Should I Worry About GPS Jamming?

I have been flying GPS-based LPV approaches for a few years. But now I am flying them for real because the LPV is the best approach, and the only approach with precision glideslope guidance, to Runway 6 at my homebase at Muskegon, Michigan. When the visibility and clouds are low in snow, and the wind is from the east like it was last week when I returned home, the LPV is the sure way to find the runway.

LPV stands for localizer precision with vertical guidance, or something like that. The exact root words of the acronym have changed some over the life of the program. LPV requires a WAAS-capable GPS because an additional satellite is required to broadcast a correction factor that brings LPV up to the precision of ILS.

The important thing to know is that LPV guidance in your instrument panel behaves just like an ILS signal. Other RNAV or GPS approaches present linear guidance, meaning one dot of deviation equals the same distance off the centerline no matter how far you are from the runway or waypoint. The LPV, like an ILS, shows angular deviation, so any tracking error shown on your instruments narrows as you near the runway. Like an ILS, when you get to the runway threshold, a dot of deviation off centerline equals only a few feet of actual distance from the center.

If it were up to me, I’d use linear deviation guidance for all approaches because I think that method is easier to fly. The “sensitivity” of the linear display stays the same all the way to the runway, while the LPV, like the ILS with angular deviation, “cones in” the closer you get to the decision point. But the FAA people who created the LPV specs wanted LPV to behave exactly like an ILS, so we pilots don’t need to learn anything new. Old dogs, new tricks – that sort of thing.

In spite of having angular deviation, I have found the LPV easier to fly than an ILS because the GPS-derived LPV guidance is rock steady. You don’t realize how much a typical ILS signal is wandering around until you fly with LPV on one display and raw data ILS on the other. Because it is an analog signal, and its radio beams are susceptible to all sorts of reflection and distortion, the ILS guidance can never be as steady as the LPV, which comes from a new GPS position and velocity calculation being made several times each second.

All of this has taken on new significance to me given the several potential GPS interference sources that are in the news. If I lose GPS guidance en route, it is important because that is my primary source, but there is a lot of time and several navigation alternatives to fall back on. If nothing else, the controller’s radar can provide guidance en route to get you where you are going. But if GPS signals are interfered with while you are flying a few hundred feet above the ground on an instrument approach in the clouds, snow, or murk, that is a different and much more critical matter.

A potential wide-scale GPS interference source is a new 4G broadband Internet network called LightSquared that has been given preliminary approval by the FCC. LightSquared’s proposed thousands of transmitters would operate on frequencies closely adjacent to the GPS frequencies. The GPS industry is very concerned that the comparatively powerful transmitters of the network will cause widespread interference and loss of navigation for airplanes flying within miles of the transmitters. Garmin is among those expressing concern to the FCC about the new network. The FAA is also onboard in seeking to prevent possible GPS interference.

But there is also potential GPS navigation interference already out there from some unknown number of GPS jammers that are sold mostly over the Internet. These devices are designed to temporarily disable a GPS device that may be in your car or truck and is transmitting your movements to others. If you don’t want your spouse to know where you are, or don’t want the boss to know how fast you’re driving (or not driving), these jammers can block reception of GPS signals by a receiver in your vehicle.

Using a GPS device to record, then transmit, the location and movement of a vehicle has become very common. For example, trucking companies want to know where their trucks are located and how well they are progressing toward the destination, and a GPS device can automatically send that information. You can also imagine why people would be curious about the movement and location of others and could “plant” one of these small GPS devices in a car to report its activity. Let’s just say these devices create a privacy issue.

The jammers that can prevent GPS reception cost only a few hundred bucks. The jammers are in a legal gray area at best, but they are proliferating. The effective range of most jammers is advertised to be in the 10s of meters, with some I have seen claiming to disable a GPS and cell phone out to 40 meters. That’s no issue for airplanes at cruise altitude, but what about nearing the decision point of only 300 or so feet above the runway on an LPV approach? The jammer would have to disrupt the signal for only a couple seconds to create a problem at the end of a GPS approach.

All of us should be concerned about the possible interference of new networks such as LightSquared. But those transmitters are regulated. If public pressure is kept on the FCC, as I know it will be, testing and modification if necessary can protect GPS operation interference from legal and authorized broadcasts.

That is not true for the many small portable devices designed specifically to interrupt GPS reception. That is a cat and mouse game in which those who want the information GPS can provide will continually search for ways to defeat the jammers. Those who want privacy from GPS reporting on their activities will pay more and more for powerful devices that provide privacy. It’s a GPS issue not envisioned when the system was designed by the Air Force for military navigation and weapons guidance beginning about 40 years ago.

Newly designed GPS satellites will contain advanced technology to help prevent jamming, but those satellites will take years to deploy. And the people designing the jammers won’t stand still in their search to find more effective ways to block GPS reception.

What we can do is use our aviation groups such as EAA to keep reminding the FCC that GPS reception must be protected from interference from any and all authorized transmitters. And we can also ask for strict enforcement of laws that prohibit intentional disruption of transmitted signals being used by others. Who could have guessed that a spying spouse, or concerned parents of teenage drivers, could become the source for potential GPS navigation disruption? But they have.

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35 Responses to Should I Worry About GPS Jamming?

  1. Mac, I was concerned about this when LightSquared was first announced and I was not familiar with the jamers so widely available.

    These are not the only threats to GPS. There is a likelihood of transmitters AND receivers failing and putting out signals on unwanted frequencies. Yes, I did say receivers. Most receivers generate signals internally that are used to aid in the reception of the desired signals. (I’ll skip receiver theory here). These signals are of such a power level that should they escape they can be heard for hundreds of meters, or even farther.

    Jammers : Virtually any device made to radiate can be modified to radiate a stronger signal. Selling these sets a very dangerous precedent. Think of one of these jammers intentionally radiating a single watt, or just a half watt (500 milliwatts ) Even a 100 milliwatts can be heard for several miles.

    Then there is the sun: Several times solar storms have briefly interrupted GPS. Should we find ourselves directly in the path of a major class M Coronal Mass Ejection (CME) navigation could be interrupted for hours. For planes on an instrument approach we should have plenty of warning, but some of the more energetic CMEs can have an effect within a couple of hours which would be more than inconvenient for transoceanic flights. A direct hit from a major CME could even take out satellites and here we are putting all our eggs in one basket. IOW satellite based.

    Of course with a direct hit from a major CME navigation might cease to be of primary concern except for those of us using it at the time. With the power grid shut down the folks on the ground would have other worries and that has happened before. Those big transformers might take weeks (or longer) to replace.

  2. One more thought: There is “no such thing as a jam proof receiver”. Encoding can prevent reading false signals, but they can not prevent loss of signal. Diversity reception (receiving multiple signals on widely separated frequencies) can help, (similar to the way GPS signals work now but on a much wider scale) but again knowing the frequencies is all that is needed. Spread spectrum and rapidly switching between frequencies would help, but applying this to 9 or more satellites plus the augmentation signals is no trivial matter.

    IOW it does not matter what they do to the transmitted signals, if it or they is/are over ridden by a stronger signal the receiver will not hear the desired signal resulting in loss of signal.

    We really need a “ground based” back up system for GPS. When I think of the way LORAN was decommissioned (and destroyed) I can not help but think of Megs Field.

  3. James Gathings says:

    Enjoyed the article. It brings back old memories when I was involved in placing the original “Transit” satellites in orbit.

  4. Author says:

    I think we all agree that LightSquared is a non-problem. Jammers are a problem. Fortunately, a couple of things help. First, WAAS is a million times more powerful than GPS satellite (in the receiver anthenna), that makes it correspondingly more resistant to jamming. Second, expensive airplanes can use phased array anthennas that lock and track satellites, which also reduces interference. And finally, buy a set of GALILEO, GLONASS, and BEIDOU receivers if you’re concerned.

  5. Light squared is not a problem only if they are not permitted to operate on the frequencies selected and the way the FCC has been operating lately that is by no means guaranteed
    Quoted from Diginetlink.com “Each wide area ground reference station in the network relays the data to the wide area master station (WMS) where correction information is computed. The WMS calculates correction algorithms and assesses the integrity of the system. A correction message is prepared and uplinked to a geosynchronous satellite via a ground uplink system (GUS). The message is then broadcast from the satellite on the same frequency as GPS (L1, 1575.42MHz) to GPS receivers, which are within the broadcast coverage area of the WAAS.”
    IOW if you can’t receive the satellite signal or receive it in an uncorrupted form, it doesn’t mater how strong the WASS signal is. WASS is ground based, but it only provides a corrective signal to the satellites which rebroadcast it to the GPS receivers.

    And as I said, there is no such thing as a jam proof receiver. Provide a strong enough signal so it can not pick the other signal or signals out of the noise and it’s all done. Even if these receivers could guarantee a properly decoded signal under all circumstances which they can’t, the price would be prohibitive for all except airlines and very top end exec transportation…if they could get them.

    OTOH we could develop a jam *resistant* system, but it would be complex and expensive. One direct hit from a CME and it’d be all over anyway.

    The present system is susceptible to interference, jamming, solar storms, and even space debris. To develop a much more robust system would likely take a decade or two to develop and implement.

  6. Phil says:

    I agree there is some probability that a GPS jamming device could interfere with an approach, but I suggest it is very very low. The first question I have is just how many GPS tracking devices have been installed by suspicious spouses, or law enforcement agencies, and secondly of those vehicles, how many of those vehicles would then have jammers installed as well? In addition, how many of these jammer equipped vehicles are driving close enough to a given runway to be an issue? Without actual numbers this is an unwarranted concern in my opinion. I think the probability of this occurring is near zero. A search of the FAA accident data base back to 2006 has zero entries for GPS failure, or GPS interference. As someone else mentioned, if you are concerned, install a directional antenna!

  7. S Klein says:

    I heard about the possibility of LightSquared causing GPS problems an decided to dig a little deeper on the subject. It turns out LightSquared purchased the satellite frequency band from Inmarsat. I wonder, if there wasn’t a problem with GPS jamming from Inmarsat then why would there be a problem for LightSquared to use the same frequency? Some have said the problem is the antenna, the largest ever used – 17 feet in diameter. (But, it’s at 22,000 miles above the earth – not so big after all)

    Further research into the subject revealed LightSquared’s goal is to cover 92% of the USA with LOW COST 4G service by 2015. That would put a SERIOUS dent in Verizon, ATT and other wireless company’s bottom lines (and the fact after many years, they’ve only gotten to 60% coverage in the US). What better way to defeat your competition than to create a public panic about GPS in the whole country getting jammed!

    Light squared has offered to not only demonstrate the system for a 3 month trial period for the FCC but to also pay (up to $20 million) for the tests to prove the technology.

    Looking over the letters filed with the FCC on the subject, you will notice many are just form letters with the wording: ‘this is not simply a “turf war” over spectrum allocation’. (I always wonder about the sincerity about people’s “concern” when someone else wrote the letter and tells folks to make a copy of it and send it in… If you’re that upset about something, USE YOUR OWN WORDS!)

    We’ll know in 3 months if this really is a problem or if we are being used as pawns by ATT and Verizon in a “turf war”. In the mean time, I trust the FCC to remain impartial and judge based on the facts.

  8. S Klein says:

    update: Sorry – 72 feet in diameter

  9. Jim Carriere says:

    GPS signals are in frequency bands that make them fairly directional and dependent on line-of-sight reception. Interfering with an airborne receiver–whose antenna is located on the top of a (metal) airplane, “looking up” at satellites, by using a jammer whose signal originates on the ground and from underneath the airplane–requires a very strong jamming signal. The radio waves from such a jammer lose a lot of strength by having to bend around the airplane before reaching the antenna.

    Think of it like flying an airplane with only side and top windows and enjoying the view of the moon. Someone shining a searchlight from directly underneath you cannot easily disturbing your view of the moon. Granted, the searchlight will also reflect off of different parts of the airplane and someone shining the searchlight diagonally (rather than straight up) will have a somewhat less difficulty. Both of those principles are also basically true about interference and jamming in the GPS band. And also granted, GPS signals are normally very weak because they have to travel so far from their satellites to GPS receivers on airplanes, in your car, or on your smartphone.

    In other words, yes, this is something that warrants concern but at the same time it is science and not magic. It is not necessarily a dangerous side effect of innocent radio transmissions nor an easy way miscreants to deliberately wreak havoc.

  10. K Anderson says:

    This is exactly one of the reasons that LORAN was recommended for continuation and upgrade as the official back-up for GPS. A decision upon which I acted in starting a company to develop modern LORAN equipment for the cockpit, only to be left ‘holding the bag’ when the new administration did a quick 180 without so much as a moment’s pause to look at the real issue.

  11. M Michel says:

    Backup solution, ” E-Loran with DGPS corrections combined with the Omega-VLF Navigation System” all in your GPS.

  12. Kelly Wright says:

    We have privacy laws in place to cover a number of things such as health
    information, finacial information ect. Where we are at a given time or moment
    should also be a matter that each one of gets to decide who needs that information
    and the right to deny access. Just make retransmission of GPS signals or position information illegal
    without the permission of the person involved, and a large portion of possible
    interfearance goes away on its own.

  13. A few more points here:
    First, the intentional jamming of GPS is already illegal,
    Second, it is not illegal for trucking companies to track their equipment. Most GPS receivers record their track as it is. Equipment to transmit the location legally could readily be obtained and it’s inexpensive. The same for your own car or truck. Look up APRS. We intentionally track storm chasers with no problem. The jammers are to prevent the GPS receivers from being able to receive signals.
    Third: Its already illegal to jam GPS but jammers are readily available on the open market.
    Fourth: To address and earlier point, Garmin (and others) reportedly ran tests with the light squared equipment. They found that signal degradation started at a bit more than 13 miles. Complete loss occurred at over one mile.
    Fifth : Line of Sight: I have regularly used VHF and UHF (GPS is also UHF) hand helds in aircraft and talked to stations over 200 miles distant using only a couple of watts output power. I normally use my GPS mounted on the yoke with the little antenna mounted on the GPS. The reason GPS often needs a window mounted, or external antenna is because the signal is so weak. Cellphones work just fine in an airliner until it reaches an altitude where the signals are too weak due primarily to the distance between the tower and the cell phone.
    Sixth: A top mounted GPS antenna can see to the sides and down a bit as well as up and needs to as it is looking at satellites over a wide arc.
    The law and privacy issues: Position information has been used in court cases, both criminal and civil. It is not illegal to track your own car or truck. Cell phone companies are now required to keep a record just in case some one might want to check. This does not require retransmission of the GPS signal. It is illegal to use the jammers but that does not appear to be stopping wide spread use of the devices as there is quite a market for them. Enough for it to make the news.

    All of this ignores equipment failures and interference from nature.

  14. Mark Easton says:

    Yes, we most certainly should worry about terrestrial based radiators jamming GPS signals. Read this article from GPS world, and you be the final judge.

    http://www.gpsworld.com/gnss-system/news/data-shows-disastrous-gps-jamming-fcc-approved-broadcaster-11029

    Kind regards to my fellow aviators.
    Mark Easton

  15. Charlie says:

    If your GPS device has adequate filtering to reject the Lightsquared terrestrial network signals, then it’s a non issue for you. The problem is very few GPS receivers are designed that way and so they are susceptible to being overloaded thus impairing reception of the very weak GPS signals .

    There hasn’t been a problem because those Lightsquared frequencies were understood to be utilized for satellite downlinks. The FCC waiver opened them to high power terrestrial operations catching the GPS industry completely off guard.

  16. If you read the article, it appears that LightSpeed expects the GPS industry to fix the problem. They “claim” they are going to see what filtering is necessary on the GPS receivers, but the proof remains for LightSpeed to prove they can coexist with GPS and they must do so by June 15th. These transmitters BTW are authorized a power level of 45 KW according to “Inside GNSS” (The Garmin simulations were done at substantially less power)
    http://freegeographytools.com/2011/how-the-fcc-plans-to-destroy-gps-a-simple-explanation. Around the larger cities with a number of these transmitters GPS would be virtually unusable. From their statements LighSpeed’s expectation that the GPS industry “fix the problem” would basically require nearly every device that currently uses GPS in addition to aircraft such as cell phones and consumer devices to be replaced.

    Lots of information out there for the conspiracists among us.

    Note that the FCC issued the wavier for a ground based system in the satellite bands against the concerns and recommendations of the Department of Defense, Transportation, and Homeland Security AND its own guidelines. The NPRM was issued in such a manner that the comment period was far shorter than normal. On top of that the accelerated test schedule, LightSquared is the only one who will present the data to the FCC, and they are required to have equipment in place “IF” the OK is given.

    I’m inclined to place my faith in what the *established* GPS industry says in this case.

  17. Hobo says:

    Two comments:
    1. Don’t take what LightSquared is doing lightly. I’ve conducted a lot of research on their proposed system and the studies conducted by Garmin and its partners, there is great reason for concern with this new system. It’s not the space-based 72 ft receiver reflector, but the ground-based uplink nodes that is the major concern as incorrectly mentioned above. I second the recommendation to check out gpsworld.com’s article as it lays down the basics of the issue at hand.

    2. VERY IMPORTANT: The author fails to mention one critical step that each of us must take as responsible aviation GPS users. That is, to report any interference or loss of coverage not caused by our own means. The jammers mentioned above have caused interference with air traffic approach/terminal operations. If you ever experience a “loss of locks” with GPS while flying, and you don’t believe you caused the issue, you must report it to NAVCEN. Every report will be looked at and in some cases have actually found these types of jammers in use near airports.

  18. Charlie says:

    We need to differentiate between jammers that are designed to intentionally disrupt GPS reception and jamming that results as a consequence of faulty engineering.

    Lightsquared will not intentionally block GPS reception. That would be illegal and they will undoubtedly prove their signal power does not encroach into the GPS spectrum.

    If you lose GPS reception then your equipment is incompatible with the new band plan. Perhaps it might be salvageable by installation of a filter in series with the antenna feed line.

    FCC spectrum utilization decisions, such as channel splitting, have historically rendered perfectly working equipment into obsolescence.

  19. Except GPS is essential to public safety, national security, and aircraft navigation. These present extenuating circumstances. Even the TV channels (a non essential service) were given a 4 MHz buffer between channels (called white space)

    IF the implementation of LightSquared’s equipment proceeds as scheduled, these other services will not have time to compensate.

    I would also argue that LightSquared purchased a satellite service where ground augmentation is authorized with the intention of using it primarily as a ground based system, but systems are expected to coexist. Being that LightSquared already knows their signals will interfere with GPS then any interference “is intentional” by default even if they are in their own allocation.

    But lets say they are right. IF their transmissions caused a “incident” do you think they could survive the “civil” actions that would follow? I don’t.

    Also, FCC spectrum allocation has never forced out an essential service that I can find. Equipment and services often fade into obscurity due to more advanced technology replacing them. Wireless broadband nation wide is neither essential nor does it offer more advanced technology to replace GPS.

  20. Pingback: Should I Worry About GPS Jamming? | Aviation Blogs

  21. The FCC just clarified and stated it is up to LightSquared to prove they will not interfere with GPS. Time will tell.

  22. Greg Broburg says:

    It’s obvious we have some good intellect here in this discussion however it seems to me that there is a key point that is getting glossed over. That is one of occupied bandwidth. It happens in some form in most (essentially all) allocations that there is residual signal spill over into other channels outside of the licensed channel. This is a very very important issue with regards to GPS. Have a look at the out of band emissions that the FCC allows and apply that in context to the extremely sensitive GPS receivers. A raised noise floor for a com band radio service that is completely acceptable becomes a catastrophe for receivers with the sensitivity of typical non WAAS receivers. The experience with the WAAS series receivers is that they are much more sensitive than their non WAAS predecessors. These hopped up receivers are designed to see signals (satellites) transmitting closer to the horizon and they are failing from in band noise that is not a problem with the older L1 receivers nor are these noise contributors even visible with normal swept spectral analytical techniques. If it ain’t visible to swept spectrum analysis techniques then the FCC assumes that it is not there. Translation; if there is no visible interference signal to regulate then the FCC really cant do anything. We will need new technology in the form of a test device to physically quantify the interference. So far all we have to go on is the result in the cockpit. Not really enough hard and fast physical evidence for anyone at the FCC to do anything even if it does happen.

  23. Charlie says:

    Lightsquared contends its terrestrial transmitters have been designed with a sophisticated filter that will attenuate out of band power. That’s why they contend the Garmin interference report is insignificant; it’s not representative of the real world electromagnetic environment.

    This issue is finally getting the attention it deserves from the Air Force brass:

    http://www.airforce-magazine.com/DRArchive/Pages/2011/February%202011/February%2017%202011/GPSinJeopardy.aspx

    Although we are concerned with the L1 GPS open signals, the US Department of Defense operates encrypted signals on L1. There are two, the legacy Precision (P) code and the newer Modernized precision (M) code. I would think DoD would protect its capability to access these signals on the US mainland.

    Survey GPS equipment is designed with expanded bandwidth to improve accuracy:

    http://www.gpsworld.com/survey/the-fccs-decision-lightsquared-high-precision-users-would-be-affected-most-11089

    A Lightsquared designed ‘real world’ test that clears everyone’s technical scenario is going to be interesting.

  24. Gordon Arnaut says:

    About those rock-steady needles on an LPV approach. A number of years ago I had an opportunity to log some hours in the Yak 18T, a fully aerobatic 4 seater, with a 400 hp round engine. These very sturdy craft were used to train aeroflot crews back in the day.

    Well the radios in this plane are amazing. All vacuum tube and crystal clear receive transmit fidelity—and those rock-steady instrument approach needles, which I have not seen before or since. My understanding is that the Russians spared no expense in this airplane and it gives a feel of solidity that you simply will not get in an American light plane.

    My point is that we seem to abandon a technology before we fully develop the old one, vacuum tubes being a case in point. Ask any audiophile and he will show you his 80 lb tube amp. No kind of digital technology can come close. In phased array radar, microwave tube technology has big power advantage over solid-state, but the US abandoned tubes years ago.

    Same thing with mechanical gyros. Now we are paying huge amounts of money for glass panel gyros based on MEMS, which are basically integrated circuits and are stamped out like other computer chips, with the same kind of defect potential, which must be caught on the assembly line before a wafer goes out the door.

    That Yak’s artificial horizon is a thing of beauty, a huge 28-volt gyro in the middle of the panel that could not be tumbled no matter what kind of aerobatics you pulled. And it will never go dark like the glass panels do with alarming frequency.

    Now I have nothing against GPS, and for the most part the satellites work well and the signals are usually available. But it is a complex system and a lot depends on the radios in the airplane and the software they run. No argument that having virtual ILS in lots of places is a good thing, but I don’t think that ILS and other radio navaids should be dismantled, which seems to be the plan. Also agree with others here who mentioned Loran as a backup.

    As for the potential problems about the new cell frequencies, well that ship long ago sailed when the Amercian people, who supposedly own the airwaves, let their government give away this public resource to big business. People should have made this an election issue long ago and we would not have these problems now.

    Nobody cares in Washington if the declining private airplane segment goes the way of the Dodo bird. In fact they would prefer it. I have not looked into the technical aspects of this question, but I tend to believe Garmin and others, who are really the minnows in the overall scheme of things, and basically lunchmeat for the big dogs in the corporate world.

  25. Michael Sheridan says:

    I think a better article would be on the foolish approval by the FCC of spectrum and equipment that will knock out GPS (and therefore approaches) for miles.

  26. If I recall correctly the FCC issued a Wavier to allow testing of this service and the FCC has said LightSquared has to prove they do not or will not interfere with GPS (contrary to their spin). Although the FCC cheerleading this system makes me very nervous, it is not set in stone that the service will be approved particularly when you have the Department of Defense, Department of Transportation, and Department of Homeland Security weighing in against it. Then add the potential public safety aspects of interference to GPS I’d not say “it’s a done deal”.

    As for mechanical instruments, I’d not compare military grade instruments to run of the mill instruments in small planes be they solid state or mechanical. Tubes? I used to fly a number of “old” planes with tube type receivers including nave equipment. The NDB wandered around to the point where I had one guy ask how I did that approach. I told him I just took the extremes of the needle swing and went for the middle. Tubes have a history of short life where vibration and temperature extremes are present.

    BTW the last instrument approaches I shot using solid state equipment were rock solid. Even at my age I think the new glass panels are great compared to the old mechanical systems. They are more affordable and hold up better on average than the old mechanical systems to which I was exposed did.

    New receivers are far less prone to front end overload than were the old tube type. I have one receiver that has over 120 db dynamic range. IIRC in the “old days” 80 to 90 db was considered outstanding. Think of trying to operate GPS on a frequency adjacent to a 45 KW transmitter only a few miles away using the tube technology we had in the 50′s and 60′s. That equipment required about 3 times the separation of com channels we use now. Come to think of it even operating on today’s satellite frequencies would have been quite an achievement.

  27. Charlie says:

    Here’s an information paper concerning GPS jamming:

    http://www.pnt.gov/advisory/recommendations/2010-11-jammingwhitepaper.pdf

  28. Bob Briggs says:

    Another example of steady LPV and wavy ILS is KLVK, Livermore CA. KLVK lies in a valley and the ILS is probably distorted due to the hill it passes over.

  29. Charlie says:

    The FAA has issued two flight advisories stating that GPS may be unreliable or unavailable from May 16 – 27, 2011 (0700Z – 1300Z) due to LightSquared testing of a mobile broadband service in Las Vegas, NV and Boulder City, NV. Please refer to FAA NOTAMs LSQ-LAS and LSQ-BVU for more information.

    The Las Vegas transmitters are a few miles northwest of the airport. FAA welcomes constructive interference reports.

  30. Roger says:

    It is my understanding that these jammers are illegal. They have already caused disruptions at several major airports out East.

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  32. JimC says:

    (bump)

    Yesterday the FCC ruled *not* in favor of LightSquared. This latest development is getting moderate coverage in the mainstream media, but it is easy to pull up plenty of stories by using the search function of any online news website… and there is a wide variety of interpretations out there depending on who is telling what version the story.

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