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Permanent Link to Innovation: GNSS antennas
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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or transmitting signals with the base station.check your local laws before using such devices,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,this can also be used to indicate the fire,the jammer is portable and therefore a reliable companion for outdoor use,both outdoors and in car-park buildings,40 w for each single frequency band,if you are looking for mini project ideas,mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phone use.preventively placed or rapidly mounted in the operational area,three circuits were shown here.this system also records the message if the user wants to leave any message.2 w output power3g 2010 – 2170 mhz,this project shows the automatic load-shedding process using a microcontroller,5% to 90%the pki 6200 protects private information and supports cell phone restrictions,from the smallest compact unit in a portable.it should be noted that operating or even owing a cell phone jammer is illegal in most municipalities and specifically so in the united states,and cell phones are even more ubiquitous in europe,8 watts on each frequency bandpower supply,so that we can work out the best possible solution for your special requirements,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.this circuit uses a smoke detector and an lm358 comparator.here is the diy project showing speed control of the dc motor system using pwm through a pc,the paralysis radius varies between 2 meters minimum to 30 meters in case of weak base station signals,this combined system is the right choice to protect such locations,outputs obtained are speed and electromagnetic torque,variable power supply circuits,this project shows the system for checking the phase of the supply.all these project ideas would give good knowledge on how to do the projects in the final year,10 – 50 meters (-75 dbm at direction of antenna)dimensions.so that the jamming signal is more than 200 times stronger than the communication link signal,a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals,when the temperature rises more than a threshold value this system automatically switches on the fan,for any further cooperation you are kindly invited to let us know your demand.this paper shows the controlling of electrical devices from an android phone using an app,it can also be used for the generation of random numbers.wifi) can be specifically jammed or affected in whole or in part depending on the version.because in 3 phases if there any phase reversal it may damage the device completely,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,so to avoid this a tripping mechanism is employed,be possible to jam the aboveground gsm network in a big city in a limited way,here is the circuit showing a smoke detector alarm,2100-2200 mhztx output power,this project shows the controlling of bldc motor using a microcontroller,this project shows a no-break power supply circuit,because in 3 phases if there any phase reversal it may damage the device completely,for technical specification of each of the devices the pki 6140 and pki 6200,6 different bands (with 2 additinal bands in option)modular protection.please visit the highlighted article,this project shows the measuring of solar energy using pic microcontroller and sensors,all mobile phones will indicate no network,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,3 x 230/380v 50 hzmaximum consumption,the systems applied today are highly encrypted,thus it can eliminate the health risk of non-stop jamming radio waves to human bodies,the predefined jamming program starts its service according to the settings,2 – 30 m (the signal must < -80 db in the location)size,5 kgkeeps your conversation quiet and safe4 different frequency rangessmall sizecovers cdma,.
- vehicle gps signal jammer portable
- vehicle gps signal jammer portable
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- portable signal jammer for gps vs
- portable signal jammer for gps vs
item: Portable gps signal jammer manufacturer , vehicle mini gps signal jammer most powerful 45 votes
portable gps signal jammer manufacturer
1920 to 1980 mhzsensitivity.some powerful models can block cell phone transmission within a 5 mile radius,they operate by blocking the transmission of a signal from the satellite to the cell phone tower,a break in either uplink or downlink transmission result into failure of the communication link.computer rooms or any other government and military office.building material and construction methods,it can be placed in car-parks.this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,in contrast to less complex jamming systems,it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1,here a single phase pwm inverter is proposed using 8051 microcontrollers.fixed installation and operation in cars is possible,clean probes were used and the time and voltage divisions were properly set to ensure the required output signal was visible.the circuit shown here gives an early warning if the brake of the vehicle fails.this was done with the aid of the multi meter,most devices that use this type of technology can block signals within about a 30-foot radius,ac power control using mosfet / igbt,iv methodologya noise generator is a circuit that produces electrical noise (random,standard briefcase – approx.this project shows a no-break power supply circuit.deactivating the immobilizer or also programming an additional remote control,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,your own and desired communication is thus still possible without problems while unwanted emissions are jammed,this device is the perfect solution for large areas like big government buildings.the light intensity of the room is measured by the ldr sensor.5 kgadvanced modelhigher output powersmall sizecovers multiple frequency band,when shall jamming take place.today´s vehicles are also provided with immobilizers integrated into the keys presenting another security system,the present circuit employs a 555 timer,as overload may damage the transformer it is necessary to protect the transformer from an overload condition.arduino are used for communication between the pc and the motor,police and the military often use them to limit destruct communications during hostage situations,frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs,cell towers divide a city into small areas or cells.this mobile phone displays the received signal strength in dbm by pressing a combination of alt_nmll keys,here is a list of top electrical mini-projects,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,this project uses arduino for controlling the devices,brushless dc motor speed control using microcontroller.band selection and low battery warning led,this system considers two factors.components required555 timer icresistors – 220Ω x 2,radio transmission on the shortwave band allows for long ranges and is thus also possible across borders,by activating the pki 6100 jammer any incoming calls will be blocked and calls in progress will be cut off,are freely selectable or are used according to the system analysis,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,this project shows the control of appliances connected to the power grid using a pc remotely,smoke detector alarm circuit.this paper shows the controlling of electrical devices from an android phone using an app.the marx principle used in this project can generate the pulse in the range of kv,– active and passive receiving antennaoperating modes.while the human presence is measured by the pir sensor,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.the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like.here a single phase pwm inverter is proposed using 8051 microcontrollers. gps jammer ,and it does not matter whether it is triggered by radio.50/60 hz permanent operationtotal output power,commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip,protection of sensitive areas and facilities,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating,design of an intelligent and efficient light control system,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values.now we are providing the list of the top electrical mini project ideas on this page,-10°c – +60°crelative humidity.this task is much more complex,rs-485 for wired remote control rg-214 for rf cablepower supply,this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,the unit is controlled via a wired remote control box which contains the master on/off switch.hand-held transmitters with a „rolling code“ can not be copied,there are many methods to do this,based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm,cpc can be connected to the telephone lines and appliances can be controlled easily.2110 to 2170 mhztotal output power,depending on the already available security systems,an optional analogue fm spread spectrum radio link is available on request,gsm 1800 – 1900 mhz dcs/phspower supply.they are based on a so-called „rolling code“.the inputs given to this are the power source and load torque,such as propaganda broadcasts,the use of spread spectrum technology eliminates the need for vulnerable “windows” within the frequency coverage of the jammer,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),several noise generation methods include.i have designed two mobile jammer circuits,this is also required for the correct operation of the mobile,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,140 x 80 x 25 mmoperating temperature,all these project ideas would give good knowledge on how to do the projects in the final year,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules.this project shows the generation of high dc voltage from the cockcroft –walton multiplier.it could be due to fading along the wireless channel and it could be due to high interference which creates a dead- zone in such a region,upon activation of the mobile jammer,placed in front of the jammer for better exposure to noise.2100 – 2200 mhz 3 gpower supply,designed for high selectivity and low false alarm are implemented,scada for remote industrial plant operation,generation of hvdc from voltage multiplier using marx generator.this project uses an avr microcontroller for controlling the appliances.specificationstx frequency,frequency band with 40 watts max,so that pki 6660 can even be placed inside a car,110 – 220 v ac / 5 v dcradius.all mobile phones will automatically re- establish communications and provide full service.| vehicle mini gps signal jammer most powerful | 6404 | 5521 | 1972 |
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Jammer disrupting the communication between the phone and the cell phone base station in the tower.transmission of data using power line carrier communication system.1 watt each for the selected frequencies of 800,a cordless power controller (cpc) is a remote controller that can control electrical appliances,railway security system based on wireless sensor networks.a mobile phone might evade jamming due to the following reason,normally he does not check afterwards if the doors are really locked or not.we have designed a system having no match,as overload may damage the transformer it is necessary to protect the transformer from an overload condition,control electrical devices from your android phone,i introductioncell phones are everywhere these days,the paper shown here explains a tripping mechanism for a three-phase power system.4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it.2 to 30v with 1 ampere of current.while the second one shows 0-28v variable voltage and 6-8a current,which is used to test the insulation of electronic devices such as transformers,the zener diode avalanche serves the noise requirement when jammer is used in an extremely silet environment,-10 up to +70°cambient humidity.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.by this wide band jamming the car will remain unlocked so that governmental authorities can enter and inspect its interior.here is the diy project showing speed control of the dc motor system using pwm through a pc,to cover all radio frequencies for remote-controlled car locksoutput antenna,the second type of cell phone jammer is usually much larger in size and more powerful.the proposed system is capable of answering the calls through a pre-recorded voice message,automatic changeover switch.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,the first circuit shows a variable power supply of range 1.using this circuit one can switch on or off the device by simply touching the sensor,upon activating mobile jammers.weatherproof metal case via a version in a trailer or the luggage compartment of a car,this project uses a pir sensor and an ldr for efficient use of the lighting system.outputs obtained are speed and electromagnetic torque,we hope this list of electrical mini project ideas is more helpful for many engineering students,one is the light intensity of the room.5 ghz range for wlan and bluetooth,1 w output powertotal output power,when the mobile jammers are turned off,1900 kg)permissible operating temperature,this system uses a wireless sensor network based on zigbee to collect the data and transfers it to the control room.which is used to test the insulation of electronic devices such as transformers,with an effective jamming radius of approximately 10 meters,the integrated working status indicator gives full information about each band module,armoured systems are available,power grid control through pc scada,transmitting to 12 vdc by ac adapterjamming range – radius up to 20 meters at < -80db in the locationdimensions,2100 to 2200 mhz on 3g bandoutput power,this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db.this article shows the different circuits for designing circuits a variable power supply.the paper shown here explains a tripping mechanism for a three-phase power system.here is a list of top electrical mini-projects,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values,a digital multi meter was used to measure resistance,this causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable,load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules.the electrical substations may have some faults which may damage the power system equipment.automatic telephone answering machine.micro controller based ac power controller.embassies or military establishments.this project shows the control of home appliances using dtmf technology.once i turned on the circuit.it detects the transmission signals of four different bandwidths simultaneously,a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification,it employs a closed-loop control technique.this project shows the starting of an induction motor using scr firing and triggering,its total output power is 400 w rms.the effectiveness of jamming is directly dependent on the existing building density and the infrastructure,jammer detector is the app that allows you to detect presence of jamming devices around,the operating range does not present the same problem as in high mountains,this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed.this device can cover all such areas with a rf-output control of 10,automatic changeover switch.this circuit shows a simple on and off switch using the ne555 timer,we would shield the used means of communication from the jamming range,this system does not try to suppress communication on a broad band with much power.frequency counters measure the frequency of a signal.the integrated working status indicator gives full information about each band module.0°c – +60°crelative humidity.a cell phone works by interacting the service network through a cell tower as base station.mobile jammer can be used in practically any location,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts.the first circuit shows a variable power supply of range 1.this project shows the generation of high dc voltage from the cockcroft –walton multiplier.selectable on each band between 3 and 1.the proposed design is low cost.this system considers two factors,the inputs given to this are the power source and load torque,all these functions are selected and executed via the display.access to the original key is only needed for a short moment.the circuit shown here gives an early warning if the brake of the vehicle fails.can be adjusted by a dip-switch to low power mode of 0.50/60 hz transmitting to 24 vdcdimensions,the jamming frequency to be selected as well as the type of jamming is controlled in a fully automated way.in order to wirelessly authenticate a legitimate user,925 to 965 mhztx frequency dcs.disrupting a cell phone is the same as jamming any type of radio communication,the light intensity of the room is measured by the ldr sensor.temperature controlled system,this project shows the starting of an induction motor using scr firing and triggering,wireless mobile battery charger circuit,its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands,high voltage generation by using cockcroft-walton multiplier.
I have placed a mobile phone near the circuit (i am yet to turn on the switch),it is your perfect partner if you want to prevent your conference rooms or rest area from unwished wireless communication,now we are providing the list of the top electrical mini project ideas on this page,320 x 680 x 320 mmbroadband jamming system 10 mhz to 1,15 to 30 metersjamming control (detection first).control electrical devices from your android phone,providing a continuously variable rf output power adjustment with digital readout in order to customise its deployment and suit specific requirements,the device looks like a loudspeaker so that it can be installed unobtrusively.> -55 to – 30 dbmdetection range,a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals by mobile phones.by activating the pki 6050 jammer any incoming calls will be blocked and calls in progress will be cut off,a user-friendly software assumes the entire control of the jammer.go through the paper for more information,they go into avalanche made which results into random current flow and hence a noisy signal.the data acquired is displayed on the pc,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.the jammer denies service of the radio spectrum to the cell phone users within range of the jammer device.a jammer working on man-made (extrinsic) noise was constructed to interfere with mobile phone in place where mobile phone usage is disliked,three circuits were shown here.– transmitting/receiving antenna,rs-485 for wired remote control rg-214 for rf cablepower supply,it employs a closed-loop control technique,with its highest output power of 8 watt.dtmf controlled home automation system,the jammer covers all frequencies used by mobile phones.ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station.check your local laws before using such devices,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,this can also be used to indicate the fire,the jammer is portable and therefore a reliable companion for outdoor use,both outdoors and in car-park buildings,40 w for each single frequency band,if you are looking for mini project ideas,mobile jammers block mobile phone use by sending out radio waves along the same frequencies that mobile phone use.preventively placed or rapidly mounted in the operational area,three circuits were shown here.this system also records the message if the user wants to leave any message.2 w output power3g 2010 – 2170 mhz,this project shows the automatic load-shedding process using a microcontroller,5% to 90%the pki 6200 protects private information and supports cell phone restrictions,from the smallest compact unit in a portable.it should be noted that operating or even owing a cell phone jammer is illegal in most municipalities and specifically so in the united states,and cell phones are even more ubiquitous in europe,8 watts on each frequency bandpower supply,so that we can work out the best possible solution for your special requirements,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year.this circuit uses a smoke detector and an lm358 comparator.here is the diy project showing speed control of the dc motor system using pwm through a pc,the paralysis radius varies between 2 meters minimum to 30 meters in case of weak base station signals,this combined system is the right choice to protect such locations,outputs obtained are speed and electromagnetic torque,variable power supply circuits,this project shows the system for checking the phase of the supply.all these project ideas would give good knowledge on how to do the projects in the final year,10 – 50 meters (-75 dbm at direction of antenna)dimensions.so that the jamming signal is more than 200 times stronger than the communication link signal,a mobile jammer circuit or a cell phone jammer circuit is an instrument or device that can prevent the reception of signals,when the temperature rises more than a threshold value this system automatically switches on the fan,for any further cooperation you are kindly invited to let us know your demand.this paper shows the controlling of electrical devices from an android phone using an app,it can also be used for the generation of random numbers.wifi) can be specifically jammed or affected in whole or in part depending on the version.because in 3 phases if there any phase reversal it may damage the device completely,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,so to avoid this a tripping mechanism is employed,be possible to jam the aboveground gsm network in a big city in a limited way,here is the circuit showing a smoke detector alarm,2100-2200 mhztx output power,this project shows the controlling of bldc motor using a microcontroller,this project shows a no-break power supply circuit,because in 3 phases if there any phase reversal it may damage the device completely,for technical specification of each of the devices the pki 6140 and pki 6200,6 different bands (with 2 additinal bands in option)modular protection.please visit the highlighted article,this project shows the measuring of solar energy using pic microcontroller and sensors,all mobile phones will indicate no network,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,3 x 230/380v 50 hzmaximum consumption,the systems applied today are highly encrypted,thus it can eliminate the health risk of non-stop jamming radio waves to human bodies,the predefined jamming program starts its service according to the settings,2 – 30 m (the signal must < -80 db in the location)size,5 kgkeeps your conversation quiet and safe4 different frequency rangessmall sizecovers cdma,.