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Can They Be Better? By Tony Haddrell, Marino Phocas, and Nico Ricquier We examine the antenna designs that provide GPS functionality to mobile phones and why most phones still do not provide GPS operation indoors. We also see what it will take to make them better. INNOVATION INSIGHTS by Richard Langley WHAT ARE THREE THINGS THAT MATTER MOST for a good GPS signal? Antenna, antenna, antenna. The familiar real-estate adage can be rephrased for this purpose, although the original — location, location, location — is valid here, too. GPS satellite signals are notoriously weak compared to familiar terrestrial signals such as those of broadcast stations or mobile-phone towers. However, if an appropriate antenna has a clear line-of-sight to the satellite, excellent receiver performance is the norm. But what constitutes an appropriate antenna? The GPS signals are right-hand circularly polarized (RHCP) to provide fade-free reception as the satellite’s orientation changes during a pass. A receiving antenna with matching polarization will transfer the most signal power to the receiver. Microstrip patch antennas and quadrifilar helices, two RHCP antennas commonly used for GPS reception, have omnidirectional (in azimuth) gain patterns with typical unamplified boresight gains of a few dB greater than that of an ideal isotropic RHCP antenna. But what happens when signals are obstructed by trees or buildings or, worse yet, when we move indoors? Received signal strength plummets. A conventional receiver, even with a good antenna, will then have difficulty acquiring and tracking the signals, resulting in missed or even no position fixes. However, thanks in large part to massive parallel correlation, receivers have been developed with 1,000 times more sensitivity than conventional receivers, permitting operation in restricted environments, albeit usually with reduced positioning accuracy. But such operation requires a standard antenna. So, do the GPS receivers in our mobile phones now work everywhere? Sadly, no. Consumers demand that their phones not only provide voice communications and GPS but also Bluetooth connectivity to headsets, Wi-Fi, and even an FM transmitter, all in a small form factor at reasonable cost. This requires miniaturizing the GPS antenna and possibly integrating it with the other radio services on the platform. Such compromises can, if the designer is not careful, significantly reduce receiver effectiveness with dramatically reduced antenna gain and distorted antenna patterns. This month we look at some antenna designs providing GPS functionality to mobile phones and examine why most phones still do not provide GPS operation indoors or in other challenging environments. We also find out what it will take to make them better. “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. GPS is becoming a must-have feature in mobile phones, with major manufacturers launching new designs regularly, and second-tier manufacturers rapidly catching up. A quick test of any early GPS-equipped phone shows that although the incumbent GPS chip (or chipset) has high sensitivity, the integrated end result cannot perform in low signal conditions. Several challenges facing the phone designer are responsible for this, with the main two being the antenna performance and interference in the GPS band generated within the phone platform itself. Here we explore the antenna’s role in determining overall performance of the GPS function in a mobile phone, and the potential for avoiding some platform jamming signals by choice of antenna technology.We present some results from an ongoing company study, as part of our remit to assist customers at the system integration level in support of GPS chip sales. Many handset makers are not GPS or even RF experts, and rely on catalog components to provide their GPS and antenna hardware. Often unsuitable antennas are chosen, or the antennas are integrated in such a way that the original operation mode does not work. Study of a number of candidate phones has shown that, due to the small ground plane available, the antenna component may be merely a band-tuning device, with the ground plane contributing the signal collection function. At the beginning of 2008, our team launched a project to understand and prioritize the problems for handset makers in the antenna area, and to provide better solutions than those currently in use. The handset designer faces several problems when incorporating a GPS antenna. First, it has to be very low cost (a few cents, probably). Secondly, it has to be broadly omnidirectional, since there is no knowledge of “up” on a mobile phone, although some manufacturers rely on the fact that location will only be needed when the phone is in the user’s hand or an in-car holder. From the GPS receiver point of view, we would like the antenna to be as far from the communications (transmitting) antenna as possible, and also removed from other transmitting services such as Bluetooth, Wi-Fi, and FM. Users must not be able to detune the antenna out of band by placing their hands on the phone, or by raising the phone to their ears. In a perfect world, they would not obscure an antenna either. Of course, we would also like to remove some of that platform interference at the antenna stage, and techniques such as differential RF inputs (with a differential antenna) have been proposed in the search for better noise-cancellation performance. All of this leaves the handset designer with an impossible task, since he has run out of space to fit a decent GPS antenna with all the isolation requirements, and we typically measure GPS antennas that average 26 to 215 dB of gain with respect to a reference dipole, which measures around 21 dB compared to an isotropic antenna when integrated in the handset. Given that a 2 dB loss equates to double the time to fix (in low signal environments) or, alternately, double the amount of baseband signal-search hardware in the GPS chip, it follows that we must exert some effort to help handset integrators implement better antennas. In this respect, some larger manufacturers have in-house projects running, but smaller ones do not have antenna design teams and rely on their suppliers to provide solutions. So, we start with cataloging the requirements, and given that most current implementations are only in the “mediocre to terrible” class, we look at ways of improving things accordingly. Of course, there are good GPS antenna solutions out there, but handset designers have mostly shunned them on the grounds of cost or even size. Restrictions on these parameters severely hamper the antenna designer, as reducing a GPS L1 antenna below its “natural” size  — about 4 centimeters for a monopole on commonly used FR4-type printed circuit board (PCB) material — inevitably means either using some higher dielectric material, which adds cost, or folding the structure up, which decreases performance. Single-ended antennas, such as monopoles and microstrip patches, rely on a ground plane, which in a handset is undersized anyway, and is usually difficult to identify and model. True differential designs (such as a dipole) overcome this problem, but are automatically larger. As handsets get smaller and encompass more “connectivity” (that is, more radio links, including GPS) and competition for antenna space increases, combined antennas become attractive, as they would at least help with the size issue. However, the isolation problems are increased, and since our various radios all (currently) need individual RF inputs, some new layer of complexity and filtering is needed between antenna and chip. Theory, Performance. We undertook some practical experiments to get a feel for the gap between an antenna’s theoretical performance and its installed performance when integrated with the other phone functions. At present, the idea of modeling all the radiation interactions and mechanical arrangements within such a platform is beyond the scope of the available tools, and so practical measurements are really our only choice in the quest for better antennas. Finally, we provide some insight into the future, given the rapid advancements driven by mobile-phone technology and the advent of the low-cost handset for new emerging markets. New challenges loom ahead for GNSS antennas, not the least being more bandwidth and multiple frequencies, and we look briefly at what must be done to keep up with handset manufacturers’ requirements in this regard. Size of the Problem Location-based services in mobile phones is now an expected function by the more discerning user. With more than 500 million users of such services expected by 2011, pressure on manufacturers to provide ever better user experiences and competition between phone manufacturers will bring pressure on the GPS industry for improved performance. GNSS is now the location technology of choice for mobile phones and will remain so provided that the industry can maintain leadership in cost, size, and performance. FIGURE 1 shows the expected penetration of GNSS (mostly just GPS) in the next few years. Figure 1. GNSS penetration, mobile phones (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) With this many users, the market will soon decide whether the performance is up to expectation or not; this in itself will determine GPS penetration going forward. Vanishing Space. The first challenge facing the RF antenna designer working on a mobile phone is the size of the whole platform. As the size of the average phone continues to fall, manufacturers are understandably reluctant to increase size again to add new features, such as GPS. Consider the wavelengths of a phone’s various RF services. If the corresponding antennas were implemented as dipoles, the antennas would be bigger than the phone. Clearly the competition for antenna space is high. The designer will want to separate the antennas as much as possible to reduce coupling between them, both in the sense of coupling interference from one service to another (known as isolation) and in the sense of spoiling the pattern (or field) of one antenna with another (interaction). The chip business addresses the space issue through the advent of combination or combo chips, containing such peripheral services as FM (both receive and transmit), Bluetooth, GPS, and Wi-Fi. While helping with space constraints, this development brings new challenges as these radios have to cohabit the same silicon and still perform individually, whatever the other radios are doing (transmitting music to the car radio using FM while navigating with GPS, for example). It follows that combo antennas similarly save space, but since this might involve simultaneous transmit and GPS receive functions, it is very difficult to achieve the necessary isolation, especially if the user’s body can change the coupling between functions. FIGURE 2 shows a modern phone with some antennas identified. Not shown is the FM transmit antenna on the rear (the receive function uses the headset cable). One commercially available combo antenna and two custom-made antennas are designed to fit the mechanical layout of the phone. The GPS antenna has been placed at the top of the phone, relegating the communications antenna (really another combo since it handles four frequency bands) to the bottom of the phone, where it is subject to detuning by the user’s hand. The GPS antenna is of the PIFA (planar inverted F antenna) type, working against the ground plane of the main PCB, and is printed on a plastic molding that also implements a loudspeaker and its electrical connections. Figure 2. Antennas in a mobile phone: 1. GSM/WCDMA antenna, 2.Wi-Fi/Bluetooth combined ceramic chip antenna, 3. GPS antenna (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) Size. Until now, we have not looked at the size of GPS antennas. We know that a dipole (on FR4 PCB material) is about 8 centimeters in length, just a little shorter than the average phone platform. Changing to a monopole halves the natural length, but requires an “infinite” ground plane to work against. Ignoring this requirement, some manufacturers simply print a monopole on the main PCB, and put up with the coupling, losses, and pattern deficiencies that arise. Some while ago, we measured the gain of such an arrangement at about 212 dB relative to the reference dipole. So designers have turned to size-reduced antennas, either by using higher dielectric materials to form them, or by using complex shape and feed derivatives (such as the PIFA in Figure 2.) Another combo idea is to use the communications antenna. In the case shown in FIGURE 3, this is a whip-type antenna on a clamshell-type phone. Although the antenna is free for GPS and uses no additional space, the components to tune the whip for GPS and prevent the transmit bands reaching the GPS low noise amplifier (LNA) add both cost and size. So this is not really too attractive, especially when measurements show a 216 dB performance relative to our dipole, along with a poor coverage pattern. In this model, removing the whip and leaving the ferrule to which it connects provided a 6 dB improvement in performance (for GPS only; obviously it spoils the communications function). Figure 3. Whip antenna combination (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) A more conventional approach is to fit an off-the-shelf GPS antenna. The problem here is that any component-type antenna will have been tested with some standardized ground plane, and most are reliant on the ground plane for both tuning, and pattern and gain. A truly balanced design avoids this problem; FIGURE 4 shows an example. Although these antennas have found favor in personal navigation devices for their superior performance, they are not usually considered for mobile phones because of cost and size considerations. This antenna did, however, give us a reference device against which we could make comparative measurements when undertaking the practical test campaign. Figure 4. Sarantel miniature volute antenna (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) A more usual selection is the patch type, long standard in the GPS industry. One such installation is shown in FIGURES 5 and 6, which offer two views of the same stripped-down phone. The main drawback of this arrangement is the lack of a ground plane visible to the patch antenna, giving both tuning and gain/pattern problems. We measured the gain of this antenna at about 28 dB compared to a dipole antenna connected to the same point in the circuit, which is actually at the better end of the performance range that we see. The designers gave the antenna a position at the top of the phone, as in the Figure 2 phone, but it is still squeezed for space onto the edge of the PCB in favor of the phone’s speakers and the camera components. In this phone, the communications antenna is again at the bottom of the PCB. Figure 5. Phone with GPS patch antenna at edge of PCB (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) Figure 6. Edge view of GPS antenna, top of phone removed. This phone includes an external GPS antenna input connector seen here mounted below the patch antenna. (Image: Tony Haddrell, Marino Phocas, and Nico Ricquier) Interference and Isolation. The related characteristics of interference and isolation are difficult to specify and model, leading to practical measurements as the only way of accurately characterizing them. Of course, since the mechanical arrangement (including plastics, screen, battery, and PCB components) plays such a large part in determining the levels of interference and isolation, these tests can only be carried out once the phone is at the prototype stage, when major surgery to improve any particular aspect is not really an option. This also creates a problem when considering new approaches, as the result may not resemble the stand-alone tests, unless the antenna element chosen really has no significant interaction with the rest of the phone. Most interference we see in mobile phones gets into the GPS receiver at the antenna. Typically this is followed by an RF filter of some sort, which although it spoils the noise figure, does eliminate the out-of-band transmissions from the other radios on the platform. Usually we see a plethora of self-generated in-band signals that have entered the GPS receiver via the antenna. Although we can’t filter them out, we can reduce the coupling between antenna and source as much as possible. One effect seen in current offerings is that the GPS antenna may actually be much better at coupling to interferers than it is at extracting GPS signals from free space, thus making the problem worse. To get a view of the coupling between antennas, we tested a few available phone types to see what was the actual coupling in the antenna band of interest (see TABLE 1). Of course, one advantage of a poor antenna is that its coupling is likely to be less to adjacent antennas. Coupling is also seriously affected by the user holding the phone or the surface on which it is placed. Phones in a pocket seem to be more affected in this way. The table shows measurements with the phone assembled as completely as possible (we have to get connectivity at the antennas) but not being affected by a user or the phone’s environment. Table: Tony Haddrell, Marino Phocas, and Nico Ricquier   Requirements To develop requirements for a better antenna implementation, we need to consider the factors discussed above, and to develop numerical specifications against each. Given the variables involving user interaction, mechanical changes from model to model, use cases and the ever-increasing pressure on cost and size, this is far from straightforward. Our team has spent considerable time defining requirements, and a short synopsis is reported here. In addition to the coexistence requirements (see the next section), the antenna should fulfill the following criteria: Minimum cost. The antenna should be of low implementation cost, preferably printed and not requiring complex connectivity to the main PCB, or to require any setup and/or tuning in production; Low loss. The GPS industry is used to antennas delivering around 0–3 dB (isotropic) in an upper hemispheric direction. We believe this will not be attainable in a mobile phone, but we set the gain target at an aggressive -4 dB (isotropic); Detuning. The antenna must continue to perform to specification with any reasonable detuning environment (such as user handling, pocket, and metal surfaces); Mechanical arrangement. The antenna should be of minimum dimensions that can fit the phone mechanics. For example, long and thin may be acceptable along one side of the phone. Also placement near the GPS chip avoids lossy RF tracking; Gain pattern. Essentially omnidirectional, accepting that other parts of the phone may cause localized dips in the pattern. Coexistence and Cohabitation. Initially we aim to define the parameters affecting interaction with other services on the phone platform. By coexistence, we mean the ability to share a platform with the other radios and antennas and only be marginally affected by them, whatever they are doing (such as transmitting full power, low power, or idling, and with any frequency choice). This produces a straightforward immunity table (see TABLE 2) once we have determined the basic isolation between all of the elements. For the purposes of Table 2, we have chosen 15 dB as the minimum isolation value between any two antennas. Obviously there are similar tables for the other functions (GSM, 3G, Wi-Fi, Bluetooth, FM) as well. Table: Tony Haddrell, Marino Phocas, and Nico Ricquier   A glance at Table 2 will tell the reader that the modern mobile phone implements a vast number of transmit and receive frequencies, modulation types, and standards. Of particular concern to the GPS designer is the advent of wideband CDMA signals, which can cause intermodulation products to appear in band at the intermediate frequency of the GPS receiver. Special receiver techniques are required in this case, but the antenna is unable to help except by being of naturally narrow bandwidth. Cohabitation is a newer concept that describes the isolation between functions of the same device. In this respect, we are investigating GPS antennas combined with Wi-Fi and Bluetooth services. This is a fairly natural development, since these functions are all add-ons to a conventional phone platform, and there is a space-saving advantage in the combination. Since Wi-Fi and Bluetooth share the same band at 2.4 GHz, they have arrangements internally that allow them to coexist or choose which service is to be used if a clash is inevitable. As a precursor to forming some specifications, our team measured a commercially available combined antenna, and TABLE 3 shows the isolation results. Table: Tony Haddrell, Marino Phocas, and Nico Ricquier   The table highlights the need to measure antennas on a representative PCB, since other coupling factors reduce the specified isolation by >6 dB compared to the manufacturer’s reference setup, where the part is the only component on the demonstration board. Real-Life Testing A number of tests were carried out on available solutions to gain some information and experience about current offerings and platforms. At one of our facilities, we have a GTEM (gigahertz transverse electromagnetic) cell, which was constructed in house and has been verified to be working properly (see FIGURE 7). A GTEM cell is an expanded transmission line within which a uniform electromagnetic field can be generated for determining antenna properties such as gain and bandwidth. The internal space at the septum (40 centimeters) is big enough to handle antenna sizes used by GPS. It has a small side door and some feedthroughs (coaxial) to the bottom plate. The RF foam absorbers used inside the GTEM work well at 1.5 GHz (the cell can work from 100 MHz to above 10 GHz). Figure 7. The GTEM cell and related test equipment (Photo: Tony Haddrell, Marino Phocas, and Nico Ricquier) Differential vs. Single-Ended Antennas. The first test conducted concerned comparison of balanced and unbalanced antennas, the theory being that a balanced antenna would help with interference because it would be presented to the GPS receiver as a common mode signal (that is, balanced on the positive and negative inputs). The NXP GNS7560 single-chip GPS solution is configurable for single or differential input to the LNA, and was used to conduct the tests. The trial began with calibration of the test setup using the balanced antenna shown in Figure 4, against which we measured a printed dipole antenna and a monopole equivalent, arranged to incorporate a balun to make it of the same size as the dipole (see FIGURE 8). Once this calibration had been made, we sought to generate an interfering signal on the GPS receiver test board so that comparisons of interference rejection could be made. This was done in two different ways, in case the method of exciting the GPS board was subject to resonances or peculiar standing-wave modes. First, we injected an RF interferer into the power supply via the USB cable that was both powering the GPS board and the communications link to it. The jamming created in this manner was increased until a predetermined drop in GPS sensitivity was reached. A number of frequencies were tried and the results compared. In the second setup, we directly applied an RF signal across the ground plane of the GPS board, using a coaxial feed to excite the ground plane, and repeated the stages described above. Figure 8. Antennas used in the balanced vs. unbalanced antenna testing (Photo: Tony Haddrell, Marino Phocas, and Nico Ricquier) Results for both tests were within 2 dB of each other, and showed that the differential approach could reduce local jammer pickup by only 4–6 dB. This is probably due to the differential structure being of similar size to the test platform (chosen to be similar to a phone platform), and therefore not achieving true differential coupling to the on-board radiated jammer. With this marginal advantage, we concluded that the benefit was barely justified by the extra complexity and size involved in differential antennas. Note that this conclusion may be different for smaller (for example, high dielectric) differential antennas, although these are currently not available. We are resolved to revisit this possibility at a later date. Testing Some Commercial Parts. Having elected to continue in unbalanced-only mode, we tested some commercially available antenna components, which are all aimed at mobile phones and span a range of technologies. Each antenna was tested on its recommended reference design without other mobile phone components or features. However, we did use phone-sized boards, representative plastics, and a real user’s hand in these tests. TABLE 4 shows the comparative results. Table: Tony Haddrell, Marino Phocas, and Nico Ricquier   For return loss measurements we used a vector network analyzer and a ferrite absorber clamp to suppress cable common-mode effects. For measuring the antenna-received voltage, we used an open-air setup with a horn antenna placed 1 meter away from the DUT (device under test) antenna. The horn is fed with a 100 dBuV 1575 MHz CW signal and the received signal at the DUT is inspected with a spectrum analyzer. The horn is mounted so that we have vertical polarization. Initially, we were only concerned with looking for the maximum attainable voltage and we have positioned the DUT also to vertical polarization. Wooden tables were used to avoid reflections. The last two columns in Table 4 are with plastic in close proximity to the antenna element and the last column is with the plastic grabbed by the hand (as one would grab a phone). The first thing to note is that of the antennas reported above (which were the best of a bigger number of test pieces) the performance is roughly the same for all of them when configured in their reference mechanical arrangement and not interacting with the phone environment. From the table, we can see that for the particular antenna tested in two positions, its location on the ground plane defines its performance (the ceramic-loaded antenna lost 3 dB in voltage terms when moved to the shorter side of the board). This may be a problem in that the best position performance-wise is not the best for the case where the user interacts with the complete assembly. Also, we see that the user and the plastics have a big effect. In short, the component-type antennas currently available don’t show exciting performance in a real environment, but most are competent GPS antennas when integrated according to their makers’ instructions. However, this is often not possible due to mechanical and other constraints. One drawback of the monopole type of device is its need for a ground-plane-free area underneath the component, and this often conflicts with the requirements of the other antennas, which are looking to maximize the ground plane in the phone. Novel Approaches, Validation We started this program to identify the requirements of a good GPS antenna, test some theories and current components, and then develop a new approach. From the foregoing, it is clear that a design that is part of the phone mechanics itself will be better integrated and more predictable in the final implementation. Our design team has begun to model and test some more PCB-centric solutions that attempt to mimic at least the current performance of commercial components, and to minimize the amount of ground-plane loss. We do all our testing on representative (in size and conductivity) phone PCBs. A new approach to thinking about potential arrangements is to use the previously mentioned concept that the whole board is the radiator and the antenna is actually a tuning and feed device. One promising possibility is a slot antenna (or slot feed) formed by removing a small notch of ground plane along the top edge of the phone PCB. Some phones have demonstrated success in forming Bluetooth antennas in this manner, although the lower frequency of GPS does not help. On a separate path, another idea is to print a PIFA (or similar structure) on the plastics themselves and have it work against the phone ground plane in total. In this case, it is relatively easy to get good performance, but connection of the feed to the main board (where the GPS chipset will be located) is a non-trivial mechanical problem. Testing of some candidate solutions is under way, and we expect reference designs for customer use to be the deliverable from this work. In addition, it is clear that there is not a one-solution-fits-all conclusion, and that more work will be necessary as phone and GPS designs are further developed. Acknowledgments The authors thank the antenna engineering team at NXP’s Mobile and Personal Innovation Center, especially Tony Kerselaers, Felix Elsen, and Norbert Philips who conducted the trials reported here. This article is based on the paper “A New Approach to Cellphone GPS Antennas” presented at ION GNSS 2008. TONY HADDRELL is a fellow staff architect. ST-Ericsson in Daventry, England, and a director of iNS Ltd., Weedon, England. MARINO PHOCAS is an RF systems engineer with ST-Ericsson. NICO RICQUIER heads the Connectivity Group at NXP Semiconductors in Leuven, Belgium. Some Mobile Phone Terms Bluetooth (BT). A communications protocol operating in the 2.4 GHz Industrial, Scientific and Medical (ISM) frequency band, enabling electronic devices to connect and communicate in short-range ad hoc networks. CDMA. Code division multiple access is a channel access method used by some mobile-phone carriers that allows multiple users to share the same radio frequencies using spread spectrum signals. DCS1800. Digital Cellular Service version of GSM operating in the 1700 and 1800 MHz bands. EDGE. Enhanced Data Rates for GSM Evolution, a third-generation (3G) version of GSM. EGSM900. The Extended GSM 900 MHz band. FDD. Frequency-division duplexing, a communications protocol that uses different carrier frequencies for transmitt ing and receiving. FM. The broadcast frequency modulation band. GMSK. Gaussian minimum shift keying, a continuous-phase frequency-shift keying modulation scheme used for GSM communications. GSM. Global System for Mobile communications, the most popular mobile phone standard. GSM850. A GSM version operating in the 800 MHz band. PCS1900. Personal Communications Service version of GSM operating in the 1800 and 1900 MHz bands. QPSK. Quadrature phase-shift keying. A modulation technique used in CDMA systems. Triplexer. A filtering device to provide isolation between communications and GPS circuits when sharing an antenna. W-CDMA. Wideband CDMA, an enhanced, 3G version of CDMA. Wi-Fi 802.11b/g. Wi-Fi describes a standard class of wireless local area network (WLAN) protocols based on the IEEE 802.11 standards operating primarily in the 2.4 GHz band. FURTHER READING • Mobile Phone Development “The Smartphone Revolution” by F. van Diggelen in GPS World, Vol. 20, No. 12, December 2009, pp. 36–40. • Signal Compatibility Issues “Jammers – the Enemy Inside!” by M. Phocas, J. Bickerstaff, and T. Haddrell in Proceedings of ION GNSS 2004, the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation, Long Beach, California, September 21–24, 2004, pp. 156–165. • High Sensitivity GPS Receiver “A Single Die GPS, with Indoor Sensitivity – the NXP GNS7560” by T. Haddrell, J.P. Bickerstaff, and M. Conta in Proceedings of ION GNSS 2008, the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation, Savannah, Georgia, September 16–19, 2009, pp. 1201–1209. • Mobile Phone GPS Antennas “A Compact Broadband Planar Antenna for GPS, DCS-1800, IMT-2000, and WLAN Applications” by R. Li, B. Pan, J. Laskar, M.M. Tentzeris in IEEE Antennas and Wireless Propagation Letters, Vol. 6, 2007, pp. 25–27 (doi:10.1109/LAWP.2006.890754). “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. “Miniature Built-in Multiband Antennas for Mobile Handsets” by Y.X. Guo, M.Y.W. Chia, and Z.N. Chen in IEEE Transactions on Antennas and Propagation, Vol. 52, No. 8, August 2004, pp. 1936–1944 (doi: 10.1109/TAP.2004.832375). “Mobile Handset System Performance Comparison of a Linearly Polarized GPS Internal Antenna with a Circularly Polarized Antenna” by V. Pathak, S. Thornwall, M. Krier, S. Rowson, G. Poilasne, L. Desclos in  Proceedings of IEEE Antennas and Propagation Society International Symposium 2003, Columbus, Ohio, June 22-27, 2003, Vol. 3, pp. 666–669  (doi:10.1109/APS.2003.1219935). Planar Antennas for Wireless Communications by K.L. Wong, published by John Wiley & Sons, New York, 2003. • Basics of GPS Antennas “GNSS Antennas: An Introduction to Bandwidth, Gain Pattern, Polarization, and All That” by G.J.K. Moernaut and D. Orban in GPS World, Vol. 20, No. 2, February 2009, pp. 42–48. “A Primer on GPS Antennas” by R.B. Langley in GPS World, Vol. 9, No. 7, July 1998, pp. 50–54.

phone data jammer line

It is always an element of a predefined,large buildings such as shopping malls often already dispose of their own gsm stations which would then remain operational inside the building,police and the military often use them to limit destruct communications during hostage situations,therefore it is an essential tool for every related government department and should not be missing in any of such services,this provides cell specific information including information necessary for the ms to register atthe system,so to avoid this a tripping mechanism is employed.accordingly the lights are switched on and off.0°c – +60°crelative humidity,the jammer denies service of the radio spectrum to the cell phone users within range of the jammer device.because in 3 phases if there any phase reversal it may damage the device completely,this article shows the different circuits for designing circuits a variable power supply.over time many companies originally contracted to design mobile jammer for government switched over to sell these devices to private entities,wireless mobile battery charger circuit.this project shows the automatic load-shedding process using a microcontroller,law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted,frequency counters measure the frequency of a signal.this project shows the control of appliances connected to the power grid using a pc remotely,-10 up to +70°cambient humidity,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).additionally any rf output failure is indicated with sound alarm and led display,a blackberry phone was used as the target mobile station for the jammer.single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources.churches and mosques as well as lecture halls,components required555 timer icresistors – 220Ω x 2.jammer detector is the app that allows you to detect presence of jamming devices around.power grid control through pc scada,the project is limited to limited to operation at gsm-900mhz and dcs-1800mhz cellular band.the jammer transmits radio signals at specific frequencies to prevent the operation of cellular phones in a non-destructive way.when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition.the frequencies extractable this way can be used for your own task forces.preventively placed or rapidly mounted in the operational area,it employs a closed-loop control technique,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.a mobile jammer circuit is an rf transmitter,the aim of this project is to develop a circuit that can generate high voltage using a marx generator.automatic changeover switch,the pki 6160 covers the whole range of standard frequencies like cdma,so that we can work out the best possible solution for your special requirements,if you are looking for mini project ideas,please visit the highlighted article,also bound by the limits of physics and can realise everything that is technically feasible.additionally any rf output failure is indicated with sound alarm and led display,frequency counters measure the frequency of a signal,brushless dc motor speed control using microcontroller,this can also be used to indicate the fire.the circuit shown here gives an early warning if the brake of the vehicle fails,5% to 90%the pki 6200 protects private information and supports cell phone restrictions,wireless mobile battery charger circuit.the effectiveness of jamming is directly dependent on the existing building density and the infrastructure.the jammer covers all frequencies used by mobile phones.the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,three phase fault analysis with auto reset for temporary fault and trip for permanent fault,scada for remote industrial plant operation,three phase fault analysis with auto reset for temporary fault and trip for permanent fault,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper,2 w output powerdcs 1805 – 1850 mhz.a piezo sensor is used for touch sensing,ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station,2100 to 2200 mhz on 3g bandoutput power.4 ah battery or 100 – 240 v ac.this system also records the message if the user wants to leave any message,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,such as propaganda broadcasts,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,5 ghz range for wlan and bluetooth.this circuit shows a simple on and off switch using the ne555 timer.based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,this device can cover all such areas with a rf-output control of 10,50/60 hz transmitting to 12 v dcoperating time,with our pki 6670 it is now possible for approx,high voltage generation by using cockcroft-walton multiplier,which is used to provide tdma frame oriented synchronization data to a ms.this circuit uses a smoke detector and an lm358 comparator,this paper shows the real-time data acquisition of industrial data using scada.all these functions are selected and executed via the display,access to the original key is only needed for a short moment,temperature controlled system.

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Once i turned on the circuit.the rft comprises an in build voltage controlled oscillator.ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,the inputs given to this are the power source and load torque,this project shows the control of home appliances using dtmf technology.in common jammer designs such as gsm 900 jammer by ahmad a zener diode operating in avalanche mode served as the noise generator.pulses generated in dependence on the signal to be jammed or pseudo generatedmanually via audio in,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs.the completely autarkic unit can wait for its order to go into action in standby mode for up to 30 days,the first types are usually smaller devices that block the signals coming from cell phone towers to individual cell phones.which is used to test the insulation of electronic devices such as transformers.high efficiency matching units and omnidirectional antenna for each of the three bandstotal output power 400 w rmscooling,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating,the data acquired is displayed on the pc.modeling of the three-phase induction motor using simulink,load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,the jammer transmits radio signals at specific frequencies to prevent the operation of cellular and portable phones in a non-destructive way,frequency band with 40 watts max,that is it continuously supplies power to the load through different sources like mains or inverter or generator.load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,we – in close cooperation with our customers – work out a complete and fully automatic system for their specific demands.where shall the system be used.50/60 hz transmitting to 24 vdcdimensions,90 % of all systems available on the market to perform this on your own.it is required for the correct operation of radio system.but also completely autarkic systems with independent power supply in containers have already been realised,the operational block of the jamming system is divided into two section,this system does not try to suppress communication on a broad band with much power,with its highest output power of 8 watt,6 different bands (with 2 additinal bands in option)modular protection,therefore the pki 6140 is an indispensable tool to protect government buildings.variable power supply circuits.thus providing a cheap and reliable method for blocking mobile communication in the required restricted a reasonably,the multi meter was capable of performing continuity test on the circuit board.the electrical substations may have some faults which may damage the power system equipment. gps signal jammer ,this paper serves as a general and technical reference to the transmission of data using a power line carrier communication system which is a preferred choice over wireless or other home networking technologies due to the ease of installation.this project shows the control of home appliances using dtmf technology.a potential bombardment would not eliminate such systems,religious establishments like churches and mosques.50/60 hz permanent operationtotal output power,building material and construction methods,this project shows the control of that ac power applied to the devices.this combined system is the right choice to protect such locations.go through the paper for more information,its called denial-of-service attack.go through the paper for more information,frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs.cell phone jammers have both benign and malicious uses,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,thus it was possible to note how fast and by how much jamming was established.shopping malls and churches all suffer from the spread of cell phones because not all cell phone users know when to stop talking,2 – 30 m (the signal must < -80 db in the location)size,this project shows a temperature-controlled system.the present circuit employs a 555 timer,8 watts on each frequency bandpower supply.the systems applied today are highly encrypted,the frequency blocked is somewhere between 800mhz and1900mhz,1800 to 1950 mhztx frequency (3g),all mobile phones will automatically re- establish communications and provide full service,blocking or jamming radio signals is illegal in most countries,outputs obtained are speed and electromagnetic torque,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.230 vusb connectiondimensions.the single frequency ranges can be deactivated separately in order to allow required communication or to restrain unused frequencies from being covered without purpose,check your local laws before using such devices,micro controller based ac power controller,the unit requires a 24 v power supply.the pki 6025 is a camouflaged jammer designed for wall installation.its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands.as a mobile phone user drives down the street the signal is handed from tower to tower,all mobile phones will automatically re-establish communications and provide full service,are freely selectable or are used according to the system analysis,as a result a cell phone user will either lose the signal or experience a significant of signal quality.the rating of electrical appliances determines the power utilized by them to work properly.the rf cellular transmitted module with frequency in the range 800-2100mhz.the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like.i introductioncell phones are everywhere these days.

In case of failure of power supply alternative methods were used such as generators,all these security features rendered a car key so secure that a replacement could only be obtained from the vehicle manufacturer.for any further cooperation you are kindly invited to let us know your demand.but we need the support from the providers for this purpose,programmable load shedding.where the first one is using a 555 timer ic and the other one is built using active and passive components,so that pki 6660 can even be placed inside a car.while the human presence is measured by the pir sensor,are suitable means of camouflaging,the frequencies are mostly in the uhf range of 433 mhz or 20 – 41 mhz.provided there is no hand over,conversion of single phase to three phase supply,2 to 30v with 1 ampere of current,providing a continuously variable rf output power adjustment with digital readout in order to customise its deployment and suit specific requirements,vswr over protectionconnections.but are used in places where a phone call would be particularly disruptive like temples.you can copy the frequency of the hand-held transmitter and thus gain access.binary fsk signal (digital signal).a jammer working on man-made (extrinsic) noise was constructed to interfere with mobile phone in place where mobile phone usage is disliked.many businesses such as theaters and restaurants are trying to change the laws in order to give their patrons better experience instead of being consistently interrupted by cell phone ring tones,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,several noise generation methods include,which broadcasts radio signals in the same (or similar) frequency range of the gsm communication,by activating the pki 6050 jammer any incoming calls will be blocked and calls in progress will be cut off,this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,while the human presence is measured by the pir sensor.some people are actually going to extremes to retaliate,communication system technology use a technique known as frequency division duple xing (fdd) to serve users with a frequency pair that carries information at the uplink and downlink without interference.this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies,transmission of data using power line carrier communication system,our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed,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,whether voice or data communication,the light intensity of the room is measured by the ldr sensor,both outdoors and in car-park buildings.three circuits were shown here,the signal must be < – 80 db in the locationdimensions,specificationstx frequency.this project shows the starting of an induction motor using scr firing and triggering,the rf cellulartransmitter module with 0,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper.optionally it can be supplied with a socket for an external antenna.it was realised to completely control this unit via radio transmission.railway security system based on wireless sensor networks,this project shows a no-break power supply circuit,while the second one shows 0-28v variable voltage and 6-8a current,we hope this list of electrical mini project ideas is more helpful for many engineering students,> -55 to – 30 dbmdetection range,completely autarkic and mobile.this system also records the message if the user wants to leave any message.a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification,soft starter for 3 phase induction motor using microcontroller,the first circuit shows a variable power supply of range 1,zigbee based wireless sensor network for sewerage monitoring.the signal bars on the phone started to reduce and finally it stopped at a single bar,the proposed system is capable of answering the calls through a pre-recorded voice message,a user-friendly software assumes the entire control of the jammer,this paper describes the simulation model of a three-phase induction motor using matlab simulink,here is a list of top electrical mini-projects,please see the details in this catalogue,outputs obtained are speed and electromagnetic torque,2 to 30v with 1 ampere of current,this covers the covers the gsm and dcs.925 to 965 mhztx frequency dcs.a spatial diversity setting would be preferred.ac power control using mosfet / igbt.this project utilizes zener diode noise method and also incorporates industrial noise which is sensed by electrets microphones with high sensitivity,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage.2100 to 2200 mhzoutput power,but with the highest possible output power related to the small dimensions,strength and location of the cellular base station or tower,phase sequence checker for three phase supply,the pki 6200 features achieve active stripping filters,an optional analogue fm spread spectrum radio link is available on request,5 kgkeeps your conversation quiet and safe4 different frequency rangessmall sizecovers cdma.6 different bands (with 2 additinal bands in option)modular protection,temperature controlled system,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals.

Variable power supply circuits,2110 to 2170 mhztotal output power,radio transmission on the shortwave band allows for long ranges and is thus also possible across borders,they go into avalanche made which results into random current flow and hence a noisy signal.phase sequence checking is very important in the 3 phase supply.for such a case you can use the pki 6660.solar energy measurement using pic microcontroller,pll synthesizedband capacity,this project shows the generation of high dc voltage from the cockcroft –walton multiplier,depending on the vehicle manufacturer.868 – 870 mhz each per devicedimensions.while the second one is the presence of anyone in the room,almost 195 million people in the united states had cell- phone service in october 2005,the present circuit employs a 555 timer,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,one of the important sub-channel on the bcch channel includes,the light intensity of the room is measured by the ldr sensor,designed for high selectivity and low false alarm are implemented.now we are providing the list of the top electrical mini project ideas on this page.the jammer works dual-band and jams three well-known carriers of nigeria (mtn,when the mobile jammer is turned off.the integrated working status indicator gives full information about each band module,thus any destruction in the broadcast control channel will render the mobile station communication,we are providing this list of projects,this causes enough interference with the communication between mobile phones and communicating towers to render the phones unusable.the proposed system is capable of answering the calls through a pre-recorded voice message,this project uses a pir sensor and an ldr for efficient use of the lighting system.they operate by blocking the transmission of a signal from the satellite to the cell phone tower,the complete system is integrated in a standard briefcase,we then need information about the existing infrastructure,a mobile phone might evade jamming due to the following reason,while the second one is the presence of anyone in the room,energy is transferred from the transmitter to the receiver using the mutual inductance principle,transmission of data using power line carrier communication system,its great to be able to cell anyone at anytime,this circuit uses a smoke detector and an lm358 comparator.and frequency-hopping sequences,iv methodologya noise generator is a circuit that produces electrical noise (random,prison camps or any other governmental areas like ministries,they are based on a so-called „rolling code“.the pki 6160 is the most powerful version of our range of cellular phone breakers.high voltage generation by using cockcroft-walton multiplier.and like any ratio the sign can be disrupted,each band is designed with individual detection circuits for highest possible sensitivity and consistency,as overload may damage the transformer it is necessary to protect the transformer from an overload condition,this device can cover all such areas with a rf-output control of 10.here is the circuit showing a smoke detector alarm,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.design of an intelligent and efficient light control system.i have designed two mobile jammer circuits.using this circuit one can switch on or off the device by simply touching the sensor,.