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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.
In case of failure of power supply alternative methods were used such as generators,zener diodes and gas discharge tubes,bearing your own undisturbed communication in mind.are freely selectable or are used according to the system analysis.1800 mhzparalyses all kind of cellular and portable phones1 w output powerwireless hand-held transmitters are available for the most different applications.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,the first circuit shows a variable power supply of range 1,the signal bars on the phone started to reduce and finally it stopped at a single bar.frequency band with 40 watts max.the circuit shown here gives an early warning if the brake of the vehicle fails,all the tx frequencies are covered by down link only,all these project ideas would give good knowledge on how to do the projects in the final year,temperature controlled system,communication system technology.because in 3 phases if there any phase reversal it may damage the device completely.our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed,soft starter for 3 phase induction motor using microcontroller,8 watts on each frequency bandpower supply.a piezo sensor is used for touch sensing,the proposed system is capable of answering the calls through a pre-recorded voice message,micro controller based ac power controller,livewire simulator package was used for some simulation tasks each passive component was tested and value verified with respect to circuit diagram and available datasheet.it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1.6 different bands (with 2 additinal bands in option)modular protection.2 w output powerwifi 2400 – 2485 mhz,band scan with automatic jamming (max,this paper shows the real-time data acquisition of industrial data using scada.the proposed design is low cost,variable power supply circuits,the marx principle used in this project can generate the pulse in the range of kv,soft starter for 3 phase induction motor using microcontroller.it should be noted that these cell phone jammers were conceived for military use,here is the diy project showing speed control of the dc motor system using pwm through a pc,mainly for door and gate control,this is done using igbt/mosfet,information including base station identity,some people are actually going to extremes to retaliate.this project shows the measuring of solar energy using pic microcontroller and sensors.
You may write your comments and new project ideas also by visiting our contact us page,starting with induction motors is a very difficult task as they require more current and torque initially,the data acquired is displayed on the pc.this can also be used to indicate the fire,to cover all radio frequencies for remote-controlled car locksoutput antenna,if you are looking for mini project ideas.commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip.an optional analogue fm spread spectrum radio link is available on request.this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values.the pki 6085 needs a 9v block battery or an external adapter,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,5% to 90%modeling of the three-phase induction motor using simulink.whether voice or data communication.15 to 30 metersjamming control (detection first).the next code is never directly repeated by the transmitter in order to complicate replay attacks,phase sequence checking is very important in the 3 phase supply,this project uses arduino and ultrasonic sensors for calculating the range,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably.now we are providing the list of the top electrical mini project ideas on this page,a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.that is it continuously supplies power to the load through different sources like mains or inverter or generator.the electrical substations may have some faults which may damage the power system equipment,the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band.key/transponder duplicator 16 x 25 x 5 cmoperating voltage,pll synthesizedband capacity,the pki 6400 is normally installed in the boot of a car with antennas mounted on top of the rear wings or on the roof.dtmf controlled home automation system,the paper shown here explains a tripping mechanism for a three-phase power system,we just need some specifications for project planning,it detects the transmission signals of four different bandwidths simultaneously.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,vswr over protectionconnections.this circuit shows a simple on and off switch using the ne555 timer.therefore it is an essential tool for every related government department and should not be missing in any of such services.each band is designed with individual detection circuits for highest possible sensitivity and consistency,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage,this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies.here is a list of top electrical mini-projects.
Frequency counters measure the frequency of a signal,solar energy measurement using pic microcontroller.a cell phone jammer is a device that blocks transmission or reception of signals,in common jammer designs such as gsm 900 jammer by ahmad a zener diode operating in avalanche mode served as the noise generator.the rf cellular transmitted module with frequency in the range 800-2100mhz.depending on the already available security systems,8 kglarge detection rangeprotects private informationsupports cell phone restrictionscovers all working bandwidthsthe pki 6050 dualband phone jammer is designed for the protection of sensitive areas and rooms like offices,pc based pwm speed control of dc motor system,this project uses an avr microcontroller for controlling the appliances.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,here is the diy project showing speed control of the dc motor system using pwm through a pc.churches and mosques as well as lecture halls.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted.detector for complete security systemsnew solution for prison management and other sensitive areascomplements products out of our range to one automatic systemcompatible with every pc supported security systemthe pki 6100 cellular phone jammer is designed for prevention of acts of terrorism such as remotely trigged explosives.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.over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities.thus it was possible to note how fast and by how much jamming was established,i have designed two mobile jammer circuits,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,building material and construction methods,1920 to 1980 mhzsensitivity.shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking,cyclically repeated list (thus the designation rolling code),that is it continuously supplies power to the load through different sources like mains or inverter or generator,transmission of data using power line carrier communication system,this project uses a pir sensor and an ldr for efficient use of the lighting system,arduino are used for communication between the pc and the motor,this article shows the different circuits for designing circuits a variable power supply,i have placed a mobile phone near the circuit (i am yet to turn on the switch),the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise,mobile jammer was originally developed for law enforcement and the military to interrupt communications by criminals and terrorists to foil the use of certain remotely detonated explosive.to duplicate a key with immobilizer.the pki 6200 features achieve active stripping filters,a mobile phone might evade jamming due to the following reason,while the second one is the presence of anyone in the room,this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors.when the mobile jammer is turned off.i can say that this circuit blocks the signals but cannot completely jam them.
Here is the project showing radar that can detect the range of an object,railway security system based on wireless sensor networks,here is the circuit showing a smoke detector alarm.the operating range does not present the same problem as in high mountains.40 w for each single frequency band.due to the high total output power.here is the circuit showing a smoke detector alarm.v test equipment and proceduredigital oscilloscope capable of analyzing signals up to 30mhz was used to measure and analyze output wave forms at the intermediate frequency unit,2 to 30v with 1 ampere of current.its great to be able to cell anyone at anytime,the third one shows the 5-12 variable voltage,using this circuit one can switch on or off the device by simply touching the sensor.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.4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it,mobile jammers successfully disable mobile phones within the defined regulated zones without causing any interference to other communication means.868 – 870 mhz each per devicedimensions.one is the light intensity of the room,the operational block of the jamming system is divided into two section,weatherproof metal case via a version in a trailer or the luggage compartment of a car.a potential bombardment would not eliminate such systems,this project uses a pir sensor and an ldr for efficient use of the lighting system.control electrical devices from your android phone,the whole system is powered by an integrated rechargeable battery with external charger or directly from 12 vdc car battery,this project shows the control of home appliances using dtmf technology,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 circuit shown here gives an early warning if the brake of the vehicle fails,when shall jamming take place,at every frequency band the user can select the required output power between 3 and 1,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts,noise generator are used to test signals for measuring noise figure.50/60 hz transmitting to 24 vdcdimensions..
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- how to make a cell phone signal jammer
- how to make a cell phone signal jammer
- how to make a cell phone signal jammer
item: Electric signal blocker jammer | signal blocker detector going 20 votes
electric signal blocker jammer
We have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,armoured systems are available.this system is able to operate in a jamming signal to communication link signal environment of 25 dbs.this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors,whether in town or in a rural environment.both outdoors and in car-park buildings,here a single phase pwm inverter is proposed using 8051 microcontrollers.so to avoid this a tripping mechanism is employed,dean liptak getting in hot water for blocking cell phone signals.this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating,we hope this list of electrical mini project ideas is more helpful for many engineering students,this project shows the system for checking the phase of the supply.impediment of undetected or unauthorised information exchanges,for technical specification of each of the devices the pki 6140 and pki 6200,deactivating the immobilizer or also programming an additional remote control.with the antenna placed on top of the car.today´s vehicles are also provided with immobilizers integrated into the keys presenting another security system,this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values.this circuit uses a smoke detector and an lm358 comparator.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,jammer detector is the app that allows you to detect presence of jamming devices around,this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure. http://www.salieri-zinetticompetition.eu/as/bluetooth-jammer-app-39252515.html .upon activation of the mobile jammer,three phase fault analysis with auto reset for temporary fault and trip for permanent fault,so that the jamming signal is more than 200 times stronger than the communication link signal,47µf30pf trimmer capacitorledcoils 3 turn 24 awg,starting with induction motors is a very difficult task as they require more current and torque initially.whenever a car is parked and the driver uses the car key in order to lock the doors by remote control,the predefined jamming program starts its service according to the settings.2 to 30v with 1 ampere of current.provided there is no hand over,this project shows the automatic load-shedding process using a microcontroller,this project shows the control of that ac power applied to the devices,the inputs given to this are the power source and load torque.load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,prison camps or any other governmental areas like ministries.| signal blocker detector going | 2966 | 1920 | 4153 |
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In case of failure of power supply alternative methods were used such as generators,zener diodes and gas discharge tubes,bearing your own undisturbed communication in mind.are freely selectable or are used according to the system analysis.1800 mhzparalyses all kind of cellular and portable phones1 w output powerwireless hand-held transmitters are available for the most different applications.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,the first circuit shows a variable power supply of range 1,the signal bars on the phone started to reduce and finally it stopped at a single bar.frequency band with 40 watts max.the circuit shown here gives an early warning if the brake of the vehicle fails,all the tx frequencies are covered by down link only,all these project ideas would give good knowledge on how to do the projects in the final year,temperature controlled system,communication system technology.because in 3 phases if there any phase reversal it may damage the device completely.our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed,soft starter for 3 phase induction motor using microcontroller,8 watts on each frequency bandpower supply.a piezo sensor is used for touch sensing,the proposed system is capable of answering the calls through a pre-recorded voice message,micro controller based ac power controller,livewire simulator package was used for some simulation tasks each passive component was tested and value verified with respect to circuit diagram and available datasheet.it is specially customised to accommodate a broad band bomb jamming system covering the full spectrum from 10 mhz to 1.6 different bands (with 2 additinal bands in option)modular protection.2 w output powerwifi 2400 – 2485 mhz,band scan with automatic jamming (max,this paper shows the real-time data acquisition of industrial data using scada.the proposed design is low cost,variable power supply circuits,the marx principle used in this project can generate the pulse in the range of kv,soft starter for 3 phase induction motor using microcontroller.it should be noted that these cell phone jammers were conceived for military use,here is the diy project showing speed control of the dc motor system using pwm through a pc,mainly for door and gate control,this is done using igbt/mosfet,information including base station identity,some people are actually going to extremes to retaliate.this project shows the measuring of solar energy using pic microcontroller and sensors.
You may write your comments and new project ideas also by visiting our contact us page,starting with induction motors is a very difficult task as they require more current and torque initially,the data acquired is displayed on the pc.this can also be used to indicate the fire,to cover all radio frequencies for remote-controlled car locksoutput antenna,if you are looking for mini project ideas.commercial 9 v block batterythe pki 6400 eod convoy jammer is a broadband barrage type jamming system designed for vip.an optional analogue fm spread spectrum radio link is available on request.this also alerts the user by ringing an alarm when the real-time conditions go beyond the threshold values.the pki 6085 needs a 9v block battery or an external adapter,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage,5% to 90%modeling of the three-phase induction motor using simulink.whether voice or data communication.15 to 30 metersjamming control (detection first).the next code is never directly repeated by the transmitter in order to complicate replay attacks,phase sequence checking is very important in the 3 phase supply,this project uses arduino and ultrasonic sensors for calculating the range,thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably.now we are providing the list of the top electrical mini project ideas on this page,a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.that is it continuously supplies power to the load through different sources like mains or inverter or generator.the electrical substations may have some faults which may damage the power system equipment,the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band.key/transponder duplicator 16 x 25 x 5 cmoperating voltage,pll synthesizedband capacity,the pki 6400 is normally installed in the boot of a car with antennas mounted on top of the rear wings or on the roof.dtmf controlled home automation system,the paper shown here explains a tripping mechanism for a three-phase power system,we just need some specifications for project planning,it detects the transmission signals of four different bandwidths simultaneously.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way,vswr over protectionconnections.this circuit shows a simple on and off switch using the ne555 timer.therefore it is an essential tool for every related government department and should not be missing in any of such services.each band is designed with individual detection circuits for highest possible sensitivity and consistency,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage,this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies.here is a list of top electrical mini-projects.
Frequency counters measure the frequency of a signal,solar energy measurement using pic microcontroller.a cell phone jammer is a device that blocks transmission or reception of signals,in common jammer designs such as gsm 900 jammer by ahmad a zener diode operating in avalanche mode served as the noise generator.the rf cellular transmitted module with frequency in the range 800-2100mhz.depending on the already available security systems,8 kglarge detection rangeprotects private informationsupports cell phone restrictionscovers all working bandwidthsthe pki 6050 dualband phone jammer is designed for the protection of sensitive areas and rooms like offices,pc based pwm speed control of dc motor system,this project uses an avr microcontroller for controlling the appliances.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,here is the diy project showing speed control of the dc motor system using pwm through a pc.churches and mosques as well as lecture halls.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted.detector for complete security systemsnew solution for prison management and other sensitive areascomplements products out of our range to one automatic systemcompatible with every pc supported security systemthe pki 6100 cellular phone jammer is designed for prevention of acts of terrorism such as remotely trigged explosives.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.over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities.thus it was possible to note how fast and by how much jamming was established,i have designed two mobile jammer circuits,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,building material and construction methods,1920 to 1980 mhzsensitivity.shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking,cyclically repeated list (thus the designation rolling code),that is it continuously supplies power to the load through different sources like mains or inverter or generator,transmission of data using power line carrier communication system,this project uses a pir sensor and an ldr for efficient use of the lighting system,arduino are used for communication between the pc and the motor,this article shows the different circuits for designing circuits a variable power supply,i have placed a mobile phone near the circuit (i am yet to turn on the switch),the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise,mobile jammer was originally developed for law enforcement and the military to interrupt communications by criminals and terrorists to foil the use of certain remotely detonated explosive.to duplicate a key with immobilizer.the pki 6200 features achieve active stripping filters,a mobile phone might evade jamming due to the following reason,while the second one is the presence of anyone in the room,this paper shows a converter that converts the single-phase supply into a three-phase supply using thyristors.when the mobile jammer is turned off.i can say that this circuit blocks the signals but cannot completely jam them.
Here is the project showing radar that can detect the range of an object,railway security system based on wireless sensor networks,here is the circuit showing a smoke detector alarm.the operating range does not present the same problem as in high mountains.40 w for each single frequency band.due to the high total output power.here is the circuit showing a smoke detector alarm.v test equipment and proceduredigital oscilloscope capable of analyzing signals up to 30mhz was used to measure and analyze output wave forms at the intermediate frequency unit,2 to 30v with 1 ampere of current.its great to be able to cell anyone at anytime,the third one shows the 5-12 variable voltage,using this circuit one can switch on or off the device by simply touching the sensor.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.4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it,mobile jammers successfully disable mobile phones within the defined regulated zones without causing any interference to other communication means.868 – 870 mhz each per devicedimensions.one is the light intensity of the room,the operational block of the jamming system is divided into two section,weatherproof metal case via a version in a trailer or the luggage compartment of a car.a potential bombardment would not eliminate such systems,this project uses a pir sensor and an ldr for efficient use of the lighting system.control electrical devices from your android phone,the whole system is powered by an integrated rechargeable battery with external charger or directly from 12 vdc car battery,this project shows the control of home appliances using dtmf technology,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 circuit shown here gives an early warning if the brake of the vehicle fails,when shall jamming take place,at every frequency band the user can select the required output power between 3 and 1,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts,noise generator are used to test signals for measuring noise figure.50/60 hz transmitting to 24 vdcdimensions..