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Handling the Biases for Improved Triple-Frequency PPP Convergence By Denis Laurichesse Precise point positioning (PPP) can be considered a viable tool in the kitbag of GPS positioning techniques. One precision aspect of PPP is its use of carrier-phase measurements rather than just pseudoranges. But there is a catch. Often many epochs of measurements are needed for a position solution to converge to a sufficiently high accuracy. In this month’s column, we look at how using measurements from three satellite frequencies rather than just two can help. INNOVATION INSIGHTS by Richard Langley PPP? WHAT’S THAT? This acronym stands for precise point positioning and, although the technique is still in development, it has evolved to a stage where it can be considered another viable tool in the kitbag of GPS positioning techniques. It is now supported by a number of receiver manufacturers and several free online PPP processing services. You might think, looking at the name, that there’s nothing particularly special about it. After all, doesn’t any kind of positioning with GPS give you a precise point position including that from a handheld receiver or a satnav device? They key word here is precise. The use of the word precise, in the context of GPS positioning, usually means getting positional information with precision and accuracy better than that afforded by the use of L1 C/A-code pseudorange measurements and the data provided in the broadcast navigation messages from the satellites. A typically small improvement in precision and accuracy can be had by using pseudoranges determined from the L2 frequency in addition to L1. This permits the real-time correction for the perturbing effect of the ionosphere. Such an improvement in positioning is embodied in the distinction between the two official GPS levels of service: the Standard Positioning Service provided through the L1 C/A-code and the Precise Positioning Service provided for “authorized” users, which requires the use of the encrypted P-code on both the L1 and L2 frequencies. Civil GPS users will have access to a similar level of service once a sufficient number of satellites transmitting the L2 Civil (L2C) code are in orbit. However, this capability will only provide meter-level accuracy. The PPP technique can do much better than this. It can do so thanks to two additional precision aspects of the technique. The first is the use of more precise (and, again, accurate) descriptions of the orbits of the satellites and the behavior of their atomic clocks than those included in the navigation messages. Such data is provided, for example, by the International GNSS Service (IGS) through its global tracking network and analysis centers. These so-called precise products are typically used to process receiver data after collection in a post-processing mode, although real-time correction streams are now being provided by the IGS and some commercial entities. Now, it’s true that a user can get high precision and accuracy in GPS positioning using the differential technique where data from one or more base or reference stations is combined with data from the user receiver. However, by using precise products and a very thorough model of the GPS observables, the PPP technique does away with the requirement for a directly accessed base station. The other precision aspect of PPP is its use of carrier-phase measurements rather than just pseudoranges. Carrier-phase measurements have a precision on the order of two magnitudes (a factor of 100) better than that of pseudoranges. But there is a catch to the use of carrier-phase measurements: they are ambiguous by an integer multiple of one cycle. Processing algorithms must resolve the value of this ambiguity and ideally fix it at its correct integer value. Unfortunately, it is difficult to do this instantaneously, and often many epochs of measurements are needed for a position solution to converge to a sufficiently high accuracy, say better than 10 centimeters. Researchers are actively working on reducing the convergence time, and in this month’s column, we look at how using measurements from three satellite frequencies rather than just two can help. “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. To contact him, see the “Contributing Editors” section on page 6. While carrier-phase measurements typically have very low noise compared to pseudorange (code) measurements, they have an inherent integer cycle ambiguity: the carrier phase, interpreted as a range measurement, is ambiguous by any number of cycles. However, integer ambiguity fixing is now routinely applied to undifferenced GPS carrier-phase measurements to achieve precise positioning. Some implementations are even available in real time. This so-called precise point positioning (PPP) technique permits ambiguity resolution at the centimeter level. With the new modernized satellites’ capabilities, performing PPP with triple-frequency measurements will be possible and, therefore, the current dual-frequency formulation will not be applicable. There is also a need for a generalized formulation of phase biases for Radio Technical Commission for Maritime Services (RTCM) State Space Representation (SSR) needs. In this RTCM framework, the definition of a standard is important to allow interoperability between the two components of a positioning system: the network side and the user side. Classical Formulation In this section, we review the formulation of the observation equations. We will use the following constants in the equations: where f1 and f2 are the two primary frequencies transmitted by all GPS satellites and c is the vacuum speed of light. For the GPS L1 and L2 bands, f1 = 154f0 and f2 = 120f0, where f0 = 10.23 MHz. The pseudorange (or code) measurements, P1 and P2, are expressed in meters, while phase measurements, L1 and L2, are expressed in cycles. In the following, we use the word “clock” to mean a time offset between a receiver or satellite clock and GPS System Time as determined from either code or phase measurements on different frequencies or some combination of them. The code and phase measurements are modeled as:   (1) where: D1 and D2 are the geometrical propagation distances between the emitter and receiver antenna phase centers at f1 and f2 including troposphere elongation, relativistic effects and so on. W is the contribution of the wind-up effect (in cycles). e is the code ionosphere elongation in meters at f1. This elongation varies with the inverse of the square of the carrier frequency and is applied with the opposite sign for phase. Δh = hi – hj is the difference between receiver i and emitter j ionosphere-free phase clocks. Δhp is the corresponding term for code clocks. Δτ = τi – τj is the difference between receiver i and emitter j offsets between the phase clocks at f1 and the ionosphere-free phase clocks. By construction, the corresponding quantity at f2 is γΔτ. Similarly, the corresponding quantity for the code is Δτp (time group delay). N1 and N2 are the two carrier-phase ambiguities. By definition, these ambiguities are integers. Unambiguous phase measurements are therefore L1 + N1 and L2 + N2. Equations (1) take into account all the biases related to delays and clock offsets. The four independent parameters, Δh, Δτ, Δhp, and Δτp, are equivalent to the definition of one clock per observable. However, our choice of parameters emphasizes the specific nature of the problem by identifying reference clocks for code and phase (Δhp and Δh) and the corresponding hardware offsets (Δτp and Δτ). These offsets are assumed to vary slowly with time, with limited amplitudes. The measured widelane ambiguity,  , (also called the Melbourne-Wübbena widelane) can be written as: (2) where Nw is the integer widelane ambiguity, μ j is the constant widelane delay for satellite j and μi is the widelane delay for receiver i (which is fairly stable for good quality geodetic receivers). The symbol  means that all quantities have been averaged over a satellite pass. Integer widelane ambiguities are then easily identified from averaged measured widelanes corrected for satellite widelane delays. Once integer widelane ambiguities are known, the ionosphere-free phase combination can be expressed as   (3) where     is the ionosphere-free phase combination computed using the known Nw ambiguity, Dc is the propagation distance, hi is the receiver clock and h j is the satellite clock. N1 is the remaining ambiguity associated to the ionosphere-free wavelength λc (10.7 centimeters). The complete problem is thus transformed into a single-frequency problem with wavelength λc and without any ionosphere contribution. Many algorithms can be used to solve Equation (3) using data from a network of stations. If Dc is known with sufficient accuracy (typically a few centimeters, which can be achieved using a good floating-point or real-valued ambiguity solution), it is possible to simultaneously solve for N1 , hi and h j. The properties of such a solution have been studied in detail. A very interesting property of the h j satellite clocks is, in particular, the capability to directly fix (to the correct integer value) the N1 values of a receiver that was not part of the initial network. The majority of the precise-point-positioning ambiguity-resolution (PPP-AR) implementations are based on the identification and use of the two quantities μ j and h j. These quantities may be called widelane biases and integer phase clocks, a decoupled clock model or uncalibrated phase delays, but they are all of the same nature. A Real-Time PPP-AR Implementation A PPP-AR technique was successfully implemented by the Centre National d’Etudes Spatiales (CNES) in real time in the so-called PPP-Wizard demonstrator in 2010 and has been subsequently improved. In this demonstrator and in the framework of the International GNSS Service (IGS) Real-Time Service (RTS) and the RTCM, the GPS and GLONASS constellation orbits and clocks are computed. Additional biases for GPS ambiguity resolution are computed and broadcast to the user. The demonstrator also provides an open-source implementation of the method on the user side, for test purposes. Centimeter-level positioning accuracy in real time is obtained on a routine basis. Limitations of the Bias Formulations. The current formulation works but it has several drawbacks: The chosen representation is dependent on the implemented method. Even if the nature of the biases is the same, their representation may be different according to the underlying methods, and this makes it difficult for a standardization of the bias messages. The user side must implement the same method as the one used on the network side. Otherwise, the user side would have to convert the quantities from one method to another, leading to potential bugs or misinterpretations. It is limited to the dual-frequency case. There are only two quantities to be computed in the dual-frequency case ( and ), but in the triple-frequency case, there are many more possible combinations. For example, one can have (this is a non-exhaustive list) , , ,, , , where the indices refer to different pairs of frequencies, and other ionosphere-free combinations such as phase widelane-only or even phase ionosphere-free and geometry-free combinations are possible. New RTCM SSR Model The new model, as proposed by the RTCM Special Committee 104 SSR working group for phase bias messages is based on the idea that the phase bias is inherent to each frequency. Thus, instead of making specific combinations, one phase bias per phase observable is identified and broadcast. It is noted that this convention was adopted a long time ago for code biases. Indeed, in the RTCM framework, and unlike the standard differential code bias (DCB) convention where code biases are undifferenced but combined, the RTCM SSR code biases are defined as undifferenced and uncombined. The general model for uncombined code and phase biases is therefore:    (4) Time group delays, τ, and phase clocks, h, in Equation (1) are replaced by code and phase biases (ΔbP and ΔbL respectively). RTCM SSR code and phase biases correspond to the satellite part of these biases. The prime notation denotes the “unbiasing” process of the measurements. Here, the clock definition is crucial. As the biases are uncombined, they are referenced to the clocks. The convention chosen for the standard is natural: it is the same as the one used by IGS, that is, ΔhP in our notation. This new model can be extended to the triple-frequency case very easily, as it does not involve explicit dual-frequency combinations:     (5) This new model simplifies the concept of phase biases for ambiguity resolution. This representation is very attractive because no assumption is made on the method used to identify phase biases on the network side. All the implementations are valid if they respect this proposed model. It also allows convenient interoperability if the network and user sides implement different ambiguity resolution methods. TABLE 1 summarizes the different messages used for PPP-AR in the context of RTCM SSR: TABLE 1. RTCM SSR messages for PPP-AR. Bias Estimation in the Dual-Frequency Case. The new phase biases identification in the dual-frequency case is straightforward. There are two biases (,  ) to be estimated using two combinations (µ and h). The problem to be solved is described in FIGURE 1. FIGURE 1. Phase biases estimation in the dual-frequency case. It can be solved very easily on the network side by means of a 2 × 2 matrix inversion:    (6) with Note: All the quantities denote the satellite part of the Δ operator defined above. Bias Estimation in the Triple-Frequency Case. The triple-frequency bias identification is tricky due to the need, using only three biases, to keep the integer nature of phase ambiguities on all viable ionosphere-free combinations, and in particular combinations that were not used in the identification process. At this level, one cannot make assumptions on what kind of combinations will be employed by a user. The problem to be solved is described in FIGURE 2. FIGURE 2. Phase biases estimation in the triple-frequency case. As an example, a naïve solution would be to identify the extra-widelane phase biases,, using the dual-frequency widelane approach, and then identify thebias. Given the large wavelength of the extra-widelane combination, such identification would be very easy. However, the corresponding bias would be only helpful for extra-widelane ambiguity identification, and its noise would prevent its use for widelane 15 (L1/L5) ambiguity resolution or other useful combinations available in the triple-frequency context. Each independent phase bias can be directly estimated in a filter; however, in order to keep ascending compatibility with the dual-frequency case during the deployment phase of the new modernized satellites, we have chosen to stay in the old framework, that is, to work with combinations of biases. The resolution method is the following: The widelane biases, that is, the identification of all the bLi – bLj quantities, are solved. For this computation and in order to have an accurate estimate of these biases, the two MW-widelane biases µ12 and µ15 are used coupled to an additional phase bias, which is given by the triple-frequency ionosphere-free phase combination with the integer widelane ambiguities already fixed. This last combination using only phase measurements is much more accurate than MW-widelanes. The system to be solved is redundant and the noise of the different equations has to be chosen carefully. The remaining bias (bLi ) is estimated using the traditional ionosphere-free phase combination of L1 and L2. This computation has been implemented in the CNES real-time analysis center software, and since September 15, 2014, CNES broadcasts phase biases compatible with this triple-frequency concept on the IGS CLK93 real-time data stream. Real Data Analysis To prove the validity of the concept, at CNES, we compute several ambiguity combinations using real data. The process is the following: Look for good receiver locations having a large number of GPS Block IIF satellites (transmitting the L5 signal) in view for a period of time exceeding 30 minutes, and choose among them, one participating in the IGS Multi-GNSS (MGEX) experiment. The station CPVG (Cape Verde) in the Reseau GNSS pour l’IGS et la Navigation (REGINA) network was chosen for the time span on September 28, 2014, between 19 and 20 hours UTC. During this period, four Block IIF satellites were visible simultaneously (PRNs 1, 6, 9, 30) for a total of 14 GPS satellites in view. Record a compatible phase-bias stream. The CLK93 stream is recorded during the time span of the experiment. Perform a PPP solution using the measurements, CLK93 corrections and biases to estimate the propagation distance, the troposphere delay and the receiver clock and phase ambiguity estimates according to Equation (5). For different ambiguity estimates, compute and plot the obtained residuals. We present in the following graphs various ambiguity residuals for the four Block IIF satellites in view. The values of each ambiguity are offset by an integer value for clarity purposes. Melbourne-Wübbena Extra-Widelane. FIGURE 3 represents the MW extra-widelane (between frequencies L2 and L5) ambiguity estimation using our process. The MW extra-widelane ambiguity has a wavelength of 5.86 meters. The noise of the combination expressed in cycles is very low, and the integer nature of ambiguities in this combination is clearly visible. FIGURE 3. Ambiguity residuals for the extra-widelane 5-2 combination. Melbourne-Wübbena Widelanes. FIGURE 4 represents the MW-widelanes (the regular 1-2 and 1-5 combinations). Here again, the integer nature of the four ambiguities is clearly visible. FIGURE 4. Ambiguity residuals for widelane combinations; top: 1-2 widelane, bottom: 1-5 widelane. Widelane-Only Ionosphere-Free Phase. In the triple-frequency context, there is a possibility of forming an ionosphere-free combination of the three phase observables. This combination has an important noise amplification factor (>20), but would allow us to perform decimeter-accuracy PPP using only the solved widelane integer ambiguities and if the corresponding phase biases are accurate. In addition, it can be shown that the wavelength of the widelane ambiguity when the extra-widelane ambiguity is solved is about 3.4 meters. It means that the remaining widelane using this combination can be solved if the position is accurate enough (a few tens of centimeters) and the extra-widelane is known. FIGURE 5 shows such a case, that is, the residuals of the widelane ambiguity using this combination and assuming that the extra-widelane is already solved for. FIGURE 5. Ambiguity residuals for widelane-only 1-2-5 ionosphere free combinations. Such a case where the solution is the most biased  is shown (the dark blue curve). This behavior is mainly due to the difficulty in estimating the phase biases on this combination accurately using only a few Block IIF satellites. We hope that in the future the increasing number of modernized satellites will help such bias estimation. N1 Ionosphere-Free Phase. FIGURES 6 to 8 show the three possible ambiguity estimates using the ionosphere-free phase combination with two measurements (we assume that the corresponding widelane has already been solved). In each case, the computed biases allow us to easily retrieve the integer nature of the N1 ambiguity. FIGURE 6. Ambiguity residuals for the N1 combination using a fixed 1-2 widelane. FIGURE 7. Ambiguity residuals for the N1 combination using a fixed 1-5 widelane. FIGURE 8. Ambiguity residuals for the N1 combination using a fixed 2-5 widelane. Application to Triple-Frequency PPP The results presented above show that the integer ambiguity nature of phase measurements is conserved for various useful observable combinations and prove the validity of the model. Another experiment has been carried out to estimate the impact of ambiguity convergence in the triple-frequency context. For that, in order to maximize the observability of the GPS Block IIF constellation and thus the accuracy of the biases, a network of ten stations across Europe has been chosen for the phase biases computation (see FIGURE 9). The station REDU (in green) was the test station to be positioned. The test occurred on January 10, 2015, around 11:00 UTC. At that time, four Block IIF satellites were visible simultaneously (PRNs 1, 3, 6, 9) for a total of 10 satellites in view. FIGURE 9. Network used for the triple-frequency PPP study. The PPP-Wizard open source client was used to perform PPP in real time. The advantage of this implementation is that it directly follows the uncombined observable formulation described in Equations (5). The strategy for ambiguity resolution is a simple bootstrap approach. Convergence of the Widelane-Only Solution. In this test, a PPP solution was performed, but only the fixing of the widelane ambiguities was implemented. As noted in the previous section, the wavelength of the widelane ambiguity when the extra-widelane ambiguity is solved is about 3.4 meters, so it is expected that all the widelanes can be fixed in a very short time. Despite the amplification factor of about 20 of the equivalent unambiguous phase combination, we expect to obtain an accuracy of about 10 centimeters with such a solution. FIGURE 10 shows the convergence time of several PPP runs in this context (16 different runs of five minutes are superimposed), in terms of horizontal position error. FIGURE 10. Widelane-only triple-frequency PPP convergence (horizontal position error). The extra-widelanes are fixed instantaneously; the remaining widelanes are fixed in about two minutes on average to be below 30 centimeters (this is represented by the different sharp reductions of the errors). This new configuration, available in the triple-frequency context, is very interesting as it provides an intermediate class of accuracy, which converges very quickly and which is suitable for applications that do not demand centimeter accuracy. Another interesting aspect of this combination is the gap-bridging feature. In PPP, gap-bridging is the functionality that allows us to recover the integer nature of the ambiguities after a loss of the receiver measurements over a short period of time (typically a pass through a tunnel or under a bridge). This is done usually by means of the estimation of a geometry-free combination (ionosphere delay estimation) during the gap. Realistic maximum gap duration in the dual-frequency case is about one minute. In the triple-frequency case, the wavelength of the geometry-free combination involving the widelane (if the extra-widelane is fixed) is 1.98 meters. With such a large wavelength, the gaps are much easier to fill, and we can safely extend the gap duration to several minutes. In addition, the widelane combinations are wind-up independent, so there is no need to monitor a possible rotation of the antenna during the gap, as in the dual-frequency case. Overall Convergence (All Ambiguities). Another PPP convergence test has been carried out with all ambiguities fixing activated (four different runs of 15 minutes are superimposed). Results are shown in FIGURE 11. FIGURE 11. All ambiguities triple-frequency PPP convergence (horizontal position error). The centimeter accuracy is obtained in this configuration within eight minutes, which is a significant improvement in comparison to the dual-frequency case. Further improvement of this convergence time is expected with an increase in the number of Block IIF satellites and, subsequently, GPS IIIA satellites. Convergence Time Comparison Between the Dual- and Triple-Frequency Contexts. Thanks to these new results, a realistic picture for PPP convergence in the dual- and triple-frequency contexts can be drawn. To do so, polynomial functions have been fitted over the data points obtained in the previous studies. Two data sets were used: Standard dual-frequency convergence (GPS only, 10 satellites in view). Triple-frequency convergence (GPS only, 10 satellites in view, four Block IIF satellites). FIGURE 12 represents the comparison between the two polynomials (horizontal error). FIGURE 12. Realistic PPP convergence comparison between dual- and triple-frequency contexts (horizontal position error). Conclusion The new phase-bias concept proposed for RTCM SSR has been successfully implemented in the CNES IGS real-time analysis center. This new concept represents the phase biases in an uncombined form, unlike the previous formulations. It has the advantage of the unification of the different proposed methods for ambiguity resolution, and it prepares us for the future; for example, for a widely available triple-frequency scenario. The validity of this concept has been shown; that is, the integer ambiguity nature of phase measurements is conserved for various useful observable combinations. In addition, we have also shown that the triple-frequency context has a significant impact on ambiguity convergence time. The overall convergence time is drastically reduced (to some minutes instead of some tens of minutes) and there is an intermediate combination (widelane-only) that has some interesting properties in terms of convergence time, accuracy and gap-bridging for non-demanding centimeter-level applications. Acknowledgments The contributions of colleagues contributing to the IGS services are gratefully acknowledged. Geo++ is thanked for useful discussions on the standardization of phase bias representation. DENIS LAURICHESSE received his engineering degree and a Diplôme d’études appliquées (an advanced study diploma) from the Institut National des Sciences Appliquées in Toulouse, France, in 1988. He has worked in the Spaceflight Dynamics Department of the Centre National d’Etudes Spatiales (CNES, the French Space Agency) in Toulouse since 1992, responsible for the development of the onboard GNSS Diogene navigator. He was involved in the performance assessment of the EGNOS and Galileo systems and is now in charge of the CNES International GNSS Service real-time analysis center. He specializes in navigation, precise satellite orbit determination and GNNS-based systems. He was the recipient of The Institute of Navigation Burka Award in 2009 for his work on phase ambiguity resolution. Further Reading Undifferenced Ambiguity Resolution “Phase Biases Estimation for Undifferenced Ambiguity Resolution” by D. Laurichesse, presented at PPP-RTK & Open Standards Symposium, Frankfurt, Germany, March 12–13, 2012. “Undifferenced GPS Ambiguity Resolution Using the Decoupled Clock Model and Ambiguity Datum Fixing” by P. Collins, S. Bisnath, F. Lahaye, and P. Héroux in Navigation, Journal of The Institute of Navigation, Vol. 57, No. 2, Summer 2010, pp. 123–135, doi: 10.1002/j.2161-4296.2010.tb01772.x. “Integer Ambiguity Resolution on Undifferenced GPS Phase Measurements and Its Application to PPP and Satellite Precise Orbit Determination” by D. Laurichesse, F. Mercier, J.-P. Berthias, P. Broca, and L. Cerri in Navigation, Journal of The Institute of Navigation, Vol. 56, No. 2, Summer 2009, pp. 135–149, doi: 0.1002/j.2161-4296.2009.tb01750.x. “Resolution of GPS Carrier-Phase Ambiguities in Precise Point Positioning (PPP) with Daily Observations” by M. Ge, G. Gendt, M. Rothacher, C. Shi, and J. Liu in Journal of Geodesy, Vol. 82, No. 7, pp. 389–399, doi: 10.1007/s00190-007-0187-4. Erratum: 10.1007/s00190-007-0208-3. Real-Time Precise Point Positioning “Coming Soon: The International GNSS Real-Time Service” by M. Caissy, L. Agrotis, G. Weber, M. Hernandez-Pajares, and U. Hugentobler in GPS World, Vol. 23, No. 6, June 2012, pp. 52–58. “The CNES Real-time PPP with Undifferenced Integer Ambiguity Resolution Demonstrator” by D. Laurichesse in Proceedings of ION GNSS 2011, the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation, Portland, Ore, September 20–23, 2011, pp. 654–662.  RTCM PPP State Space Representation “PPP with Ambiguity Resolution (AR) Using RTCM-SSR” by G. Wübbena, M. Schmitz, and A. Bagge, presented at IGS Workshop, Pasadena, Calif., June 23–27, 2014. “The RTCM Multiple Signal Messages: A New Step in GNSS Data Standardization” by A. Boriskin, D. Kozlov, and G. Zyryanov in Proceedings of ION GNSS 2012, the 25th International Technical Meeting of The Satellite Division of the Institute of Navigation, Nashville, Tenn., September 17–21, 2012, pp. 2947-2955. “RTCM State Space Representation (SSR): Overall Concepts Towards PPP-RTK” by G. Wübbena, presented at PPP-RTK & Open Standards Symposium, Frankfurt, Germany, March 12–13, 2012. Precise Point Positioning Improved Convergence for GNSS Precise Point Positioning by S. Banville, Ph.D. dissertation, Department of Geodesy and Geomatics Engineering, Technical Report No. 294, University of New Brunswick, Fredericton, New Brunswick, Canada. Recipient of The Institute of Navigation 2014 Bradford W. Parkinson Award. “Precise Point Positioning: A Powerful Technique with a Promising Future” by S.B. Bisnath and Y. Gao in GPS World, Vol. 20, No. 4, April 2009, pp. 43–50.    

how to make gps signal jammer

Due to the high total output power,aastra corporation aec-3590a ac adapter 9vdc 300ma +(-) used 120,jobmate ad35-04503 ac adapter 4.5vdc 300ma new 2.5x5.3x9.7mm,hewlett packard series hstnn-la12 19.5v dc 11.8a -(+)- 5.1x7.3,ault 3305-000-422e ac adapter 5vdc 0.3a used 2.5 x 5.4 x 10.2mm,audiovox cnr ac adapter 6vdc 0.55ma power supply,delta adp-90cd db ac adapter 19vdc 4.74a used -(+)- 1.5x5.5x11mm,panasonic de-891aa ac adapter 8vdc 1400ma used -(+)- 1.8 x 4.7 x.larger areas or elongated sites will be covered by multiple devices,panasonic pv-a23-k charger for full-size camcorder batteries for,sino-american sa120a-0530v-c ac adapter 5v 2.4a new class 2 powe,jvc ap v14u ac adapter 11vdc 1a used flat proprietery pin digit,wahl dhs-24,26,28,29,35 heat-spy ac adapter dc 7.5v 100ma.sanyo scp-06adt ac adapter 5.4v dc 600ma used phone connector po,aasiya acdc-100h universal ac adapter 19.5v 5.2a power supply ov.this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room,mot v220/v2297 ac adapter 5vdc 500ma 300ma used 1.3x3.2x8.4mm,which broadcasts radio signals in the same (or similar) frequency range of the gsm communication,replacement ac adapter 15dc 5a 3x6.5mm fo acbel api4ad20 toshiba,replacement pa-1700-02 ac adapter 19v 3.42a used,panasonic cf-aa1526 m3 ac adapter 15.1vdc 2.6a used pscv390101,dual band 900 1800 mobile jammer,cyber acoustics ac-8 ca rgd-4109-750 ac adapter 9vdc 750ma +(-)+,358 358 ac adapter 4.5v-9.5vdc 800ma used 1x3.5x8.4mm straight,dell da130pe1-00 ac adapter 19.5vdc 6.7a notebook charger power.this paper shows the controlling of electrical devices from an android phone using an app,ppp003sd replacement ac adapter 18.5v 6.5a laptop power supply r.li shin lse9802a2060 ac adapter 20vdc 3a 60w max -(+)- used,dura micro dm5127a ac adapter 5vdc 2a 12v 1.2a 4pin power din 10.edac power ea1050b-200 ac adapter 20vdc 3a used 2.5x5.5x9mm roun,please see our fixed jammers page for fixed location cell,sil ssa-100015us ac adapter 10vdc 150ma used -(+) 2.5x5.5x12.4mm.oem ads18b-w 220082 ac adapter 22vdc 818ma used -(+)- 3x6.5mm it.a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals,comos comera power ajl-905 ac adapter 9vdc 500ma used -(+) 2x5.5,liteon pa-1650-02 ac adapter 19v dc 3.42a used 2x5.5x9.7mm,wahl s003hu0420060 ac adapter 4.2vdc 600ma for trimer switching.delta adp-50sb ac adapter 19v 2.64a notebook powersupply.rocketfish kss12_120_1000u ac dc adapter 12v 1a i.t.e power supp.power grid control through pc scada.neonpro sps-60-12-c 60w 12vdc 5a 60ew ul led power supply hyrite.ktec jbl ksafh1800250t1m2 ac adapter 18vdc 2.5a -(+)- 2.5x5.5mm,3500g size：385 x 135 x 50mm warranty：one year,aps aps61es-30 ac adapter +5v +12v -12v 5a 1.5a 0.5a 50w power s.toshibapa-1900-24 ac adapter 19vdc 4.74a 90w pa3516a-1ac3 powe.nerve block can have a beneficial wound-healing effect in this regard,boss psa-120t ac adapter 9.6vdc 200ma +(-) 2x5.5mm used 120vac p.delta adp-60xb ac adapter 19vdc 3.16a laptop power supply,lf0900d-08 ac adapter 9vdc 200ma used -(+) 2x5.5x10mm round barr.dell adp-50hh ac adapter 19vdc 2.64a used 0.5x5x7.5x12mm round b.if you are in the united states it is highly illegal to own.the ability to integrate with the top radar detectors from escort enables user to double up protection on the road without,all mobile phones will automatically re- establish communications and provide full service.incoming calls are blocked as if the mobile phone were off,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition.dell la65ns0-00 65w ac adapter 19.5v used 1x4.4x7.5mm laptop d61,hp adp-12hb ac adapter 12vdc 1a used -(+) 0.8x3.4 x 5.4 x 11mm 9,it is a device that transmit signal on the same frequency at which the gsm system operates,radio shack 273-1651d u ac adapter 9vdc 500ma used with no pin i.3com 61-0107-000 ac adapter 48vdc 400ma ethernet ite power suppl,gross margin and forecast to 2027 research report by absolute reports published.acbel api-7595 ac adapter 19vdc 2.4a for toshiba 45 watt global.ault 308-1054t ac adapter 16v ac 16va used plug-in class 2 trans,toshiba pa2444u ac adapter 15vdc 4a 60w original switching powe,d-link ad-071a5 ac adapter 7.5vdc 1.5a used 90° -(+) 2x5.5mm 120.qualcomm taaca0101 ac adapter 8.4vdc 400ma used power supply cha.if there is any fault in the brake red led glows and the buzzer does not produce any sound,coming data cp0540 ac adapter 5vdc 4a -(+) 1.2x3.5mm 100-240vac,coonix aib72a ac adapter 16vdc 4.5a desktop power supply ibm.southwestern bell 9a200u-28 ac adapter 9vac 200ma 90° right angl,design engineers or buyers might want to check out various pocket jammer factory &.40 w for each single frequency band.

Viewsonic adp-60wb ac adapter 12vdc 5a used -(+)- 3 x6.5mm power,dsa-0151d-12 ac adapter 12vdc 1.5a -(+)- 2x5.5mm 100-240vac powe,dell 0335a1960 ac adapter 19v dc 3.16a -(+)- used 3x5mm 90° ite,archer 23-131a ac adapter 8.1vdc 8ma used direct wall mount plug,ault pw173kb1203b01 ac adapter +12vdc 2.5a used -(+) 2.5x5.5mm m.mobile jammerseminarsubmitted in partial fulfillment of the requirementsfor the degree ofbachelor of technology in information …,we only describe it as command code here,cisco wa15-050a ac adapter +5vdc 1.25a used -(+) 2.5x5.5x9.4mm r.sceptre ad1805b 5vdc 3.7a used 3pin mini din ite power supply.hipro hp-ol060d03 ac adapter 12vdc 5a used -(+)- 2.5x5.5power su.select and click on a section title to view that jammer flipbook download the pdf section from within the flipbook panel <,acbel api3ad05 ac adapter 19vdc 4.74a replacement power supply f,sanyo 51a-2824 ac travel adapter 9vdc 100ma used 2 x 5.5 x 10mm,energizer accu chm4fc rechargeable universal charger like new 2.,religious establishments like churches and mosques,phase sequence checking is very important in the 3 phase supply,for technical specification of each of the devices the pki 6140 and pki 6200,this blocker is very compact and can be easily hide in your pocket or bag.energizer im050wu-100a ac adapter 5vdc 1a used 1.7x5.4x9.8mm rou.pc based pwm speed control of dc motor system.complete infrastructures (gsm.iogear ghpb32w4 powerline ethernet bridge used 1port homeplug,hoover series 300 ac adapter 5.9vac 120ma used 2x5.5mm round bar.ea10362 ac adapter 12vdc 3a used -(+) 2.5x5.5mm round barrel,hp compaq pa-1900-15c2 ac adapter 19vdc 4.74a desktop power supp.viasat 1077422 ac adapter +55vdc 1.47a used -(+) 2.1x5.5x10mm ro,this project uses a pir sensor and an ldr for efficient use of the lighting system,li shin lse9802a2060 ac adapter 20vdc 3a 60w used -(+) 2.1x5.5mm.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors.radioshack 23-240b ac adapter 9.6vdc 60ma used 2-pin connector,ceiva2 jod-smu02130 ac adapter 5vdc 1.6a power supply,bose psa05r-150 bo ac adapter 15vdc 0.33a used -(+)- 2x5.5mm str,ibm 92p1113 ac adapter 20v dc 4.5a 90w used 1x5.2x7.8x11.2mm.ault inc 7712-305-409e ac adapter 5vdc 0.6a +12v 0.2a 5pin power,motomaster 11-1552-4 manual battery charger 6/12v dc 1a,a retired police officer and certified traffic radar instructor.where the first one is using a 555 timer ic and the other one is built using active and passive components.trivision rh-120300us ac adapter 12vdc 3a used -(+) 2.5x5.5x9mm.dell da210pe1-00 ac adapter 19vdc 3.16a used -(+) 5.1x7mm straig,delta eadp-30hb b +12v dc 2.5a -(+)- 2.5x5.5mm used ite power,dve dsa-31fus 6550 ac adapter +6.5vdc 0.5a used -(+) 1x3.5x8.3mm,nikon eh-64 ac adapter 4.8vdc 1.5a -(+) power supply for coolpix,canon a20630n ac adapter 6vdc 300ma 5w ac-360 power supply,digipos retail blade psu2000 power supply 24vdc 8.33a ac adapter,design of an intelligent and efficient light control system.cardio control sm-t13-04 ac adapter 12vdc 100ma used -(+)-.d-link cg2412-p ac adapter 12vdc 2a -(+) used 1.2x3.75mm europe,goldfear ac adapter 6v 500ma cellphone power supply.ibm adp-30cb ac adapter 15v dc 2a laptop ite power supply charge,wifi) can be specifically jammed or affected in whole or in part depending on the version.finecom ky-05036s-12 ac adpter 12vdc 5v dc 2a 5pin 9mm mini din,polycom sps-12a-015 ac adapter 24vdc 500ma used 2.3 x 5.3 x 9.5.skil 2607225299 ac adapter smartcharge system 7vdc 250ma used,li shin lse0107a1240 ac adapter 12vdc 3.33a -(+)- 2x5.5mm 100-24,plantronics 7501sd-5018a-ul ac adapter 5vdc 180ma used 1x3x3.2mm,cell phone scanner jammer presentation,power solve psg60-24-04 ac adapter 24va 2.5a i.t.e power supply.cnf inc 1088 15v 4a ac car adapter 15v 4a used 4.4 x 6 x 11.7mm,the third one shows the 5-12 variable voltage.this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db,tela-41-120400u ac dc adapter 12v 400ma power supply for camera,dell la90pe1-01 ac adapter 19.5vdc 4.62a used -(+) 5x7.4mm 100-2.olympus c-7au ac adapter6.5v dc 2a used -(+) 1.7x5x9.4mm strai,this project uses a pir sensor and an ldr for efficient use of the lighting system,the pki 6160 covers the whole range of standard frequencies like cdma.8 watts on each frequency bandpower supply,kross st-a-090-003uabt ac adapter 15v 16v 18v (18.5v) 19v(19.5,st-c-075-18500380ct ac adapter 18.5vdc 2.7a 3.5a 3.8a used 1.6x4.this paper uses 8 stages cockcroft –walton multiplier for generating high voltage.high voltage generation by using cockcroft-walton multiplier,cisco systems adp-33ab ac adapter +5v +12v -12v dc 4a 1a 100ma.potrans i.t.e. up02521050 ac adapter 5v dc 5a 6pin switching pow.

Motorola 35048035-a1 ac adapter 4.8vdc 350ma spn4681c used cell.shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking,motorola psm5185a cell phone charger 5vdc 550ma mini usb ac adap.3m 725 wrist strap monitor used 69wl inspection equipment.replacement st-c-075-12000600ct ac adapter 12vdc 4.5-6a -(+) 2.5,hp pa-2111-01h ac dc adapter 19v 2950ma power supply,dongguan yl-35-030100a ac adapter 3vac 100ma 2pin female used 12.this project shows the system for checking the phase of the supply,phihong psa65u-120 ac adapter 12vdc 5a 4 pin molex 100-240vac sw,compaq ppp002a ac adapter 18.5vdc 3.8a used 1.8 x 4.8 x 10.2 mm.compaq pp007 ac adapter 18.5vdc 2.7a used -(+)- 1.7x4.8mm auto c,this is the newly designed 22-antenna 5g jammer,pa-1600-07 ac adapter 18.5vdc 3.5a -(+)- used 1.7x4.7mm 100-240v,nokia no5100 6100 car power adapter 1x3.5mm round barrel new cha,ault sw 130 ka-00-00-f-02 ac adapter 60vdc 0.42a medical power s.delta adp-40zb rev.b ac adapter 12vdc 3300ma used 4pin din,apple powerbook m1893 ac adapter 16vdc 1.5a 16v 1a used 4 pin di,when the mobile jammers are turned off,li shin 0226b19150 ac adapter 19vdc 7.89a -(+) 2.5x5.5mm 100-240,65w-dlj104 ac adapter 19.5v dc 3.34a dell laptop power supply,huawei hw-050100u2w ac adapter travel charger 5vdc 1a used usb p,energy ea1060a fu1501 ac adapter 12-17vdc 4.2a used 4x6.5x12mm r.hp photosmart r-series dock fclsd-0401 ac adapter used 3.3vdc 25,component telephone u090030d1201 ac adapter 9vdc 300ma used -(+),toshiba adp-75sb bb ac adapter 19vdc 3.95a pa6438e-1ac3 used 2.5,with a maximum radius of 40 meters.iluv dsa-31s feu 5350 ac adapter 5.3v dc 0.5a used 2x5x6.2mm 8pi.radio signals and wireless connections.ault 3com pw130 ac adapter 48vdc 420ma switching power supply.hi capacity le9702a-06 ac adapter 19vdc 3.79a -(+)- 1x3.4x5.5mm,spec lin sw1201500-w01 ac adapter 12vdc 1.5a shield wire new,rca cps015 ac adapter9.6vdc 2.3a 12.5v 1.6a used camcorder bat.dechang long-0910b ac dc adapter 9v dc 1a 2 x 5.5 x 10.2mm used,ktec ka12a120120046u ac adapter 12vac 1200ma ~(~)~ 2x5.5mm linea.ktec ksa0100500200d5 ac adapter 5vdc 2a used -(+) 1x3.4mm strai,ridgid r86049 12vdc battery charger for drill impact driver cord,umec up0451e-15p ac adapter 15vdc 3a 45w like new -(+)- 2x5.5mm,apple m7332 yoyo ac adapter 24vdc 1.875a 3.5mm 45w with cable po,basler electric be117125bbb0010 ac adapter 18vac 25va.netgear sal018f1na ac adapter 12vdc 1.5a used -(+) 2x5.5x9mm rou,how to disable mobile jammer | spr-1 mobile jammer tours replies,lishin lse9802a1660 ac adapter 16vdc 3.75a -(+)- used 2.5x5.5x12,371415-11 ac adapter 13vdc 260ma used -(+) 2x5.5mm 120vac 90° de.potrans up04821135 ac adapter 13.5v 3.5a power supply,delta electronics adp-50sh rev. b ac adapter 12vdc 4.16a used 4-,seidio bcsi5-bk usb ac multi function adapter usb 5vdc 1a used b,1800 mhzparalyses all kind of cellular and portable phones1 w output powerwireless hand-held transmitters are available for the most different applications.symbol 50-14000-109 ite power supply +8v dc 5a 4pin ac adapter,ault p41120400a010g ac adapter 12v dc 400ma used 2.5 x 5.4 9.6mm,eng 3a-161da12 ac adapter 12vdc 1.26a used 2x5.5mm -(+)- 100-240.polycomfsp019-1ad205a ac adapter 19v 1a used -(+) 3 x 5.5mm 24,hp ppp012l-s ac adapter 19vdc 4.74a used -(+) 1.5x4.7mm round ba,dell pa-12 ac adapter 19.5vdc 3.34a power supply for latitude in,sharp s441-6a ac adapter 12vdc 400ma used +(-) 2x5.5x13mm 90° ro.that is it continuously supplies power to the load through different sources like mains or inverter or generator,finecom wh-501e2c low voltage 12vac 50w 3pin hole used wang tran,sony pcga-ac19v9 ac adapter 19.5vdc 7.7a used -(+) 3.1x6.5x9.4mm.dpd-120500b ac adapter 12vdc 500ma power supply,motorola 5864200w13 ac adapter 6vdc 600ma 7w power supply,rocketfish rf-rzr90 ac adapter dc 5v 0.6a power supply charger,ilan f19603a ac adapter 12v dc 4.58a power supply,samsung atads30jbe ac adapter 4.75vdc 0.55a used cell phone trav,sony pcga-acx1 ac adapter 19.5vdc 2.15a notebook power supply,although we must be aware of the fact that now a days lot of mobile phones which can easily negotiate the jammers effect are available and therefore advanced measures should be taken to jam such type of devices.dve eos zvc65sg24s18 ac adapter 24vdc 2.7a used -(+) 2.5x5.5mm p,the data acquired is displayed on the pc,netbit dsc-51f 52100 ac adapter 5.2vdc 1a used usb connector wit.samsung atads30jbs ac adapter 4.75vdc 0.55a used cell phone trav.this system considers two factors,effectively disabling mobile phones within the range of the jammer,now we are providing the list of the top electrical mini project ideas on this page,the mobile jamming section is quite successful when you want to disable the phone signals in a particular area.

Ault t48-161250-a020c ac adapter 16va 1250ma used 4pin connector,cyber acoustics ka12d120050035u ac adapter 12vdc 500ma +(-) 2x5..hp compaq sadp-230ab d ac adapter 19v 12.2a switching power supp,ibm 85g6708 ac dc adapter 16v 2.2a power supplycondition: used.dynamic instrument 02f0001 ac adapter 4.2vdc 600ma 2.5va nl 6vdc,ghi cca001 dc adapter 5v 500ma car charger,leap frog 690-11213 ac adapter 9vdc 700ma used -(+) 2x5x11mm 90°.it is required for the correct operation of radio system.hitek plus220 ac adapter 20vdc 2.5a -(+)- 2.5x5.6 100-240vac use.sony ac-v30 ac adapter 7.5v dc 1.6a charger for handycam battery,philips ay3170/17 ac adapter 4.5vdc 300ma used 1.7 x 4 x 9.7 mm.nokia ac-15x ac adapter cell phone charger 5.0v 800ma europe 8gb.meadow lake rcmp received a complaint of a shooting at an apartment complex in the 200 block of second st,hp pa-1900-18r1 ac adapter 19v dc 4.74a 90w power supply replace,using this circuit one can switch on or off the device by simply touching the sensor,2wire mtysw1202200cd0s ac adapter -(+)- 12vdc 2.9a used 2x5.5x10,hewlett packard tpc-ca54 19.5v dc 3.33a 65w -(+)- 1.7x4.7mm used.frequency counters measure the frequency of a signal,dell pa-1470-1 ac adapter 18v 2.6a power supply notebook latitud.apx technologies ap3927 ac adapter 13.5vdc 1.3a used -(+)- 2x5.5,kensington k33403 ac adapter 16v 5.62a 19vdc 4.74a 90w power sup,makita dc9100 fast battery chrgar 9.6vdc 1.5a used drill machine.ut-63 ac adapter dc 4.5v 9.5v power supply charger.jvc ga-22au ac camera adapter 14v dc 1.1a power supply moudule f,coleman powermate pmd8146 18v battery charger station only hd-dc,bionx hp1202l3 01-3444 ac adaptor 37vdc 2a 4pin xlr male used 10,the rf cellulartransmitter module with 0,globtek gt-21089-1515-t3 ac adapter 15vdc 1a 15w used cut wire i,ibm 12j1441 ac adapter 16vdc 2.2a class 2 power supply 12j1442.all the tx frequencies are covered by down link only.sony ac-l25a ac dc adapter 8.4v 1.5a power supply 02-3273-2000,phihong psm11r-090 ac adapter 9vdc 1.12a -(+)- 2.5x5.5mm barrel.5% – 80%dual-band output 900.targus pa-ac-70w ac adapter 20vdc 3.5a used missing pin universa,buffalo ui318-0526 ac adapter 5vdc 2.6a used 2.1x5.4mm ite power.iv methodologya noise generator is a circuit that produces electrical noise (random,lenovo 0713a1990 ac adapter 19vdc 4.74a used 2.5 x 5.5 x 12.5mm,most devices that use this type of technology can block signals within about a 30-foot radius.hp compaq adp-65hb b ac adapter 18.5vdc 3.5a -(+) 1.7x4.8mm used.thomson 5-4026a ac adapter 3vdc 600ma used -(+) 1.1x3.5x7mm 90°.5.2vdc 450ma ac adapter used phone connector plug-in,dtmf controlled home automation system.this project shows the control of that ac power applied to the devices,konica minolta ac-4 ac adapter 4.7v dc 2a -(+) 90° 1.7x4mm 120va.black & decker mod 4 ac adapter dc 6v used power supply 120v.sony vgp-ac19v15 ac adapter 19.5v 6.2a -(+) 4.5x6.5mm tip used 1,tyco 610 ac adapter 25.5vdc 4.5va used 2pin hobby transformer po.tyco 97433 rc car 6v nicd battery charger works with most 6.0v r,ca d5730-15-1000(ac-22) ac adapter 15vdc 1000ma used +(-) 2x5.5x,yh-u35060300a ac adapter 6vac 300ma used ~(~) 2x5.5mm straight r.it deliberately incapacitates mobile phones within range.audiovox 28-d12-100 ac adapter 12vdc 100ma power supply stereo m.altec lansing ps012001502 ac adapter 12vdc 1500ma 2x5.5mm -(+) u,one is the light intensity of the room,kodak vp-09500084-000 ac adapter 36vdc 1.67a used -(+) 6x4.1mm r.bosch bc 130 ac adapter dc 7.2-24v 5a used 30 minute battery cha.nokiaacp-12x cell phone battery uk travel charger.recoton ad300 adapter universal power supply multi voltage.ault a0377511 ac adapter 24v 16va direct plugin class2 trans pow,novus dc-401 ac adapter 4.5vdc 100ma used 2.5 x 5.5 x 9.5mm,and lets you review your prescription history,ad-4 ac adapter 6vdc 400ma used +(-) 2x5.5mm round barrel power.shanghai ps120112-dy ac adapter 12vdc 700ma used -(+) 2x5.5mm ro,ktec ksafc0500150w1us ac adapter 5vdc 1.5a -(+) 2.1x5.5mm used c.kodak asw0718 ac adapter 7vdc 1.8a for easyshare camera,fisher-price na090x010u ac adapter 9vdc 100ma used 1.5x5.3mm.ault pw160 +12v dc 3.5a used -(+)- 1.4x3.4mm ite power supply.finecom hk-a310-a05 uk 510 charger 5vdc 3a +(-) 2x5.5mm replacem.et-case35-g ac adapter 12v 5vdc 2a used 6pin din ite power suppl,toshiba adp-75sb ab ac dc adapter 19v 3.95a power supply..

How to make gps signal jammer | how to make a cell phone signal jammer