The first two satellites for Europe’s Galileo global navigation satellite system were lofted into orbit October 21 by the first Russian Soyuz vehicle ever launched from Europe’s Spaceport in French Guiana in a milestone mission, reports the European Space Agency (ESA).
The launch occurred one day after initially scheduled to resolve a problem with the ground-support fueling system.
The Soyuz VS01 flight, operated by Arianespace, started with liftoff from the new launch complex in French Guiana at 10:30 UTC on October 21. All of the Soyuz stages performed as expected and the Fregat-MT upper stage released the Galileo satellites into their target orbit at 23,222 kilometers altitude, 3 hours 49 minutes after liftoff.
The two Galileo satellites are part of the In-Orbit Validation (IOV) phase that will see the Galileo system’s space, ground, and user segments extensively tested. During initial operations, the satellites will be controlled by a joint ESA and CNES French space agency team in Toulouse, France. Once that week-long phase ends, the satellites will be handed over to the Ober-pfaffenhofen Galileo Control Centre near Munich, operated by the DLR German Aerospace Center, which will be responsible for routine operations. Operating the satellite payloads to provide navigation services will be the task of the Fucino Control Centre, near Rome, operated by Telespazio.
The next two Galileo satellites, completing the IOV quartet, are scheduled for launch in summer 2012. Together, alll four are intended to prove the design of the Galileo system in advance of the other 26 satellites.
These first four satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo satnav constellation. According to ESA, the satellites combine the best atomic clock ever flown for navigation — accurate to one second in three million years — with a powerful transmitter to broadcast precise navigation data worldwide.
Artist’s depiction of a Galileo satellites being ejected from the dispenser.
Second IIF Good Now
The second GPS Block IIF satellite, SVN63/PRN01, launched in mid-July, was finally set healthy on October 14. The delay in bringing the satellite into service was due, in part, to extended testing of the cesium atomic frequency standard (AFS) on the satellite.
GPS IIF satellites carry three AFSs: one cesium and two rubidiums. The performance of the cesium AFS, independently confirmed, was poor. A switch to one of the rubidium AFSs took place on October 5.
U.S. Agencies Speak Out on LightSquared; Others Hide Their Cards
The U.S. House of Representatives Committee on Science, Space, and Technology has released some of the impact statements provided by federal agencies to the National Telecommunications and Information Administration (NTIA). The reports reveal deep concerns about and opposition to the LightSquared proposal, and detail cost estimates and other adverse impacts to government-wide operations should it go forward.
The NTIA itself has refused to make these agency reports public, rebuffing a Freedom of Information Act (FOIA) request by GPS World magazine and, so far, giving the same response to congressional committees on both the House and Senate side.
Missing in Action. The House Committee does not yet have access to all the agency statements; still missing are those from:
the Department of Homeland Security,
the Department of Commerce,
the National Oceanic and Atmospheric Administration,
the National Institutes of Standards and Technology.
The House committee has written to those departments asking for their reports; GPS World has also filed further FOIA requests specifically with those agencies. The Department of Defense impact statement is presumed to be classified.
Seventy-Two Billion. The Federal Aviation Administration (FAA) impact statement is the strongest statement of those provided so far to the House committee. It asserts, among many other findings, that the LightSquared proposal would cost the aviation community at least $72 billion, preclude elimination/reduction of an estimated 794 air-traffic fatalities over the next 10 years, set back planned air-traffic safety and efficiency measures by that same period, affect U.S. leadership in aviation, and damage the international market for U.S. satellite technology.
“FAA cannot conclude that operations using just the lower portion of the spectrum are compatible with civil aircraft receivers without definition of LightSquared’s end-state deployment and further study,” the FAA said. “Proposed LightSquared deployment (both upper and lower channels by 2014) would result in an estimated aviation community cost impact of at least $72 billion and delay NextGen implementation by approximately 10 years.
“Proposed LightSquared operations would severely impact the efficiency and modernization of the safest, most efficient aerospace system in the world.”
Not Feasible. The National Aeronautics and Space Administration stated, in part:
“NASA feels that due to the severity of the operational impacts, to both government and commercial users, it is conclusive that LightSquared’s implementation on the upper 10-MHz is not feasible in the near or long-term.”
Constellation Updates from ION-GNSS
During the Civil GPS Service Interface Committee (CGSIC) meeting held in conjunction with the ION GNSS 2011 conference in September, several presentations were given on the status and future of the global navigation satellite systems. Here are highlights, with updated information from elsewhere:
GPS. As of today, 30 satellites are in operation and set healthy. SVN27/PRN27, a Block IIA satellite launched in 1992, was decommissioned on August 10, 2011. The satellite has been removed from broadcast almanacs but continues to transmit L-band signals, presumably for end-of-life testing.
SVN35 returned to active service, once again, this time as PRN30, on August 16, to replace SVN30/PRN30, which was decommissioned from active service on July 20. SVN35 is being moved to the B1-F slot, previously occupied by SVN30.
There are currently four backup or residual satellites: SVNs 30, 32, 37, and 49. SVN30 is deemed no longer usable and there are plans to dispose of it.
SVN24/PRN24, a Block IIA satellite launched in 1991 and the second oldest active GPS satellite, reportedly experienced a reaction wheel failure on September 30. It has stopped broadcasting L-band signals.
GLONASS. Currently, 23 GLONASS satellites transmit usable L-band signals; 22 are set healthy. The first GLONASS-K1 satellite is still undergoing flight tests and is set unhealthy. According to Sergey Revnivykh, deputy director general, Central Research Institute of Machine Building of the Russian Federal Space Agency, the satellite will likely not be set healthy for users in the near future, not even for just the legacy FDMA signals. It will be considered a backup satellite that could be pressed into service if necessary. This decision was taken based on the fact that five GLONASS-M satellites are scheduled to launch this fall — indeed, one did so on October 2 — and they should be adequate to maintain a healthy 24-satellite constellation for some time. The current GLONASS signal specification cannot handle more than 24 operational satellites.
QZSS. The Japanese press reported that a government ministerial council consisting of the entire cabinet and headed by Prime Minister Yoshihiko Noda has taken the decision to expand the Quasi-Zenith Satellite System to seven satellites and will seek 4.1 billion yen (about $53 million) in the fiscal 2012 national budget to start the process. According to Hiroshi Nishiguchi of the Japan GPS Council, QZSS has a top priority in the budget.
The future QZSS constellation structure is still under design. Nishiguchi stated that the constellation could involve a mixture of inclined geosynchronous orbit (IGSO) and geostationary Earth orbit (GEO) satellites. For a seven-satellite constellation, options include three IGSOs + four GEOs, or four IGSOs + three GEOs, or five IGSOs + two GEOs. He said that hopefully the funding and the future constellation structure will be known by the end of the year.
Beidou-2/Compass. A special Compass workshop (see also the October issue of GPS World) stated that there are nine Compass satellites “in service.” But that may not be correct. While nine Beidou-2 or Compass satellites have been launched, Beidou G2, the first GEO to be launched, appears to be uncontrollable and is in a librating orbit. Some reports, perhaps overly optimistic, claim this satellite is undergoing “in-orbit maintenance.”
The last IGSO satellite to be launched, Beidou IGSO4, may not be in service yet. One workshop presenter indicated that the currently used constellation consists of three GEOs and three IGSO satellites. It seems that the medium Earth orbit (MEO) satellite, Beidou M1, is not considered useful for actual applications at the present time. It was also stated that this satellite is undergoing “in-orbit maintenance.”’
Two more Beidou-2/Compass satellites are to be launched in 2011 and five satellites are to be launched in 2012 to bring the number of operational satellites to 14 by the end of 2012: five GEOs, five IGSOs, and four MEOs. This is a sufficient number of satellites to provide the planned regional Phase II service. A 30-satellite global service, expected by 2020, will reportedly use three GEOs, three IGSOs, and 24 MEOs.
Beidou-2/Compass will also offer a 1-meter level differential service.
A Beidou-2/Compass Interface Control Document (ICD) is to be published this month. As of press time for this magazine, it had not yet appeared.
GPS World’s eighth annual Leadership Dinner took place during ION-GNSS in Portland, and was sponsored by Litton Consulting Group, Sigtem Technology, and JAVAD GNSS. Excerpts from some of the speakers’ remarks appear here, as well as photos from the “You Bet Your System” after-dinner game, the first GNSS Sweepstakes, a group exercise in probabilistic and equestrian studies.
■ Col. Robert Hessin, National Coordination Office for Space-Based PNT.
From my perspective, we have not communicated well enough at a national level a vision for the future of spectrum management and customer access to emerging wireless technologies. The bottom line is, had we planned in 2001 to go deliberately down this path with MSS spectrum, I’m confident we would have found a way to co-exist by 2014.
■ Col. Bernard Gruber, GPS Directorate.
The NPEF test conducted in April was robust and comprehensive, involving over 100 receivers from 24 organizations, spanning military, government, aviation, precision agriculture, automotive, and general use communities. The results demonstrated empirically that the LightSquared terrestrial signals in their original deployment plan interfered with all types of receivers tested. The military results were consistent with results obtained by commercial GPS industry organizations such as Trimble, Garmin, and John Deere through their own independently conducted tests.
We stand ready to work with the NTIA and LightSquared to complete additional testing on the newly proposed deployment plan and receiver filter designs. We are conducting additional tests of cellular and general navigation devices on the LightSquared “Lower 10” MHz terrestrial and handset signals. We are also prepared to test filters proposed as mitigations for high-precision GPS receivers when they become available. As General Shelton stated in his recent congressional testimony, AFSPC remains open to ideas on mitigation strategies that will ensure continued GPS service to billions of users worldwide.
■ Günter Heinrichs, IFEN GmbH.
We in Europe follow very closely — and not without worry — the situation with regard to LightSquared difficulties. It would be very shortsighted for us to say that this problem will not concern us in Europe. Because all of us eventually sit in the same boat. Galileo signals will also be affected by the LightSquared problem — and not only in the USA. Due to the worldwide scarce frequency resources, the times are past that one can look at an application for a certain frequency spectrum in isolation. Decision-makers must sharpen their awareness of the effects their decisions will have on the surroundings, worldwide. In the future, avoidance or minimization of such problems can only be managed by unity and increased coordination of the different responsible stakeholders. We live in a globalized world — this must be taken into account at all future decisions. An early cooperation and coordination between all parties involved at all levels will be essential — also across border.
■ Jim Litton, Litton Consulting.
I want to speak of my pride in our industry, which is confronted with a manmade threat from forces that have support from politically and financially powerful special interests. My former colleagues in NavCom and John Deere have been highly instrumental in this effort. In this crisis, with its unreasonable time-line demands, the industry has pulled together, and competitors have worked with each other to meet the threat with evidence-based, scientifically sound testing and analysis as opposed to the obfuscation, historical distortion, backdoor influence, and fact-denial seemingly characteristic of the ethics of hedge-fund operators. Even some in our industry who are ambivalent about the trade-offs between the integrity of legacy systems and opportunity for new sales have acted with propriety, openness, and respect for the truth. Millions have been spent, and program schedules delayed, to respond in this manner.
■ Greg Turetzky, CSR.
The basics of the problem are that the current rules in the FCC do not provide sufficient protection for GPS. Lightsquared is not the first group to go to the FCC and propose a change to the plan that meets the rules, but still degrades GPS performance. Remember UWB? If we don’t want to have to keep raising our hand and saying, “I know it follows the rules, but we are special,” we should work to change the rules. I would like to see our industry get together and propose any changes that are needed to the FCC. Let’s not forget that this is an international problem. As Tony Pratt reminded me, we could also take this to the ITU. The rules were created to protect one communication system from another. The rules we need would protect a below-the-noise navigation system from a high-power communication system.
■ Javad Ashjaee, JAVAD GNSS.
Spectrum is getting congested, and we cannot assume the luxury that we had can continue any longer. We should not be selfish and expect all others to stay away from us because their smell bothers us! Every GNSS receiver should put in a good filter so that others can coexist near us.
LightSquared is a very nice complement to GNSS. It can provide a nice communication channel for our RTK. If military receivers cannot tolerate LightSquared, how can they survive electronic warfare? If an enemy puts LightSquared-like transmitters in the theater of operation, our military equipment gets affected? Military units with P-code are more sensitive than JAVAD receivers that use encrypted P-code? Starting today, everything JAVAD GNSS ships will be LightSquared-hardened, or eligible for free upgrade later.
Mike Swiek (U.S. GPS Industry Council) and Stuart Riley (Trimble).
You Bet Your System
Over dessert and coffee, 150 VIP dinner guests played the ponies: six races, with horses from five GNSS racing stables.
Track stewards Ismael Colomina (Institut de Geomàtica) and Allison Kealy (University of Melbourne) get instructions and prepare to sell tickets.
Mike Shaw (Lockheed Martin) appreciates Jane Wilde’s (European PNT Industry Council) all-in bet.
Tom Hunter (JAVAD GNSS) sees his horse lose by a nose.
Sherman Lo (Stanford), Logan Scott (consultant), and Alan Grant (UK General Lighthouse Authorities) peruse the racing card: “We devised a betting strategy that left us flat broke.”
Compass delegates Yuanxi Yang (China National Administration of GNSS and Applications) and colleague Jing Tang enjoyed the evening — and now plan a GNSS racing event in China — with Fang Sheng (Raytheon).
Gard Ueland (Kongsberg Seatex and Galileo Services) holds a winning ticket, flanked by Grace Gao (Stanford) and Gordon Dale (NovAtel).
Eric Gakstatter counts his winnings as Allison Kealy and Alan Cameron frantically make payouts to Antje Tucci (IFEN GmbH), Rick Hamilton (CGSIC), and Dorota Brzezinska (Ohio State University).
Track stewards Sasha Mitelman (consultant), Fabio Dovis (Politecnico di Torino), and Michael Glutting (JAVAD GNSS).
Mitch Narins (FAA) puts his last dollar down on a bet with Di Qiu (Sigtem).
Col. Bernie Gruber (GPS Directorate) and Ron Hatch (NavCom) celebrate their onscreen winner; trackmaster Sam Pullen (Stanford) at the controls on right.
The first pair of satellites for Europe’s Galileo global navigation satellite system has been lofted into orbit by the first Russian Soyuz vehicle ever launched from Europe’s Spaceport in French Guiana in a milestone mission, reports the European Space Agency.
The launch occurred one day after initially scheduled to resolve a problem with the ground-support fueling system.
The Soyuz VS01 flight, operated by Arianespace, started with liftoff from the new launch complex in French Guiana at 10:30 GMT on October 21. All of the Soyuz stages performed as expected and the Fregat-MT upper stage released the Galileo satellites into their target orbit at 23,222 km altitude, 3 hours 49 minutes after liftoff. A launch replay is available. A look inside the IOV satellite is available on the BBC website.
The two Galileo satellites riding the Soyuz are part of the In-Orbit Validation (IOV) phase that will see the Galileo system’s space, ground and user segments extensively tested. The satellites are now being controlled by a joint ESA and CNES French space agency team in Toulouse, France. After these initial operations, they will be handed over to SpaceOpal, a joint company of the DLR German Aerospace Center and Italy’s Telespazio, to undergo 90 days of testing before being commissioned for the IOV phase.
The next two Galileo satellites, completing the IOV quartet, are scheduled for launch in summer 2012.
“This launch represents a lot for Europe: we have placed in orbit the first two satellites of Galileo, a system that will position our continent as a world-class player in the strategic domain of satellite navigation, a domain with huge economic perspectives,” said Jean-Jacques Dordain, director General of ESA. “Moreover, this historic first launch of a genuine European system like Galileo was performed by the legendary Russian launcher that was used for Sputnik and Yuri Gagarin, a launcher that will, from now on, lift off from Europe’s Spaceport.
“These two historical events are also symbols of cooperation: cooperation between ESA and Russia, with a strong essential contribution of France; and cooperation between ESA and the European Union, in a joint initiative with the EU. This launch consolidates Europe’s pivotal role in space cooperation at the global level. All that has been possible thanks to the vision and commitment of ESA member states.”
This was also the first Soyuz to be launched from a site outside of Baikonur in Kazakhstan or Plesetsk in Russia. A new site for Soyuz in French Guiana, operated by Arianespace, adds to the flexibility and competitiveness of Europe’s fleet of launchers.
Soyuz is a medium-size vehicle, complementing ESA’s launchers: Ariane 5 handles large payloads, and the new Vega, planned to debut in 2012, will lift smaller satellites.
Launching from close to the equator allows the European Soyuz to offer improved performance. From French Guiana, Soyuz can carry up to 3 tonnes into the ‘geostationary transfer orbit’ typically required by commercial telecommunications satellites, compared to the 1.7 tonnes that can be delivered from Baikonur.
LightSquared’s been in the news quite a bit since my last Survey Scene newsletter a month ago, but very little of it has actual consequence. A lot of the “news” is just noise. LightSquared pumped up its propaganda campaign nationwide to try to build a consensus in their favor and put pressure on the FCC, and is threatening a lawsuit if the FCC doesn’t do what LightSquared wants. No surprises there. However, other things have happened that I think you might be interested in hearing about.
Most interesting was the partnership announced between JAVAD GNSS and LightSquared to develop a solution for LightSquared’s GPS-jamming problem. I had the opportunity to sit down briefly with Dr. Javad Ashjaee at the INTERGEO conference in Germany after he announced his company’s partnership with LightSquared. He’s a sharp engineer and well-worth listening to. Essentially, he made three points:
1. This is a spectrum issue that isn’t going away even if LightSquared isn’t allowed to proceed, so it’s in the best interest of the GPS industry to work on a solution no matter what the FCC’s decision is.
I’ve written about this issue before and I agree that the MSS spectrum has got a bull’s-eye on it. It’s a big piece of spectrum when not a lot of wireless spectrum is left to be developed. One could argue that it has its purpose as an MSS band, but the counter to that argument is that it’s under-performing. There’s only so much one can do with MSS spectrum.
That leaves two choices: the first is to keep it allocated as low-power MSS (satellite-to-earth communications) as it has historically been used. It could also be officially established and recognized as a guard band for GPS so this problem doesn’t crop up again. GPS is an important enough national asset to make this a reasonable discussion. The LightSquared debate has done a fantastic job of raising awareness of the importance of GPS technology in our everyday lives as well as the commercial and military markets. GPS has and will continue to contribute more jobs, revenue, and growth to the U.S. and world economy than LightSquared could ever dream of. You can quickly dismiss anyone who claims otherwise.
2.Secondly, Dr. Ashjaee opines that 4G LTE is something that the GPS industry needs. I don’t disagree with that statement. More and more you see the latest high-precision GPS receivers designed with integrated communications, primarily GSM modems to enable internet connectivity in the field. Connectivity in the field has always been a weak point of GPS systems. If one wireless technology could replace UHF/VHF/Spreadspectrum/GSM/MSS, that would be a good thing.
I’m skeptical, though. I don’t believe LightSquared will be available where many GPS users need wireless communications even when it’s fully deployed — namely rural areas. They are going to chase after the money. The money is in the urban areas where the population is dense. Who in their right mind would spend money to establish and maintain infrastructure in areas with a very sparse potential customer base? I wouldn’t.
So, that still leaves us with needing UHF/VHF/Spreadspectrum/GSM/MSS communications technology. It doesn’t solve the problem. But, I’m not against trying as long as LightSquared’s system has no affect on the performance of high-precision GPS/GNSS receivers.
Incidentally, JAVAD GNSS intends to integrate a LightSquared mobile device into their product to manage potential interference from the uplink band (1626.50-1660.5MHz). However, this still doesn’t prevent interference from LightSquared mobile devices in the vicinity of JAVAD receivers. To this, Dr. Ashjaee says (I’m paraphrasing) “interference already exists today. Our mobile phones of today already create interference. If that happens, we simply move it away.”
3. Lastly, Dr. Ashjaee states that with GPS modernization in full swing and with new GPS signals being deployed, GPS users are going to need to upgrade their equipment to keep up with the latest technology in order to stay productive.
This is a point that he and I disagree on.
There is no reason your GPS L1 receiver will become obsolete in the foreseeable future, whether it’s a high-performance sub-meter receiver or a cm-level surveying receiver (L1-only). There is no plan by the U.S. Government to change or obsolete the L1 C/A signal.
For legacy L1/L2 GPS receivers that aren’t designed to utilize L2C or L5, it’s a different story. If you recall, back in 2008 the U.S. government floated the idea that it wanted to discontinue supporting the legacy semicodeless technique used by every L1/L2 GPS receiver in existence. Literally, several hundred thousand high-precision dual frequency GPS receivers would be rendered obsolete. At the end of the public comment period, the U.S. Air Force and Department of Commerce established a date of December 31, 2020 for this to happen. I wrote about this extensively at the time. My point is that there’s certain high-precision equipment that’s going to become obsolete at that time. However, that’s nearly ten years from now.
Should those users be forced to upgrade earlier to accommodate LightSquared?
Another point, and more serious, are the users who already upgraded in the past few years to equipment that was advertised as “future-proof”. In other words, they paid a premium for GNSS equipment that could track “all current and planned signals” such as L2C, L5, Galileo, GLONASS, etc. There is absolutely no reason those users would be required to upgrade their equipment for any imaginable reason. In fact, I’d be rather miffed if someone suggested I needed to spend money to do so.
How much money are we talking about?
That’s an interesting question.
Dr. Ashjaee guarantees that he will upgrade all JAVAD GNSS receivers for between US$300 and US$800. If you think about it, that’s similar to what you might pay in annual maintenance fees on many receivers. The issue is that JAVAD receivers aren’t that common in the U.S. Realistically, there’s a wide variety of high-precision GPS receivers in the U.S. market. Many of them are not the latest models, but still working perfectly fine. Manufacturers are not going to re-open those product designs and try to implement LightSquared-hardened antenna and circuitry. At that point, the user’s only choice is to purchase new equipment. I think that would be a step backwards. Many small organizations were able to purchase GPS technology with a one-time grant or specific project funds. Faced with the prospect of spending thousands of dollars on a new high-precision GPS receiver, I think many would opt not to use GPS.
To its credit, LightSquared has offered up $50 million to help retrofit or otherwise upgrade receivers owned by Federal government agencies. I think it will cost a lot more than that. I don’t believe $50 million would come close to covering the hard costs, not to mention the amount of time and effort that would be required to facilitate such a trade-in.
Let’s talk about “the fix”
JAVAD GNSS has a lot on the line, so it’s hard to imagine that the company hasn’t come up with something that works. That said, the conversation about retrofitting is meaningless until the design concept is proven, and empirical data demonstrates that it isn’t affected by LightSquared’s downlink (1526-1536MHz) or uplink (1626.5-1660.5MHz) signals, and that GPS receiver performance doesn’t pay a penalty.
Of course, LightSquared is talking like this is a done deal and predicting FCC approval by the end of the year. This is just noise, like back in August when it predicted an FCC decision within a month. Do not put any credibility in LightSquared statements. Its track record is poor, as few of their claims have materialized.
There’s no way the FCC is going to announce a decision by the end of the year. Mark my words. There’s not enough time to confirm a fix, how it might be implemented across multiple manufacturer’s receivers, and what the impact is. Believe me, there are many more hearings and information requests that are going to take place before any decisions are made by the FCC.
The “fix”, as I understand it, includes a new antenna design as well as new circuitry (filter). If you understand the high-precision GPS industry, you know this includes a substantial number of handheld units such as the Trimble Geo series, Ashtech (formerly Magellan) Mobile Mapper and ProMark series to name a few. Replacing antennas and changing circuit design is not a minor effort in a handheld unit that’s already packed tight with electronics. Which models do you support? Which models don’t you support? Which models can’t be upgraded? There are many questions to answer.
New antennas also mean new antenna calibrations by the NGS if you’re an OPUS user. Manufacturer software needs to be updated to reflect any change in antenna phase center. All of this will take time to investigate and understand. It should not be rushed just because LightSquared is in a hurry. Its “end of year” decision prediction, I’m sure, is directly correlated to an agreement with Sprint, which says the deal is off if FCC approval isn’t granted by the end of the year. Take a look at the Sprint presentation here.
Don’t let LightSquared over-simplify this “fix.” LightSquared Executive VP and lawyer Jeff Carlisle likes to play “engineer” like he did last week at a congressional hearing looking at the LightSquared GPS-jamming impact on small business. I couldn’t believe it when he pulled out a massive GPS receiver head and demonstrated how he would retrofit it with a $6 component to solve the problem, even going so far as showing where he would place it on a circuit board. The sad part is that there was not an engineer in sight to call him on it. Take a look at the 4:50 mark in this video:
Whoever put that panel together really did a disservice to this entire debate. LightSquared clearly came out on top, not because they should have, but because the witness list was not informed/prepared and the witness list wasn’t represented by the largest users of GPS in small business, surveying/engineering/construction/GIS.
The epitome of this trainwreck was when Rep. Steve King asked the guy representing the agricultural community about delineation of spectrum.
The grilling starts at the 1:49 minute mark and ends at the 4:20 minute mark.
Somehow, the witness doesn’t know or doesn’t know how to communicate that LightSquared/Skyterra sells satellite communications services to the high-precision GPS user community (via OmniSTAR) and therefore has encouraged GPS receiver manufacturers to design receivers to look into the MSS spectrum. LightSquared/Skyterra has generated tens of millions of dollars in revenue from agriculture and other high-precision GPS users, and now it is whining about the very people who are paying for its satellite communications data services? Are you kidding me?
Look, if LightSquared doesn’t want to sell satellite data communication services to the high-precision GPS industry anymore, that’s its decision, but don’t make this ridiculous claim that somehow GPS receiver designers are abusing LightSquared-licensed spectrum when LightSquared has been cashing in on it.
By the way, if you watch the grilling video, the “first-come, first-served” argument is really weak. Someone needs to brief the witness better than that. Even I don’t believe in squatter’s rights, and that argument will never fly with the FCC.
ACSM Radio Show Last Monday on LightSquared
I spent an hour talking with ACSM Executive Director Curt Sumner about the latest on LightSquared. We also touched a bit on the exciting Galileo satellite launch scheduled for this week, Oct. 20, that ended up being postponed for a day. You can listen to the radio broadcast here or download and listen to it on your MP3 player.
UPDATE: Following the work performed on the Soyuz launch facility and the associated additional checks, Arianespace has decided to restart the countdown operations for the launch VS01, Soyuz STB – Galileo IOV-1. Liftoff of the Soyuz ST-B launcher is now set for Friday, October 21, at
exactly:
10:30:26 a.m. (UTC) Friday, October 21
07:30:26 a.m. (French Guiana time)
12:30:26 p.m. (Paris time)
06:30:26 a.m. (Washington, D.C., time)
02:30:26 p.m. (Moscow time)
Galileo's Soyuz awaits it's flight.
A problem with the ground-support fueling system for the rocket carrying two Galileo in-orbit validation (IOV) satellites has delayed their launch either until Friday, October 21, or perhaps indefinitely.
A statement from launch operator Arianespace said, “A ground support system leak during third-stage fueling of the Soyuz launcher was the cause of today’s delay for this medium-lift vehicle’s inaugural flight from French Guiana. Arianespace Chairman & CEO Jean-Yves Le Gall said the leak was in a launch pad pneumatic system that activates the pre-planned disconnection of fueling lines to Soyuz’ third stage before the vehicle lifts off."
“During the final phase of third-stage fueling, there apparently was a change in pressure in this pneumatic system, and we observed the unplanned disconnection of the two connectors that enable the fueling of Soyuz’ third stage with liquid oxygen and kerosene,” Le Gall told reporters during a briefing at the Kourou Spaceport’s Jupiter mission control room. “The problem apparently is due to a valve leak in this pneumatic system, and we have taken the decision to empty the launcher and replace the valve.”
Le Gall underscored that the identified anomaly is in the ground-based pneumatic system, not on the launch vehicle. Fueling of the Soyuz is performed inside the mobile service gantry, which continues to remain in place on the launch pad. The launcher and its payload of two Galileo IOV satellites are in a safe mode, as is the ELS launch site.
Le Gall said a decision is to be made later today on whether to reschedule the liftoff for tomorrow. “We will confirm this once the valve is replaced; the decision also will take into account the launch team members — who worked all night during the original countdown.” If the launch is approved for tomorrow, October 21, the lift-off time would be four minutes earlier — at 7:30 a.m. local time.
One scientist who is following the situation from afar commented that possibly lyrics by the rock group Queen would be appropriate for the launch watch:
"Open your eyes. Look up to the skies and see
Thunderbolt and lightning, very, very fright'ning me
(Galileo) Galileo (Galileo) Galileo
Galileo figaro – magnifico"
Artist's depiction of a Galileo satellites being ejected from the dispenser.
This unusual view from underneath the launch table at French Guiana highlights the nozzle clusters of Soyuz’ four first-stage boosters and its central-core second stage.
The first Soyuz to take off from Europe’s Spaceport in French Guiana was moved to the launch pad October 14. The rocket that will carry the first two Galileo navigation satellites into orbit is on track for liftoff on October 20, reports the European Space Agency (ESA). Video of the transfer is available here.
Launch of the first two Galileo IOV satellites is scheduled for October 20 at 10:34:28 UTC.
The three-stage Soyuz ST-B was rolled out horizontally on its erector from the preparation building using the 600 m-long railway that leads to the pad. The vehicle was then raised into its launch position.
Earlier this week, the two Galileo In-Orbit Validation satellites, attached to their dispenser, were mated to the Fregat-MT upper stage and then enclosed in the fairing. This ‘Upper Composite’ was also transferred October 14 and added onto the vehicle from above, completing the very first Soyuz on its launch pad at Europe’s Spaceport. The new mobile launch gantry, built specifically for the rocket’s operations in French Guiana, also protects the satellites and the vehicle from the humid tropical environment.
The Soyuz and Upper Composite will undergo a full launch dress rehearsal in the next few days, including preparations for fuelling the vehicle, which will begin four and a half hours before liftoff.
According to ESA, October’s launch will be doubly historic: the first Soyuz from a spaceport outside of Baikonur in Kazakhstan or Plesetsk in Russia and the start of building Europe’s Galileo satnav constellation.In 2012 the second pair of satellites will arrive in orbit, ready to prove the design of the Galileo system in advance of the other 26 satellites. This quartet of satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo constellation.
More images and details are available at ESA’s website.
To watch the launch live, visit one of these sites:
The first two Galileo navigation satellites are both now fueled and checked for their launch by Soyuz from French Guiana on October 20, reports the European Space Agency.
The two Galileo In-Orbit Validation satellites reached Europe’s Spaceport in September. Galileo’s second flight model, FM2, touched down on September 7 on an Antonov-124, and the Galileo Protoflight Model followed it seven days later on an Ilyushin 76. Both satellites are now fueled and ready to be mated this week onto the dispenser that will hold them in place during launch before deploying them into their final 23 222 km orbit.
The combined payload stack — the dispenser and both satellites — will then be transported from the fueling facility to the Upper Composite Integration Facility S3B for integration with their Fregat-MT upper stage and subsequent encapsulation.
By Roland Bauernfeind, Thomas Kraus, Dominik Dötterböck, Bernd Eissfeller, Erwin Loehnert, and Elmar Wittmann
Open-field tests of jamming signals from widely available in-car jammers, measured with an experimental software receiver that records the intermediate frequency (IF) samples, enable a detailed analysis of interference effects from these looming threats.
In-car GNSS jammers, openly advertised online as personal protection devices, constitute the most serious threat of all the GNSS interference sources. Such jammers are relatively easy to purchase from abroad over the Internet and to operate by plugging into the cigarette lighter of a vehicle.
Their usage may be motivated by criminal intention such as disabling a vehicle theft-protection system, a fraud attempt against a distance-based road-user charging system or distance-based vehicle insurance, or by privacy concerns, to escape monitoring by a fleet-management or other tracking system. Since most current GNSS receivers carry a communication link, it is difficult to keep full control of the data flow. Further concerns arise from reports of companies storing user location data, as was the case with Apple. Concerns about privacy issues will grow with the widespread introduction of intelligent transport systems (ITSs), vehicles and transport infrastructure that apply information and communications technology to improve transportation efficiency, sustainability, and safety. The primary information source is GNSS for location enabled applications like eCall, a pan-European location based emergency call, which shall be in place and installed in every new car from 2015 on.
Cooperative ITSs, which are currently undergoing standardization, are transport systems that communicate their positions such that each vehicle has a virtual picture of the real world in its vicinity. The cooperative ITS network connects the vehicles with the transportation infrastructure. Vehicles establish a wireless vehicular ad-hoc network (VANET), based on their geographical position. In a VANET the position is communicated to be used at the application layer but is also required at the physical layer to enable geographical routing and addressing. This emerging vehicular communication is an enabling technology many novel and innovative driver assistance systems and location-based services. The result of using an in-car jammer is the complete destruction of GNSS signals not only in the vehicle it is operated in, but also within vehicles in the vicinity. This creates a serious threat to ITS’ future.
To counter the interference threat by in-car jammers, the University of Federal Armed Forces (FAF) Munich purchased some jammers offered online, for analysis in a laboratory environment and in open-field tests in the GAlileo TEst range (GATE). Measurements were taken with an experimental software receiver developed at the Institute of Space Technology and Space Applications. This receiver enables recording of intermediate frequency (IF) samples and detailed analysis of the interference effects on the receiver.
Jammer Interference Signals
First, we analyzed the purchased jammers shown in the Opening Photo. It is always better to understand the signal structure of undesired signals well, before starting development of applicable countermeasures and mitigation technologies. Therefore, the jammers were analyzed in the frequency domain with a spectrum analyzer, and the analyses were extended by a time-domain analysis by recording the signal with a software radio-defined card.
The first results showed that the majority of low-cost in-car jammers transmit a chirp signal with a bandwidth between 9.4 to 44.9 MHz in the E1/L1 band (other frequency bands haven’t been considered yet). The others are sine-wave oscillators with a 3-dB bandwidth of around 0.92 kHz and have a temperature-dependent center frequency around the Galileo/GPS center frequency, but they are not considered further in this article. Both jammer types belong to the category of narrowband interference, however the chirp jammers are much more effective in jamming the signal within the GNSS receivers.
The construction of an in-car jammer chirp signal is usually done by a voltage controlled oscillator (VCO) with an input voltage of a saw-tooth function. In general, it is a sine function with a frequency change over time, which can be described by
(1)
For a unidirectional linear chirp signal the instantaneous frequency f(t) varies linearly over time as
(2)
where f0 is the starting frequency and k is the chirp rate. The amplitude a(t) is usually constant. The corresponding time domain function for a sinusoidal unidirectional linear chirp is
. (3)
All in-car chirp jammers are linear with a positive uni- or bidirectional sweep. The negative slope is so high that we can neglect them for modeling and can describe jammer 1 with the equation (3)
. (4)
Tsw = sweep time.
The frequency spectrum of jammer 1 and jammer 3 is given in Figure 1 and Figure 4, respectively, where we can extract the bandwidth and the peak power from the graph. For measuring the peak power of the jammer it is important to take the max-function mode of the spectrum analyzer, because the internal sweep of the jammer and the spectrum analyzer is never synchronized. Table 1 shows the important parameters of the jammers.
Table 1. Chirp jammer parameters.Figure 1. Power spectrum of jammer No. 1.
To get the timing information of the signal, the analysis must be done in the time-domain. Therefore, we converted the jammer signal into an intermediate frequency and recorded the signal with a SDR card. The further processing has been done with Matlab, where we could extract the frequency change over time for jammers 1, 2, and 3, given in Figure 2, Figure 3, and Figure 5, respectively. Finally, these functions are exactly the same, which were generated for the VCO within the jammers.
Figure 2. Frequency over time at jammer No. 1.Figure 3. Frequency over time at jammer No. 2.Figure 4. Power spectrum of jammer No. 3.Figure 5. Frequency over time at jammer No. 3.
If we compare the jammers, we can see how the complexity increases from one to the other. For jammer 1, a standard saw-tooth generator with a rising slope has been used only for the input of the VCO. Jammer 2 uses two generators. Compared to jammer 1, a second saw-tooth generator with a falling slope and a four-times longer sweep time is added. In the most complex case, jammer 3, we find four generators in total. Jammer 3 causes a frequency burst every 1.12, 1.35, or 2.28 milliseconds. These frequency bursts can be seen also in the power spectrum in Figure 6.
Interference Tests in GATE
Various static and dynamic interference tests were performed in the Galileo Test Range (GATE) in Berchtes-gaden, Germany, where the impact of the jammer signals on both GPS and Galileo RF signals could be evaluated in a realistic manner. GATE is a unique outdoor test and development environment for Galileo and GPS satellite navigation. Consisting of eight virtual Galileo satellites located atop several mountains around the test area in Berchtesgaden, GATE provides a topology to support different testing scenarios. The Galileo signals are transmitted simultaneously on all three frequencies. E1, E5ab, and E6, compliant to the Galileo OS ICD specification. GATE’s virtual-satellite mode simulates a realistic moving Galileo satellite constellation and supports commercial Galileo receivers without any modification. Two monitoring stations within the test area receive and process these signals. A central processing facility steers and controls the signals transmitted.
Figure 6 gives an overview of the test range with its transmit and monitoring stations as well as the GATE central point. The interference tests with the GNSS jammers were performed in the area close to this central point.
With respect to the testing of RF jamming scenarios including GPS as well as real over-the-air Galileo signals in the GATE test area, some requirements have to be taken into account.
Transmission of any interference signals on the GPS and Galileo frequency bands requires an official license from the responsible authority in Germany (Bundesnetzagentur). An appropriate permission for trial radio transmission was available in the framework of the jamming tests. The disturbance of other GPS receivers in the vicinity has to be minimized in any case. Therefore the transmission power of the jammers must be limited so that a distinct impact on the GPS L1 signal reception is restricted to a radius of a few hundred meters at the most. Furthermore, the interference signal source must be placed at an adequate distance from the GATE monitoring station antennas in order not to affect the processing and steering process for the GATE signals.
Finally, in the case of performing GATE tests with a dynamic test user receiver, a severe degradation of the user reference position must be avoided. As the steering of GATE signals in the virtual-satellite mode is based on accurate and reliable user position information transferred in near-real-time to the GATE processing facility. a combined GPS-RTK and inertial measurement unit (IMU) solution is applied. Thanks to the use of the IMU, a GPS signal outage can be well compensated for a certain time period. In order to meet the GATE accuracy requirements, the jammer transmission was restricted to time intervals of about 30 seconds.
Ipex Software Receiver
The Institute of Space Technology and Applications PC-based Experimental Software Receiver (ipexSR) is a multi-frequency GNSS receiver realized completely in software (Visual C++/assembler), capable of tracking GPS and other GNSS signals in real time or post-processing.
For signal analysis, IF samples were recorded and analyzed in post-processing, using two front ends that can be operated in different modes depending on required frequency bands. For the interference analysis, only L1 was recorded with the front end parameters summarized in Table 2.
Table 2. Front-end parameters.
The front-end gain is set once for the measurement in the receiver’s configuration menu. The front end uses no automatic gain control. All the tracking loops settings can be set in the receiver’s configuration menu. For the phase lock loop (PLL), we used a non-coherent (Costas) dot-product discriminator and for the delay lock loop (DLL) an early-minus-late discriminator with the settings in Table 3.
Table 3. Tracking loop settings.
Jammer Effect on Receiver
To analyze the interference effect on the receiver, we took measurements with static receivers and different jammers approaching the receivers, starting from a distance of 1,200 meters. Both commercial receivers, capable of recording the carrier-to-noise density ratio, and the Ipex software receiver, capable of recording IF samples, were set up. Receiver antennas were mounted on the car roof. For jammer reference trajectory, we used an odometer with a GPS receiver providing initial position and reference time.
A measurement for the degradation in the receiver is the carrier-to-noise density ratio. The theoretical effective carrier-to-noise density ratio is defined as
where Q is the spectral separation gain adjustment factor. While moving the jammer towards the receivers, the received interference power Preceived(r) increases relative the distance according to the free-space loss as
where Pjammer is the jammer transmission power. Figures 7 to 10 give the C/N0 degradation for the four different receivers interfered with by the three different jammers in respect to the distance. The measurements have been taken at different times so the undisturbed C/N0 is varying.
Figure 7. Carrier-to-noise ratio for IpexSR.Figure 8. Carrier-to-noise density ratio for BeeLine receiver.Figure 9.Carrier-to-noise density ratio for NAVILoc receiver.Figure 10. Carrier-to-noise density ratio for Garmin receiver.
Comparing the professional receivers with professional antenna to the mass-market receivers with patch antenna, it is evident that the professional receivers are interfered with at a later point but lose lock on the signal earlier.
The degradation of the C/N0 for ipexSR compared with the theoretical curve as introduced before is given in Figure 11. The measured curves follow the theoretical one as long as the front end is not saturated. As soon as the front-end analog-to-digital converter (ADC) is saturated, it causes severe degradation of the signal which exceeds the pure degradation caused by the increased interference power until loss of lock on the signal.
Figure 11. Carrier-to-noise ratio for IpexSR (Jammer 1).
Saturation is caused because the amplitude of the received interference power exceeds the range of the ADC. The comparison between the theoretical and actual received signal strength in respect of distance for the measurements of jammer 1 is shown in Figure 12. With an effective jammer transmission power of –40 dBW, the curves show good alignment for the interval where the received interference power is noticeable above the noise floor, until the front
end goes into saturation and the received signal strength converges to an upper limit.
Figure 12. Received signal strength (Jammer 1).Figure 13. Sample distribution over 8-bit ADC (Jammer 1).
The rising received interference power drives the IF samples to the outer limit of the ADC and changes the distribution of the IF samples over the bins of the ADC as shown in Figure 13. For these measurements, the gain of the front end was set to have the samples without interference distributed over all the ADC bins. This setting with low remaining dynamic range is optimal when no interference is present, whereas with interference the ADC goes immediately into saturation. The red line shows the distribution of the samples where 0.2 percent of the samples are at the outer boundary.
Figure 14. Punctual correlator output (Jammer 1).
Until saturation of the front end, the interference degrades the correlation process by raising the noise floor. When the dynamic range of the front end can no longer occupy the received interference power, the degradation by saturation dominates. For the undisturbed signal, all the signal power is in the I-channel as seen at the punctual correlator output in Figure 14. The correlation is degraded until loss of lock on the PLL occurs.
Degradation of the correlator output has a direct effect on the performance of the tracking loops and their discriminator outputs, as shown in Figure 15. The discriminator error rises until it is out of the discriminator function’s pull-in range. When the PLL error is outside the pull-in range, the tracking loop loses lock on the signal.
Figure 15. DLL and PLL discriminator outputs (Jammer 1).
The degradation of DLL performance causes a position error as shown in Figure 16.
The measurements show that currently available in-car jammers degrade the receiver performance in an radius of about 1 kilometer around the interference source and disable position determination within a radius of about 200 meters.
Interference Detection
Jammers constitute a serious threat to the future of intelligent transport systems. Their use is forbidden by law, and their illegal use must be prosecuted. To have awareness of the actual number of jammers in use requires deploying jammer detectors at dedicated points and recording interference events. Promising points for initial measurements would be highway interchanges or highly frequented border crossings. Reliable numbers on the actual use of GNSS jammers would be required to support government decision-making regarding further actions, and to support the final goal of an comprehensive GNSS interference monitoring network.
For the interference detection test, we recorded were recorded with five static receivers deployed in the GATE core area as shown in Figure 17, with jammer trajectory in red.
Detection of the interference source is based on monitoring the jammer-signal-to-noise ratio (JNR). To prosecute malicious intentional jamming, it is necessary to assign the detected interference signal to the jamming device. Therefore, the signal was analyzed in the time-frequency domain for the characteristic chirp signal of a jammer. The gain of the front end was set to the minimum so that the front end could cover high interference power levels
First, signals were recorded with the chirp jammer located at the central point. The jammer is located outside the car, with line-of-sight to position 1. The measurements at position 1 at about 200 meters from the jammer are shown in Figure 18. Short-time Fourier transformations of the signals in Figure 19 and Figure 20 clearly show the presence of the chirp signal.
Figure 18. JNR at Position 1.Figure 19. STFT of Jammer 1 at Position 1.Figure 20. STFT of Jammer 3 at Position 1.
For the second measurement, the jammer was used inside a car. The car started at position 1, where it switched on the jammer and drove along the main street, passing position 3. The car then turned and drove back the same way. The measured JNR at the five positions is illustrated in Figure 21.
Figure 21. JNR with jammer 1 moving.The resulting degradation in C/N0 is presented for GPS PRN 9 in Figure 22 and for GATE PRN 46 in Figure 23. The measurements show that the jammer can be detected and identified within the distributed receiver network.Figure 22. C/N0 of GPS PRN9 with jammer 1 moving.Figure 23. C/N0 of GATE PRN46 with jammer 1 moving.
The next step in developing a comprehensive interference-monitoring network would be to have automotive GNSS receivers enabled to detect and report interference events. For this scenario, a jammer was operated in a moving car and measurements with the ipexSR driving in another car on the same road were made.
Both cars started at the same position. The pattern in Figure 24 corresponds to the following events. The jammer started first, followed by the receiver with a random car in between. After 170 seconds, the jammer parked at the roadside, and the receiver passed by, indicated by the single spike. At about 240 seconds, the receiver turned and passed by the parked jammer again, as indicated by the second spike at 310 seconds. After the receiver passed by the jammer, the jammer started again, approached the receiver from behind and overtook the receiver at 450 seconds.
During this measurement, neither of the two cars could track or re-acquire a signal. Reporting of the loss of lock on all satellites could therfore be used for a coarse localization of jammers.
Figure 24. JNR in a traffic environment with jammer 1.
Conclusion
The analysis has shown that the interference range of a jammer is very dependent on the receiver architecture. In every scenario, the jammers had severe effects. After detecting interference events, the next step is to mitigate their effect within the receiver. Mitigation techniques based on time-frequency transformations like short-time Fourier transform or wavelet packets are envisaged. With the ipexSR IF Sample API, Figure 25, it is possible to implement and test these algorithms in real time.
Figure 25. IF sample API.
Also the possibility of localizing the interference source based on the JNR and C/N0 measurements will be e
valuated.
Steps against the use of in-car jammers must be taken. To prosecute the use of jammers, detector units must be deployed. This would also help to gather reliable numbers on the use of jammers and would support and justify future actions. Clearly, degrading the integrity of GNSS positioning is a threat for all safety-relevant ITS applications. Therefore, avoidance and mitigation of interference signals should be subject of safety-related vehicular communication, and its standards should be able to handle this in the same way as other safety-related issues. We propose discussion of the GNSS jammer threat within the working groups for cooperative ITS standardization: GNSS interference should be handled in the same way as any other road hazard.
Acknowledgments
These results were developed during the InCarITS Project (Analysis, Detection and Mitigation of In-car GNSS Jammer Interference in Intelligent Transport Systems), founded by the Bundesministerium für Wirtschaft und Technologie and administered by the Project Management Agency for Aeronautics Research of the DLR in Bonn (FKZ 50 NA 1001).
Manufacturers
Jammers were analyzed with a Will’tek 9102B spectrum analyzer and signals recorded with a GE ICS-572B software-defined radio card. The two front ends were developed by Fraunhofer Gesellschaft (FhG). Receivers used for jamming testing were ipexSR with NovAtel GPS-704-X antenna and FhGIII front end, a NovAtel BEELINE with the same antenna, a NAVILock NL-302U Sirf3, and a Garmin GPSMap 76, the latter two both with patch antennae. Only the IpexSR was used for tests to locate jammers, using an FHGIII front end and NovAtel GPS 511 antenna (Position 1, 5), the same antenna with an FHGII front end (Position 2, 3), and an FHGIII front end with SensorSystems S67-1575-96 antenna (Position 4). The two-car driving test used the IpexSR with Novatel GPS-704-X antenna and FHGII front end. IFEN GmbH developed and installed the test range and is GATE operator at least until end of 2013.
Roland Bauernfeind works at the Institute of Space Technology and Space Applications at the University FAF Munich. He received a diploma in aerospace engineering from University of Stuttgart.
Thomas Kraus is a research associate of the Institute of Space Technology and Space Applications at University FAF Munich.
Dominik Dötterböck is a research associate of the Institute. He received his diploma in electrical engineering and information technology from Technical University Munich.
Bernd Eisfeller is director of the Institute of Space Technology and Space Applications at the University FAF Munich. He is responsible for teaching and research in the field of navigation and signal processing.
Erwin Loehnert received a diploma in aerospace engineering in from the Munich University of Technology. He is head of the Mobile Solutions department at IFEN GmbH, and GATE manager.
Elmar Wittman received a Dipl.-Ing. degree in geodesy from the Munich University of Technology. He works as a systems engineer in the field of GPS/Galileo satellite navigation for IFEN GmbH.
The long-awaited signal interface control document (ICD) for China’s growing GNSS will appear this month, according to representatives of the system who spoke in a “Compass: Progress, Status, and Future Outlook” workshop as part of ION GNSS and the CGSIC meetings in Portland in September.
The ICD has been rumored to be available previously to receiver manufacturers within China, creating some disgruntlement among companies outside the country. One of the workshop panelists affirmed that GPS/Compass chips and receivers are being actively developed by many Chinese manufacturers and research institutes.
The ICD announcement came among many valuable pieces of information presented during the pre-ION workshop, sponsored by the International Association of Chinese Professionals in Global Positioning Systems and chaired by Jade Morton, professor of electrical and computer engineering at Miami University, Ohio.
Xiancheng Ding of the Beidou Program Office described Compass as a demo system in transition to an operating navigation system. Two more satellites will launch in 2011, making a total of five new space vehicles this year,as part of a total “simple navigational system” of nine satellites that has been built up, and what is termed a test system over the Asia-Pacific region, to be complete by the end of the year.
Five more satellites will rise into orbit in 2012, and the system will gradually extend its coverage and improve its performance. Compass will start official regional service by the end of 2012, meeting user requirements in the Asia-Pacific region.
ICD document v1.0 will be published in 2011, and probably in the month of October. It will be available for international download on the Compass website (as yet without an English version).
There was some disagreement among panelists as to the final targeted number of satellites in the system: either 30, or 35. Subsequent comments indicated that much of the structure may still be under discussion. The impression given was very much of a dynamic system in formation and growing rapidly.
In a presentation on “Preliminary Results of GPS/Compass Integrated Positioning and Navigation,” Uanxi Yang of China’s National Administration of GNSS and Applications reported integrated navigation with a Unicore UB 240 Compass/GPS receiver with up to 9-centimeter accuracy, and also mentioned a Shanghai Huace Compass/GPS receiver. Some systematic errors in Compass positioning were reported, and attributed to the sparse satellite distribution currently.
Yang concluded with the exhortation, “Reasonable Wishes for Compass!” emphasizing the delegation’s desire to continue working diligently on, but with realistic expectations for, the new system.
Orbit Roundup
In other satellite news and debuts anticipated around the world:
GPS. Back-channel reports say the cesium clock aboard SVN-63, the second IIF satellite, is not functioning properly, and that this is at least one reason why the satellite, turned over to 2SOPS control on August 19, has not been set healthy to users.
[Correction: The September issue and env-gpsworld-integration.kinsta.cloud mistakenly reported that SVN-63 had been set operational on August 23. This is not the case. As of September 29, the satellite is still not healthy to users.]
After repeated attempts to get the clock working, operators are ready to switch to a rubidium clock onboard, and may already have done so.
GLONASS. The launch of GLONASS-M No. 42 from Plesetsk is scheduled for October 1. GLONASS-M Nos. 43, 44, 45 from Baikonur may occur as early as November 2. GLONASS-M No. 46 from Plesetsk is now scheduled for November 22. The launch of the next-generation GLONASS-K1 No. 12 from Plesetsk will likely slip to 2012.
The K1 satellites will not be set healthy, but held in reserve only. The remaining M-generation vehicles launching this year will fill up the 24 almanac slots. GLONASS will have plenty of satellites held in reserve.
Luch-5A, a Russian geostationary communications satellite that includes an SBAS payload, will launch on December 10 from Baikonur.
FCC Calls for More Testing on LightSquared Interference
The U.S. Federal Communications Commission (FCC)issued a Public Notice on September 14 stating that additional testing is necessary to ensure that LightSquared’s broadband network will not interfere with GPS.
The notice states: “Following extensive comments received as a result of the technical working group process required by the International Bureau’s Order and Authorization dated January 26, 2011, the Federal Communications Commission, in consultation with NTIA, has determined that additional targeted testing is needed to ensure that any potential commercial terrestrial services offered by LightSquared will not cause harmful interference to GPS operations….
“For more than three months, the technical working group, comprised of more than 120 participants including representatives from the Department of Defense, Department of Transportation and other federal agencies, the GPS community, various telecommunications companies and LightSquared, conducted an extensive set of tests, and LightSquared submitted a final report on June 30, 2011. The technical working group effort identified potential for harmful interference from LightSquared’s originally proposed deployment based on operation of terrestrial transmitters in both the upper and lower 10 MHz portions of its spectrum. The FCC issued a public notice on June 30, 2011, seeking comment on the report.
“LightSquared submitted proposed mitigation techniques to remedy the interference to GPS simultaneously with the technical working group final report. Notably, LightSquared proposed to revise its planned deployment to operate terrestrial transmitters only in the lower 10 MHz of its spectrum. The results thus far from the testing using the lower 10 MHz showed significant improvement compared to tests of the upper 10 MHz, although there continue to be interference concerns, e.g., with certain types of high precision GPS receivers, including devices used in national security and aviation applications. Additional tests are therefore necessary.”
Galileo Counts Down to October 20 for First Validation Satellites
The first flight of a Russian rocket, Soyuz, from Europe’s spaceport in French Guiana will carry the first two satellites of Europe’s Galileo navigation system into orbit on October 20, and the European Space Agency is reporting on the preparations.
The Soyuz launcher will be rolled out horizontally to the launch pad on October 14 and raised into its vertical launch position. The upper composite, comprising the Fregat upper stage, payload and fairing, will then be hoisted on top of Soyuz.
The two Galileo satellites arrived from the Rome facility of Thales Alenia Space Italy, also in mid-September. In 2012, a second pair of satellites will join them in orbit, with the task of proving the design of the Galileo system in advance of the other 26 satellites. The four satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo satnav constellation. They combine reportedly the best atomic clock ever flown for navigation — accurate to one second in three million years — with a powerful transmitter to broadcast precise navigation data worldwide.
The first Soyuz to rocket up from a port outside Baikonur in Kazakhstan or Plesetsk in Russia, the launch will take place from a new facility 13 kilometers northwest of the Ariane 5 launch site. French Guiana is much closer to the Equator than other launch possibilities, so each Galileo effort will benefit from the Earth’s spin, increasing the maximum payload into geostationary transfer orbit from 1.7 tons to 3 tons.
By Pratibha B. Anantharamu, Daniele Borio, and Gérard Lachapelle
Spatial and temporal information of signals received from multiple antennas can be applied to mitigate the impact of new GPS and Galileo signals’ binary-offset sub-carrier, reducing multipath and interference effects.
New modernized GNSS such as GPS, Galileo, GLONASS, and Compass broadcast signals with enhanced correlation properties as compared to the first generation GPS signals. These new signals are characterized by different modulations that provide improved time resolution, resulting in more precise range measurements, along with the advantage of being more resilient to multipath and RF interference. One of these modulations is the binary-offset-carrier (BOC) modulation transmitted by Galileo and modernized GPS.
Despite the benefits of BOC modulation schemes, difficulties in tracking BOC signals can arise. The autocorrelation function (ACF) of BOC signals is multi-peaked, potentially leading to false peak-lock and ambiguous tracking. Intense research activities have produced different BOC tracking schemes that address the issue of multi-peaked BOC signal tracking. Additionally, new tracking schemes including space-time processing can be adopted to further improve the performance of existing algorithms.
Space-time equalization is a technique that utilizes spatial and temporal information of signals received from multiple antennas to compensate for the effects of multipath fading and co-channel interference. In the context of BOC signals, these kinds of techniques can be applied to mitigate the impact of the sub-carrier, which is responsible for a multi-peaked ACF, reducing multipath and interference effects. In temporal processing, traditional equalizers in time-domain are useful to compensate for signal distortions. But equalization becomes more challenging in the case of BOC signals, where the effect of both sub-carrier and multipath must be accounted for. On the other hand, by using spatial processing, it should be possible to extract the desired signal component from a set of received signals by electronically varying the antenna array directivity (beamforming).
The combination of an antenna array and a temporal equalizer results in better system performance. Hence the main objective of this research is to apply space-time processing techniques to BOC modulated signals received by an antenna array. The main intent is to enhance the signal quality, avoid ambiguous tracking and improve tracking performance under weak signal environments or in the presence of harsh multipath components.
The focus of previous antenna-array processing using GNSS signals was on enhancing GNSS signal quality and mitigating interference and/or multipath related issues. Unambiguous tracking was not considered. Here, we develop a space-time algorithm to mitigate ambiguous tracking of BOC signals along with improved signal quality. The main objective is to obtain an equalization technique that can operate on BOC signals to provide unambiguous BPSK-like correlation function capable of altering the antenna array beam pattern to improve the signal to interference plus noise ratio.
Space-time adaptive processing structure proposed for BOC signal tracking; the temporal filter provides signal with unambiguous ACF whereas the spatial filter provides enhanced performance with respect to multipath, interference, and noise.
Initially, temporal equalization based on the minimum mean square error (MMSE) technique is considered to obtain unambiguous ACF on individual antenna outputs. Spatial processing is then applied on the correlator outputs based on a modified minimum variance distortionless response (MVDR) approach. As part of spatial processing, online calibration of the real antenna array is performed which also provides signal and noise information for the computation of the beamforming weights. Finally, the signal resulting from temporal and spatial equalization is fed to a common code and carrier tracking loop for further processing.
The effectiveness of the proposed technique is demonstrated by simulating different antenna array structures for BOC signals. Intermediate-frequency (IF) simulations have been performed and linear/planar array structures along with different signal to interference plus noise ratios have been considered. A modified version of The University of Calgary software receiver, GSNRx, has been used to simultaneously process multi-antenna data. Further tests have been performed using real data collected from Galileo test satellites, GIOVE-A and GIOVE-B, using an array structure comprising of two to four antennas. A 4-channel front-end designed in the PLAN group, and a National Instruments (NI) signal vector analyzer equipped with three PXI-5661 front-ends (NI 2006) have been used to collect data synchronously from several antennas. The data collected from the antennas were progressively attenuated for the analysis of the proposed algorithm in weak signal environments.
From the performed tests and analysis, it is observed that the proposed methodology provides unambiguous ACF. Spatial processing is able to efficiently estimate the calibration parameters and steer the antenna array beam towards the direction of arrival of the desired signal. Thus, the proposed methodology can be used for efficient space-time processing of new BOC modulated GNSS signals.
Signal and Systems Model
The complex baseband GNSS signal vector received at the input of an antenna array can be modeled as (1)
where
• M is the number of antenna elements;
• L is the number of satellites;
• C is a M × M calibration matrix capturing the effects of antenna gain/phase mismatch and mutual coupling;
• si = is the complex M × 1 steering vector relative to the signal from the ith satellite. si captures the phase offsets between signals from different antennas;
• is the noise plus interference vector observed by the M antennas.
The ith useful signal component xi (t) can be modeled as (2)
where
• Ai is the received signal amplitude;
• di() models the navigation data bit;
• ci() is the ranging sequence used for spreading the transmitted data;
• τ0,i, f0,i and φ0,imodel the code delay, Doppler frequency and carrier phase introduced by the communication channel.
The index i is used to denote quantities relative to the ith satellite. The ranging code ci() is made up of several components including a primary spreading sequence, a secondary code and a sub-carrier.
For a BPSK modulated signal, the sub-carrier is a rectangular window of duration Tc. In the case of BOC modulated signals, the sub-carrier is generated as the sign of a sinusoidal carrier. The presence of this sub-carrier produces a multi-peaked autocorrelation function making the acquisition/tracking processes ambiguous.
In order to extract signal parameters such as code delay and Doppler frequency of the ith useful signal xi(t), the incoming signal is correlated with a locally generated replica of the incoming code and carrier. This process is referred to as correlation where the carrier of the incoming signal is at first wiped off using a local complex carrier replica. The spreading code is also wiped off using a ranging code generator. The signal obtained after carrier and code removal is integrated and dumped over T seconds to provide correlator outputs. The correlator output for the hth satellite and mth antenna can be modeled as: (3)
where vm,kare the coefficients of the calibration matrix, C and R(Δτh) is the multi-peaked ACF. τh, fD,h and φh are the code delay, Doppler frequency and carrier phase estimated by the receiver and Δτh, ΔfD,h and Δφh are the residual delay, frequency, and phase errors. is the residual noise term obtained from the processing of η(t). Eq. (3) is the basic signal model that will be used for the development of a space-time technique suitable for unambiguous BOC tracking.
When BOC signals are considered, algorithms should be developed to reduce the impact of that include receiver noise, interference and multipath components, along with the mitigation of ambiguities in R(Δτh). Space-time processing techniques have the potential to fulfill those requirements.
Space-Time Processing
A simplified representation of a typical space-time processing structure is provided in Figure 1. Each antenna element is followed by K taps with δ denoting the time delay between successive taps forming the temporal filter. The combination of several antennas forms the spatial filter. wmk are the space-time weights with 0 ≤ k ≤ K and 0 ≤ m ≤ M. k is the temporal index and m is the antenna index.
Figure 1. Block diagram of space-time processing.
The array output after applying the space-time filter can be expressed as (4)
where (wmk)* denotes complex conjugate. The spatial-only filter can be realized by setting K=1 and a temporal only filter is obtained when M=1. The weights are updated depending on the signal/channel characteristics subject to user-defined constraints using different adaptive techniques. This kind of processing is often referred to as Space-Time Adaptive Processing (STAP). The success of STAP techniques has been well demonstrated in radar, airborne and mobile communication systems. This has led to the application of STAP techniques in the field of GNSS signal processing. Several STAP techniques have been developed for improving the performance of GNSS signal processing. These techniques exploit the advantages of STAP to minimize the effect of multipath and interference along with improving the overall signal quality.
Space-time processing algorithms can be broadly classified into two categories: decoupled and joint space-time processing. The joint space-time approach exploits both spatial and temporal characteristics of the incoming signal in a single space-time filter while the decoupled approach involves several temporal equalizers and a spatial beamformer that are realized in two separate stages (Figure 2).
Figure 2. Representation of two different space-time processing techniques
When considering the decoupled approach for GNSS signals, temporal filters can be applied on the data from the different antennas whereas the spatial filter can be applied at two different stages, namely pre-correlation or post-correlation. In the pre-correlation stage, spatial weights are applied on the incoming signal after carrier wipe-off while in the post-correlation stage, spatial weights are applied after the Integrate & Dump (I&D) block on the correlator outputs. In pre-correlation processing, the update rate of the weight vector is in the order of MHz (same as the sampling frequency) whereas the post-correlation processing has the advantage of lower update rates in the order of kHz (I&D frequency). In the pre-correlation case, the interference and noise components prevail significantly in the spatial correlation matrix and would result in efficient interference mitigation and noise reduction. But the information on direct and reflected signals are unavailable since the GNSS signals are well below the noise level. This information can be extracted using post-correlation processing.
In the context of new GNSS signals, efforts to utilize multi-antenna array to enhance signal quality along with interference and multipath mitigation have been documented using both joint and decoupled approaches where the problem of ambiguous signal tracking was not considered.
In our research, we considered the decoupled space-time processing structure. Temporal processing is applied at each antenna output and spatial processing is applied at the post-correlation stage. Temporal processing based on MMSE equalization and spatial processing based on the adaptive MVDR beamformer are considered.
Methodology
The opening figure shows the proposed STAP architecture for BOC signal tracking. In this approach, the incoming BOC signals are at first processed using a temporal equalizer that produces a signal with a BPSK-like spectrum. The filtered spectra from several antennas are then combined using a spatial beamformer that produces maximum gain at the desired signal direction of arrival. The beamformed signal is then fed to the code and carrier lock loops for further processing. The transfer function of the temporal filter is obtained by minimizing the error: (5)
where H(f) is the transfer function of the temporal filter that minimizes the MSE, εMMSES, between the desired spectrum, GD(f), and filtered spectrum, Gx(f)H(f). The spectrum of the incoming BOC signal is denoted by Gx(f). λ is a weighting factor determining the impact of noise with respect to that of an ambiguous correlation function. N0 is the noise power spectral density and C the carrier power. The desired spectrum is considered to be a BPSK spectrum. Since this type of processing minimizes the MSE, it is denoted MMSE Shaping (MMSES).
Figure 3 shows a sample plot of the ACF obtained after applying MMSES on live Galileo BOCs(1,1) signals collected from the GIOVE-B satellite. The input C/N0 was equal to 40 dB-Hz and the ACF was averaged over 1 second of data. It can be observed
that the multi-peaked ACF was successfully modified by MMSES to produce a BPSK-like ACF without secondary peaks. Also narrow ACF were obtained by modifying the filter design for improved multipath mitigation. Thus using temporal processing, the antenna array data are devoid of ambiguity due to the presence of the sub-carrier.
After temporal equalization, the spatial weights are computed and updated based on the following information:
The signal and noise covariance matrix obtained from the correlator outputs;
Calibration parameters estimated to minimize the effect of mutual coupling and antenna gain/phase mismatch;
Satellite data decoded from the ephemeris/almanac containing information on the GNSS signal DoA.
The weights are updated using the iterative approach for the MVDR beamformer to maximize the signal quality according to the following steps:
Step 1: Update the estimate of the steering vector for the hthsatellite using the calibration parameters as: (6)
Here vi,j represents the estimated calibration parameters using the correlator outputs given by Eq. (3) and shm is the element of the steering vector computed using the satellite ephemeris/almanac data.
Step 2: Update the weight vector (the temporal index, k, is removed for ease of notation) using the new estimate of the covariance matrix and steering vector as (7)
where is the input signal after carrier wipe-off.
Repeat Steps 1 and 2 until the weights converge. Finally compute the correlator output to drive the code and carrier tracking loop according to Equation (4).
The C/N0 gain obtained after performing calibration and beamforming on a two-antenna linear array and four-antenna planar array data collected using the four channel front-end is provided in Figure 4 and Figure 5. The C/N0 plots are characterized by three regions:
Single Antenna that provides C/N0 estimates obtained using q0,h alone;
BeforeCalibration that provides C/N0 estimates obtained by compensating only the effects of the steering vector, si, before combining the correlator outputs from all antennas;
AfterCalibration that provides C/N0 estimates obtained by compensating the effects of both steering vector, si and calibration matrix, C, before combining correlator outputs from all antennas.
After calibration, beamforming provides approximately a C/N0 gain equal to the theoretical one on most of the satellites whereas before calibration, the gain is minimal and, in some cases, negative with respect to the single antenna case. These results support the effectiveness of the adopted calibration algorithm and the proposed methodology that enables efficient beamforming.
Figure 4. C/N0 estimates obtained after performing calibration and beamforming on linear array data.Figure 5. C/N0 estimates obtained after performing calibration and beamforming on the planar array data.
Results and Analysis
IF simulated BOCs(1,1) signals for a 4-element planar array with array spacing equal to half the wavelength of the incoming signal has been considered to analyze the proposed algorithm. The input signal was characterized by a C/N0 equal to 42 dB-Hz at an angle of arrival of 20° elevation and 315° azimuth angle.
A sample plot of the antenna array pattern using the spatial beamformer is shown in Figure 6. In the upper part of Figure 6, the ideal case in the absence of interference was considered. The algorithm is able to place a maximum of the array factor in correspondence of the signal DoA.
Figure 6. Antenna array pattern for a 4-element planar array computed using a MVDR beamformer in the presence of two interference sources.
In the bottom part, results in the presence of interference are shown. Two interference signals were introduced at 60 and 45 degree elevation angles. It can be clearly observed that, in the presence of interference, the MVDR beamformer successfully adapted the array beam pattern to place nulls in the interference DoA.
In order to further test the tracking capabilities of the full system, semi-analytic simulations were performed for the analysis of digital tracking loops. The simulation scheme is shown in Figure 7 and consists of M antenna elements. Each antenna input for the hth satellite is defined by a code delay (τm,h) and a carrier phase value (φm,h) for DLL and PLL analysis. φm,h captures the effect of mutual coupling, antenna phase mismatch and phase effects due to different antenna hardware paths. To analyze the post-correlation processing structure, each antenna input is processed independently to obtain the error signal, Δτm,h / Δφm,h as where are the current delay/phase estimates.
Figure 7. Semi-analytic simulation model for a multi-antenna system comprising M antennas with a spatial beamformer.
Each error signal is then used to obtain the signal components that are added along with the independent noise components, . The combined signal and noise components from all antenna elements are fed to the spatial beamformer to produce a single output according to the algorithm described in the Methodology section. Finally, the beamformer output is passed through the loop discriminator, filter and NCO to provide a new estimate . The Error to Signal mapping block and the noise generation process accounts for the impact of temporal filtering.
Figure 8 shows sample tracking jitter plots for a PLL with a single, dual and three-antenna array system obtained using the structure described above.
Figure 8. Phase-tracking jitter obtained for single, dual and three-antenna linear array as a function of the input C/N0 for a Costas discriminator (20 milliseconds coherent integration and 5-Hz bandwidth).
The number of simulation runs considered was 50000 with a coherent integration time of 20 ms and a PLL bandwidth equal to 5 Hz. As expected the tracking jitter improves when the number of antenna elements is increased along with improved tracking sensitivity. As expected, the C/N0 values at which loss of lock occurs for a three antenna system is reduced with respect to the single antenna system, showing its superiority.
Real data analysis. Figure 9 shows the experimental setup considered for analysis of the proposed combined space-time algorithm. Two antennas spaced 8.48 centimeters apart were used to form a 2-element linear antenna array structure. The NI front-end was employed for the data collection process to synchronously collect data from the two-antenna system.
Data on both channels were progressively attenuated by 1 dB every 10 seconds to simulate a weak signal environment until an attenuation of 20 dB was reached. When this level of attenuation was reached, the data were attenuated by 1 dB every 20 seconds to allow for longer processing under weak signal conditions. In this way, data on both antennas were attenuated simultaneously. Data from Antenna 1 were passed through a splitter, as shown in Figure 9, before being attenuated in order to collect signals used to produce reference code delay and carrier Doppler frequencies.
Figure 9. Experimental setup with signals collected using two antennas spaced 8.48 centimeters apart.
BOCs(1,1) signals collected using Figure 9 were tracked using the temporal and spatial processing technique described in the opening figure. The C/N0 results obtained using single and two antennas are provided in Figure 10. In the single antenna case, only temporal processing was used. In this case, the loop was able to track signals for an approximate C/N0 of 19 dB-Hz. Using the space-time processing, the dual antenna system was able to track for nearly 40 seconds longer than the single antenna case, thus providing around 2 dB improvement in tracking sensitivity.
Figure 10. C/N0 estimates obtained using a single antenna, temporal only processing and a dual-antenna array system using space-time processing.
Conclusions
A combined space-time technique for the processing of new GNSS signals including a temporal filter at the output of each antenna, a calibration algorithm and a spatial beamformer has been developed. The proposed methodology has been tested with simulations and real data. It was observed that the proposed methodology was able to provide unambiguous tracking after applying the temporal filter and enhance the signal quality after applying a spatial beamformer. The effectiveness of the proposed algorithm to provide maximum signal gain in the presence of several interference sources was shown using simulated data. C/N0 analysis for real data collected using a dual antenna array showed the effectiveness of combined space-time processing in attenuated signal environments providing a 2 dB improvement in tracking sensitivity.
Pratibha B. Anantharamu received her doctoral degree from Department of Geomatics Engineering, University of Calgary, Canada. She is a senior systems engineer at Accord Software & Systems Pvt. Ltd., India.
Daniele Borio received a doctoral degree in electrical engineering from Politecnico di Torino. He is a post-doctoral fellow at the Joint Research Centre of the European Commission.
Gérard Lachapelle holds a Canada Research Chair in Wireless Location in the Department of Geomatics Engineering, University of Calgary, where he heads the Position, Location, and Navigation (PLAN) Group.
PORTLAND, Oregon — Spectracom announced at the ION-GNSS conference the introduction of new capabilities for its GSG line of GPS GNSS constellation simulators. These features reinforce Spectracom’s offerings for flexible, user-friendly, and affordable characterization and test of GPS and GNSS devices and systems. Key features include:
GLONASS+GPS capability: the first in a line of GNSS simulators to simultaneously reproduce multiple GNSS signals, in accurate synchronization, for testing the latest multi-constellation receivers.
The introduction of GSG StudioView PC software to provide easy creation and editing of simulation scenarios including a Google Maps-based trajectory builder.
The ability to support very high velocity and acceleration simulations for aerospace applications.
A web browser interface for easy remote control and monitoring of the simulator.
Designed with development and test engineers in mind, the GSG-54 8-channel simulator and GSG-55 16-channel simulator support quick and efficient qualification of designs and performance under virtually any condition unlike live-sky or record-and-replay solutions, Spectracom said. Together with the simplicity, portability, and repeatability, users can run more tests, and extend the test set-up into manufacturing and final test environments.
“As the integration of GPS receivers continue to proliferate in a wide range of devices, engineers need efficient and practical solutions to qualify the robustness of their designs and final assembled products. We understand the importance value plays in GPS and GNSS test solutions and are excited to introduce the ability to readily test complex scenarios at a price under $20K,” said Spectracom chief technical officer John Fischer.
As a part of Spectracom’s focus on supporting fast and efficient test operations, the company also announced GSG StudioView PC software. In addition to Spectracom’s GSG simulators capability of configuration and operation without the need for an external computer, GSG StudioView allows users to build and manage complex simulation scenarios including visual trajectories. It also supports the import and conversion of trajectory files from other software applications and devices such as Google Earth.
Spectracom also announced the new model GSG-56 GNSS constellation simulator with support for GPS and GLONASS receivers. “We understand the importance of the industry trend to augment GPS and ensure a high degree of reliability and affordability of new products and services that depend on new GNSS constellations,” said Lisa Withers, Spectracom president and CEO. “Toward that end, we believe our newly expanded line of simulators will stand up to these challenges and with the new GSG-56 provide easy access to test multiple GNSS receivers.” Availability of the GSG-56 is slated for the first quarter of 2012.
The ION-GNSS conference runs September 21-23 at the Portland Convention Center. Spectracom is exhibiting with its sister company, SpectraTime, in booth #718.
Assembly of the three-stage Soyuz takes place. The Soyuz will carry the first two Galileo satellites into orbit. (Photo courtesy of ESA.)
The first Soyuz flight from Europe’s Spaceport in French Guiana will carry the first two satellites of Europe’s Galileo navigation system into orbit on October 20, and the European Space Agency is reporting on the preparations.
On September 12, final assembly began on the three-stage Soyuz ST-B, consisting of four first-stage boosters clustered around the core second stage, topped off by the third stage. The Launcher Flight Readiness Review in July gave the green light to begin assembling the rocket.
The campaign began on August 16 in the assembly and testing building — known by its original "MIK" Russian acronym — with electrical and mechanical tests of the upgraded, reignitable Fregat-MT upper stage. It will carry an additional 900 kg of propellants for its double-satellite load. Fregat was then moved to the Payload Preparation Building S3B to fill its four spherical propellant tanks.
Soyuz will be rolled out horizontally to the launch pad on October 14 and raised into its vertical launch position. A new 45-meter-tall mobile gantry was built specifically for Soyuz operations in French Guiana. It protects the satellites and the launcher from the humid tropical environment and provides access to the Soyuz at various levels for checkout activities. The upper composite, comprising the Fregat upper stage, payload and fairing, is then hoisted on top of Soyuz.
October’s launch will be doubly historic: the first Soyuz from a spaceport outside of Baikonur in Kazakhstan or Plesetsk in Russia and the start of building Europe’s Galileo satnav constellation. The two Galileo satellites have arrived from the Rome facility of Thales Alenia Space Italy — the first on September 7, the second on September 14 — and are undergoing initial preparations.
The next step will be to attach the satellites to Fregat, followed by the fairing.
Next year, the second pair of satellites will join them in orbit, proving the design of the Galileo system in advance of the other 26 satellites. These first four satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo satnav constellation. They combine the best atomic clock ever flown for navigation — accurate to one second in three million years — with a powerful transmitter to broadcast precise navigation data worldwide, ESA reports.
The first Soyuz to take off from Europe’s Spaceport in French Guiana was moved to the launch pad October 14. The rocket that will carry the first two Galileo navigation satellites into orbit is on track for liftoff on October 20, reports the European Space Agency (ESA). 
