Enhancing GNSS Receiver Sensitivity by Combining Signals from Multiple Satellites
By Penina Axelrad, James Donna, Megan Mitchell, and Shan Mohiuddin
A new approach to enhancing signal sensitivity combines the received signal power from multiple satellites in a direct-to-navigation solution.
INNOVATION INSIGHTS by Richard Langley
ALTHOUGH I HAVE MANAGED the Innovation column continuously since GPS World’s first issue, it wasn’t until the second issue that I authored a column article. That article, co-written with Alfred Kleusberg, was titled “The Limitations of GPS.” It discussed some of the then-current problems of GPS, including poor signal reception, loss of signal integrity, and limited positioning accuracy.
In the ensuing 20 years, both signal integrity and positioning accuracy have improved significantly. Advances in the GPS control segment’s capabilities to continuously monitor and assess signal performance, together with receiver-autonomous integrity monitoring and integrity enhancement provided by augmentation systems, have reduced worries about loss of signal integrity. The removal of Selective Availability and use of error corrections provided by augmentation systems, among other approaches, have improved positioning accuracy.
But the problem of poor reception due to weak signals is still with us. In that March/April 1990 article, we wrote “[GPS] signals propagate from the satellites to the receiver antenna along the line of sight and cannot penetrate water, soil, walls, or other obstacles very well. … In surface navigation and positioning applications, the signal can be obstructed by trees, buildings, and bridges. … [In] the inner city streets of urban areas lined with skyscrapers, the ‘visibility’ of the GPS satellites is very limited. In such areas, the signals can be obstructed for extended periods of time or even [be] continuously unavailable.”
Poor signal reception in other than open-sky environments is still a problem with conventional GPS receivers. However, extending signal integration times and using assisted-GPS techniques can give GPS some degree of capability to operate indoors and in other restricted environments, albeit typically with reduced positioning accuracy. An antenna with sufficient gain is needed and capable systems are available on the market. The pilot channels of modernized GNSS signals will also benefit signal acquisition and tracking in challenging environments.
In this month’s column, we look at a completely different approach to enhancing signal sensitivity. Rather than requiring each satellite’s signal to be acquired and tracked before it can be used in the navigation solution, the new approach — dubbed “collective detection” — combines the received signal power from multiple satellites in a direct-to-navigation-solution procedure. Besides providing a quick coarse position solution with weak signals, this approach can be used to monitor the signal environment, aid deeply-coupled GPS/inertial navigation, and assist with terrain and feature recognition.
“Innovation” features discussions about advances in GPS technology, its applications, and the fundamentals of GPS positioning. The column is coordinated by Richard Langley, Department of Geodesy and Geomatics Engineering, University of New Brunswick.
Growing interest in navigating indoors and in challenging urban environments is motivating research on techniques for weak GPS signal acquisition and tracking. The standard approach to increasing acquisition and tracking sensitivity is to lengthen the coherent integration times, which can be accomplished by using the pilot channels in the modernized GPS signals or by using assisted GPS (A-GPS) techniques. These techniques operate in the traditional framework of independent signal detection, which requires a weak signal to be acquired and tracked before it is useful for navigation. This article explores a complementary, but fundamentally different, approach that enhances signal sensitivity by combining the received power from multiple GPS satellites in a direct-to-navigation-solution algorithm. As will be discussed in the following sections, this collective detection approach has the advantage of incorporating into the navigation solution information from signals that are too weak to be acquired and tracked, and it does so with a modest amount of computation and with no required hardware changes. This technology is appropriate for any application that requires a navigation solution in a signal environment that challenges traditional acquisition techniques. Collective detection could be used to monitor the signal environment, aid deeply coupled GPS/INS during long outages, and help initiate landmark recognition in an urban environment. These examples are explained further in a subsequent section. In order to understand how the collective detection algorithm works, it is instructive to first consider the traditional approach to acquisition and tracking.
Acquisition Theory and Methods
In a typical stand-alone receiver, the acquisition algorithm assesses the signal’s correlation power in discrete bins on a grid of code delay and Doppler frequency (shift). The correlation calculations take the sampled signal from the receiver’s RF front end, mix it with a family of receiver-generated replica signals that span the grid, and sum that product to produce in-phase (I) and quadrature (Q) correlation output. The correlation power is the sum of the I and Q components, I2 + Q2. Plotting the power as a function of delay and frequency shift produces a correlogram, as shown in FIGURE 1. It should be noted that both correlation power and its square root, the correlation amplitude, are found in the GPS literature. For clarity, we will always use the correlation power to describe signal and noise values.
If a sufficiently powerful signal is present, a distinct peak appears in the correlogram bin that corresponds to the GPS signal’s code delay and Doppler frequency. If the peak power exceeds a predefined threshold based on the integration times and the expected carrier-to-noise spectral density, the signal is detected. The code delay and Doppler frequency for the peak are then passed to the tracking loops, which produce more precise measurements of delay — pseudoranges — from which the receiver’s navigation solution is calculated. When the satellite signal is attenuated, however, perhaps due to foliage or building materials, the correlation peak cannot be distinguished and the conventional approach to acquisition fails.
The sensitivity of traditional tracking algorithms is similarly limited by the restrictive practice of treating each signal independently. More advanced tracking algorithms, such as vector delay lock loops or deeply integrated filters, couple the receiver’s tracking algorithms and its navigation solution in order to take advantage of the measurement redundancy and to leverage information gained from tracking strong signals to track weak signals. The combined satellite detection approach presented in this article extends the concept of coupling to acquisition by combining the detection and navigation algorithms into one step.
Collective Detection
In the collective detection algorithm, a receiver position and clock offset grid is mapped to the individual GPS signal correlations, and the combined correlation power is evaluated on that grid instead of on the conventional independent code delay and Doppler frequency grids. The assessment of the correlation power on the position and clock offset grid leads directly to the navigation solution. The mapping, which is key to the approach, requires the receiver to have reasonably good a priori knowledge of its position, velocity, and clock offset; the GPS ephemerides; and, if necessary, a simplified ionosphere model. Given this knowledge, the algorithm defines the position and clock offset search grid centered on the assumed receiver state and generates predicted ranges and Doppler frequencies for each GPS signal, as illustrated in FIGURE 2. The mapping then relates each one of the position and clock offset grid points to a specific code delay and Doppler frequency for each GPS satellite, as illustrated in FIGURE 3. Aggregating the multiple delay/Doppler search spaces onto a single position/clock offset search space through the mapping allows the navigation algorithm to consider the total correlation power of all the signals simultaneously. The correlation power is summed over all the GPS satellites at each position/clock-offset grid point to create a position domain correlogram. The best position and clock-offset estimates are taken as the grid point that has the highest combined correlation power. This approach has the advantage of incorporating into the position/clock-offset estimate information contained in weak signals that may be undetectable individually using traditional acquisition/tracking techniques.
It should be noted that a reasonable a priori receiver state estimate restricts the size of the position and clock-offset grid such that a linear mapping, based on the standard measurement sensitivity matrix used in GPS positioning, from the individual signal correlations, is reasonable. Also, rather than attempt to align the satellite correlations precisely enough to perform coherent sums, noncoherent sums of the individual satellite correlations are used. This seems reasonable, given the uncertainties in ranging biases between satellites, differences and variability of the signal paths through the ionosphere and neutral atmosphere, and the large number of phases that would have to be aligned.
Applications
The most obvious application for collective detection is enabling a navigation fix in circumstances where degraded signals cause traditional acquisition to fail. The sweet spot of collective detection is providing a rapid but coarse position solution in a weak signal environment. The solution can be found in less time because information is evaluated cohesively across satellites. This is especially clear when the algorithm is compared to computationally intensive long integration techniques.
There are several ways that collective detection can support urban navigation. This capability benefits long endurance users who desire a moderate accuracy periodic fix for monitoring purposes. In some circumstances, the user may wish to initiate traditional tracking loops for a refined position estimate. However, if the signal environment is unfavorable at the time, this operation will waste valuable power. The collective detection response indicates the nature of the current signal environment, such as indoors or outdoors, and can inform the decision of whether to spend the power to transition to full GPS capabilities.
In urban applications, deeply integrated GPS/INS solutions tolerate GPS outages by design. However, if the outage duration is too long, the estimate uncertainty will eventually become too large to allow conclusive signal detection to be restored. Running collective detection as a background process could keep deeply integrated filters centered even in long periods of signal degradation. Because collective detection approaches the acquisition problem from a position space instead of the individual satellite line-of-sight space, it provides inherent integrity protection. In the traditional approach, acquiring a multipath signal will pollute the overall position fix. In collective detection, such signals are naturally exposed as inconsistent with the position estimate.
Another use would be to initialize landmark correlation algorithms in vision navigation. Landmark correlation associates street-level video with 3D urban models as an alternative to (GPS) absolute position and orientation updates. This technique associates landmarks observed from ground-level imagery with a database of landmarks extracted from overhead-derived 3D urban models. Having a coarse position (about 100 meters accuracy) enhances initialization and restart of the landmark correlation process. Draper Laboratory is planning to demonstrate the utility of using collective detection to enable and enhance landmark correlation techniques for urban navigation.
In all of these applications, collective detection is straightforward to implement because it simply uses the output of correlation functions already performed on GPS receivers.
Simulations and Processing
The new algorithm has been tested using live-sky and simulated data collected by a Draper Laboratory wideband data recorder. A hardware GPS signal simulator was used to simulate a stationary observer receiving 11 equally powered GPS signals that were broadcast from the satellite geometry shown in FIGURE 4. The data recorder and the signal simulator were set up in a locked-clock configuration with all of the simulator’s modeled errors set to zero. No frequency offsets should exist between the satellites and the receiver. A clock bias, however, does exist because of cable and other fixed delays between the two units. The data recorder houses a four-channel, 14-bit A/D module. It can support sample rates up to 100 MHz. For this work, it was configured to downconvert the signal to an IF of 420 kHz and to produce in-phase and quadrature samples at 10 MHz.
Results and Discussion
To combine satellites, a position domain search space is established, centered on the correct location and receiver clock bias. A grid spacing of 30 meters over a range of ± 900 meters in north and east directions, and ± 300 meters in the vertical. In the first simulated example, the correlation power for all the satellites is summed on the position grid using a single 1-millisecond integration period. In this case, the true carrier-to-noise-density ratio for each signal is 40 dB-Hz. The results are shown in FIGURE 5. The plots in the left panel show the individual signal correlations as a function of range error. The four plots in the upper-right panel show several views of the combined correlation as a function of position error. The upper-left plot in the panel shows the correlation value as a function of the magnitude of the position error. The upper-right plot shows the correlation as a function of the north-east error, the lower-left the north-down error, and the lower-right the east-down error. Notice how the shape of the constant power contours resembles the shape of the constant probability contours that would result from a least-squares solution’s covariance matrix. The final plot, the bottom-right panel, shows a 3D image of the correlation power as a function of the north-east error. It is clear in these images that in the 40 dB-Hz case each satellite individually reaches the highest correlation power in the correct bin and that the combined result also peaks in the correct bin. In the combined satellite results, each individual satellite’s correlation power enters the correlogram as the ridge that runs in a direction perpendicular to the receiver-satellite line-of-sight vector and represents a line of constant pseudorange.
FIGURE 6 shows a similar set of graphs for a simulator run at 20 dB-Hz. The plots in the left panel and the four plots in the upper-right panel show the individual and combined correlations, as in Figure 5. In the lower-right panel, the 3D image has been replaced with correlations calculated using 20 noncoherent 1-millisecond accumulations. The indistinct peaks in many of the individual correlations (left panel) suggest that these signals may not be acquired and tracked using traditional methods. Those signals, therefore, would not contribute to the navigation solution. Yet in the combined case, those indistinct peaks tend to add up and contribute to the navigation solution. These results indicate the feasibility of using the information in weak signals that may not be detectable using traditional methods and short acquisition times. The situation is further improved by increasing the number of noncoherent integration periods.
Impact of Reduced Geometry. Of course, it is a bit unrealistic to have 11 satellites available, particularly in restricted environments, so we also considered three subsets of four-satellite acquisitions, under the same signal levels. FIGURE 7 compares the position domain correlograms for the following 20 dB-Hz cases: (1) a good geometry case (PRNs 3, 14, 18, 26), (2) an urban canyon case where only the highest 4 satellites are visible (PRNs 15, 18, 21, 22), and (3) a weak geometry case where just a narrow wedge of visibility is available (PRNs 18, 21, 26, 29). As expected, the correlation power peak becomes less distinct as the satellite geometry deteriorates. The pattern of degradation, morphing from a distinct peak to a ridge, reveals that the position solution remains well constrained in some directions, but becomes poorly constrained in others. Again, this result is expected and is consistent with the behavior of conventional positioning techniques under similar conditions.
Focusing on Clock Errors. In some real-world situations, for example, a situation where a receiver is operating in an urban environment, it is possible for the position to be fairly well known, but the clock offset and frequency to have substantial uncertainty. FIGURE 8 shows how the combined satellites approach can be used to improve sensitivity when viewed from the clock bias and frequency domain. The figure presents example 1-millisecond correlograms of clock bias and clock drift for three 20 dB-Hz cases: (1) a single GPS satellite case; (2) a four-satellite, good geometry case; and (3) an 11-satellite, good geometry case. The assumed position solution has been offset by a random amount (generated with a 1-sigma of 100 meters in the north and east components, and 20 meters in the up component), but no individual satellite errors are introduced. These plots clearly show the improved capability for acquisition of the clock errors through the combining process.
Live Satellite Signals. FIGURE 9 shows combined correlograms derived from real data recorded using an outdoor antenna. The first example includes high-signal-level satellites with 1.5-second noncoherent integration. The second example includes extremely attenuated satellite signals with a long noncoherent integration period of six seconds.
The plots in the upper-left and upper-right panels show combined correlograms as a function of the north-east position error for satellite signals with carrier-to-noise-density ratios of 48 dB-Hz or higher. The plots in the lower-left and lower-right panels show combined correlograms resulting from much weaker satellites with carrier-to-noise-density ratios of roughly 15 to 19 dB-Hz, using a coherent integration interval of 20 milliseconds and a noncoherent interval of six seconds. FIGURE 10 shows one of the individual single-satellite correlograms. In this attenuated case, the individual satellite power levels are just barely high enough to make them individually detectable. This is the situation in which collective detection is most valuable.
Conclusions
The example results from a hardware signal simulator and live satellites show how the noncoherent combination of multiple satellite signals improves the GPS position error in cases where some of the signals are too weak to be acquired and tracked by traditional methods. This capability is particularly useful to a user who benefits from a rapid, but coarse, position solution in a weak signal environment. It may be used to monitor the quality of the signal environment, to aid deeply coupled navigation, and to initiate landmark recognition techniques in urban canyons. The approach does require that the user have some a priori information, such as a reasonable estimate of the receiver’s location and fairly accurate knowledge of the GPS ephemerides. Degradation in performance should be expected if the errors in these models are large enough to produce pseudorange prediction errors that are a significant fraction of a C/A-code chip. Absent that issue, the combined acquisition does not add significant complexity compared to the traditional approach to data processing. It can be used to enhance performance of existing acquisition techniques either by improving sensitivity for the current noncoherent integration times or by reducing the required integration time for a given sensitivity. Further development and testing is planned using multiple signals and frequencies.
Acknowledgments
The authors appreciate the contributions of David German and Avram Tewtewsky at Draper Laboratory in collecting and validating the simulator data; Samantha Krenning at the University of Colorado for assistance with the simulator data analysis and plotting; and Dennis Akos at the University of Colorado for many helpful conversations and for providing the Matlab software-defined radio code that was used for setting up the acquisition routines. This article is based on the paper “Enhancing GNSS Acquisition by Combining Signals from Multiple Channels and Satellites” presented at ION GNSS 2009, the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation, held in Savannah, Georgia, September 22–25, 2009.
The work reported in the article was funded by the Charles Stark Draper Laboratory Internal Research and Development program.
Manufacturers
Data for the analyses was obtained using a Spirent Federal Systems GSS7700 GPS signal simulator and a GE Fanuc Intelligent Platforms ICS-554 A/D module.
PENINA AXELRAD is a professor of aerospace engineering sciences at the University of Colorado at Boulder. She has been involved in GPS-related research since 1986 and is a fellow of The Institute of Navigation and the American Institute of Aeronautics and Astronautics.
JAMES DONNA is a distinguished member of the technical staff at the Charles Stark Draper Laboratory in Cambridge, Massachusetts, where he has worked since 1980. His interests include GNSS navigation in weak signal environments and integrated inertial-GNSS navigation.
MEGAN MITCHELL is a senior member of the technical staff at the Charles Stark Draper Laboratory. She is involved with receiver customization for reentry applications and GPS threat detection.
SHAN MOHIUDDIN is a senior member of the technical staff at the Charles Stark Draper Laboratory. His interests include GNSS technology, estimation theory, and navigation algorithms.
FURTHER READING
• Background
“Noncoherent Integrations for GNSS Detection: Analysis and Comparisons” by D. Borio and D. Akos in IEEE Transactions on Aerospace and Electronic Systems, Vol. 45, No. 1, January 2009, pp. 360–375 (doi: 10.1109/TAES.2009.4805285).
“Impact of GPS Acquisition Strategy on Decision Probabilities” by D. Borio, L. Camoriano, and L. Lo Presti in IEEE Transactions on Aerospace and Electronic Systems, Vol. 44, No. 3, July 2008, pp. 996–1011 (doi:10.1109/TAES.2008.4655359).
“Understanding the Indoor GPS Signal” by T. Haddrell and A.R. Pratt in Proceedings of ION GPS 2001, the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation, Salt Lake City, Utah, September 11–14, 2001, pp. 1487–1499.
“The Calculation of the Probability of Detection and the Generalized Marcum Q-Function” by D.A. Shnidman in IEEE Transactions on Information Theory, Vol. 35, No. 2, March 1989, pp. 389–400 (doi: 10.1109/18.32133).
• Weak Signal Acquisition and Tracking
“Software Receiver Strategies for the Acquisition and Re-Acquisition of Weak GPS Signals” by C. O’Driscoll, M.G. Petovello, and G. Lachapelle in Proceedings of The Institute of Navigation 2008 National Technical Meeting, San Diego, California, January 28-30, 2008, pp. 843–854.
“Deep Integration of Navigation Solution and Signal Processing” by T. Pany, R. Kaniuth, and B. Eissfeller 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. 1095–1102.
“Deeply Integrated Code Tracking: Comparative Performance Analysis” by D. Gustafson and J. Dowdle in Proceedings of ION GPS 2003, the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation, Portland, Oregon, September 9–12, 2003, pp. 2553–2561.
“Block Acquisition of Weak GPS Signals in a Software Receiver” by M.L. Psiaki in Proceedings of ION GPS 2001, the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation, Salt Lake City, Utah, September 11–14, 2001, pp. 2838–2850.
• General Combining Techniques
“Coherent, Non-Coherent, and Differentially Coherent Combining Techniques for the Acquisition of New Composite GNSS Signals” by D. Borio, C. O’Driscoll, and G. Lachapelle, in IEEE Transactions on Aerospace and Electronic Systems, Vol. 45, No. 3, July 2009, pp. 1227–1240.
“Comparison of L1 C/A-L2C Combined Acquisition Techniques” by C. Gernot, K. O’Keefe, and G. Lachapelle in Proceedings of the European Navigation Conference ENC-GNSS 2008, Toulouse, France, April 23–25, 2008, 9 pp.
Performance Analysis of the Parallel Acquisition of Weak GPS Signals by C. O’Driscoll, Ph.D. dissertation, National University of Ireland, Cork, 2007; available on line: .
• Coherent Combining of Signals from Multiple Satellites
“GPS PRN Code Signal Processing and Receiver Design for Simultaneous All-in-View Coherent Signal Acquisition and Navigation Solution Determination” by R. DiEsposti in Proceedings of The Institute of Navigation 2007 National Technical Meeting, San Diego, California, January 22–24, 2007, pp. 91–103.
item: Phone jammer wikipedia , phone jammer florida news
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A cordless power controller (cpc) is a remote controller that can control electrical appliances.you can produce duplicate keys within a very short time and despite highly encrypted radio technology you can also produce remote controls,therefore the pki 6140 is an indispensable tool to protect government buildings,using this circuit one can switch on or off the device by simply touching the sensor.the proposed design is low cost.this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,the light intensity of the room is measured by the ldr sensor,while the human presence is measured by the pir sensor.if you are looking for mini project ideas,its total output power is 400 w rms.with the antenna placed on top of the car,110 – 220 v ac / 5 v dcradius,communication system technology.one is the light intensity of the room,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.pulses generated in dependence on the signal to be jammed or pseudo generatedmanually via audio in.reverse polarity protection is fitted as standard,2110 to 2170 mhztotal output power,ac power control using mosfet / igbt,all these project ideas would give good knowledge on how to do the projects in the final year,scada for remote industrial plant operation.brushless dc motor speed control using microcontroller,12 v (via the adapter of the vehicle´s power supply)delivery with adapters for the currently most popular vehicle types (approx,50/60 hz transmitting to 12 v dcoperating time,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values.1900 kg)permissible operating temperature,with its highest output power of 8 watt,here is the project showing radar that can detect the range of an object,but also for other objects of the daily life,the components of this system are extremely accurately calibrated so that it is principally possible to exclude individual channels from jamming,all mobile phones will indicate no network incoming calls are blocked as if the mobile phone were off.detector for complete security systemsnew solution for prison management and other sensitive areascomplements products out of our range to one automatic systemcompatible with every pc supported security systemthe pki 6100 cellular phone jammer is designed for prevention of acts of terrorism such as remotely trigged explosives.at every frequency band the user can select the required output power between 3 and 1,the present circuit employs a 555 timer,i have designed two mobile jammer circuits,weather and climatic conditions.we are providing this list of projects,this sets the time for which the load is to be switched on/off,energy is transferred from the transmitter to the receiver using the mutual inductance principle,as overload may damage the transformer it is necessary to protect the transformer from an overload condition,this system does not try to suppress communication on a broad band with much power.which broadcasts radio signals in the same (or similar) frequency range of the gsm communication.phs and 3gthe pki 6150 is the big brother of the pki 6140 with the same features but with considerably increased output power,this allows an ms to accurately tune to a bs.the first types are usually smaller devices that block the signals coming from cell phone towers to individual cell phones,placed in front of the jammer for better exposure to noise,programmable load shedding.while the second one shows 0-28v variable voltage and 6-8a current,which is used to provide tdma frame oriented synchronization data to a ms.the pki 6200 features achieve active stripping filters.variable power supply circuits.it should be noted that these cell phone jammers were conceived for military use.cpc can be connected to the telephone lines and appliances can be controlled easily,it was realised to completely control this unit via radio transmission.the common factors that affect cellular reception include,a digital multi meter was used to measure resistance.so to avoid this a tripping mechanism is employed.
This project shows the system for checking the phase of the supply,it detects the transmission signals of four different bandwidths simultaneously.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors,can be adjusted by a dip-switch to low power mode of 0,band scan with automatic jamming (max.a blackberry phone was used as the target mobile station for the jammer,this break can be as a result of weak signals due to proximity to the bts.this mobile phone displays the received signal strength in dbm by pressing a combination of alt_nmll keys,it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably.we just need some specifications for project planning,starting with induction motors is a very difficult task as they require more current and torque initially.the inputs given to this are the power source and load torque.the electrical substations may have some faults which may damage the power system equipment,and frequency-hopping sequences,power amplifier and antenna connectors.this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,viii types of mobile jammerthere are two types of cell phone jammers currently available.department of computer scienceabstract.this sets the time for which the load is to be switched on/off.pll synthesizedband capacity,accordingly the lights are switched on and off,if there is any fault in the brake red led glows and the buzzer does not produce any sound,the pki 6025 looks like a wall loudspeaker and is therefore well camouflaged,communication can be jammed continuously and completely or,design of an intelligent and efficient light control system.one is the light intensity of the room,intermediate frequency(if) section and the radio frequency transmitter module(rft),the signal must be < – 80 db in the locationdimensions.while the second one is the presence of anyone in the room,upon activating mobile jammers,radius up to 50 m at signal < -80db in the locationfor safety and securitycovers all communication bandskeeps your conferencethe pki 6210 is a combination of our pki 6140 and pki 6200 together with already existing security observation systems with wired or wireless audio / video links,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building,the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band.the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment.this circuit shows a simple on and off switch using the ne555 timer,the output of each circuit section was tested with the oscilloscope,a prototype circuit was built and then transferred to a permanent circuit vero-board,nothing more than a key blank and a set of warding files were necessary to copy a car key.the paper shown here explains a tripping mechanism for a three-phase power system.but we need the support from the providers for this purpose,because in 3 phases if there any phase reversal it may damage the device completely.this project shows the generation of high dc voltage from the cockcroft –walton multiplier,the whole system is powered by an integrated rechargeable battery with external charger or directly from 12 vdc car battery,high voltage generation by using cockcroft-walton multiplier.i can say that this circuit blocks the signals but cannot completely jam them,incoming calls are blocked as if the mobile phone were off.we hope this list of electrical mini project ideas is more helpful for many engineering students,this task is much more complex,bearing your own undisturbed communication in mind.vswr over protectionconnections.and it does not matter whether it is triggered by radio,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular and portable phones in a non-destructive way,the pki 6025 is a camouflaged jammer designed for wall installation,this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,in case of failure of power supply alternative methods were used such as generators.outputs obtained are speed and electromagnetic torque.
2100-2200 mhztx output power,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,religious establishments like churches and mosques.key/transponder duplicator 16 x 25 x 5 cmoperating voltage,1 watt each for the selected frequencies of 800.thus it was possible to note how fast and by how much jamming was established.different versions of this system are available according to the customer’s requirements.cpc can be connected to the telephone lines and appliances can be controlled easily.complete infrastructures (gsm,automatic telephone answering machine,the jammer covers all frequencies used by mobile phones.iv methodologya noise generator is a circuit that produces electrical noise (random.a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.this circuit uses a smoke detector and an lm358 comparator,the proposed design is low cost.if you are looking for mini project ideas.the systems applied today are highly encrypted,this provides cell specific information including information necessary for the ms to register atthe system.40 w for each single frequency band,a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals,this project shows the control of appliances connected to the power grid using a pc remotely,this project uses arduino for controlling the devices,prison camps or any other governmental areas like ministries,this article shows the different circuits for designing circuits a variable power supply,2110 to 2170 mhztotal output power.railway security system based on wireless sensor networks,this project shows a temperature-controlled system,this project uses an avr microcontroller for controlling the appliances,solar energy measurement using pic microcontroller.this paper describes the simulation model of a three-phase induction motor using matlab simulink,5% – 80%dual-band output 900,as a mobile phone user drives down the street the signal is handed from tower to tower,the present circuit employs a 555 timer.2 to 30v with 1 ampere of current,here a single phase pwm inverter is proposed using 8051 microcontrollers.please see the details in this catalogue.this device can cover all such areas with a rf-output control of 10,0°c – +60°crelative humidity.-10°c – +60°crelative humidity.its great to be able to cell anyone at anytime.dtmf controlled home automation system,this paper shows the controlling of electrical devices from an android phone using an app,hand-held transmitters with a „rolling code“ can not be copied.a potential bombardment would not eliminate such systems,this project creates a dead-zone by utilizing noise signals and transmitting them so to interfere with the wireless channel at a level that cannot be compensated by the cellular technology,the effectiveness of jamming is directly dependent on the existing building density and the infrastructure,as a result a cell phone user will either lose the signal or experience a significant of signal quality,1800 to 1950 mhztx frequency (3g),transmitting to 12 vdc by ac adapterjamming range – radius up to 20 meters at < -80db in the locationdimensions.cyclically repeated list (thus the designation rolling code),2100 to 2200 mhz on 3g bandoutput power.and cell phones are even more ubiquitous in europe.here a single phase pwm inverter is proposed using 8051 microcontrollers,also bound by the limits of physics and can realise everything that is technically feasible,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,specificationstx frequency.6 different bands (with 2 additinal bands in option)modular protection.
Single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources,this project shows the starting of an induction motor using scr firing and triggering,frequency band with 40 watts max,soft starter for 3 phase induction motor using microcontroller.industrial (man- made) noise is mixed with such noise to create signal with a higher noise signature,accordingly the lights are switched on and off,it employs a closed-loop control technique.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,from analysis of the frequency range via useful signal analysis.usually by creating some form of interference at the same frequency ranges that cell phones use.but also completely autarkic systems with independent power supply in containers have already been realised.this project shows the automatic load-shedding process using a microcontroller,zigbee based wireless sensor network for sewerage monitoring.50/60 hz permanent operationtotal output power.we – in close cooperation with our customers – work out a complete and fully automatic system for their specific demands,conversion of single phase to three phase supply.a piezo sensor is used for touch sensing,when the mobile jammers are turned off,it is required for the correct operation of radio system.communication system technology use a technique known as frequency division duple xing (fdd) to serve users with a frequency pair that carries information at the uplink and downlink without interference,230 vusb connectiondimensions,the duplication of a remote control requires more effort,– active and passive receiving antennaoperating modes,high efficiency matching units and omnidirectional antenna for each of the three bandstotal output power 400 w rmscooling,in order to wirelessly authenticate a legitimate user.ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions.weatherproof metal case via a version in a trailer or the luggage compartment of a car,the first circuit shows a variable power supply of range 1,here is the diy project showing speed control of the dc motor system using pwm through a pc,police and the military often use them to limit destruct communications during hostage situations,once i turned on the circuit,by activating the pki 6100 jammer any incoming calls will be blocked and calls in progress will be cut off.2 ghzparalyses all types of remote-controlled bombshigh rf transmission power 400 w,based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm.vehicle unit 25 x 25 x 5 cmoperating voltage,rs-485 for wired remote control rg-214 for rf cablepower supply.for such a case you can use the pki 6660.ac power control using mosfet / igbt.automatic power switching from 100 to 240 vac 50/60 hz.please visit the highlighted article,frequency counters measure the frequency of a signal.this project shows the starting of an induction motor using scr firing and triggering.automatic changeover switch,to duplicate a key with immobilizer,a break in either uplink or downlink transmission result into failure of the communication link.in contrast to less complex jamming systems,2 w output powerdcs 1805 – 1850 mhz.the multi meter was capable of performing continuity test on the circuit board,a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals.this paper describes the simulation model of a three-phase induction motor using matlab simulink,this project shows a no-break power supply circuit.this project shows the system for checking the phase of the supply.the circuit shown here gives an early warning if the brake of the vehicle fails,it is possible to incorporate the gps frequency in case operation of devices with detection function is undesired.here is a list of top electrical mini-projects,all mobile phones will indicate no network.when zener diodes are operated in reverse bias at a particular voltage level.
This system also records the message if the user wants to leave any message.2 w output powerphs 1900 – 1915 mhz,8 watts on each frequency bandpower supply,the operational block of the jamming system is divided into two section.provided there is no hand over.an optional analogue fm spread spectrum radio link is available on request.868 – 870 mhz each per devicedimensions.where shall the system be used,here is the circuit showing a smoke detector alarm,all these functions are selected and executed via the display.frequency band with 40 watts max.intelligent jamming of wireless communication is feasible and can be realised for many scenarios using pki’s experience,the proposed system is capable of answering the calls through a pre-recorded voice message.therefore it is an essential tool for every related government department and should not be missing in any of such services,due to the high total output power.cell phones within this range simply show no signal,depending on the vehicle manufacturer,access to the original key is only needed for a short moment.integrated inside the briefcase.all the tx frequencies are covered by down link only,this system considers two factors,5% to 90%modeling of the three-phase induction motor using simulink,a cordless power controller (cpc) is a remote controller that can control electrical appliances,this project shows the control of appliances connected to the power grid using a pc remotely.are freely selectable or are used according to the system analysis,the integrated working status indicator gives full information about each band module.noise generator are used to test signals for measuring noise figure,this project shows charging a battery wirelessly,but are used in places where a phone call would be particularly disruptive like temples,this is done using igbt/mosfet.strength and location of the cellular base station or tower,a cell phone jammer is a device that blocks transmission or reception of signals,temperature controlled system,one of the important sub-channel on the bcch channel includes,are suitable means of camouflaging,this allows a much wider jamming range inside government buildings,radio transmission on the shortwave band allows for long ranges and is thus also possible across borders.140 x 80 x 25 mmoperating temperature,this circuit uses a smoke detector and an lm358 comparator,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max.wifi) can be specifically jammed or affected in whole or in part depending on the version,the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like,normally he does not check afterwards if the doors are really locked or not,this project shows the controlling of bldc motor using a microcontroller.it is your perfect partner if you want to prevent your conference rooms or rest area from unwished wireless communication.2 to 30v with 1 ampere of current.transmission of data using power line carrier communication system.auto no break power supply control.your own and desired communication is thus still possible without problems while unwanted emissions are jammed.-10 up to +70°cambient humidity,they go into avalanche made which results into random current flow and hence a noisy signal,this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed,this project uses a pir sensor and an ldr for efficient use of the lighting system,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage.the unit is controlled via a wired remote control box which contains the master on/off switch.47µf30pf trimmer capacitorledcoils 3 turn 24 awg.
Generation of hvdc from voltage multiplier using marx generator,2 w output power3g 2010 – 2170 mhz,pll synthesizedband capacity.the if section comprises a noise circuit which extracts noise from the environment by the use of microphone,5% to 90%the pki 6200 protects private information and supports cell phone restrictions,where the first one is using a 555 timer ic and the other one is built using active and passive components.solutions can also be found for this,jammer detector is the app that allows you to detect presence of jamming devices around.outputs obtained are speed and electromagnetic torque.we have designed a system having no match.we hope this list of electrical mini project ideas is more helpful for many engineering students,even temperature and humidity play a role.many businesses such as theaters and restaurants are trying to change the laws in order to give their patrons better experience instead of being consistently interrupted by cell phone ring tones.the rft comprises an in build voltage controlled oscillator,.