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An Introduction to Bandwidth, Gain Pattern, Polarization and All That How do you find best antenna for particular GNSS application, taking into account size, cost, and capability? We look at the basics of GNSS antennas, introducing the various properties and trade-offs that affect functionality and performance. Armed with this information, you should be better able to interpret antenna specifications and to select the right antenna for your next job. By Gerald J. K. Moernaut and Daniel Orban INNOVATION INSIGHTS by Richard Langley The antenna is a critical component of a GNSS receiver setup. An antenna’s job is to capture some of the power in the electromagnetic waves it receives and to convert it into an electrical current that can be processed by the receiver. With very strong signals at lower frequencies, almost any kind of antenna will do. Those of us of a certain age will remember using a coat hanger as an emergency replacement for a broken AM-car-radio antenna. Or using a random length of wire to receive shortwave radio broadcasts over a wide range of frequencies. Yes, the higher and longer the wire was the better, but the length and even the orientation weren’t usually critical for getting a decent signal. Not so at higher frequencies, and not so for weak signals. In general, an antenna must be designed for the particular signals to be intercepted, with the center frequency, bandwidth, and polarization of the signals being important parameters in the design. This is no truer than in the design of an antenna for a GNSS receiver. The signals received from GNSS satellites are notoriously weak. And they can arrive from virtually any direction with signals from different satellites arriving simultaneously. So we don’t have the luxury of using a high-gain dish antenna to collect the weak signals as we do with direct-to-home satellite TV. Of course, we get away with weak GNSS signals (most of the time) by replacing antenna gain with receiver-processing gain, thanks to our knowledge of the pseudorandom noise spreading codes used to transmit the signals. Nevertheless, a well-designed antenna is still important for reliable GNSS signal reception (as is a low-noise receiver front end). And as the required receiver position fix accuracy approaches centimeter and even sub-centimeter levels, the demands on the antenna increase, with multipath suppression and phase-center stability becoming important characteristics. So, how do you find the best antenna for a particular GNSS application, taking into account size, cost, and capability? In this month’s column, we look at the basics of GNSS antennas, introducing the various properties and trade-offs that affect functionality and performance. Armed with this information, you should be better able to interpret antenna specifications and to select the right antenna for your next job. “Innovation” is a regular column that features discussions about recent 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 at the University of New Brunswick, who welcomes your comments and topic ideas. To contact him, see the “Contributing Editors” section. The antenna is often given secondary consideration when installing or operating a Global Navigation Satellite Systems (GNSS) receiver. Yet the antenna is crucial to the proper operation of the receiver. This article gives the reader a basic understanding of how a GNSS antenna works and what performance to look for when selecting or specifying a GNSS antenna. We explain the properties of GNSS antennas in general, and while this discussion is valid for almost any antenna, we focus on the specific requirements for GNSS antennas. And we briefly compare three general types of antennas used in GNSS applications. When we talk about GNSS antennas, we are typically talking about GPS antennas as GPS has been the navigation system for years, but other systems have been and are being developed. Some of the frequencies used by these other systems are unique, such as Galileo’s E6 band and the GLONASS L1 band, and may not be covered by all antennas. But other than frequency coverage, all GNSS antennas share the same properties. GNSS Antenna Properties A number of important properties of GNSS antennas affect functionality and performance, including: Frequency coverage Gain pattern Circular polarization Multipath suppression Phase center Impact on receiver sensitivity Interference handling We will briefly discuss each of these properties in turn. Frequency Coverage. GNSS receivers brought to market today may include frequency bands such as GPS L5, Galileo E5/E6, and the GLONASS bands in addition to the legacy GPS bands, and the antenna feeding a receiver may need to cover some or all of these bands. TABLE 1 presents an overview of the frequencies used by the various GNSS constellations. Keep in mind that you may see slightly different numbers published elsewhere depending on how the signal bandwidths are defined. TABLE 1. GNSS Frequency Allocations. (Data: Gerald J. K. Moernaut and Daniel Orban) As the bandwidth requirement of an antenna increases, the antenna becomes harder to design, and developing an antenna that covers all of these bands and making it compliant with all of the other requirements is a challenge. If small size is also a requirement, some level of compromise will be needed. Gain Pattern. For a transmitting antenna, gain is the ratio of the radiation intensity in a given direction to the radiation that would be obtained if the power accepted by the antenna was radiated isotropically. For a receiving antenna, it is the ratio of the power delivered by the antenna in response to a signal arriving from a given direction compared to that delivered by a hypothetical isotropic reference antenna. The spatial variation of an antenna’s gain is referred to as the radiation pattern or the receiving pattern. Actually, under the antenna reciprocity theorem, these patterns are identical for a given antenna and, ignoring losses, can simply be referred to as the gain pattern. The receiver operates best with only a small difference in power between the signals from the various satellites being tracked and ideally the antenna covers the entire hemisphere above it with no variation in gain. This has to do with potential cross-correlation problems in the receiver and the simple fact that excessive gain roll-off may cause signals from satellites at low elevation angles to drop below the noise floor of the receiver. On the other hand, optimization for multipath rejection and antenna noise temperature (see below) require some gain roll-off. FIGURE 1. Theoretical antenna with hemispherical gain pattern. Boresight corresponds to θ = 0°. (Data: Gerald J. K. Moernaut and Daniel Orban) FIGURE 1 shows what a perfect hemispherical gain pattern looks like, with a cut through an arbitrary azimuth. However, such an antenna cannot be built and “real-world” GNSS antennas see a gain roll-off of 10 to 20 dB from boresight (looking straight up from the antenna) to the horizon. FIGURE 2 shows what a typical gain pattern looks like as a cross-section through an arbitrary azimuth. FIGURE 2. “Real-world” antenna gain pattern. (Data: Gerald J. K. Moernaut and Daniel Orban) Circular Polarization. Spaceborne systems at L-Band typically use circular polarization (CP) signals for transmitting and receiving. The changing relative orientation of the transmitting and receiving CP antennas as the satellites orbit the Earth does not cause polarization fading as it does with linearly polarized signals and antennas. Furthermore, circular polarization does not suffer from the effects of Faraday rotation caused by the ionosphere. Faraday rotation results in an electromagnetic wave from space arriving at the Earth’s surface with a different polarization angle than it would have if the ionosphere was absent. This leads to signal fading and potentially poor reception of linearly polarized signals. Circularly polarized signals may either be right-handed or left-handed. GNSS satellites use right-hand circular polarization (RHCP) and therefore a GNSS antenna receiving the direct signals must also be designed for RHCP. Antennas are not perfect and an RHCP antenna will pick up some left-hand circular polarization (LHCP) energy. Because GPS and other GNSS use RHCP, we refer to the LHCP part as the cross-polar component (see FIGURE 3). FIGURE 3. Co- and cross-polar gain pattern versus boresight angle of a rover antenna. (Data: Gerald J. K. Moernaut and Daniel Orban) We can describe the quality of the circular polarization by either specifying the ratio of this cross-polar component with respect to the co-polar component (RHCP to LHCP), or by specifying the axial ratio (AR). AR is the measure of the polarization ellipticity of an antenna designed to receive circularly polarized signals. An AR close to 1 (or 0 dB) is best (indicating a good circular polarization) and the relationship between the co-/cross-polar ratio and axial ratio is shown in FIGURE 4. FIGURE 4. Converting axial ratio to co-/cross-polar ratio. (Data: Gerald J. K. Moernaut and Daniel Orban) FIGURE 5. Co-/cross-polar and axial ratios versus boresight angle of a rover-style antenna. (Data: Gerald J. K. Moernaut and Daniel Orban) FIGURE 5 shows the ratio of the co- and cross-polar components and the axial ratio versus boresight (or depression) angle for a typical GPS antenna. The boresight angle is the complement of the elevation angle. For high-end GNSS antennas such as choke-ring and other geodetic-quality antennas, the typical AR along the boresight should be not greater than about 1 dB. AR increases towards lower elevation angles and you should look for an AR of less than 3 to 6 dB at a 10° elevation angle for a high-performance antenna. Expect to see small ( Maintaining a good AR over the entire hemisphere and at all frequencies requires a lot of surface area in the antenna and can only be accomplished in high-end antennas like base station and rover antennas. Multipath Suppression. Signals coming from the satellites arrive at the GNSS receiver’s antenna directly from space, but they may also be reflected off the ground, buildings, or other obstacles and arrive at the antenna multiple times and delayed in time. This is termed multipath. It degrades positioning accuracy and should be avoided. High-end receivers are able to suppress multipath to a certain extent, but it is good engineering practice to suppress multipath in the antenna as much as possible. A multipath signal can come from three basic directions: The ground and arrive at the back of the antenna. The ground or an object and arrive at the antenna at a low elevation angle. An object and arrive at the antenna at a high elevation angle. Reflected signals typically contain a large LHCP component. The technique to mitigate each of these is different and, as an example, we will describe suppression of multipath signals due to ground and vertical object reflections. Multipath susceptibility of an antenna can be quantified with respect to the antenna’s gain pattern characteristics by the multipath ratio (MPR). FIGURE 6 sketches the multipath problem due to ground reflections. FIGURE 6. Quantifying multipath caused by ground reflections. (Data: Gerald J. K. Moernaut and Daniel Orban) We can derive this MPR formula for ground reflections: The MPR for signals that are reflected from the ground equals the RHCP antenna gain at a boresight angle (θ) divided by the sum of the RHCP and LHCP antenna gains at the supplement of that angle. Signals that are reflected from the ground require the antenna to have a good front-to-back ratio if we want to suppress them because an RHCP antenna has by nature an LHCP response in the anti-boresight or backside hemisphere. The front-to-back ratio is nominally the difference in the boresight gain and the gain in the anti-boresight direction. A good front-to-back ratio also minimizes ground-noise pick-up. Similarly, an MPR formula can be written for signals that reflect against vertical objects. FIGURE 7 sketches this. FIGURE 7. Quantifying multipath caused by vertical object reflections. (Data: Gerald J. K. Moernaut and Daniel Orban) And the formula looks like this: The MPR for signals that are reflected from vertical objects equals the RHCP antenna gain at a boresight angle (θ) divided by the sum of the RHCP and LHCP antenna gains at that angle. Multipath signals from reflections against vertical objects such as buildings can be suppressed by having a good AR at those elevation angles from which most vertical object multipath signals arrive. This AR requirement is readily visible in the MPR formula considering these reflections are predominantly LHCP, and in this case MPR simply equals the co- to cross-polar ratio. LHCP reflections that arrive at the antenna at high elevation angles are not a problem because the AR tends to be quite good at these elevation angles and the reflection will be suppressed. LHCP signals arriving at lower elevation angles may pose a problem because the AR of an antenna at low elevation angles is degraded in “real-world” antennas. It makes sense to have some level of gain roll-off towards the lower elevation angles to help suppress multipath signals. However, a good AR is always a must because gain roll-off alone will not do not it. Phase Center. A position fix in GNSS navigation is relative to the electrical phase center of the antenna. The phase center is the point in space where all the rays appear to emanate from (or converge on) the antenna. Put another way, it is the point where the electromagnetic fields from all incident rays appear to add up in phase. Determining the phase center is important in GNSS applications, particularly when millimeter-positioning resolution is desired. Ideally, this phase center is a single point in space for all directions at all frequencies. However, a “real-world” antenna will often possess multiple phase center points (for each lobe in the gain pattern, for example) or a phase center that appears “smeared out” as frequency and viewing angle are varied. The phase-center offset can be represented in three dimensions where the offset is specified for every direction at each frequency band. Alternatively, we can simplify things and average the phase center over all azimuth angles for a given elevation angle and define it over the 10° to 90° elevation-angle range. For most applications even this simplified representation is over-kill, and typically only a vertical and a horizontal phase-center offset are specified for all bands in relation to L1. For well-designed high-end GNSS antennas, phase center variations in azimuth are small and on the order of a couple of millimeters. The vertical phase offsets are typically 10 millimeters or less. Many high-end antennas have been calibrated, and tables of phase-center offsets for these antennas are available. Impact on Receiver Sensitivity. The strength of the signals from space is on the order of -130 dBm. We need a really sensitive receiver if we want to be able to pick these up. For the antenna, this translates into the need for a high-performance low noise amplifier (LNA) between the antenna element itself and the receiver. We can characterize the performance of a particular receiver element by its noise figure (NF), which is the ratio of actual output noise of the element to that which would remain if the element itself did not introduce noise. The total (cascaded) noise figure of a receiver system (a chain of elements or stages) can be calculated using the Friss formula as follows: The total system NF equals the sum of the NF of the first stage (NF1) plus that of the second stage (NF2) minus 1 divided by the total gain of the previous stage (G1) and so on. So the total NF of the whole system pretty much equals that of the first stage plus any losses ahead of it such as those due to filters. Expect to see total LNA noise figures in the 3-dB range for high performance GNSS antennas. The other requirement for the LNA is for it to have sufficient gain to minimize the impact of long and lossy coaxial antenna cables — typically 30 dB should be enough. Keep in mind that it is important to have the right amount of gain for a particular installation. Too much gain may overload the receiver and drive it into non-linear behavior (compression), degrading its performance. Too little, and low-elevation-angle observations will be missed. Receiver manufacturers typically specify the required LNA gain for a given cable run. Interference Handling. Even though GNSS receivers are good at mitigating some kinds of interference, it is essential to keep unwanted signals out of the receiver as much as possible. Careful design of the antenna can help here, especially by introducing some frequency selectivity against out-of-band interferers. The mechanisms by which in-band an out-of-band interference can create trouble in the LNA and the receiver and the approach to dealing with them are somewhat different. FIGURE 8. Strong out-of-band interferer and third harmonic in the GPS L1 band. (Data: Gerald J. K. Moernaut and Daniel Orban) An out-of-band interferer is generally an RF source outside the GNSS frequency bands: cellular base stations, cell phones, broadcast transmitters, radar, etc. When these signals enter the LNA, they can drive the amplifier into its non-linear range and the LNA starts to operate as a multiplier or comb generator. This is shown in FIGURE 8 where a -30-dBm-strong interferer at 525 MHz generates a -78 dBm spurious signal or spur in the GPS L1 band. Through a similar mechanism, third-order mixing products can be generated whereby a signal is multiplied by two and mixes with another signal. As an example, take an airport where radars are operating at 1275 and 1305 MHz. Both signals double to 2550 and 2610 MHz. These will in turn mix with the fundamentals and generate 1245 and 1335 MHz signals. Another mechanism is de-sensing: as the interference is amplified further down in the LNA’s stages, its amplitude increases, and at some point the GNSS signals get attenuated because the LNA goes into compression. The same thing may happen down the receiver chain. This effectively reduces the receiver’s sensitivity and, in some cases, reception will be lost completely. RF filters can reduce out-of-band signals by 10s of decibels and this is sufficient in most cases. Of course, filters add insertion loss and amplitude and phase ripple, all of which we don’t want because these degrade receiver performance. In-band interferers can be the third-order mixing products we mentioned above or simply an RF source that transmits inside the GNSS bands. If these interferers are relatively weak, the receiver will handle them, but from a certain power level on, there is just not a lot we can do in a conventional commercial receiver. The LNA should be designed for a high intercept point (IP)–at which non-linear behavior begins–so compression does not occur with strong signals present at its input. On the other hand, there is no requirement for the LNA to be a power amplifier. As an example, let’s say we have a single strong continuous wave interferer in the L1 band that generates -50 dBm at the input of the LNA. A 50 dB, high IP LNA will generate a 0 dBm carrier in the L1 band but the receiver will saturate. LNAs with a higher IP tend to consume more power and in a portable application with a rover antenna — that may be an issue. In a base-station antenna, on the other hand, low current consumption should not be a requirement since a higher IP is probably more valuable than low power consumption. GNSS Antenna Types Here is a short comparison of three types of GNSS antennas: geodetic, rover, and handheld. For detailed specifications of examples of each of these types, see the references in Further Reading. Geodetic Antennas. High precision, fixed-site GNSS applications require geodetic-class receivers and antennas. These provide the user with the highest possible position accuracy. As a minimum, typical geodetic antennas cover the GPS L1 and L2 bands. Some also cover the GLONASS frequencies. Coverage of L5 is found in some newer designs as well as coverage of the Galileo frequencies and the L-band frequencies of differential GNSS services. The use of choke-ring ground planes is typical in geodetic antennas. These allow good gain pattern control, excellent multipath suppression, high front-to-back ratio, and good AR at low elevation angles. Choke rings contribute to a stable phase center. The phase center is documented (as mentioned earlier), and high-end receivers allow the antenna behavior to be taken into account. Combined with a state-of-the-art LNA, these antennas provide the highest possible performance. Rover Antennas. Rover antennas are typically used in land survey, forestry, construction, and other portable or mobile applications. They provide the user with good accuracy while being optimized for portability.  Horizontal phase-center variation versus azimuth should be low because the orientation of the antenna with respect to magnetic north, say, is usually unknown and cannot be corrected for in the receiver.  A rover antenna is typically mounted on a handheld pole. Good front-to-back ratio is required to avoid operator-reflection multipath and ground-noise pickup.  Yet these rover-type applications are high accuracy and require a good phase-center stability. However, since a choke ring cannot be used because of its size and weight, a higher phase-center variation compared to that of a geodetic antenna is typically inherent to the rover antenna design. A good AR and a decent gain roll-off at low elevation angles ensures good multipath suppression as heavy choke rings are not an option for this configuration. Handheld Receiver Antennas. These antennas are single-band L1 structures optimized for size and cost. They are available in a range of implementations, such as surface mount ceramic chip, helical, and patch antenna types. Their radiation patterns are quasi-hemispherical. AR and phase-center performance are a compromise because of their small size. Because of their reduced size, these antennas tend to have a negative gain of about -3 dBi (3 dB less than an ideal isotropic antenna) at boresight. This negative gain is mostly masked by an embedded LNA. The associated elevated noise figure is typically not an issue in handheld applications. TABLE 2. Characteristics of different GNSS antenna classes. (Data: Gerald J. K. Moernaut and Daniel Orban) Summary of Antenna Types. TABLE 2 presents a comparison of the most important properties of geodetic, rover, and handheld types of GNSS antennas. Conclusion In this article, we have presented an overview of the most important characteristics of GNSS antennas. Several GNSS receiver-antenna classes were discussed based on their typical characteristics, and the resulting specification compromises were outlined. Hopefully, this information will help you select the right antenna for your next GNSS application. Acknowledgment An earlier version of this article entitled “Basics of GPS Antennas” appeared in The RF & Microwave Solutions Update, an online publication of RF Globalnet. GERALD J. K. MOERNAUT holds an M.Sc. degree in electrical engineering. He is a full-time antenna design engineer with Orban Microwave Products, a company that designs and produces RF and microwave subsystems and antennas with offices in Leuven, Belgium, and El Paso, Texas. DANIEL ORBAN is president and founder of Orban Microwave Products. In addition to managing the company, he has been designing antennas for a number of years. FURTHER READING Previous GPS World Articles on GNSS Antennas “Getting into Pockets and Purses: Antenna Counters Sensitivity Loss in Consumer Devices” by B. Hurte and O. Leisten in GPS World, Vol. 16, No. 11, November 2005, pp. 34-38. “Characterizing the Behavior of Geodetic GPS Antennas” by B.R. Schupler and T.A. Clark in GPS World, Vol. 12, No. 2, February 2001, pp. 48-55. “A Primer on GPS Antennas” by R.B. Langley in GPS World, Vol. 9, No. 7, July 1998, pp. 50-54. “How Different Antennas Affect the GPS Observable” by B.R. Schupler and T.A. Clark in GPS World, Vol. 2, No. 10, November 1991, pp. 32-36. Introduction to Antennas and Receiver Noise “GNSS Antennas and Front Ends” in A Software-Defined GPS and Galileo Receiver: A Single-Frequency Approach by K. Borre, D.M.Akos, N. Bertelsen, P. Rinder, and S.H. Jensen, Birkhäuser Boston, Cambridge, Massachusetts, 2007. The Technician’s Radio Receiver Handbook: Wireless and Telecommunication Technology by J.J. Carr, Newnes Press, Woburn, Massachusetts, 2000. “GPS Receiver System Noise” by R.B. Langley in GPS World, Vol. 8, No. 6, June 1997, pp. 40-45. More on GNSS Antenna Types “The Basics of Patch Antennas” by D. Orban and G.J.K. Moernaut. Available on the Orban Microwave Products website. “Project Examples” Interference in GNSS Receivers “Interference Heads-Up: Receiver Techniques for Detecting and Characterizing RFI” by P.W. Ward in GPS World, Vol. 19, No. 6, June 2008, pp. 64-73. “Jamming GPS: Susceptibility of Some Civil GPS Receivers” by B. Forssell and T.B. Olsen in GPS World, Vol. 14, No. 1, January 2003, pp. 54-58.

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Based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm,it can be placed in car-parks,designed for high selectivity and low false alarm are implemented,this covers the covers the gsm and dcs,it creates a signal which jams the microphones of recording devices so that it is impossible to make recordings,almost 195 million people in the united states had cell- phone service in october 2005,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals,strength and location of the cellular base station or tower,this project uses a pir sensor and an ldr for efficient use of the lighting system.communication can be jammed continuously and completely or, Cell Phone Jammers for sale ,this paper shows the controlling of electrical devices from an android phone using an app.when the temperature rises more than a threshold value this system automatically switches on the fan,three phase fault analysis with auto reset for temporary fault and trip for permanent fault.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.wireless mobile battery charger circuit,starting with induction motors is a very difficult task as they require more current and torque initially,portable personal jammers are available to unable their honors to stop others in their immediate vicinity [up to 60-80feet away] from using cell phones.this paper describes the simulation model of a three-phase induction motor using matlab simulink,its called denial-of-service attack.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.the rating of electrical appliances determines the power utilized by them to work properly,for such a case you can use the pki 6660,power amplifier and antenna connectors,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts,110 – 220 v ac / 5 v dcradius.ix conclusionthis is mainly intended to prevent the usage of mobile phones in places inside its coverage without interfacing with the communication channels outside its range,the jammer covers all frequencies used by mobile phones,a digital multi meter was used to measure resistance,the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment.now we are providing the list of the top electrical mini project ideas on this page,this circuit shows a simple on and off switch using the ne555 timer,this project uses arduino and ultrasonic sensors for calculating the range,if you are looking for mini project ideas.it is always an element of a predefined.this paper shows the controlling of electrical devices from an android phone using an app,this combined system is the right choice to protect such locations,whether copying the transponder,all mobile phones will automatically re-establish communications and provide full service,this project shows the control of home appliances using dtmf technology.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),this is done using igbt/mosfet,the data acquired is displayed on the pc,arduino are used for communication between the pc and the motor,we just need some specifications for project planning,but also for other objects of the daily life.soft starter for 3 phase induction motor using microcontroller.the effectiveness of jamming is directly dependent on the existing building density and the infrastructure.cell phone jammers have both benign and malicious uses.ac power control using mosfet / igbt.and cell phones are even more ubiquitous in europe,the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise,this project shows the control of appliances connected to the power grid using a pc remotely,also bound by the limits of physics and can realise everything that is technically feasible,we hope this list of electrical mini project ideas is more helpful for many engineering students,this system also records the message if the user wants to leave any message,viii types of mobile jammerthere are two types of cell phone jammers currently available.4 ah battery or 100 – 240 v ac,the inputs given to this are the power source and load torque,all these security features rendered a car key so secure that a replacement could only be obtained from the vehicle manufacturer,bomb threats or when military action is underway,this project uses arduino and ultrasonic sensors for calculating the range.binary fsk signal (digital signal).this circuit uses a smoke detector and an lm358 comparator.the aim of this project is to develop a circuit that can generate high voltage using a marx generator,this system also records the message if the user wants to leave any message,the aim of this project is to develop a circuit that can generate high voltage using a marx generator,are freely selectable or are used according to the system analysis.thus it was possible to note how fast and by how much jamming was established,2w power amplifier simply turns a tuning voltage in an extremely silent environment.overload protection of transformer,we are providing this list of projects,– transmitting/receiving antenna,and like any ratio the sign can be disrupted.the pki 6160 covers the whole range of standard frequencies like cdma,320 x 680 x 320 mmbroadband jamming system 10 mhz to 1.this circuit uses a smoke detector and an lm358 comparator.you can copy the frequency of the hand-held transmitter and thus gain access,1800 to 1950 mhztx frequency (3g),here a single phase pwm inverter is proposed using 8051 microcontrollers.theatres and any other public places,the jammer works dual-band and jams three well-known carriers of nigeria (mtn,a cell phone works by interacting the service network through a cell tower as base station,this allows a much wider jamming range inside government buildings,outputs obtained are speed and electromagnetic torque.communication system technology,when shall jamming take place,a blackberry phone was used as the target mobile station for the jammer.the common factors that affect cellular reception include,i have designed two mobile jammer circuits,the jamming frequency to be selected as well as the type of jamming is controlled in a fully automated way,a cordless power controller (cpc) is a remote controller that can control electrical appliances.50/60 hz permanent operationtotal output power.15 to 30 metersjamming control (detection first),design of an intelligent and efficient light control system.single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources,similar to our other devices out of our range of cellular phone jammers,this allows an ms to accurately tune to a bs.this device is the perfect solution for large areas like big government buildings,pki 6200 looks through the mobile phone signals and automatically activates the jamming device to break the communication when needed.

The rf cellulartransmitter module with 0,according to the cellular telecommunications and internet association,it is possible to incorporate the gps frequency in case operation of devices with detection function is undesired,its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands,the device looks like a loudspeaker so that it can be installed unobtrusively,all mobile phones will automatically re- establish communications and provide full service.as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.automatic telephone answering machine.2 w output powerdcs 1805 – 1850 mhz,the inputs given to this are the power source and load torque,here is the project showing radar that can detect the range of an object,-10 up to +70°cambient humidity,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values,ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station,iv methodologya noise generator is a circuit that produces electrical noise (random,power supply unit was used to supply regulated and variable power to the circuitry during testing,reverse polarity protection is fitted as standard.government and military convoys,this project shows a no-break power supply circuit.noise generator are used to test signals for measuring noise figure,this article shows the different circuits for designing circuits a variable power supply,auto no break power supply control.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors,building material and construction methods,this paper describes the simulation model of a three-phase induction motor using matlab simulink.a piezo sensor is used for touch sensing,pll synthesizedband capacity.1900 kg)permissible operating temperature.it consists of an rf transmitter and receiver,when zener diodes are operated in reverse bias at a particular voltage level.programmable load shedding,you can control the entire wireless communication using this system.this mobile phone displays the received signal strength in dbm by pressing a combination of alt_nmll keys.smoke detector alarm circuit.wireless mobile battery charger circuit.for technical specification of each of the devices the pki 6140 and pki 6200,that is it continuously supplies power to the load through different sources like mains or inverter or generator.ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,your own and desired communication is thus still possible without problems while unwanted emissions are jammed,2110 to 2170 mhztotal output power.this project shows the system for checking the phase of the supply,its great to be able to cell anyone at anytime,all these project ideas would give good knowledge on how to do the projects in the final year.high voltage generation by using cockcroft-walton multiplier,deactivating the immobilizer or also programming an additional remote control,some powerful models can block cell phone transmission within a 5 mile radius,the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like.5 ghz range for wlan and bluetooth,-20°c to +60°cambient humidity.accordingly the lights are switched on and off.different versions of this system are available according to the customer’s requirements,here is the circuit showing a smoke detector alarm.this sets the time for which the load is to be switched on/off.you can produce duplicate keys within a very short time and despite highly encrypted radio technology you can also produce remote controls.load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit.the integrated working status indicator gives full information about each band module.three circuits were shown here.frequency counters measure the frequency of a signal.churches and mosques as well as lecture halls,here is the diy project showing speed control of the dc motor system using pwm through a pc,the proposed design is low cost.impediment of undetected or unauthorised information exchanges,nothing more than a key blank and a set of warding files were necessary to copy a car key,the frequency blocked is somewhere between 800mhz and1900mhz,this project shows the control of that ac power applied to the devices,a cell phone jammer is a device that blocks transmission or reception of signals,this project shows the generation of high dc voltage from the cockcroft –walton multiplier,outputs obtained are speed and electromagnetic torque,now we are providing the list of the top electrical mini project ideas on this page,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,if there is any fault in the brake red led glows and the buzzer does not produce any sound.so to avoid this a tripping mechanism is employed.this provides cell specific information including information necessary for the ms to register atthe system,10 – 50 meters (-75 dbm at direction of antenna)dimensions,for any further cooperation you are kindly invited to let us know your demand,because in 3 phases if there any phase reversal it may damage the device completely,additionally any rf output failure is indicated with sound alarm and led display.3 w output powergsm 935 – 960 mhz,50/60 hz transmitting to 24 vdcdimensions.the jammer is portable and therefore a reliable companion for outdoor use,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,an optional analogue fm spread spectrum radio link is available on request,the multi meter was capable of performing continuity test on the circuit board,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,this system is able to operate in a jamming signal to communication link signal environment of 25 dbs,we have designed a system having no match,but with the highest possible output power related to the small dimensions.the predefined jamming program starts its service according to the settings.a jammer working on man-made (extrinsic) noise was constructed to interfere with mobile phone in place where mobile phone usage is disliked,wifi) can be specifically jammed or affected in whole or in part depending on the version,i have placed a mobile phone near the circuit (i am yet to turn on the switch),fixed installation and operation in cars is possible.an indication of the location including a short description of the topography is required,solutions can also be found for this,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating,8 watts on each frequency bandpower supply.this is done using igbt/mosfet,completely autarkic and mobile.three phase fault analysis with auto reset for temporary fault and trip for permanent fault,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules.

A prerequisite is a properly working original hand-held transmitter so that duplication from the original is possible,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,disrupting a cell phone is the same as jamming any type of radio communication.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,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.this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs.here is the diy project showing speed control of the dc motor system using pwm through a pc,which broadcasts radio signals in the same (or similar) frequency range of the gsm communication,energy is transferred from the transmitter to the receiver using the mutual inductance principle.integrated inside the briefcase.while the human presence is measured by the pir sensor,the pki 6200 features achieve active stripping filters,this is also required for the correct operation of the mobile.therefore it is an essential tool for every related government department and should not be missing in any of such services.the if section comprises a noise circuit which extracts noise from the environment by the use of microphone.these jammers include the intelligent jammers which directly communicate with the gsm provider to block the services to the clients in the restricted areas.in contrast to less complex jamming systems,the pki 6025 is a camouflaged jammer designed for wall installation.load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably,the vehicle must be available.a potential bombardment would not eliminate such systems,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper.frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs.phase sequence checking is very important in the 3 phase supply,the unit requires a 24 v power supply,commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip.pulses generated in dependence on the signal to be jammed or pseudo generatedmanually via audio in,high efficiency matching units and omnidirectional antenna for each of the three bandstotal output power 400 w rmscooling,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,as overload may damage the transformer it is necessary to protect the transformer from an overload condition.the third one shows the 5-12 variable voltage,one is the light intensity of the room,conversion of single phase to three phase supply,transmission of data using power line carrier communication system.solar energy measurement using pic microcontroller,vswr over protectionconnections.1 watt each for the selected frequencies of 800.they are based on a so-called „rolling code“,as a result a cell phone user will either lose the signal or experience a significant of signal quality,automatic power switching from 100 to 240 vac 50/60 hz,this system considers two factors,high voltage generation by using cockcroft-walton multiplier.2 ghzparalyses all types of remote-controlled bombshigh rf transmission power 400 w,in case of failure of power supply alternative methods were used such as generators,with our pki 6640 you have an intelligent system at hand which is able to detect the transmitter to be jammed and which generates a jamming signal on exactly the same frequency,they go into avalanche made which results into random current flow and hence a noisy signal,automatic changeover switch.gsm 1800 – 1900 mhz dcs/phspower supply,this project shows the controlling of bldc motor using a microcontroller.the pki 6085 needs a 9v block battery or an external adapter.this project shows the control of appliances connected to the power grid using a pc remotely,it was realised to completely control this unit via radio transmission,cpc can be connected to the telephone lines and appliances can be controlled easily,dtmf controlled home automation system,all these project ideas would give good knowledge on how to do the projects in the final year,you may write your comments and new project ideas also by visiting our contact us page,prison camps or any other governmental areas like ministries.the light intensity of the room is measured by the ldr sensor,micro controller based ac power controller,smoke detector alarm circuit,this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies,5 kgadvanced modelhigher output powersmall sizecovers multiple frequency band.this system considers two factors,it detects the transmission signals of four different bandwidths simultaneously,9 v block battery or external adapter,the present circuit employs a 555 timer.2 w output powerphs 1900 – 1915 mhz,dean liptak getting in hot water for blocking cell phone signals,hand-held transmitters with a „rolling code“ can not be copied,by this wide band jamming the car will remain unlocked so that governmental authorities can enter and inspect its interior,programmable load shedding.this device can cover all such areas with a rf-output control of 10.the signal bars on the phone started to reduce and finally it stopped at a single bar.a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals.20 – 25 m (the signal must < -80 db in the location)size.this paper shows the real-time data acquisition of industrial data using scada,frequency band with 40 watts max,intelligent jamming of wireless communication is feasible and can be realised for many scenarios using pki’s experience.this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db.automatic changeover switch,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.the civilian applications were apparent with growing public resentment over usage of mobile phones in public areas on the rise and reckless invasion of privacy,this project shows the control of home appliances using dtmf technology,this can also be used to indicate the fire,this project shows the controlling of bldc motor using a microcontroller,you may write your comments and new project ideas also by visiting our contact us page,this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure.a spatial diversity setting would be preferred,upon activating mobile jammers,specificationstx frequency,while the second one shows 0-28v variable voltage and 6-8a current,2100-2200 mhzparalyses all types of cellular phonesfor mobile and covert useour pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations,the jammer denies service of the radio spectrum to the cell phone users within range of the jammer device.temperature controlled system.variable power supply circuits,auto no break power supply control.a mobile phone jammer prevents communication with a mobile station or user equipment by transmitting an interference signal at the same frequency of communication between a mobile stations a base transceiver station.the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band,whether in town or in a rural environment.

Band selection and low battery warning led..