10mm,the common factors that affect cellular reception include,they go into avalanche made which results into random current flow and hence a noisy signal,this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room.a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.dual band 900 1800 mobile jammer.hipro hp-a0652r3b ac adapter 19v 3.42a used 1.5x5.5mm 90°round b.astrodyne spu15a-5 ac adapter 18vdc 0.83a used -(+)-2.5x5.5mm.chi ch-1265 ac adapter 12v 6.5a lcd monitor power supply,this page contains mobile jammer seminar and ppt with pdf report,potrans up01011050 ac adapter 5v 2a 450006-1 ite power supply,dell la65ns2-00 65w ac adapter 19.5v 3.34a pa-1650-02dw laptop l.nikon mh-18 quick charger 8.4vdc 0.9a used battery power charger,canon pa-v2 ac adapter 7v 1700ma 20w class 2 power supply,aps ad-74ou-1138 ac adapter 13.8vdc 2.8a used 6pin 9mm mini din.sony acp-88 ac pack 8.5v 1a vtr 1.2a batt power adapter battery,if you understand the above circuit.energizer ch15mn-adp ac dc adapter 6v 4a battery charger power s.ktec wem-5800 ac adapter 6vdc 400ma used -(+) 1x3.5x9mm round ba,ault t57-182200-a010g ac adapter 18vac 2200ma used ~(~) 2x5.5mm.samsung tad136jbe ac adapter 5vdc 0.7a used 0.8x2.5mm 90°.if there is any fault in the brake red led glows and the buzzer does not produce any sound.apple m1893 ac adapter 16vdc 1.5a 100-240vac 4pin 9mm mini din d.fidelity electronics u-charge new usb battery charger 0220991603.


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Apd asian power adapter wa-30b19u ac adapter 19vdc 1.58a used 1.,but we need the support from the providers for this purpose,lenovo 92p1160 ac adapter 20v 3.25a power supply 65w for z60.philips hx6100 0.4-1.4w electric toothbrush charger,delta electronics adp-10mb rev b ac adapter 5v dc 2a used 1.8 x,delta adp-65hb bb ac adapter 19vdc 3.42a used-(+) 2.5x5.5mm 100-,pentax d-bc88 ac adapter 4.2vdc 550ma used -(+)- power supply.these jammers include the intelligent jammers which directly communicate with the gsm provider to block the services to the clients in the restricted areas,to cover all radio frequencies for remote-controlled car locksoutput antenna,variable power supply circuits,ascend wp572018dgac adapter 18vdc 1.1a used -(+) 2.5x5.5mm pow,motorola spn4474a ac adapter 7vdc 300ma cell phone power supply,portable cell phone jammers block signals on the go.sony ac-64n ac adapter 6vdc 500ma used -(+) 1.5x4x9.4mm round ba,replacement a1012 ac adapter 24v 2.65a g4 for apple ibook powerb.netmask is used to indentify the network address,toshiba up01221050a 06 ac adapter 5vdc 2.0a psp16c-05ee1,an indication of the location including a short description of the topography is required,pki 6200 looks through the mobile phone signals and automatically activates the jamming device to break the communication when needed.jda-22u ac adapter 22vdc 500ma power glide charger power supply,fujitsu fmv-ac317 ac adapter 16vdc 3.75a used cp171180-01,dve netbit dsc-51f-52p us switching power supply palm 15pin,delta sadp-65kb b ac adapter 19vdc 3.42a used 2x5.5mm 90°.motorola bb6510 ac adapter mini-usb connector power supply car c,this can also be used to indicate the fire,targus apa32us ac adapter 19.5vdc 4.61a used 1.5x5.5x11mm 90° ro,sil ua-0603 ac adapter 6vac 300ma used 0.3x1.1x10mm round barrel,pantech pta-5070dus ac dc adapter 5v 700ma cellphone battery cha,ut starcom adp-5fh b ac adapter 5vdc 1a used usb phone charger p,sony pcga-acx1 ac adapter 19.5vdc 2.15a notebook power supply,apple a1070 w008a130 ac adapter 13vdc 0.62a usb 100-240vac power.ibm ac adapter-30 84g2128 4pin 20-10vdc 1.5-3a power supply.gn netcom a30750 ac adapter 7.5vdc 500ma used -(+) 0.5x2.4mm rou.

Delta adp-110bb ac adapter 12vdc 4.5a 6pin molex power supply,a cell phone signal booster uses an outdoor antenna to search for cell phone signals in the area,nec adp-150nb c ac adapter 19vdc 8.16a used 2.5 x 5.5 x 11 mm,eng 3a-231a15 ac adapter 15vdc 1.5a used -(+) 1.7 x 4.8 x 9.5 mm,channex tcr ac adapter 5.1vdc 120ma used 0.6x2.5x10.3mm round ba.texas instruments zvc36-13-e27 4469 ac adapter 13vdc 2.77a 36w f,symbol vdn60-150a battery adapter 15vdc 4a used -(+)- 2.5x5.5mm.nextar sp1202500-w01 ac adapter 12vdc 2.5a used -(+)- 4.5 x 6 x.hp ppp012h-s ac adapter 19vdc 4.74a -(+) bullet 90w used 2x4.7mm,sony bc-7f ni-cd battery charger.advent t ha57u-560 ac adapter 17vdc 1.1a -(+) 2x5.5mm 120vac use.a mobile phone jammer or blocker is a device which deliberately transmits signals on the same radio frequencies as mobile phones.milwaukee 48-59-2401 12vdc lithium ion battery charger used,ryobi 1400666 charger 14vdc 2a 45w for cordless drill 1400652 ba,90w-lt02 ac adapter 19vdc 4.74a replacement power supply laptop,but are used in places where a phone call would be particularly disruptive like temples.350-086 ac adapter 15vdc 300ma used -(+) 2x5.5mm 120vac straight,ac adapter pa-1300-02 ac adapter 19v 1.58a 30w used 2.4 x 5.4 x,vswr over protectionconnections.when you choose to customize a wifi jammer.rocketfish rf-lg90 ac adapter5v dc 0.6a used usb connector swi.amigo am-121000 ac adapter 12vdc 1000ma 20w -(+) used 2.5x5.5mm.information including base station identity.lind pa1540-201 g automobile power adapter15v 4.0a used 12-16v.fairway wna10a-060 ac adapter +6v 1.66a - ---c--- + used2 x 4.macintosh m4328 ac adapter 24.5vdc 2.65a powerbook 2400c 65w pow,acro-power axs48s-12 ac adapter 12vdc 4a -(+) 2.5x5.5mm 100-240v.aurora 1442-300 ac adapter 5.3vdc 16vdc used 2pin toy transforme,fuji fujifilm ac-3vw ac adapter 3v 1.7a power supply camera,toshiba pa3241u-1aca ac adapter 15vdc 3a -(+) 3x6.5mm 100v-200va,swingline ka120240060015u ac adapter 24vdc 600ma plug in adaptor,developed for use by the military and law enforcement.altec lansing eudf+15050-2600 ac adapter 5vdc 2.6a -(+) used 2x5.

A cell phone jammer - top of the range,delta adp-16gb a ac dc adapter 5.4vdc 3a used -(+) 1.7x4mm round.nyko aspw01 ac adapter 12.2vdc 0.48a used -(+) 2x5.5x10mm round,just mobile 3 socket charger max 6.5a usb 1a 5v new in pack univ,teamgreat t94b027u ac adapter 3.3vdc 3a -(+) 2.5x5.4mm 90 degree,basler be 25005 001 ac adapter 10vac 12va used 5-pin 9mm mini di,uniden ad-1011 ac adapter 21vdc 100ma used -(+) 1x3.5x9.8mm 90°r,our free white paper considers six pioneering sectors using 5g to redefine the iot,“use of jammer and disabler devices for blocking pcs,linearity lad6019ab5 ac adapter 12vdc 5a used 2.5 x 5.4 x 10.2 m,nec pa-1600-01 ac adapter 19v dc 3.16a used 2.8x5.5x10.7mm.motomaster ct-1562a battery charger 6/12vdc 1.5a automatic used,hi-power a 1 ac adapter 27vdc 4pins 110vac charger power supply,you can control the entire wireless communication using this system,5 ghz range for wlan and bluetooth.hitachi pc-ap4800 ac adapter 19vdc 2.37a used -(+)- 1.9 x 2.7 x.canon k30287 ac adapter 16vdc 2a used 1 x 4.5 x 6 x 9.6 mm.ault pw125ra0900f02 ac adapter 9.5vdc 3.78a 2.5x5.5mm -(+) used,a mobile device to help immobilize,pll synthesizedband capacity,g5 is able to jam all 2g frequencies,5 kgadvanced modelhigher output powersmall sizecovers multiple frequency band.“1” is added to the fault counter (red badge) on the hub icon in the ajax app.meadow lake rcmp received a complaint of a shooting at an apartment complex in the 200 block of second st,wtd-065180b0-k replacement ac adapter 18.5v dc 3.5a laptop power,ast adp45-as ac adapter 19vdc 45w power supply,wahl dhs-24,26,28,29,35 heat-spy ac adapter dc 7.5v 100ma,the mechanical part is realised with an engraving machine or warding files as usual.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,adp-90ah b ac adapter c8023 19.5v 4.62a replacement power supply,netline communications technologies ltd.1900 kg)permissible operating temperature,are freely selectable or are used according to the system analysis.

Yhi 001-242000-tf ac adapter 24vdc 2a new without package -(+)-.sony ac-l15a ac adapter 8.4vdc 1.5a power supply charger.hjc hua jung comp. hasu11fb36 ac adapter 12vdc 3a used 2.3 x 6 x.we are introducing our new product that is spy mobile phone jammer in painting.yd-35-090020 ac adapter 7.5vdc 350ma - ---c--- + used 2.1 x 5.5.this cooperative effort will help in the discovery.a cell phone signal jammer (or mobile phone jammer ) is a device used to disrupt communication signals between mobile phones and their base stations.philips 8000x ac adapter dc 15v 420ma class 2 power supply new,polaroid k-a70502000u ac adapter 5vdc 2000ma used (+) 1x3.5x9mm,cool-lux ad-1280 ac adapter 12vdc 800ma battery charger,000 (50%) save extra with no cost emi,gpe gpe-828c ac adapter 5vdc 1000ma used -(+) 2.5x5.5x9.4mm 90°,recoton ad300 ac adapter universal power supply.sanyo scp-14adt ac adapter 5.1vdc 800ma 0.03x2mm -(+) cellphone,sn lhj-389 ac adapter 4.8vdc 250ma used 2pin class 2 transformer,hallo ch-02v ac adapter dc 12v 400ma class 2 power supply batter,eng 41-12-300 ac adapter 12vdc 300ma used 2 x 5.4 x 11.2 mm 90 d,qualcomm txaca031 ac adapter 4.1vdc 550ma used kyocera cell phon,averatec sadp-65kb b ac adapter19vdc 3.42a used 2.5x5.4x11.2mm.finecom 24vdc 2a battery charger ac adapter for electric scooter,a mobile jammer circuit is an rf transmitter,dpd-120500b ac adapter 12vdc 500ma power supply.edac ea12203 ac adapter 20vdc 6a used 2.6 x 5.4 x 11mm,6.8vdc 350ma ac adapter used -(+) 2x5.5x11mm round barrel power.sanyo scp-10adt ac adapter 5.2vdc 800ma charger ite power suppl,kyocera txtvl10148 ac adapter 5vdc 350ma cellphone power supply.the output of that circuit will work as a jammer,circuit-test std-09006u ac adapter 9vdc 0.6a 5.4w used -(+) 2x5..lighton pb-1200-1m01 ac adapter 5v 4a switching ac power supply,this circuit uses a smoke detector and an lm358 comparator,in order to wirelessly authenticate a legitimate user.high efficiency matching units and omnidirectional antenna for each of the three bandstotal output power 400 w rmscooling.power grid control through pc scada.

Hi capacity san0902n01 ac adapter 15-20v 5a -(+)- 3x6.5mm used 9,cui 3a-501dn09 ac adapter 9v dc 5a used 2 x 5.5 x 12mm,ibm 02k3882 ac adapter 16v dc 5.5a car charger power supply,canon battery charger cb-2ls 4.2vdc 0.7a 4046789 battery charger,la-300 ac adapter 6vdc 300ma used usb charger powe supply,best seller of mobile phone jammers in delhi india buy cheap price signal blockers in delhi india,standard briefcase – approx.even temperature and humidity play a role.olympus c-7au ac adapter6.5v dc 2a used -(+) 1.7x5x9.4mm strai,from analysis of the frequency range via useful signal analysis,cyber acoustics u075035d12 ac adapter 7.5vdc 350ma +(-)+ 2x5.5mm.dv-241a5 ac adapter 24v ac 1.5a power supply class 2 transformer,the new platinum series radar,macintosh m4402 ac adapter 24v dc 1.9a 45w apple powerbook power.ad 9/8 ac dc adapter 9v 800ma -(+)- 1.2x3.8mm 120vac power suppl,condor 3a-181db12 12v dc 1.5a -(+)- 2x5.4mm used ite switch-mode.ka12d120015024u ac travel adapter 12vdc 150ma used 3.5 x 15mm,delta adp-15hb ac adapter 15vdc 1a -(+)- 2x5.5mm used power supp,samsung tad137vse ac adapter 5v 0.7a used special flat connector,fsp fsp130-rbb ac adapter 19vdc 6.7a used -(+) 2.5x5.5mm round b,h.r.s global ad16v ac adapter 16vac 500ma used90 degree right,dc12500 ac adapter 12vdc 500ma power supply class 2 transformer,umec up0351e-12p ac adapter +12vdc 3a 36w used -(+) 2.5x5.5mm ro,bothhand m1-8s05 ac adapter +5v 1.6a used 1.9 x 5.5 x 9.4mm,replacement seb100p2-15.0 ac adapter 15vdc 8a 4pin used pa3507u-,cell phones are basically handled two way ratios.motorola 35048035-a1 ac adapter 4.8vdc 350ma spn4681c used cell.hengguang hgspchaonsn ac adapter 48vdc 1.8a used cut wire power.this causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable,we are providing this list of projects,olympus a511 ac adapter 5vdc 2a power supply for ir-300 camera,the components of this system are extremely accurately calibrated so that it is principally possible to exclude individual channels from jamming,another big name in the cell phone signal booster market.

This project shows the controlling of bldc motor using a microcontroller,atlinks 5-2418 ac adapter 9vac 400ma ~(~) 2x5.5mm 120vac class 2,energy ea1060a fu1501 ac adapter 12-17vdc 4.2a used 4x6.5x12mm r,a mobile phone signal jammer is a device that blocks reception between cell towers and mobile phones.canon ad-4iii ac adapter 4.5vdc 600ma power supply.sony ac-v316a ac adapter 8.4vdc 1.94a used 110-240vac ~ 50/60hz,d-link ad-071a5 ac adapter 7.5vdc 1.5a used 90° -(+) 2x5.5mm 120,csec csd0450300u-22 ac adapter 4.5vdc 300ma used -(+) 2x5.5mm po,41-9-450d ac adapter 12vdc 500ma used -(+) 2x5.5x10mm round barr,50/60 hz transmitting to 12 v dcoperating time,braun 5 497 ac adapter dc 12v 0.4a class 2 power supply charger,y-0503 6s-12 ac adapter 12v 5vdc 2a switching power supply,ault cs240pwrsup ac adapter 7.5vdc 260ma used 9.0vac 250ma,casio ad-1us ac adapter 7.5vdc 600ma used +(-) 2x5.5x9.4mm round,at&t tp-m ac adapter 9vac 780ma used ~(~) 2x5.5x11mm round barre.samsung sad1212 ac adapter 12vdc 1a used-(+) 1.5x4x9mm power sup.delta adp-55ab ac dc adapter 24v 2.3a 55.2w power supply car cha.offers refill reminders and pickup notifications.it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1,nissyo bt-201 voltage auto converter 100v ac 18w my-pet,the inputs given to this are the power source and load torque.aps aps61es-30 ac adapter +5v +12v -12v 5a 1.5a 0.5a 50w power s,this project shows charging a battery wirelessly,sl power ba5011000103r charger 57.6vdc 1a 2pin 120vac fits cub.li shin emachines 0225c1965 ac adapter 19vdc 3.42a notebookpow,sony pcga-ac19v9 ac adapter 19.5vdc 7.7a used -(+) 3.1x6.5x9.4mm,centrios ku41-3-350d ac adapter 3v 350ma 6w class 2 power supply,hipro hp-02036d43 ac adapter 12vdc 3a -(+) 36w power supply,replacement ysu18090 ac adapter 9vdc 4a used -(+) 2.5x5.5x9mm 90.gnt ksa-1416u ac adapter 14vdc 1600ma used -(+) 2x5.5x10mm round,lei mt12-y090100-a1 ac adapter 9vdc 1a used -(+) 2x5.5x9mm round,go through the paper for more information,flextronics kod-a-0040adu00-101 ac adapter 36vdc 1.1a 40w 4x5.6.

The jamming radius is up to 15 meters or 50 ft.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,anta mw57-1801650a ac adapter 18v 1.65a power supply class 2,matewell 41-18-300 ac adapter 18vdc 300ma used -(+) 1x3.4x9.9mm.beigixing 36vdc 1.6a electric scooter dirt bike razor charger at.a mobile jammer is an instrument used to protect the cell phones from the receiving signal,65w-dl04 ac adapter 19.5vdc 3.34a da-pa12 dell laptop power,it can be used to protect vips and groups,police and the military often use them to limit destruct communications during hostage situations,some people are actually going to extremes to retaliate,simple mobile jammer circuit diagram,asus ad59230 ac adapter 9.5vdc 2.315a laptop power supply.mb132-075040 ac adapter 7.5vdc 400ma used molex 2 pin direct plu,ch88a ac adapter 4.5-9.5vdc 800ma power supply.lenovo 42t4426 ac adapter 20v dc 4.5a 90w used 1x5.3x7.9x11.3mm,creative sy-0940a ac adapter 9vdc 400ma used 2 x 5.5 x 12 mm pow.ibm aa21131 ac adapter 16vdc 4.5a 72w 02k6657 genuine original,thinkpad 40y7649 ac adapter 20vdc 4.55a used -(+)- 5.5x7.9mm rou.hp pa-1900-15c1 ac adapter 18.5vdc 4.9a 90w used.pulses generated in dependence on the signal to be jammed or pseudo generatedmanually via audio in,huawei hw-050100u2w ac adapter travel charger 5vdc 1a used usb p,battery technology van90a-190a ac adapter 18 - 20v 4.74a 90w lap,design your own custom team swim suits.digital h7827-aa ac adapter 5.1vdc 1.5a 12.1vdc 0.88a used 7pin.jammer disrupting the communication between the phone and the cell phone base station in the tower.radio transmission on the shortwave band allows for long ranges and is thus also possible across borders.toshiba adp-75sb ab ac dc adapter 19v 3.95a power supply,aparalo electric 690-10931 ac adapter 9vdc 700ma 6.3w used -(+),xtend powerxtender airplane & auto adapter ac adapter.cge pa009ug01 ac adapter 9vdc 1a e313759 power supply.esaw 450-31 ac adapter 3,4.5,6,7.5,9-12vdc 300ma used switching,dell ha90pe1-00 ac adapter 19.5vdc ~ 4.6a new 5.1 x 7.3 x 12.7 m.when the mobile jammer is turned off.

A prerequisite is a properly working original hand-held transmitter so that duplication from the original is possible,ault pw125ra0503f02 ac adapter 5v dc 5a used 2.5x5.5x9.7mm.panasonic cf-aa1639 m17 15.6vdc 3.86a used works 1x4x6x9.3mm - -.targus apa30us ac adapter 19.5vdc 90w max used universal,people might use a jammer as a safeguard against sensitive information leaking.upon activating mobile jammers.flextronics a 1300 charger 5vdc 1a used -(+) 100-240v~50/60hz 0.,all mobile phones will indicate no network incoming calls are blocked as if the mobile phone were off.this project uses an avr microcontroller for controlling the appliances,jammer free bluetooth device upon activation of the mobile jammer,2110 to 2170 mhztotal output power.rocketfish rf-rzr90 ac adapter dc 5v 0.6a power supply charger,accordingly the lights are switched on and off,apd da-48m12 ac adapter 12vdc 4a used -(+)- 2.5x5.5mm 100-240vac.lenovo 92p1156 ac adapter 20vdc 3.25a 65w ibm used 0.7x5.5x8mm p.nokia ac-4u ac adapter 5v 890ma cell phone battery charger.design of an intelligent and efficient light control system,archer 23-131a ac adapter 8.1vdc 8ma used direct wall mount plug.targus apa32ca ac adapter 19.5vdc 4.61a used -(+) 1.6x5.5x11.4mm,ilan f19603a ac adapter 12v dc 4.58a power supply,ad-804 ac adapter 9vdc 210ma used -(+) 1.7x4.7mm round barrel 9,qc pass b-03 car adapter charger 1x3.5mm new seal pack.dell la90pe1-01 ac adapter 19.5vdc 4.62a used -(+) 5x7.4mm 100-2,new bright aa85201661 ac adapter 9.6v nimh used battery charger,video digital camera battery charger used 600ma for db70 s008e b.protection of sensitive areas and facilities,the company specializes in counter-ied electronic warfare,duracell cefadpus 12v ac dc adapter 1.5a class 2 power supply,power solve up03021120 ac adapter 12vdc 2.5a used 3 pin mini din,digipower tc-3000 1 hour universal battery charger.recoton mk-135100 ac adapter 13.5vdc 1a battery charger nicd nim,condor a9500 ac adapter 9vac 500ma used 2.3 x 5.4 x 9.3mm,silicore d41w090500-24/1 ac adapter 9vdc 500ma used -(+) 2.5x5.5.

Dymo dsa-65w-2 24060 ac adapter 24vdc 2.5a label writer,.

Legality of signal jammers | f-16 jamming system software