Exploiting terrestrial signals of opportunity (SOPs) can significantly reduce the vertical dilution of precision (VDOP) of a GNSS navigation solution. Simulation and experimental results show that adding cellular SOP observables is more effective in reducing VDOP than adding GNSS space vehicle (SV) observables. By Joshua J. Morales, Joe J. Khalife and Zaher M. Kassas GNSS position solutions can in many cases suffer from a high vertical dilution of precision (VDOP) due to lack of space vehicle (SV) angle diversity. Signals of opportunity (SOPs) have been recently considered to enable navigation whenever GNSS signals become inaccessible or untrustworthy. Terrestrial SOPs are abundant and are available at varying geometric configurations, making them an attractive supplement to GNSS for reducing VDOP. Common metrics used to assess the quality of the spatial geometry of GNSS SVs are the parameters of the geometric dilution of precision (GDOP); namely, horizontal dilution of precision (HDOP), time dilution of precision (TDOP), and VDOP. Several methods have been investigated for selecting the best GNSS SV configuration to improve the navigation solution by minimizing the GDOP. While the navigation solution is always improved by additional observables from GNSS SVs, the solution’s VDOP generally remains of lesser quality than the HDOP. GPS augmentation with terrestrial transmitters that transmit GPS-like signals have been shown to reduce VDOP. However, this requires installation of additional proprietary infrastructure. This article studies VDOP reduction by exploiting terrestrial SOPs, particularly cellular code division multiple access (CDMA) signals, which have inherently low elevation angles and are free to use. In GNSS-based navigation, the states of the SVs are readily available. For SOPs, however, even though the position states may be known a priori, the clock-error states are dynamic; hence, they must be continuously estimated. The states of SOPs can be made available through one or more receivers in the navigating receiver’s vicinity. Here, the estimates of such SOPs are exploited and the VDOP reduction is evaluated. PROBLEM FORMULATION Consider an environment comprising a receiver, M GNSS SVs, and N terrestrial SOPs. Each SOP will be assumed to emanate from a spatially stationary transmitter, and its state vector, xsop(n), will consist of its three-dimensional (3-D) position rsop(n) and clock bias cδtsop(n), where n=1,…,N and c is the speed of light. The receiver draws pseudorange observations from the GNSS SVs and from the SOPs. The observations are fused through an estimator whose role is to estimate the state vector of the receiver xr=[rrT, cδtr] T, where rr and cδtr are the 3D position and clock bias of the receiver, respectively. To simplify the discussion, assume that the pseudorange observation noise is independent and identically distributed across all channels with variance σ2. The estimator produces an estimate of the receiver’s state vector and associated estimation error covariance P =σ2(HTH)-1. Without loss of generality, assume an East-North-Up (ENU) coordinate frame to be centered at . In this frame, the dilution of precision matrix G≡(HTH)-1 is completely determined by the azimuth and elevation angles from the receiver to each SV, denoted azsv(m) and elsv(m), respectively, and the receiver to each SOP, denoted azsop(n) and elsop(n), respectively, where m=1,…,M. Hence, the quality of the estimate depends on these angles and the pseudorange observation noise variance σ2. The diagonal elements of G, denoted gii, are the parameters of the dilution of precision (DOP) factors: Therefore, the DOP values are directly related to the estimation error covariance; hence, the more favorable the azimuth and elevation angles, the lower the DOP values. If the observation noise was not independent and identically distributed, the weighted DOP factors must be used. VDOP REDUCTION VIA SOPs With the exception of GNSS receivers mounted on high-flying and space vehicles, all GNSS SVs are typically above the receiver, that is, the receiver-to-SV elevation angles are theoretically limited between 0°≤elsv(m)≤90°. GNSS receivers typically restrict the lowest elevation angle to some elevation mask, elsv,min, so to ignore GNSS SV signals that are heavily degraded due to the ionosphere, troposphere and multipath. As a consequence, GNSS SV observables lack elevation angle diversity, and the VDOP of a GNSS-based navigation solution is degraded. For ground vehicles, elsv,min is typically between 5° and 20°. These elevation angle masks also apply to low-flying aircraft, such as small unmanned aerial vehicles (UAVs), whose flight altitudes are limited to 500 feet (approximately 152 meters) by the Federal Aviation Administration (FAA). In GNSS + SOP-based navigation, the elevation angle span may effectively double, specifically –90°≤elsop(n)≤90°. For ground vehicles, useful observations can be made on terrestrial SOPs that reside at elevation angles of elsop(n)=0°. For aerial vehicles, terrestrial SOPs can reside at elevation angles as low as elsop(n)=–90°, for example, if the vehicle is flying directly above the SOP transmitter. To illustrate the VDOP reduction by incorporating additional GNSS SV observations versus additional SOP observations, an additional observation at elnew is introduced, and the resulting VDOP(elnew) is evaluated. To this end, M SV azimuth and elevation angles were computed using GPS ephemeris files accessed from the Yucaipa, California, station from Garner GPS Archive, which are tabulated in Table 1. Table 1. SV azimuth and elevation angle (degrees). For each set of GPS SVs, the azimuth angle of an additional observation was chosen as a random sample from a uniform distribution between 0° and 360°, that is, aznew~U(0°,360°). The corresponding VDOP for introducing an additional measurement at a sweeping elevation angle –90°≤elnew≤90° are plotted in Figure 1 (a)–(d) for M=4,…,7, respectively. Figure 1. A receiver has access to M GPS SVs from Table 1. Plots (a)- (d) show the VDOP for each GPS SV configuration before adding an additional measurement (red dotted line) and the resulting VDOP(elnew) for adding an additional measurement (blue curve) at an elevation angle –90°≤elnew≤90° for M=4,…,7, respectively. The following can be concluded from these plots. First, while the VDOP is always improved by introducing an additional measurement, the improvement of adding an SOP measurement is much more significant than adding an additional GPS SV measurement. Second, for elevation angles inherent only to terrestrial SOPs, that is, –90°≤elsop(n)≤0°, the VDOP is monotonically decreasing for decreasing elevation angles. SIMULATION RESULTS To compare the VDOP of a GNSS-only navigation solution with a GNSS + SOP navigation solution, simulations were conducted using receivers mounted on ground and aerial vehicles. Ground Receiver. The position of a receiver mounted on a ground vehicle was set to rr ≡(106 )•[– 2.431171,– 4.696750, 3.553778]T expressed in an Earth-Centered-Earth-Fixed (ECEF) coordinate frame. The elevation and azimuth angles of the GPS SV constellation above the receiver over a 24-hour period was computed using GPS SV ephemeris files from the Garner GPS Archive. The elevation mask was set to elsv,min≡20°. The azimuth and elevation angles of three SOPs, which were calculated from surveyed terrestrial cellular CDMA tower positions in the navigating receiver’s vicinity, were set to azsop≡[42.4°,113.4°,230.3° ]T and elsop ≡[3.53°,1.98°,0.95°]T, respectively. The resulting VDOP, HDOP, GDOP and associated number of available GPS SVs for a 24-hour period starting from midnight, Sept. 1, 2015, are plotted in Figure 2. 20° as a function of time. Fig. (b)-(d) correspond to the resulting VDOP, HDOP, and GDOP, respectively, of the navigation solution using GPS only, GPS + 1 SOP, GPS + 2 SOPs, and GPS + 3 SOPs. Source: Joshua J. Morales, Joe J. Khalife and Zaher M. Kassas" width="600" height="630" srcset="https://www.gpsworld.com/wp-content/uploads/2016/03/VDOP_compare_large_big_legend-W.jpg 600w, https://www.gpsworld.com/wp-content/uploads/2016/03/VDOP_compare_large_big_legend-W-238x250.jpg 238w, https://www.gpsworld.com/wp-content/uploads/2016/03/VDOP_compare_large_big_legend-W-286x300.jpg 286w" sizes="(max-width: 600px) 100vw, 600px" />Figure 2. Fig. (a) represents the number of SVs with an elevation angle >20° as a function of time. Fig. (b)-(d) correspond to the resulting VDOP, HDOP, and GDOP, respectively, of the navigation solution using GPS only, GPS + 1 SOP, GPS + 2 SOPs, and GPS + 3 SOPs. The following can be concluded from these plots. First, the resulting VDOP using GPS + N SOPs for N≥1 is always less than the resulting VDOP using GPS alone. Second, using GPS + N SOPs for N≥1 prevents large spikes in VDOP when the number of GPS SVs drops. Third, using GPS + N SOPs for N≥1 also reduces both HDOP and GDOP. Unmanned Aerial Vehicle. The initial position of a receiver mounted on a UAV was set to rr ≡(106 )•[–2.504728, –4.65991, 3.551203]T. The receiver’s true trajectory evolved according to velocity random walk dynamics. Pseudorange observations on all available GPS SVs above an elevation mask set to elsv,min≡20° and three terrestrial SOPs were generated using a MATLAB-based simulator. The simulator used SV trajectories which were computed using GPS SV ephemeris files from Sept. 1, 2015, 10:00 to 10:03 a.m. The positions of the SOPs were set to rsop(1)≡(106)•[– 2.504953,– 4.659550, 3.551292]T, rsop(2)≡(106)•[– 2.503655, –4.659645, 3.552050]T, and rsop(3)≡(106)•[– 2.504124,– 4.660430, 3.550646]T, which are the locations of surveyed cellular towers in the UAV’s vicinity. The UAV’s true trajectory, navigation solution from using only GPS SV pseudoranges, and navigation solution from using GPS and SOP pseudoranges are illustrated in Figure 3 (top). The corresponding 95th-percentile uncertainty ellipsoids for a sample set of navigation solutions are illustrated in Figure 3 (bottom). Figure 3 . Simulation results for a UAV flying over downtown Los Angeles.Top: Illustration of the true trajectory (red curve), navigation solution from using pseudoranges from six GPS SVs (yellow curve), and navigation solution from using pseudoranges from six GPS SVs and three cellular CDMA SOPs (blue curve).Bottom: Illustration of uncertainty ellipsoid (yellow) of GPS only navigation solution and uncertainty ellipsoid (blue) of GPS + SOP navigation solution. The following can be noted from these plots. First, the accuracy of the vertical component of the GPS-only navigation solution is worse than that of the GPS + SOP navigation solution. Second, the uncertainty in the vertical component of the GPS-only navigation solution is larger than that of the GPS + SOP navigation solution, which is captured by the yellow and blue uncertainty ellipsoids, respectively. Third, the accuracy of the horizontal component of the navigation solution is also improved by incorporating cellular SOP pseudorange observations alongside GPS SV pseudorange observations. EXPERIMENTAL RESULTS A field experiment was conducted using software-defined receivers (SDRs) to demonstrate the reduction of VDOP obtained from including SOP pseudoranges alongside GPS pseudoranges for estimating the states of a receiver. To this end, two antennas were mounted on a vehicle to acquire and track multiple GPS signals and three cellular base transceiver stations (BTSs) whose signals were modulated through CDMA. The GPS and cellular signals were simultaneously downmixed and synchronously sampled via two universal software radio peripherals (USRPs). These front-ends fed their data to the Multichannel Adaptive TRansceiver Information eXtractor (MATRIX) SDR, developed at the Autonomous Systems Perception, Intelligence and Navigation (ASPIN) Laboratory at the University of California, Riverside. The LabVIEW-based MATRIX SDR produced pseudorange observables from five GPS L1 C/A signals in view and the three cellular BTSs. Figure 4 depicts the experimental hardware setup. Figure 4. Experiment hardware setup. The pseudoranges were drawn from a receiver located at rr≡(106)•[– 2.430701,– 4.697498, 3.553099]T, expressed in an ECEF frame, which was surveyed using a carrier-phase differential GPS receiver. The corresponding SOP state estimates were collaboratively estimated by receivers in the navigating receiver’s vicinity. The pseudoranges and SOP estimates were fed to a least-squares estimator, producing x^r and associated P from which the VDOP, HDOP, and GDOP were calculated and tabulated in Table 2 for M GPS SVs and N cellular CDMA SOPs. A sky plot of the GPS SVs used is shown in Figure 5. Figure 5. Left: Sky plot of GPS SVs: 14, 21, 22, and 27 used for the four SV scenarios. Right: Sky plot of GPS SVs: 14, 18, 21, 22, and 27 used for the five SV scenarios. The elevation mask, elsv,min, was set to 20° (dashed circle). The tower locations, receiver location and a comparison of the resulting 95th-percentile estimation uncertainty ellipsoids of for {M,N}={5,0} and {5,3} are illustrated in Figure 6. Figure 6. Top: Cellular CDMA SOP tower locations and receiver location. Bottom: Uncertainty ellipsoid (yellow) of navigation solution from using pseudoranges from five GPS SVs and uncertainty ellipsoid (blue) of navigation solution from using pseudoranges from five GPS SVs and three cellular CDMA SOPs. The corresponding vertical error was 1.82 meters and 0.65 meters respectively. Hence, adding three SOPs to the navigation solution that used five GPS SVs reduced the vertical error by 64.3 percent. Although this is a significant improvement over using GPS observables alone, improvements for aerial vehicles are expected to be even more significant, since they can exploit a full span of observable elevation angles as demonstrated in the simulation section. Table 2. DOP values for M SVs + N SOPs. CONCLUSION This article studied the VDOP reduction of a GNSS-based navigation solution by exploiting terrestrial SOPs. It was demonstrated that the VDOP of a GNSS solution can be reduced by exploiting the inherently small elevation angles of terrestrial SOPs. Experimental results using ground vehicles equipped with SDRs demonstrated VDOP reduction of a GNSS navigation solution by exploiting a varying number of cellular CDMA SOPs. Incorporating terrestrial SOP observables alongside GNSS SV observables for VDOP reduction is particularly attractive for aerial systems, since a full span of observable elevation angles becomes available. MANUFACTURERS Two National Instruments universal software radio peripherals were used in the experiment. A Trimble 5700 receiver surveyed the experimental receiver location. JOSHUA J. MORALES is pursuing a Ph.D. in electrical and computer engineering at the University of California, Riverside. JOE J. KHALIFEH is a Ph.D. student at the University of California, Riverside. ZAHER (ZAK) M. KASSAS is an assistant professor at the University of California, Riverside. He received a Ph.D. in electrical and computer engineering from the University of Texas at Austin. Previously, he was a research and development engineer with the LabVIEW Control Design and Dynamical Systems Simulation Group at National Instruments Corp. This article is based on a technical paper presented at the 2016 ION ITM conference in Monterey, California.
cell phone & gps jammer threatThe multi meter was capable of performing continuity test on the circuit board,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably,this system also records the message if the user wants to leave any message,-20°c to +60°cambient humidity,an indication of the location including a short description of the topography is required,10 – 50 meters (-75 dbm at direction of antenna)dimensions.90 % of all systems available on the market to perform this on your own,commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,the frequency blocked is somewhere between 800mhz and1900mhz,scada for remote industrial plant operation,2100 to 2200 mhzoutput power.so to avoid this a tripping mechanism is employed,this can also be used to indicate the fire,when shall jamming take place,the control unit of the vehicle is connected to the pki 6670 via a diagnostic link using an adapter (included in the scope of supply), ,50/60 hz transmitting to 24 vdcdimensions,2w power amplifier simply turns a tuning voltage in an extremely silent environment.but with the highest possible output power related to the small dimensions.it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1,once i turned on the circuit.our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations.please see the details in this catalogue,the inputs given to this are the power source and load torque.while the second one shows 0-28v variable voltage and 6-8a current,868 – 870 mhz each per devicedimensions,the operating range is optimised by the used technology and provides for maximum jamming efficiency.power grid control through pc scada,2100 – 2200 mhz 3 gpower supply.additionally any rf output failure is indicated with sound alarm and led display,we hope this list of electrical mini project ideas is more helpful for many engineering students.specificationstx frequency. This jammer jams the downlinks frequencies of the global mobile communication band- gsm900 mhz and the digital cellular band-dcs 1800mhz using noise extracted from the environment,while the second one is the presence of anyone in the room,5% to 90%modeling of the three-phase induction motor using simulink.weather and climatic conditions,we are providing this list of projects,the whole system is powered by an integrated rechargeable battery with external charger or directly from 12 vdc car battery,the mechanical part is realised with an engraving machine or warding files as usual.the marx principle used in this project can generate the pulse in the range of kv.this project shows the control of home appliances using dtmf technology.a digital multi meter was used to measure resistance,pll synthesizedband capacity,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students.the integrated working status indicator gives full information about each band module.this is as well possible for further individual frequencies.you can control the entire wireless communication using this system,i introductioncell phones are everywhere these days,as overload may damage the transformer it is necessary to protect the transformer from an overload condition.and frequency-hopping sequences.design of an intelligent and efficient light control system.when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,in contrast to less complex jamming systems.the predefined jamming program starts its service according to the settings,the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment,mobile jammer can be used in practically any location,and cell phones are even more ubiquitous in europe.here a single phase pwm inverter is proposed using 8051 microcontrollers,the output of each circuit section was tested with the oscilloscope.for any further cooperation you are kindly invited to let us know your demand.it can also be used for the generation of random numbers.a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification.viii types of mobile jammerthere are two types of cell phone jammers currently available,i can say that this circuit blocks the signals but cannot completely jam them,can be adjusted by a dip-switch to low power mode of 0. Band scan with automatic jamming (max.vi simple circuit diagramvii working of mobile jammercell phone jammer work in a similar way to radio jammers by sending out the same radio frequencies that cell phone operates on,key/transponder duplicator 16 x 25 x 5 cmoperating voltage.here is the project showing radar that can detect the range of an object.variable power supply circuits.the frequencies extractable this way can be used for your own task forces,almost 195 million people in the united states had cell- phone service in october 2005.are freely selectable or are used according to the system analysis,4 ah battery or 100 – 240 v ac,impediment of undetected or unauthorised information exchanges,this project uses arduino and ultrasonic sensors for calculating the range.a piezo sensor is used for touch sensing,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building,90 %)software update via internet for new types (optionally available)this jammer is designed for the use in situations where it is necessary to inspect a parked car,we just need some specifications for project planning,please visit the highlighted article,this project shows the automatic load-shedding process using a microcontroller,the circuit shown here gives an early warning if the brake of the vehicle fails.providing a continuously variable rf output power adjustment with digital readout in order to customise its deployment and suit specific requirements,theatres and any other public places,there are many methods to do this.thus it was possible to note how fast and by how much jamming was established,this project shows the controlling of bldc motor using a microcontroller,. 4g lte 4g wimax cell phone jammercell phone jammer walmarthidden cellphone jammer headphonescellphone and wifi jammercell phone jammer Newrycell phone & gps jammer threatcell phone & gps jammer ukcell phone & gps jammer ukcell phone & gps jammer ukcell phone & gps jammer uk cell phone & gps jammer yellowcell phone & gps jammer modelcell phone & gps jammer storescell phone & gps jammer illegalcell phone & gps jammer on animalcell phone & gps jammer threatcell phone & gps jammer threatcell phone & gps jammer threatcell phone & gps jammer threatcell phone & gps jammer threat
Otd-chg2-3.7-300 ac adapter 4.2vdc 300ma used 2.5mm jack.component telephone u093040d ac adapter 9vdc 400ma linear power,new iphone 7 6 6s plus ipod touch 5th nano usb data sync charger cable cord,0°c – +60°crelative humidity,new 5v 800ma netgear pwr-002-007 power supply ac adapter,hp envy 15 series intel cpu fan 576837-001,new 9v 200ma safety 1st. muld3509200 power supply adapter,. https://jammers.store/5g-jammer-c-34.html?lg=g www.jalanlcd.comgpshjammergps jammer work jobs
Sharp radp-a012sde0 ac adapter 6v 400ma plug in power supply,hp compaq original 417220-001 ac adapter 18.5v 3.5a 65w for 383494-001 ac-c14 dc359a 146594-001 179725-002 163444-291 pa.phihong psa15r-050p switching power supply wall charger adapter (lot of 3) brand: phihong output voltage: 5v mpn: d,new 12vdc 1000ma cui inc. tead-48-121000ut dtd120100-p5/rd-cd power supply ac adapter,sony ac-s24v1 ac power adapter charger for picture station photo printers 24v output voltage(s): 24 v modified item:,new lifespan fitness r3 & c3 recumbent exercise bike ac/dc adapter,ac power adapter 19v 3.5a power supply cord charger for acer al1703 al1714 al1714cb-8 lcd monitor.microsoft psm03r-055p ac adapter x809335-002 5.2v 500ma 0.5a,. www.iwdbaltimore.com
