What is LightSquared?
LightSquared is a gem! I am not only talking about its nationwide high-speed 4G capabilities and that it will be a boost to our lagging IT industry which has fallen behind 18 other nations. I am focusing on how it can beautifully complement high precision applications of GPS. It is a gem for GPS high precision users and for RTK.
In our GPS receivers we have 6 different communication systems to transmit/receiver RTK messages: 1) UHF, 2)Wi-Fi, 3)LAN, 4)GSM/GPRS, 5)Spread Spectrum, and 6) L-Band. None of them can conveniently provide a good, reliable and cost-effective RTK communication channel. I say LightSquared is a gem because of what it can do for GPS RTK applications.
Unfortunately, in the past several months so much misinformation has been published about this subject that many have been convinced that LightSquared and GPS cannot exist together. Every single GPS-related magazine is full of editorials and commentaries against LightSquared without giving substance and reason for what they write. There were even attacks on LightSquared executives for their political contributions and how they made their initial money! This is primarily the result of concentrated lobbies of two companies whose special interests might be affected if LightSquared is successful. The lucrative businesses and monopolies of OmniSTAR and StarFire are in danger! LightSquared is going to provide a better, faster, and cheaper communication channel for RTK and DGPS. LightSquared might and most probably will damage OmniSTAR and StarFire because it is a much better system; the same way e-mail damaged the facsimile business. It is the law of innovation.
They also use the scare tactics that LightSquared signals will interfere with GPS and that it costs billions of dollars to make the existing GPS receivers LightSquared compatible. It is not surprising that most of those who wrote letters to the FCC, testified in the Congress, and the supporting forces in the Congress against LightSquared, are either directly affiliated with these two companies or are influenced by them. In this article I try to address those issues that I am intimately involved and have direct knowledge.
Interference with High Precision GPS receiver
This is true. The root of the problem is us, the GPS manufacturers. We designed our receivers without paying reasonable attention to other systems that may come close to the GPS bands. The problem manifests itself in two ways: 1) Most GPS receivers do not have proper protective filters in the antenna section, and 2) The receivers don’t have a means to indicate if there is any interference in the area of operation.
The first problem of inadequate filter causes our GPS receivers to “invite” LightSquared signals to arrive to our GPS receiver. This can block and/or damage the GPS signals and cause the receiver to not function properly.
We solved the first problem by adding a set of Ceramic and SAW filters in the signal entry to our GNSS receivers. The filters were all existing off-the-shelf components. The filter system works fine and does not impose any noticeable negative effect on the quality of GNSS signals and solution results. In particular in has no noticeable effect on the multipath mitigation capabilities of receivers that need intact and undisturbed GNSS signals. The cost of the additional filters is negligible.
The second problem is inadequate test and warning features inside GPS receivers. Most receivers do not give any information regarding the existence of interferences. It is exactly for the lack of such test features that caused NTIA to go through a solid month of hard work to test receivers using external means. Such external means include very expensive test equipment and sophisticated test plans which can only be carried out by highly experienced people. Interferences are not only from LightSquared. Even harmonics of a radio station signal can cause interference. GNSS receiver should have a means to alarm the user of the existing interferences in its area. It is impossible to assemble NTIA-like test setups in every area that users need to use their GNSS receivers and perform such tests ahead of each daily job.
We also have solved the second problem of “self test” by adding “interference analysis” feature to our GNSS receivers. This feature analyzes the effect of interferences in a much better way than NTIA test procedures specify and it does it in a much shorter time: It does it in 30 seconds, rather than 30 days, and it does it by a click of a button which any novice user can do easily in the field.
Why some claim technical problems exist?
The problem related to technical issues got eclipsed with political ones when some GPS manufacturers tried to wash their hands and blame everything on LightSquared, instead of focusing on solving problems that were purely technical in nature.
These manufacturers went as far as claiming that the technology to protect GPS against LightSquared does not exist today and will not exist during the next decade! This is a blatant lie, or at best it shows the technical ignorance of those who made the claim. Some prominent industry figures wrote letters to the FCC and testified before Congress. The letter of Hon. Schlesinger/Parkinson to FCC is one of these unfortunate examples. False claims and advice even misled the honorable General Shelton to deliver wrong testimony to Congress.
The Schlesinger/Parkinson letter claims that technology to filter out LightSquared signals and at the same time keep the GPS signals intact, does not exist and may not come to existence for many years. Listening to Prof. Parkinson’s “filter group delay” questions and comments in the NTIA hearing of August 26 2011, it became clear to me that Parkinson did not understand the innovation that I had explained to him two years ago. In this hearing Prof. Parkinson commented that filters to protect GPS and have “flat group delay” does not exist today. At ION 2009 I had explained him that we were able to compensate for GLONASS inter-channel biases with the accuracy of 0.2 millimeters, and because of that, our GLONASS was as good as GPS. I thought he understood the underlying principal that we compensate for group and carrier delay variations of filters, and filter group delay flatness was not an issue any more. The evening of the same day at ION, Parkinson presented a GPS history at GPS World dinner meeting and at the end he said, “And today Javad was talking about 0.2 millimeter accuracy.” He got a good laugh from the audience and I thought that it was just a joke. Later, at the NTIA conference when I heard Parkinson’s focus on group delay variations of filters and his claim that a filter to protect GPS and have flat group delay does not exist, I realized that his reference to my 0.2-millimeter compensation was not a joke and he had not really understood what I had explained to him. In any event, GPS positioning is much less sensitive to group delay variations, to the point that precision positioning users will not see any significant effect. Our empirical results confirm this as well.
It is unfortunate that Prof. Parkinson was able to entice Hon. Schlesinger to coauthor the letter that was sent to FCC Chairman Genachowski. Since my academic credentials are from the University of Iowa, it gives me special privilege to also let the distinguished senator from Iowa to know that his opposition to LightSquared is ill founded and the folks from John Deere are misleading him.
The reason why here I explain the history of this specific technical issue and give references is bec
ause it has been the erroneous foundation of letters sent to the FCC and testimonies given before the Congress. Furthermore, these letters have tilted the opinions of many people and journalists in the wrong direction. It seems to me that these wrong, biased, and unfounded reports have been used to gang up unfairly against LightSquared. The good thing about technical issues is that they can readily be demonstrated, as we have and will continue to demonstrate on any platform. Electrons do not have party affiliations and do not follow the guidance of special interest groups and lobbies.
The validity of my points is backed by the filter system that we have designed and are manufacturing today. It works well. It does not have flat “group delay” across the frequency band and it does not affect the integrity of GPS signals. In particular, the multipath mitigation features of the GPS signals are well preserved. All GPS receivers we ship today are LightSquared compatible or entitled to free retrofit to be LightSquared compatible.
Our group delay compensation technique also opens the door for time transfer applications in sub-nanosecond level (as good as 0.1 or even 0.01 nanoseconds) without the need for temperature-controlled antennas. We plan to produce such products in a few months.
Retrofitting Existing Receivers
There has been a lot of discussion about what should be done with existing receivers in the field. I have the following points:
1. All existing receivers will be obsolete when new GPS satellites are launched. New GPS satellites will transmit “modernized signals” which, unlike P1 and P2 codes that we currently use, are not encrypted. Currently two of these modernized GPS satellites are on orbit and others will follow soon. It may take until 2020 before the constellation fully consists of all new satellites, but as soon as a few more are launched, users who have GPS receivers that receive the new signals will be able to benefit and have a competitive advantage in the marketplace.
2. All receivers that we currently ship are LightSquared compatible or are eligible for free retrofit. We have also offered to retrofit our existing receivers with cost of $300 to $800 depending on the model. Also, if customers chose to purchase these options, our receivers can track the new modernized GPS and GLONASS signals, as well as Galileo.
3. We have offered to retrofit receivers of other manufacturers to be LightSquared compatible. Details are in our website www.javad.com.
4. We also offer a better plan for the qualified existing units in the field. Instead of retrofitting the existing units to be LightSquared compatible and later buy an expensive new receiver, we offer attractive financial incentives to upgrade receivers to not only be LightSquared compatible, but also track new modernized GPS signals as well. To put this in perspective, a new modernized GPS receiver costs about $20,000, which must be purchased eventually. We offer a one-time option of discarding old receivers and purchasing new modern receivers at price of about $5,000. Existing qualified owners can select this one-time option or select to make their existing semi-obsolete receivers LightSquared compatible. One or the other, but not both! We do this for our existing receivers and receivers of other manufacturers in the field.
5. Existing old GPS receivers in the filed should not be a hindrance in the progress of this country to catch up in IT technology. We are currently behind 18 other nations in this area. It will be the shame of our generation if the next generation realizes that the existence of old GPS receivers was the reason they were deprived of LightSquared.
In summary, retrofitting the existing receivers can be win-win situations for all sides. Owners of existing GPS units may need to pay a little, but they will get a lot more in return; and they will not be stumbling blocks on the way of progress and innovations. GPS manufactures must also be not greedy and must cooperate for the win-win scenarios to materialize.
Retrofitting Military Receivers
There have been rumors that LightSquared signals affect military receivers. If this is true our military has a disaster in its hands. If military units cannot tolerate the LightSquared signals which 1) are far from the GPS band and, 2) are not coming from sophisticated jammers, how can they operate in a hostile theatre of operation? Were there not any anti-jam requirements in RFP of military GPS receivers? Has there been any anti-jam test performed on military receivers? Is LightSquared the first test?
The irony is that the filters that we have designed can tolerate LightSquared signals and track encrypted P-codes, but our military receivers cannot tolerate LightSquared while military receivers have access to un-encrypted P-codes which are up to 1,000 times stronger than the encrypted versions that we track.
Stand up and be counted!
The lobbies against LightSquared are powerful. They have wrongly convinced a lot of people that GPS and LightSquared cannot coexist. If they can stop LightSquared, the GPS high precision users will lose the opportunity to have a fast, reliable, nationwide and inexpensive RTK communication channel. Looking at the bigger picture, the U.S. will lose a chance to catch up with the rest of the worlds in IT technology. Also, respect for spectrum allocation will disappear and FCC’s role will get reduced to almost nothing and special interest groups will manipulate it. Most important of all, the incentive to strive for innovation will be damaged and those who have financial interest in old technologies will prevail.
My only interest in this issue is to integrate LightSquared communication channels inside our GNSS receivers and provide fast, reliable and inexpensive RTK. I am absolutely sure that we are not up against any laws of physics. We already ship LightSquared compatible GNSS receivers. I publish this article fully on my own initiative. I have had no encouragement, direction, financial support, or incentive from LightSquared in doing so.
Please explore the facts. Stand up and be counted. Support innovation. In the GPS high precision community we have a lot to lose if LightSquared loses.
In 1983, I co-pioneered high precision GPS at Trimble by introducing Trimble 4000-S. It was a 4-channel geodetic receiver. I single-handedly wrote its entire software. 16 hours a day, 7 days a week for several years. It was the first commercial geodetic GPS receiver and it changed the geodetic survey industry.
Later, after I founded Ashtech; in 1989 we introduced Ashtech L-12. This was the first All-in-One, All-in-View 12-channel geodetic GPS receiver. After that, we introduced Ashtech M-12 and the legendary Ashtech Z-12. These were the first truly portable geodetic GPS receivers. We were also the first to integrate GPS and GLONASS satellites (Link to article). It took all other companies more than 10 years to catch up and add GLONASS to their receivers.
In 1998 I founded JAVAD Positioning Systems (JPS) and introduced Legacy, Odyssey, and Regency products followed by HiPer. It was a 76-channel geodetic receiver. Other companies later copied HiPer. Today many of GNSS receivers look like it.
In 2007 I founded JAVAD GNSS and introduced TRIUMPH products. These were 216-channel receivers
, integrated with several communication channels. We also introduced their ALPHA, DELTA, and SIGMA versions. We were again the first to offer European Galileo and Japanese QZSS tracking in mass production. TRIUMPH technology has been shown to have the best signal quality and best multipath reduction capabilities against all others tested by the German Aerospace (Link to article).
In June 2010, we introduced the revolutionary and the only fully integrated geodetic receiver in the market, TRIUMPH-VS, with features like “Lift & Tilt”, “Interference Analyzer”, and “Visual Stakeout”. It is the most advanced high precision GNSS receiver in the market capable of tracking current and next generation signals of GPS, GLONASS, QZSS, and Galileo signals.
In October 2011, we introduced LightSquared compatible GNSS receivers and we plan to introduce LightSquared integrated GNSS receivers and sub-nanosecond (100- and 10-picoseconds time-transfer products.
I hold B.S. degree in Electronic Physics, M.S. in Electrical Engineering,
M.S. in Mathematics, and Ph.D. in Electrical Engineering from
the University of Iowa, Iowa City, Iowa.