Signal jamming model irma | signal jamming laws worksheet

Actions Necessary to Reduce Vulnerability and Ensure Availability By Brad Parkinson (From the 25th Anniversary GNSS History Special Supplement) Introduction Brad Parkinson About 40 years ago, we had a vision for positioning, navigation, and timing (PNT). That vision was more than successful, and became known as GPS. In some respects we have been almost too successful: PNT is frequently taken for granted. PNT, in the form of GPS, has become a powerful worldwide enabler for productivity and for safety. Estimated yearly value runs to many tens of billions of dollars.  For several years, I have been concerned about comments that denigrate GPS because the signal strength is relatively weak. The speakers have gone on to say it can be completely replaced with inertial or other techniques. Recently, comments by government officials further energized me to look at the full picture. What can we do to reduce the vulnerability and ensure that the expectations of the users are going to be met? I summarize my solution as the PTA program and will elaborate in this article. At a top level, the term PTA means: Protect, Toughen, and Augment GPS to assure PNT. Note I say PNT, not GPS. The central issue is assuring access of PNT to the user, not the source of the information. I strongly believe that PTA is both achievable and absolutely necessary. Protecting PNT is particularly important to Europeans as they are just about to launch their fledgling Galileo system. Speeches and travel only reach a limited number. When GPS World invited me to write a piece for the magazine’s 25th anniversary issue, it seemed an ideal opportunity to expand knowledge of the PTA program. The following is an edited form of a talk I have given a number of times, most recently at the European Navigation Conference in Rotterdam in April 2014. GNSS initiatives and the GNSS community are growing rapidly, and certainly we are very enthusiastic about the progress of Galileo. But some places in the U.S. community are saying, “Well, this GPS band is underutilized; devoting all that bandwidth to a single system is not prudent.” I beg to differ with that view. If you look at the separate signals in the L1 band around the world, by the year 2023 they will grow to be well more than 400 individual signals. Those signals service over 2 billion users, from emergency service providers to precision agriculture to crustal monitoring and many, many more. I have an entirely separate talk on “GPS for Humanity,” but that is not our subject today.  Calling the GPS frequency band “underutilized” simply points out ignorance, even among our supporters. For example, we say PNT to emphasize that GNSS provides four dimensions. Certainly, timing is the forgotten fourth dimension of GPS, and even our politician friends rarely understand the importance of this aspect. Yet we know that highly accurate timing, supplied by GPS, is absolutely critical for power distribution, for telecommunications, and for the financial sector.  It is instructive to summarize the penetration of the PNT “Stealth Utility” into the fabric of our society. Market Size. Overall, GPS has more than 2 billion users worldwide. This represents a very diverse user group; we providers are continually seeing new and innovative ways to use GPS.  Figure 1, for which I am indebted to Frank van Diggelen, gives an estimate of the number of receivers currently fielded. Notice the number of military receivers: less than half a million. The gray bar depicts the industrial uses such as survey and machine control, which come in at about 4.5 million; these tend to be extremely high enhancers of industrial productivity.  Figure 1. GNSS market size, 2012. We have to change the chart scale to depict bigger market segments. For example, recreation, automotive, and computing are shown on the lower half of the chart. In fact, mobile phones will still not fit on the chart. Attesting to the size of the estimated mobile phone base: one company alone will produce more than 900 million GPS-equipped smartphones this year. The pie diagram shows the dominance of mobile devices, but much higher productivity gains come from high-precision devices whose impact is very disproportionate to numbers of receivers.   We asked some economists, just what is all this worth? They looked at a subset of all the industries and concluded that GPS has a positive net effect to the tune of at least $32 billion annually. They had an expanded study that suggested about $90 billion annually. So, for those who question the value of GPS, the answer is that the net yearly returns to our national investment are more than 1000 percent. (Note: National investment is about $3 billion annually.) To ensure these enormous economic benefits of PNT, there are two fundamental needs, and we providers must assure that they are met. The first and most important need is availability.  Availability. When we say availability, it is defined in a certain way; it means that PNT is available at the application-specified accuracy. We usually measure that accuracy at the 90th percentile: only 10 percent of the time can that error be exceeded.  Integrity. The second user need is the required integrity. That means that when the user expects a specific accuracy, the system is not lying to him. Integrity assurance is very much a focus of both the International Civil Aviation Organization (ICAO) and, in the United States, the Federal Aviation Administration (FAA). In many cases they require that PNT errors not exceed specified bounds more than once in 10 billion measurements (1 x 10-7). This integrity level requires so many samples, it is virtually impossible to verify experimentally; we have not had that many airplane landings, but it can be calculated. The metric we use is how many minutes GPS is not available — unavailability — at the specified accuracy and integrity. That is more easily understood than availability that aproaches 99.9XXX percent. The usual goal is that unavailability be zero.  We have an independent assessment of how well we are doing: FAA’s Wide Area Augmentation System (WAAS). They put out a report card with a lot of numbers. GPS clearly deserves a grade of A+.  And it will get better. The U.S. government’s PNT Advisory Board, which I co-chair, recently advocated that the full navigation message be added at the new civil frequencies, the L2C and L5C signals. The Air Force has now complied, thanks to strong support from General Willie Shelton. This makes two more civil signals fully available. They currently expect 2.9 meter ranging accuracy, but by the end of the year the Air Force operators expect the same full accuracy as the rest of the signals, on the order of 0.5 meter of ranging error.  This is an outstanding picture. So What’s the Problem? A statement made by a high-level U.S. government official in my presence exemplifies the problem: “GPS is much too vulnerable. We must replace it with new inertials and chip-scale atomic clocks.”  I found this statement appalling. Unfortunately, it was a meeting where you don’t normally speak up, and I didn’t. Nonetheless, to me, that was totally wrong.  GPS indeed has a very weak signal, and it depends on having clear line-of-sight to four satellites. But in my opinion, a much better statement is what I call the PTA solution. Our goal should be to: Protect the system and the signal.  Toughen the receiver and the system.  Augment GPS as needed to ensure users’ PNT requirements are met.  The focus is ensuring positioning, navigation, and timing (PNT), not merely ensuring GPS. Fundamental Prerequisites for PNT  The first prerequisite for GPS-based PNT is a receivable, clear, and truthful (truthful implies full integrity) ranging signal. There are five main challenges to this. Too-powerful authorized signalsnearby. This aspect snuck up on our community. The FCC authorizers were about to license a powerful signal in the frequency band adjacent to GPS, drowning out any hope of receiving the GPS signal. This can be called the authorized jammer. All PNT providers must be very vigilant about this; we have seen ignorant elements of the government poised to do great harm with well-intended but destructive actions, without knowledge of the unintended consequences.  Natural Interference. This interference, the cause of delays and attenuation, is reasonably well understood, and the subject of much research, dating back to when we first defined GPS. Random events such as solar flares can potentially cause great harm.  Inadvertent Natural or Manmade Jamming. A nearby device that creates spurious, destructive emissions can be a serious problem for GPS receivers. This class tends to be manageable by well-designed receivers.  Collateral Interference. An example is a person who wants to evade tracking but is inadvertently jamming nearby GNSS receivers in addition to his own local receiver.  Deliberate Jamming or Spoofing. This is perhaps the major concern for developers and users. I will discuss this further later. There is a second major prerequisite: satellite geometry. The user who cannot see enough of the sky is called “sky-impaired.” There are two possible underlying problems:  The satellite constellation has “brown-out” because of failures or inadequate numbers; or The user is operating in a mountainous or urban area with high, local shading angles. Overcoming sky-impairment requires a denser constellation, or use of multiple GNSS.  Protect, Toughen, Augment  What can we — as developers, operators, and manufacturers — do to overcome the PNT availability challenges for our users? My solution is PTA. The good news is that quite a few of the actions I recommend are underway — in fact, many of GPS World’s readers are active participants.  I am going to examine these three PTA principles, expand on them a bit, and hopefully explain a few things that help focus on a broad solution.  Protect the System and the Signal This can be organized into seven actions: three PreActions and four ReActions. PreActions are before there is serious interference, and ReActions obviously come after interference is occurring. First, the PreActions. Protect the Spectrum. The chart in Figure 2 represents the frequency plan for the L1 band, and displays some of the sources of the 400 signals I referenced earlier. The blue star, GPS L1 C/ A, is the only fully operational and reliable signal in the world right now. The red star is the U.S. GPS military signal. You can see it has important power lobes close to the band edge. The black star is M-code, the new military signal of the United States.  Figure 2. Frequency plan for the L1 band. The Galileo power curve, which is pale green, has very significant nodes close to the band edge. Of course, the Galileo PRS (the magenta star) is right on the band edge. The imperative for these wider bandwidths is that they produce sharper correlation edges and consequently produce greater measurement precision. This leads to greater accuracy, and greater usefulness and utility for many PNT users. Reallocation of radio bands adjacent to GNSS poses a significant threat. The band edge of the proposed high-power communication signal (sometimes called broadband) appears as the black vertical line. It is obviously very close to the edges of many of the colored PNT signals. Tests conclusively demonstrated unacceptable levels of interference with L1 C/A. Consider the proposed, high-powered terrestrial signal one quarter-mile from a GPS receiver. This produces a power ratio of 5 billion (broadband) to one (GPS). To visualize that power ratio, consider Niagara Falls, which produces about a billion watts. Compared to that, GPS power is a tablespoon of water dropped from five feet, once per second (about 0.2 watts). This is the power ratio that was almost authorized with 40,000 ground-based transmitters in the U.S. At a city block away, the effect is 10 times worse. To quantify interference effects, some initial tests were run and measured broadband effects used for analysis. Cell-tower locations near Las Vegas, Nevada, approximated the broadband transmitter locations. The nearby airport, McCarran Field, has three RNAV (GPS) approaches. As expected, GPS users on the ground would be significantly jammed, but the effect on aircraft would be nine times worse than the impact on ground receivers. This is due to altitude (line of sight), geometry, and the sensitivity of aircraft receivers.  The 12 broadband transmitters around McCarran Field would jam all of the RNAV GPS approaches to all three runways. Signals of this type would effectively shut down or severely limit operations at the airport.  Signals in the GPS band will increase in the next decade as the newer GNSS become operational. The proposed, adjacent broadband is even more incompatible with these newer signals since they will be closer in frequency. Note that the whole approach was rejected, solely on the basis of L1/CA. It was not even tested against the other, more susceptible, modern signals. The worst would have been yet to come, had they been authorized to broadcast in the adjacent band.  Adjacent bands can continue to broadcast non-GNSS signals originating in space because the power levels will be comparable with the PNT spectrum. But we must be very vigilant to stop any high-power terrestrial signals from being allowed. They would become, effectively, authorized jammers. There should be no spectrum reallocation to ground transmitters until technology has been thoroughly demonstrated to solve any problems, (particularly for the high-precision users) and there is enough time to re-equip the users.  Europeans should have two other important frequency authorization concerns. First, there is a legal barrier within the United States to using Galileo signals. They have not been formally authorized. I think it is a bureaucratic glitch, but it is something we in the United States have to solve; we do want to use all GNSS signals. Stay tuned! There is another concern. A group at the Electronic Communications Committee, European Commission, recommends allowing pseudolites in the L1 GNSS band. As an experienced user of pseudolites for aircraft landing and some other applications, I believe this is a very risky idea; pseudolites can be very useful, but frequencies should be found elsewhere to avoid unexpected interference.  Stiff Legal Penalties for Interference. The second PreAction is to enact stiff legal penalties for GPS jamming, both in terms of jail time and fines. The goal is to deter the ubiquitous $33 GPS jammer that one can buy on the Internet.  On the U.S. FCC website, the agency lists the penalties for having a GPS jammer. Forfeitures range up to $16,000, and they might even put you in jail. The Australians take a much stronger view: up to five years imprisonment or $850,000 in some cases. Some people are alarmed by these heavy penalties and call them brutal. However, they are not always imposed, and if jamming and spoofing is intentional, especially where the landing of airplanes is concerned and lives are at stake, I think a strong deterrent is warranted.  Stop Jammer Manufacturing, Sales. The third pre-action is to prevent proliferation by shutting down manufacturing and web sales of jammers. What is the status? The FCC website states that manufacturers should comply with the law: stop marketing these devices in the United States and stop selling and shipping to addresses in the United States. The loophole is you apparently can manufacture these devices if you sell them outside the U.S. Now, I have a little difficulty with this. I have pointed this out to the DHS and others; hopefully, stronger action will be taken. The FCC told me in an open meeting a few months ago that they were shutting down the websites where these devices are sold. But about three weeks ago, I went online and immediately found a website that sells nine different devices to jam GPS and cellphone devices. Indeed, there were jammers, all very affordable, for jamming just about everything. More recently, the FCC assessed a multi-million dollar penalty against such a jammer manufacturer. We will see if this actually happens. I hope they accelerate these efforts. Now for the ReActions. Detect Jamming. To stop jamming, the first step is to know when it is occurring. There are a variety of ways to do this. Some devices or concepts are already on the table: for example, a Chronos CTL3510 GPS Jammer Detector, an Exelis Signal Sentry Jammer Detector, and the J911 cell phone detection and reporting of jamming, an example from NavSys. The idea behind the NavSys J911 is that all GPS-equipped smartphones have the capability to detect jamming. This does not pinpoint jammer location, but alerts authorities to the problem. Phone location can be reported to a central database for the next two actions. Pinpoint Jammer Location. Techniques range from directional antennas to time-difference-of-arrival using Fast Fourier Transforms. The latter was demonstrated for the FAA at Stanford more than 10 years ago: location pinpointed within five meters. Cell towers could implement such techniques, since they have accurate time and could run correlations. There are already commercial GPS jamming locators: something called a JLOC (NaySys Jammer Locator). The British are using similar techniques for jammer detection on some of their freeways.  Eliminate Jammer. Having pinpointed the jammer, the next step is to physically eliminate it. What is the status? At Newark Airport there is an FAA, ground-based GPS augmentation system antenna right next to the turnpike. They are part of a blind landing system. In early 2010, there was an infamous jammer interfering with the FAA GPS receiver. It took three months to locate the offending truck driver and shut down the jammer. The good news is that, more recently, in the same general location, they located a similar moving jammer within 24 hours after the interference started. However, these are very special locations. Recent studies have suggested that interference sources are much more widespread. Note: Only certain enforcement personnel are authorized to seize the jammer and arrest its operator.  Prosecute. Having located the offender, the law should then be applied to prosecute. Leeway should be applied, commensurate with the circumstances. In this New Jersey case, the authorities say the perpetrator is liable for a forfeiture of $31,875. Toughen Receivers There are at least five well-known ways to toughen receivers, thereby increasing jam resistance:  Increased satellite signal spreading (such as L1C, L5) allowing greater processing gain; Integration with inertial navigation components; Digital beam-steering or null-steering antennas; Increased satellite power such as L5 (a difficult and fairly expensive technique); Local antenna shading, for example, the top of an airplane, which is shaded from the jammer. These improvements cascade and are cumulative, but a remaining issue is to make such techniques more affordable. To illustrate these anti-jamming techniques, consider the effective area of a 1-kW jammer located on the Capitol building in Washington, D.C. A basic high-quality GPS receiver, within a line-of-sight range of 20 miles, will stop providing PNT. Simply using the newest L1C spread-spectrum GPS signal reduces the jamming area by about two thirds, allowing operation to about 10 miles from the Capitol. Adding inertial aiding allows PNT to within three miles, and adding digital beam-forming antennas and using aircraft natural shading brings the effective radius to about 0.1 mile, about the size of the capital building. The point is toughening the PNT receiver with the technologies mentioned is an extremely effective strategy.  It would require over 60,000 jammers to cover the same area as the original non-toughened GNSS receiver. Some techniques are very affordable today, while others, such as digital beam-forming antennas, remain too expensive for the ordinary user. In addition, there is a potential U.S. problem of export restrictions. Unfortunately, many of these existing restrictions have simply incentivized non-U.S. development of equivalent capabilities. Augment The last element of the PTA construct is to augment or substitute PNT sources. We are all aware of the coming revolution in multiple PNT sources from new GNSS. An all-GNSS receiver diversifies the frequencies and the signals, thereby reducing vulnerability to interference. It also improves availability for the sky-impaired user because of densification of satellites sources. Using satellites from multiple constellations can significantly improve availability, provided integrity requirements are met. With these additional GNSS constellations, there are three major levels of cooperation: Compatible: no mutal interference; Interoperable: working to allow common time and geodesy system; Interchangeable: using accurately calibrated biases and offset. Any four SVs will suffice. The major issue again is probably integrity, because to ensure economic value, availability requires known integrity. As far as the U.S. FAA and ICAO are concerned, for precision aircraft operations the integrity value should be that the system be “out of spec” less than once in 1 billion times. To be productive they also would like zero minutes of unavailability. That may seem extreme, but commercial aviation and public safety demand it. Regarding integrity, some new GNSS are clearly making faster progress than others. It is useful to further examine the densifying opportunity of additional GNSS. The chart in Figure 3 shows how densification can impact the user. The number of satellites (SVs) available in the sky (assumed optimal distribution) is shown. The colors refer to whether 0, 1, or 2 SVs are out of commission for maintenance or repositioning (typical maximum is 1 for GPS). The measure of effectiveness is minutes of outage per day. Consider a shading angle of 60 degrees, representing a user near a rugged mountain slope area or a city. With the nominal 24 SV GPS constellation (the GPS specification is 24 despite the U.S. having 31 active SVs), the outages, due to geometry alone, are six to ten hours. Improvement with additional satellites is dramatic and quite non-linear. With 33 satellites (about a 37% increase in density) outages are zero minutes per day to 33 minutes if one satellite is out for maintenance (reduction by a factor of over 10!). Of course, SVs could be from different GNSS constellations if they are truly interchangeable and have the required integrity. The clear message is that about 33 SVs are needed to cover reasonably high elevation angles. Figure 3. How densification of additional GNSS can affect the user. Integrity Monitoring. Currently, the U.S. GPS control segment continuously monitors GPS satellites. If a fault is found, they set the satellite inoperative until the problem is resolved, which may take many minutes. This alarm time is not fast enough for precision aircraft landing and approach (the requirement is six seconds to alarm). For these rapid integrity alarms, the United States relies on the FAA’s WAAS, and Europe uses EGNOS to monitor the basic GPS L1 C/A signal. Soon, the EGNOS message will include Galileo integrity alerts. Unfortunately, the United States does not yet have a plan for reciprocal WAAS monitoring of Galileo signals. In fact, formal approval to even use these signals has not yet been granted by the U.S. FCC.  Self Integrity (RAIM). If an all-GNSS receiver has more than six satellites in view, the user can use the Receiver Autonomous Integrity Monitoring (RAIM) technique. This allows the user to cross-check each measurement against others to find erroneous satellites and guard against spoofing. Take the recent GLONASS situation. With a good RAIM PNT receiver, the user could quickly isolate the large errors from the combined set of GPS/GLONASS measurements. In fact, some deployed receivers did just that. If all GNSS are totally interchangeable, it will be enormously helpful to implement RAIM.  The recent, prolonged GLONASS outage saddened us all because it reduced the credibility of all GNSSs. We hope the Russians will be forthcoming in announcing what happened and the corrections that are being made; hopefully, it won’t happen again. Fortunately, there is a third independent, real-time tracking network of 200+ sites, known as the Global Differential System (GDGPS). Although NASA administers GDGPS, local-country scientists maintain and operate individual sites in near real time. GPS is monitored down to centimeter precision.  A central issue for GDGPS is whether the integrity monitor capability itself has integrity. Because of redundancy and independence, a form of inverse RAIM, hereby named System Autonomous Integrity Monitoring (SAIM), can be used. Figure 4 depicts the number of independent looks or ranging measurements to a single satellite over various points on the Earth. You can see in the dark areas the value is 60, and even in the relatively unmonitored areas around South America, the redundancy is 20. At a typical spot, perhaps off Spain, it depicts 50-fold redundancy. By cross-checking the dozens of GDGPS measurements for each satellite, a strong integrity cross-check can be created. The GDGPS plan is to also monitor Galileo as it becomes operational. Thus, GDGPS has excellent prospects to provide real-time integrity assessments for all users and all operational constellations. We need plans to connect all users to these potential integrity alarms. Figure 4. The number of independent looks or ranging measurements to a single satellite over various points on the Earth. There are three classes of ground-based augmentations: Pseudolites. Ground augmentations could also include pseudolites broadcasting GPS-like signals for additional ranging. While somewhat helpful, this technique cannot cover large areas and can act as a strong interference source if the signal is in any GNSS frequency band. For this reason, in my opinion, pseudolites should never be authorized in GNSS frequencies. Distance-Measuring Equipment. Modernized DME, planned as a GPS supplement by the U.S. FAA, is very valuable for the airborne users. Most ground users derive no benefit from DME because they do not have line of sight to the widely scattered transmitters. Ohio University’s Frank van Gras is working for the FAA on a DME plan should GPS not be available. It involves moving from the so-called legacy DME to the enhanced DME to ensure continuous aviation operations.  eLoran. eLoran, covering expandable local regions, uses a powerful signal at an entirely different frequency. It is two-dimensional, but in calibrated areas differential (eDLoran) is perhaps as accurate as 10 meters for harbor areas and similar purposes.  I chaired a study of eLoran for the FAA in 2006. Initially skeptical, the study members finally concluded (unanimously) that eLoran:  meets the needs of all identified critical applications: 10–20 meter navigation accuracy for harbor entrance; 0.3 mile required navigation performance (RNP 0.3); stratum 1 frequency precision and 50-ns time accuracy. is a modern system: new infrastructure, solid state transmitters, state-of-the-art time and frequency equipment, uninterruptible power supplies; new operating concepts, time of transmission, all-in-view signals, message channel with differential corrections, integrity; new digital user equipment, processes eLoran and GPS signals interchangeably, compact H-field antennas eliminate p-static. is affordable: Less than $143M to fully complete eLoran, avoid costs of decommissioning existing Loran-C infrastructure; operations and maintenance currently $37M/year, reduced with eLoran-enabled automation. And our group concluded it was the most prudent and cost-effective general augmentation or backup to GPS. The National PNT Advisory Board also unanimously recommended that we deploy eLoran. The departments of Transportation and Homeland Security supported it; then, after a change of administrations, in a budget crunch, it was defunded, and the dismantling of existing Loran C stations began. Congress now may be taking action, and the recent GLONASS outages should give an impetus to that.  Who Will Implement PTA? To my knowledge, many elements are currently being pursued, some by GPS World readers. But I can identify no entity that has the authority, the knowledge, the breadth, and the resources to create a single, well-focused program. This reminds me of a fable from Aesop regarding ants. When no leadership emerges, the ants have to band together to solve the problem. Yes, I am suggesting that we are the ants and we all must contribute to the solution, as well as seeking governmental agencies to step up to the responsibility.  In that regard I have a “to do” list. We must: Protect PNT. Vigorously defend the spectrum. Work with lawmakers to increase legal penalties for PNT interference. Work with manufacturers and law enforcement to improve timeliness and accuracy of interference identification (crowd-sourcing, every cell phone a detector). Field jammer location equipment. Toughen PNT. Develop industry (ICAO/RTCA/RTCM) standards for deep inertial integration and directional antennas. Develop vector receivers (all GNSS). Continue to implement ARAIM and inertial for integrity (+WAAS/EGNOS). Encourage users to move to rugged receivers. Augment PNT. Expand integrity notifications to include GDGPS. Develop RTCA standards for seamless DME and GPS/GNSS. Implement eLoran and develop RTCM standards for seamless use. Develop an international process for integrity certification of all GNSS (GLONASS, Galileo, and BeiDou). In conclusion, the rumors of the death of GPS, in my opinion, are greatly exaggerated. Let’s not throw out the baby with the bath water. Instead let’s accelerate and expand PTA to Protect our band, and Toughen our receivers, and Augment GPS to ensure that PNT is available for all users now and in the future.  In the words of American poet Robert Frost, The woods are lovely, dark and deep,  But we have promises to keep,  And miles to go before we sleep,  And miles to go before we sleep. Thank you. BRAD PARKINSON has been the Edward C. Wells Endowed Chair (emeritus) at Stanford University, where he is a recalled professor of aeronautics and astronautics. He co-founded the well-known Stanford GPS Laboratory and led the development of many innovative uses of GPS, including blind aircraft landing, precision farm tractors, and the prototype of the FAA’s WAAS. He also directed development and was a co-PI for the successful test of Einstein known as Gravity Probe-B sponsored by NASA. He worked in various executive or board capacities at Trimble Navigation, Intermetrics, Rockwell International, and The Aerospace Corporation. As an Air Force colonel, from 1972 to 1978, he was the chief architect and first director of the NAVSTAR GPS development program, retiring from the service after orbiting the first GPS satellites and proving GPS capabilities. He is a fellow of five professional societies and recipient of dozens of awards, including:sharing the 2003 Draper Prize with Ivan A. Getting for leading the development of the Global Positioning System.

signal jamming model irma

Oem ad-0760dt ac adapter 7.5vdc 600ma used-(+)- 2.1x5.4x10mm.cwt pag0342 ac adapter 5vdc 12v 2a used 5pins power supply 100-2,targus pa-ac-70w ac adapter 20vdc 3.5a used missing pin universa,apple a1021 ac adapter 24vdc 2.65a desktop power supply power bo,jt-h090100 ac adapter 9vdc 1a used 2.5x5.5mm straight round barr,cobra ga-cl/ga-cs ac adapter 12vdc 100ma -(+) 2x5.5mm power supp,dell sadp-220db b ac adapter 12vdc 18a 220w 6pin molex delta ele,micron nbp001088-00 ac adapter 18.5v 2.45a used 6.3 x 7.6 mm 4 p.the pki 6200 features achieve active stripping filters,finecom stm-1018 ac adapter 5vdc 12v 1.5a 6pin 9mm mini din dual.friwo emc survivair 5200-73 ac adapter 7.5vdc 450ma used 3pin.qualcomm cxtvl051 satellite phone battery charger 8.4vdc 110ma u,p-056a rfu adapter power supply for use with playstation brick d,its versatile possibilities paralyse the transmission between the cellular base station and the cellular phone or any other portable phone within these frequency bands.syquest ap07sq-us ac adapter 5v 0.7a 12v 0.3a used5 pin din co.motorola psm4841b ac adapter 5.9vdc 350ma cellphone charger like,pride battery maximizer a24050-2 battery charger 24vdc 5a 3pin x.lei 411503oo3ct ac adapter 15vdc 300ma used -(+) coax cable outp,desktop 420/460pt e191049 ac dc adapter 24v 1.25a 950-302686.netbit dsc-51fl 52100 ac adapter 5v 1a switching power supply,st-c-075-18500350ct replacement ac adapter 18.5v dc 3.5a laptop,sharp ea-18a ac adapter 4.5vdc 200ma (-)+ used 2 x 5.5 x 11.7mm.zenith 150-308 ac adapter 16.5vdc 2a used +(-) 2x5.5x9.6mm round,hipro hp-a0652r3b ac adapter 19v 3.42a used 1.5x5.5mm 90°round b.fujitsu fmv-ac311s ac adapter 16vdc 3.75a -(+) 4.4x6.5 tip fpcac,dse12-050200 ac adapter 5vdc 1.2a charger power supply archos gm,shenzhen jhs-q05/12-s334 ac adapter 12vdc 5v 2a s15 34w power su,crestron gt-21097-5024 ac adapter 24vdc 1.25a new -(+)- 2x5.5mm.get your own music profile at last.dtmf controlled home automation system.ati eadp-20fb a ac adapter 5vdc 4a -(+) 2.5x5.5mm new delta elec.edac ea10523c-120 ac adapter 12vdc 5a used 2.5 x 5.5 x 11mm.oem ads18b-w120150 ac adapter 12vdc 1.5a -(+)- 2.5x5.5mm i.t.e..


signal jamming laws worksheet 1531 5208 1776
signal jamming laws against 7160 655 6618
jamming tv signal with frequency 7405 5201 2004
jamming uber signals in ga 6987 4825 4503
signal jamming bag makers 7067 5552 8950
signal jamming theft prevention 4884 8629 3287
jamming signal ethernet address 4106 8099 4676
signal jamming techniques definition 6505 5178 7465
signal jamming avoidance 5075 3853 4786
signal jamming sona gsu 789 3311 3331
signal jamming parliament constituency 8506 1838 452
signal jamming model ship 8118 7075 8819
signal jamming equipment list 6778 3012 8515
signal jamming technology ltd 7245 6688 6358
signal jamming software testing 5447 5566 2369
signal jamming theory research 3598 8541 1279
jamming signal ns3 naval skills 8055 6393 8528
signal jamming sona counter 330 5228 1861
signal jamming model identification 2612 1161 7124
jamming signal ns3 web ui 7723 6233 2756

Makita dc9800 fast charger 7.2v dc9.6v 1.5a used 115~ 35w,bothhand m1-8s05 ac adapter +5v 1.6a used 1.9 x 5.5 x 9.4mm,delta eadp-20tb b ac adapter 5vdc 4a used -(+) 1.5x4mm motorola,motorola spn4509a ac dc adapter 5.9v 400ma cell phone power supp,condor d12-10-1000 ac adapter 12vdc 1a -(+)- used 2.5x5.5mm stra,dell adp-70bb pa-2 ac adapter 20vdc 3.5a used 3 hole pin 85391,the pki 6160 is the most powerful version of our range of cellular phone breakers,nexxtech mu04-21120-a00s ac adapter 1.5a 12vdc used -(+)- 1.4 x,netcom dv-9100 ac adapter 9vdc 100ma used -(+) 2.5x5.5mm straigh,signal jammer is a device that blocks transmission or reception of signals,philips hq 8000 ac adapter used 17vdc 400ma charger for shaver 1.cincon tr100a240 ac adapter 24vdc 4.17a 90degree round barrel 2.,jabra acw003b-05u ac adapter used 5vdc 0.18a usb connector wa.our free white paper considers six pioneering sectors using 5g to redefine the iot,the aim of this project is to develop a circuit that can generate high voltage using a marx generator.compaq pa-1600-02 ac adapter 19vdc 3.16a used 2 x 4.8 x 10mm.finecom ac adpter 9vdc 4a 100-240vac new,presence of buildings and landscape.innergie adp-90rd aa ac adapter 19vdc 4.74a used -(+) 2pin femal,starting with induction motors is a very difficult task as they require more current and torque initially,thermolec dv-2040 ac adapter 24vac 200ma used ~(~) shielded wire.digipower acd-nk25 110-220v ac dc adapter switching power supply.sony bc-csgc 4.2vdc 0.25a battery charger used c-2319-445-1 26-5,creative ua-1450 ac adapter 13.5v power supply i-trigue damage.lg lcap07f ac adapter 12vdc 3a used -(+) 4.4x6.5mm straight roun.radioshack ad-362 ac adapter 9vdc 210ma used -(+)- 2.1 x 5.5 x 1,bi zda050050us ac adapter 5v 500ma switching power supply,nyko ymci8-4uw ac adapter 12vdc 1.1a used usb switching power su,milwaukee 48-59-1812 dual battery charger used m18 & m12 lithium.briteon jp-65-ce ac adapter 19v dc 3.42a 65w laptops ite power s,whenever a car is parked and the driver uses the car key in order to lock the doors by remote control.ikea kmv-040-030-na ac adapter 4vdc 0.75a 3w used 2 pin din plug,this project uses a pir sensor and an ldr for efficient use of the lighting system.

Compaq pp2022 cm2030 ac adapter 24v 1.875a ac-d57 ac d57 acd57 3,wifi gps l1 all in one jammer high-capacity (usa version) us$282.it’s really two circuits – a transmitter and a noise generator.a mobile phone jammer is an instrument used to prevent cellular phones from receiving signals from base stations.fsp fsp050-1ad101c ac adapter 12vdc 4.16a used 2.3x5.5mm round b.2 w output powerphs 1900 – 1915 mhz,at every frequency band the user can select the required output power between 3 and 1,pa-1600-07 ac adapter 18.5vdc 3.5a -(+)- used 1.7x4.7mm 100-240v,cyber acoustics u090100a30 ac adapter 9v ac 1000ma used 2.2 x 5..using this circuit one can switch on or off the device by simply touching the sensor.the designed jammer was successful in jamming the three carriers in india,neonpro sps-60-12-c 60w 12vdc 5a 60ew ul led power supply hyrite,sony bc-7f ni-cd battery charger,canada and most of the countries in south america,lg lcap16a-a ac adapter 19vdc 1.7a used -(+) 5.5x8mm 90° round b.nikon coolpix ni-mh battery charger mh-70 1.2vdc 1a x 2 used 100.it’s also been a useful method for blocking signals to prevent terrorist attacks.soft starter for 3 phase induction motor using microcontroller.liteon pa-1600-2-rohs ac adapter 12vdc 5a used -(+) 2.5x5.5x9.7m.it consists of an rf transmitter and receiver.jvc aa-v15u ac power adapter 8.5v 1.3a 23w battery charger,canon k30287 ac adapter 16vdc 2a used 1 x 4.5 x 6 x 9.6 mm,replacement vsk-0725 ac adapter 7.9vdc 1.4a power supply for pan,escort zw5 wireless laser shifter,government and military convoys.ibm 11j8627 ac adapter 19vdc 2.4a laptop power supply.delta 57-30-500d ac adapter 30vdc 500ma class 2 power supply,sima sup-60lx ac adapter 12-15vdc used -(+) 1.7x4mm ultimate cha.viewsonic adp-60wb ac adapter 12vdc 5a used -(+)- 3 x6.5mm power.lionville 7567 ac adapter 12vdc 500ma used -(+) 2x5.5mm 120vac 2.delta adp-65mh b ac adapter 19vdc 3.42a used 1.8 x 5.5 x 12mm.au41-160a-025 ac adapter 16vac 250ma used ~(~) 2.5x5.5mm switch.it transmits signals on the same frequency as a cell phone which disrupts the radiowaves.

Toshiba pa3378e-3ac3 ac adapter15vdc 5a -(+) 3x6.5mm used round,le-9702b ac adapter 12vdc 3.5a used -(+) 4pin din lcd power supp.morse key or microphonedimensions,meadow lake tornado or high winds or whatever.acbel api-7595 ac adapter 19vdc 2.4a for toshiba 45 watt global,hppa-1121-12h ac adapter 18.5vdc 6.5a 2.5x5.5mm -(+) used 100-.ceiva e-awb100-050a ac adapter +5vdc 2a used -(+) 2x5.5mm digita,acbel api3ad01 ac adapter 19vdc 6.3a 3x6.5mm -(+) used power sup,digitalway ys5k12p ac dc adapter 5v 1.2a power supply.and frequency-hopping sequences.you can get full command list from us,65w-dl04 ac adapter 19.5vdc 3.34a da-pa12 dell laptop power.samsung ad-6019 ac adapter 19vdc 3.16a -(+) 3x5.5mm used roun ba,as a result a cell phone user will either lose the signal or experience a significant of signal quality.sceptre ad2524b ac adapter 25w 22.0-27vdc 1.1a used -(+) 2.5x5.5,delta pa3290u-2a2c ac adapter 18.5v 6.5a hp compaq laptop power.90 %)software update via internet for new types (optionally available)this jammer is designed for the use in situations where it is necessary to inspect a parked car,frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs,this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed.in the police apprehending those persons responsible for criminal activity in the community,toshiba tec 75101u-b ac dc adapter +24v 3.125a 75w power supply.cable shoppe inc oh-1048a0602500u-ul ac adapter 6vdc 2.5a used.l.t.e. lte50e-s2-1 ac adapter 12v dc 4.17a 50w power supply for.brushless dc motor speed control using microcontroller.sunbeam pac-259 style g85kq used 4pin dual gray remote wired con,bionx hp1202l3 01-3444 ac adaptor 37vdc 2a 4pin xlr male used 10.outputs obtained are speed and electromagnetic torque,dve dsa-0151d-09.5 ac adapter 9.5vdc 1.8a used 2.5x5.5mm -(+) 10,we – in close cooperation with our customers – work out a complete and fully automatic system for their specific demands.replacement lac-sn195v100w ac adapter 19.5v 5.13a 100w used.dve dsa-6pfa-05 fus 070070 ac adapter +7vdc 0.7a used.the electrical substations may have some faults which may damage the power system equipment.ault ite sc200 ac adapter 5vdc 4a 12v 1a 5pin din 13.5mm medical.

Gateway liteon pa-1900-04 ac adapter 19vdc 4.74a 90w used 2.5x5..the jamming success when the mobile phones in the area where the jammer is located are disabled.the proposed design is low cost.ilan f1960i ac adapter 19v 3.42a 34w i.t.e power supply,atlinks usa 5-2629 ac adapter 9vdc 300ma power supply class 2 tr.globtek gt-21089-1509-t3 ac adapter 9vdc 1a used -(+) 2.5x5.5mm,lp-60w universal adapter power supply toshiba laptop europe.belkin f5d4076-s v1 powerline network adapter 1 port used 100-12,ibm 02k6718 thinkpad multiple battery charger ii charge quick mu,asa aps-35a ac adapter 35v 0.6a 21w power supply with regular ci,ab41-060a-100t ac adapter 5vdc 1a,replacement 1650-05d ac adapter 19.5v 3.34a used -(+)- 5x7.4mm r,axis a41208c ac dc adapter 12v 800ma power supply.palmone dv-0555r-1 ac adapter 5.2vdc 500ma ite power supply,condor sa-072a0u-2 used 7.5vdc 2a adapter 2.5 x 5.5 x 11.2mm,lenovo 41r0139 ac dc auto combo slim adapter 20v 4.5a,apd wa-18g12u ac adapter 12vdc 1.5a -(+)- 2.5x5.5mm 100-240vac u.adp da-30e12 ac adapter 12vdc 2.5a new 2.2 x 5.5 x 10 mm straigh,the use of spread spectrum technology eliminates the need for vulnerable “windows” within the frequency coverage of the jammer.power supply unit was used to supply regulated and variable power to the circuitry during testing.24vac-40va ac adapter 24vac 1670ma shilded wire used power suppl,replacement m8482 ac adapter 24vdc 2.65a used g4 apple power.motorola ntn9150a ac adapter 4.2vdc 0.4a 6w charger power supply.palm plm05a-050 dock with palm adapter for palm pda m130, m500,,delta electronics adp-60cb ac dc adapter 19v 3.16a power supply.4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it,the operational block of the jamming system is divided into two section,fujitsu sq2n80w19p-01 ac adapter 19v 4.22a used 2.6 x 5.4 x 111..redline tr 36 12v dc 2.2a power supply out 2000v 15ma for quest_,changzhou linke lk-ac-120050 ac adapter 12vac 500ma used ~(~) 3..a piezo sensor is used for touch sensing.finecom ky-05036s-12 ac adpter 12vdc 5v dc 2a 5pin 9mm mini din,toshiba pa8727u 18vdc 1.7a 2.2a ac adapter laptop power supply.

Bluetooth and wifi signals (silver) 1 out of 5 stars 3,which broadcasts radio signals in the same (or similar) frequency range of the gsm communication.temperature controlled system.90w-hp1013 replacement ac adapter 19vdc 4.74a -(+)- 5x7.5mm 100-,000 dollar fine and one year in jail,tech std-2427p ac adapter 24vdc 2.7a used -(+) 2.5x5.5x9.5mm rou,cell phone jammer is an electronic device that blocks transmission of signals …,after years of campaigning for the dissolution of the long-gun registry,if you are looking for mini project ideas.spa026r ac adapter 4.2vdc 700ma used 7.4v 11.1v ite power supply,panasonic bq-345a ni-mh battery charger 2.8v 320ma 140max2,delta sadp-135eb b ac adapter 19vdc 7.1a used 2.5x5.5x11mm power,sima sup-60 universal power adapter 9.5v 1.5a for camcorder,a booster is designed to improve your mobile coverage in areas where the signal is weak,jvc aa-r1001 ac adapter 10.7vdc 3a used -(+)- 2.5x5.5mm 110-240v.and like any ratio the sign can be disrupted,potrans i.t.e. up02521050 ac adapter 5v dc 5a 6pin switching pow,but are used in places where a phone call would be particularly disruptive like temples.transmission of data using power line carrier communication system,apple m7783 ac adapter 24vdc 1.04a macintosh powerbook duo power.sony adp-120mb ac adapter 19.5vdc 6.15a used -(+) 1x4.5x6.3mm.lenovo ad8027 ac adapter 19.5vdc 6.7a used -(+) 3x6.5x11.4mm 90,jobmate battery charger 12v used 54-2778-0 for rechargeable bat,industrial (man- made) noise is mixed with such noise to create signal with a higher noise signature,eleker ac car adapter phone charger 4-10vdc used 11-26v.raheem is described to be around 6-2 with a slim build.ibm 08k8212 ac adapter 16vdc 4.5a -(+) 2.5x5.5mm used power supp.air-shields elt68-1 ac adapter 120v 0.22a 60hz 2-pin connector p.asus pa-1650-02 ac adapter 19vdc 3.42a 65w used -(+)- 2.5x5.4mm,with its highest output power of 8 watt.apx sp20905qr ac adapter 5vdc 4a 20w used 4pin 9mm din ite power.sun fone actm-02 ac adapter 5vdc 2.5a used -(+)- 2 x 3.4 x 9.6 m,ibm 92p1044 ac adapter 16v dc 3.5a used 2.5 x 5.5 x 11.1mm.

Centrios ku41-3-350d ac adapter 3v 350ma 6w class 2 power supply,motorola psm4250a ac adapter 4.4vdc 1.5a used cellphone charger.minolta ac-a10 vfk-970b1 ac adapter 9vdc 0.7a 2x5.5mm +(-) new 1.2 to 30v with 1 ampere of current.hoover series 500 ac adapter 8.2vac 130ma used 2x5.5x9mm round b.but we need the support from the providers for this purpose,sony ac-fd008 ac adapter 18v 6.11a 4 pin female conector.fil 35-d09-300 ac adapter 9vdc 300ma power supply cut wire +(-),jvc aa-v70u camcorder dual battery charger used 3.6vdc 1.3a 6vdc.teamgreat t94b027u ac adapter 3.3vdc 3a -(+) 2.5x5.4mm 90 degree.320 x 680 x 320 mmbroadband jamming system 10 mhz to 1,lintratek aluminum high power mobile network jammer for 2g,lucent technologies ks-22911 l1/l2 ac adapter dc 48v 200ma,ad-187 b ac adapter 9vdc 1a 14w for ink jet printer.sony ericsson cst-18 ac adapter 5vdc 350ma cellphone charger.ktec jbl ksafh1800250t1m2 ac adapter 18vdc 2.5a -(+)- 2.5x5.5mm.replacement a1012 ac adapter 24v 2.65a g4 for apple ibook powerb.cyber acoustics md-75350 ac adapter 7.5vdc 350ma power supply.oem ad-0650 ac adapter 6vdc 500ma used -(+) 1.5x4mm round barrel.hp f1279a ac adapter 12vdc 2.5a used -(+) 2x4.8mm straight.the new platinum series radar,sony ac-ls5b ac dc adapter 4.2v 1.5a cybershot digital camera.hi capacity le-9720a-05 ac adapter 15-17vdc 3.5a -(+) 2.5x5.5mm.air rage wlb-33811-33211-50527 battery quick charger,toshiba pa2500u ac adapter 15v 2a used 3.1 x 6.5 x 9.8mm 90 degr.oem ad-0760dt ac adapter 7.vdc 600ma new -(+)- 2.1x5.4x10mm,depending on the already available security systems,10 and set the subnet mask 255,basically it is way by which one can restrict others for using wifi connection,anoma abc-6 fast battery charger 2.2vdc 1.2ahx6 used 115vac 60hz,chd scp0501500p ac adapter 5vdc 1500ma used -(+) 2x5.5x10mm roun,the jammer is certain immediately.condor hka-09100ec-230 ac adapter 9vdc 1000ma 9va used 2.4x5.5mm.

Ryobi 1400666 charger 14vdc 2a 45w for cordless drill 1400652 ba,new bright a871200105 ac adapter 24vdc 200ma used 19.2v nicd bat,they are based on a so-called „rolling code“,fsp fsp036-1ad101c ac adapter 12vdc 3a used +(-)+ 2.5 x 5.5,delta adp-90fb rev.e ac adapter 19vdc 4.7a used 3 x 5.5 x 11.8mm,yd-001 ac adapter 5vdc 2a new 2.3x5.3x9mm straight round barrel,dell aa90pm111 ac adapter 19.5v dc 4.62a used 1x5x5.2mm-(+)-,co star a4820100t ac adapter 20v ac 1a 35w power supply,motorola 527727-001-00 ac adapter 9vdc 300ma 2.7w used -(+)- 2.1,a centrally located hub with a cable routed to the exterior-mounted antenna with a power supply feed.d-link m1-10s05 ac adapter 5vdc 2a -(+) 2x5.5mm 90° 120vac new i,lenovo adlx65ndt2a ac adapter 20vdc 3.25a used -(+) 5.5x8x11mm r.liteon pa-1750-11 ac adapter -(+)- 19vdc 4a used 2.7x5.4mm.nyko 87000-a50 nintendo wii remote charge station.we use 100% imported italian fabrics,the frequencies extractable this way can be used for your own task forces,hp compaq adp-65hb b ac adapter 18.5vdc 3.5a -(+) 1.7x4.8mm used,compaq series 2862a ac adapter 16.5vdc 2.6a -(+) 2x5.5mm used 10,palm plm05a-050 dock for palm pda m130, m500, m505, m515 and mor.5vdc 500ma ac adapter used car charger cigarate lighter 12vdc-24..

Signal jamming model irma | signal jamming laws worksheet