The GPS program continues progress on several fronts — in space and on the ground.

During fall 2010, the U.S. Air Force and the Raytheon Company team developing the GPS Advanced Control Segment (OCX) successfully carried out an integrated baseline review (IBR) for the next-generation system on schedule.

When completed in 2015 under the current schedule, GPS OCX will deliver control segment enhancements designed to provide secure, accurate and reliable navigation and timing information to military, commercial and civil users.

The GPS program continues progress on several fronts — in space and on the ground.

During fall 2010, the U.S. Air Force and the Raytheon Company team developing the GPS Advanced Control Segment (OCX) successfully carried out an integrated baseline review (IBR) for the next-generation system on schedule.

When completed in 2015 under the current schedule, GPS OCX will deliver control segment enhancements designed to provide secure, accurate and reliable navigation and timing information to military, commercial and civil users.

Raytheon’s Intelligence and Information Systems (IIS) business, with facilities in Aurora, Colorado, is the prime contractor on the $886 million program.
The team includes ITT, The Boeing Company, Infinity Systems Engineering, Braxton Technologies and NASA’s Jet Propulsion Laboratory.

The contract represents the first two development blocks of the advanced control segment, which will have a significant effect on GPS capabilities. The OCX system will include anti-jam capabilities and improved security, accuracy and reliability and will be based on a modern service-oriented architecture to integrate government and industry open-system standards.

Lockheed Martin Ships Simulator
The Aerospace Corporation has completed acceptance testing on the GPS III Bus Real Time Simulator (BRTS) from the Lockheed Martin–led team developing the next-generation satellite program, keeping the initiative ahead of schedule.

The BRTS is a specialized piece of test equipment designed to reduce risk and ensure overall mission success for the lifecycle of the GPS III program. The simulator will enable Aerospace Corporation to independently validate GPS III bus flight software for the U.S. Air Force.

Lockheed Martin shipped the BRTS from its Newtown, Pennsylvania, facility to Aerospace’s, El Segundo, California, on September 10. Acceptance testing for the BRTS was completed seven days later.

The Lockheed Martin team recently completed the GPS III critical design review two months ahead of schedule and is now proceeding rapidly in the program’s manufacturing phase. The first launch of a GPS III satellite, which will provide significant improvements over current satellites, is scheduled for 2014 from Cape Canaveral Air Force Station, Florida.

Government Accountability Office on GPS (Again)
A new report on the GPS program from the Government Accountability Office (GAO) finds the situation considerably improved from last year, when its prediction of a significant risk of the satellite constellation falling below 24 satellites set off alarms in Congress and among the user community.

However, the agency once again finds reason for concern about the prospects for the system. These primarily have to do with the unknowns associated with new generations of spacecraft (Block IIF and Block III), the need to improve Department of Defense (DoD) oversight and U.S. Air Force procurement of GPS resources, interagency coordination of civil and military user requirements, and questions about the timing of GPS III launches and completion of the next-generation ground control system (OCX) needed to support them.

A reduced number of launch facilities and a crowded launch manifest in the near future represent other risk factors, according to the GAO report.

Cristina Chaplain, GAO director of acquisition and sourcing management, outlined the agency’s concerns in a letter to John F. Tierney, chairman, and Jeff Flake ranking Republican member of the Subcommittee on National Security and Foreign Affairs, House Committee on Oversight and Government Reform.
“Since our prior report,” Chaplain wrote, “we found that the GPS IIIA program appears to have furthered its implementation of the ‘back to basics’ approach to avoid repeating the mistakes of GPS IIF and that it has passed a key design milestone [the critical design review in August 2010]. More specifically, the program has maintained stable requirements, has used mature technologies, and is providing more oversight than under the IIF program.”

The Air Force now predicts that the probability of maintaining a constellation of at least 24 operational satellites will remain above 95 percent for the foreseeable future—through at least 2025, the date that the final GPS III satellite is expected to become operational.

Despite these efforts to develop a stable and successful program, however, the GAO noted that the GPS IIIA program faces challenges to launching its satellites on schedule, with an agreesive schedule and a need to compete for limited launch resources.

GAO also pointed out that the current schedules for GPS IIIA and OCX have the first launch of a IIIA satellite taking place in early 2014, nearly two years before the fourth quarter of Fiscal Year 2015 (FY2015) scheduled completion of the OCX needed to control them.

In written responses to questions regarding constellation sustainment raised by the GAO report, the GPS Wing (GPSW) said, “From a constellation perspective, there is no compelling need for us to launch the next IIF satellite prior to fiscal year 2012. However, GPSW continues processing IIF SV-2 and we are following a plan to launch by summer 2011.”

Moreover, the GPS Wing response added, recent longer-term analyses of the GPS constellation by the Aerospace Corporation and Air Force Space Command (AFSPC) indicate that “we have considerable margin before we absolutely MUST launch the first GPS IIIA satellite.”

Goodbye, GPS Wing; Hello, GPS Directorate
The U.S. Air Force inactivated its GPS Wing at Los Angeles Air Force Base on on November 10 and replaced it with the Global Positioning Systems Directorate.

Reflecting mostly the taxonomy and naming conventions of military commands and organization, the new designation is expected to bring little change in the new organization’s leadership or scope of responsibilities, although the organization will no longer have headquarters status.

Air Force Groups will become Divisions and Squadrons, Branches. Col. Bernard Gruber, director of the GPS Wing, will continue as director of the GPS Directorate.

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1996 soccer game in the Midwest, (Rick Dikeman image)

Nouméa ground station after the flood

A pencil and a coffee cup show the size of NASA’s teeny tiny PhoneSat

Bonus Hotspot: Naro Tartaruga AUV

Pacific lamprey spawning (photo by Jeremy Monroe, Fresh Waters Illustrated)

“Return of the Bucentaurn to the Molo on Ascension Day”, by (Giovanni Antonio Canal) Canaletto

The U.S. Naval Observatory Alternate Master Clock at 2nd Space Operations Squadron, Schriever AFB in Colorado. This photo was taken in January, 2006 during the addition of a leap second. The USNO master clocks control GPS timing. They are accurate to within one second every 20 million years (Satellites are so picky! Humans, on the other hand, just want to know if we’re too late for lunch) USAF photo by A1C Jason Ridder.

Detail of Compass/ BeiDou2 system diagram

Hotspot 6: Beluga A300 600ST

1. STORMY WEATHER
Belgium and Brazil

1. STORMY WEATHER
Belgium and Brazil
√ On the road to solar max in 2013, equatorial countries are at highest risk. Ionospheric density and low latitude storms cause GPS and WAAS signals to fade or fail altogether. Brazil’s GNSS-dependent surveying and offshore drilling could take a hit. European GNSS Agency (GSA) and Brazilian interests funded the CIGALA Consortium, led by Belgium’s Septentrio, to suggest receiver scintillation countermeasures.

2. BAD RECEIVERS
Warsaw, Poland and Afghanistan
√ A November 8 story on military procurement corruption by Polish newspaper Gazeta Wyborcza said GPS receivers used by the 2,600-member International Security Assistance Force in Afghanistan came up with sites in Africa and Poland instead of the in-country location. Field trials exposed these and other major defects, but the army bought them from Hertz Systems anyway.

3. EDGING FORWARD. . .
Oberpfaffenhofen, Germany and Fucino, Italy
√ In late October, SpaceOpal secured a US$270 million (€194million) contract for the Galileo ground control and monitoring segment, run from centers in Oberpfaffenhofen and Fucino. It is a German-Italian joint venture between Gesellschaft für Raumfahrtanwendungen (GfR) and Telespazio S.p.A. One hesitates to further embarrass the European GNSS by publishing dates, but here goes: initial deployment by 2014.

4. MILITARY SIGNALS
Moscow, Russia and New Dehli, India
√ Russia will give India access to real-time military signals from GLONASS, according to an October 26 story in India’s Business Standard. The Russian GNSS will be used in the jointly developed Fifth Generation Fighter Aircraft. With the signal, India gets instant troop and terrain location and communication. Expected delivery of the FGFA: 2016.

5. DUELING LAUNCHES
Baikonur space center, Kazakhstan and Xichang space center, China
√ Crisp December weather promises new GNSS satellites. The fifth Compass/BeiDou satellite this year — and the second IGSO spacecraft — will take off from Xichang launch center on board a Long March rocket (CZ-3A Chang Zheng-3A) and will cover high latitude and polar regions. On December 5, Russia plans to send into orbit the third set of three GLONASS-M satellites since 2010 began, completing the constellation. The first GLONASS-K 1may fly on December 24 — a nice holiday gift.

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Q: What is the difference between SNR and C/N₀?

A: GPS receivers built for various applications, such as handhelds, automobiles, mobile phones, and avionics, all have a method for indicating the signal strength of the different satellites they are tracking. Some receivers display the signal strength in the form of vertical bars, some in terms of normalized signal strength, and others in terms of carrier-to-noise density (C/N₀) or signal-to-noise ratio (SNR).

The latter two terms are regularly used so interchangeably that their fundamental differences are often overlooked. A full understanding of the differences between SNR and C/N₀ is useful both for users of GPS receivers and for GPS receiver designers and testers.

SNR and C/N₀
SNR is usually expressed in terms of decibels. It refers to the ratio of the signal power and noise power in a given bandwidth.

SNR(dB) = S  – N

S is the signal power, usually the carrier power expressed in units of decibel/milliwatt (dBm) or decibel/watts (dBW);
N is the noise power in a given bandwidth in units of dBm or dBW.

C/N₀, on the other hand, is usually expressed in decibel-Hertz (dB-Hz) and refers to the ratio of the carrier power and the noise power per unit bandwidth.

For the GPS L1 C/A signal, one can consider the received signal power as the power of the original unmodulated carrier power (at the point of reception in a receiver) that has been spread by the spreading (ranging) codes when transmitted from a satellite. We can express C/N₀ as follows:

C/N₀ (dB-Hz) = C – (N – BW) = C – N₀ = SNR + BW

where:

C is the carrier power in dBm or dBW;
N is the noise power in dBm or dBW;
N₀ is the noise power density in dBm-Hz or dBW-Hz;
BW is the bandwidth of observation, which is usually the noise equivalent bandwidth of the last filter stage in a receiver’s RF front-end.

Typical values in an L1 C/A code receiver are as follows:

C/N₀: ~ 37 to 45dB-Hz

Receiver front-end bandwidth: ~ 4MHz => BW = 10*log (4,000,000) = 66dB
SNR = C/N₀ – BW => SNR ~ (37 – 66) to (45 – 66) => SNR ~ -29dB to -21dB

In order to determine C/N₀, then, one clearly needs to determine the carrier power and noise density at the input to the receiver.

Noise and Signal Power
The sources of white noise in a GNSS receiver are usually described by the antenna noise temperature and the receiver noise temperature. The antenna temperature models the noise entering the antenna from the sky whereas the receiver noise temperature models the thermal noise due to the motion of charges within a device such as the GPS receiver front-end. These noise sources specify the noise density.

. . .

Signal and Noise Paths from Antenna to Receiver
. . . When considering signal and noise paths through the front-end, one needs to consider the noise figure of the various components in the front-end. The noise figure is given as

NF = SNR_in / SNR_out

and provides an estimate of the amount of noise added by an active component, such as a low-noise amplifier (LNA), or even a passive component, such as a filter or the cable.

. . .

Taking into consideration the noise environment and the receiver front-end components, the C/N₀ of a particular tracked satellite will scale relative to the signal power. The signal power of the various satellites being tracked by the receiver will vary in relation to the satellite elevation angle due to differences in path loss and the satellite and receiver antennas’ gain patterns. So, for example, if the signal power varies ±4dB of the nominal signal power of -158.5dBW, the corresponding C/N₀ will vary from 38.5dB-Hz to 46.5dB-Hz.

Interpretation and Significance of C/N₀
From our discussions thus far, the C/N₀ output by a receiver clearly provides an indication of the signal power of the tracked satellite and the noise density as seen by the receiver’s front-end.

Two different GPS receivers connected to the same antenna and tracking the same GPS satellite at the same time may output different C/N₀ values. If one assumes that the C/N₀ values are computed accurately by both the receivers, the differences in the C/N₀ values can be attributed to differences in the noise figure of the two front-ends and/or the receivers’ respective band-limiting and quantization schemes.

. . .

Receiver Acquisition, Processing Blocks, and SNR
The signal-to-noise ratio is most useful when considered within the baseband processing blocks of a GNSS receiver. In dealing with SNR, the bandwidth of interest needs to be specified. Typically the noise equivalent bandwidth is used, which is defined as the bandwidth of an ideal (i.e., brick-wall) filter whose bandwidth when multiplied by the white noise density of N₀/2 will result in the total noise power at the output of the original filter.

. . .

The improvement in SNR as the result of a longer integration occurs because of the reduction in the noise equivalent bandwidth. Note that the performance of the PLL and FLL in the presence of thermal noise is further affected by the bandwidths of the respective loops themselves. The integration time in this case establishes the input SNR and the loop update time for the respective loops.

Interpretation and Significance of SNR
As we have seen, the SNR in a GPS receiver depends on the receiver’s front-end bandwidth, acquisition, and tracking parameters. Referencing just the SNR value in a GPS receiver does not usually make sense unless one also specifies the bandwidth and processing stage within the receiver.

The SNR is very useful when evaluating the performance of the acquisition and tracking stages in a receiver. For example, when performing Monte Carlo simulations, the SNR needs to be determined at the various stages of the signal processing chain to properly simulate the receiver. In simulations the required C/N₀ needs to be first converted to an SNR from which the appropriate noise variance can be readily determined.

Furthermore, the SNR is an indication of the level of noise present in the measurement, whereas C/N₀ alone does not provide this information.

In conclusion, we can see that both the C/N₀ and SNR are useful quantities that can be used when designing, evaluating or verifying the performance of a GPS receiver. However the use of one quantity over the other very much depends upon the context and the purpose for which the signal quality measurement is being made or is to be used for and this should be carefully considered when choosing between the two.

(For Angelo Joseph’s complete answer to this question, including formulas and tables, please download the full article using the pdf link above.)

Additional Resources
For information on how C/N₀ is computed within a GNSS receiver, refer to the GNSS Solutions columns by B. Badke (InsideGNSS, September/October 2009) and E. Falletti et alia (January/February 2010).

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Return to main article: Military PNT — The Way Ahead

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In 1966 D.B. Leeson proposed an empirical linear model for the noise spectrum of an oscillator, which has been extensively cited in the  literature since then. G. Sauvage generalized this model to other resonant circuits in 1977, providing a deeper mathematical background. In 1998 A. Hajimiri and T.H. Lee proposed a linear time variant model (LTV) to explain the effect of each of the noise sources of an oscillator on its phase noise.

Return to main article: Local Oscillator Phase Noise

In 1966 D.B. Leeson proposed an empirical linear model for the noise spectrum of an oscillator, which has been extensively cited in the  literature since then. G. Sauvage generalized this model to other resonant circuits in 1977, providing a deeper mathematical background. In 1998 A. Hajimiri and T.H. Lee proposed a linear time variant model (LTV) to explain the effect of each of the noise sources of an oscillator on its phase noise.

Phase noise models for various wireless communication receivers have been proposed by T. Schenk (2006) (For the complete citations of this and other references, please see the Additional Resources section near the end of the main article.) The article by D. Petrovic et alia uses orthogonal frequency division multiplexing (OFDM) systems for modeling noise, while A. Demir et alia (2000) developed extensive and generic theory for phase noise models. In a 2002 article, Demir extended this theory to jitter in optical and wireless communications, and K. Kundert also developed a jitter measurement for phase noise effects on phase locked loops.

A simulation-based study of phase noise introduced by the receiver and the satellite payload was discussed by E. Rebeyrol et alia in 2006. Deriving the phase noise power spectral densities, frequency comparisons are made, but correlation losses or effects on the code tracking loop at the receiver were not included. M. Irsigler and B. Eissfeller discuss the impact of oscillator phase noise on the performance of the PLL tracking in their 2002 article, while modeling theoretical results, but they draw no conclusions regarding the phase noise requirements of the oscillator. Their analysis focused on classification of the phase noise sources and types and on the phase lock loop tracking performance at fixed phase noise random vibrations and Allan deviations.

In 2010, M. Petovello et alia discuss the effect of residual phase noise in the carrier tracking loop on the performance of C/N₀ estimation algorithms, but do not identify the effect on the code tracking loop. A. Demir et alia (2006) provides a thorough analysis of the spectral characteristics of phase noise. In 2010 Schenk demonstrated that is a stationary random variable defined for a free running local oscillator whose power spectral density (PSD), P_x(f), as given in Equation 2 in the main article.

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SIDEBAR: Frank Czopek’s Compass Points

Frank Czopek and his brothers used to go to the 1970s Detroit version of Craigslist — Trading Times — to buy two or three non-functioning Chevrolet Corvairs (air-cooled rear engine-mounted) cars, at $25 apiece.

They hoped to turn the junkers into a single functioning automobile over a weekend. Unfortunately, the results did not last long; so, the process was repeated often. But they sure had fun!

SIDEBAR: Frank Czopek’s Compass Points

Frank Czopek and his brothers used to go to the 1970s Detroit version of Craigslist — Trading Times — to buy two or three non-functioning Chevrolet Corvairs (air-cooled rear engine-mounted) cars, at $25 apiece.

They hoped to turn the junkers into a single functioning automobile over a weekend. Unfortunately, the results did not last long; so, the process was repeated often. But they sure had fun!

In all, Czopek estimates that at least 33 cars made it through the family’s backyard assembly line. 

When not working on cars, Czopek attended a boarding school, St. Mary’s Preparatory, where two events transpired that helped define his future. Because the school food was not much to his liking, he soon developed a love for McDonald’s Big Mac hamburgers — a taste that has followed him through life.

The second event occurred his junior year, when math teacher Calvin Cathers discerned in Czopek an aptitude for math that had, up till then, never been evident. At the end of the school year, he made a recommendation that stuck with Czopek.

“Your math skills are very good, and you should go into engineering,” Cathers told him.

Today, that kid-from-the-neighborhood enthusiasm (and the humility born of constant experimentation) still lives in Czopek’s optimistic, exuberant manner.

It’s carried him through a career entwined with all aspects of the GPS Block II satellites (cesium clocks, and navigation and L-band payloads), to the early design efforts on the IIF navigation payload.

It culminated with 11 years as the program manager for the Boeing’s GPS Block II/IIA support contract and, today, his participation on the GPS Block IIF team that sent up its first satellite last spring.

Czopek’s acquaintance with the GPS satellites started in 1984 when few people knew about GNSS technology. At the time, he was working with another manufacturer of defense equipment.Wanting to show a family friend how easy it was to find employment in southern California, Czopek took her to a Rockwell International engineering job fair in Seal Beach.

In no time, Czopek found himself answering questions about his space mechanical design, digital, and assembly language skills. The manager sitting next to his interviewer leaned over and said, “I want him!”

Shortly thereafter, Czopek got two job offers. One, from his employer at the time, involved extreme weather testing in Alaska for an armored vehicle program on which he was working. The other came from Rockwell. With the latter offer, he’d get to use digital equipment that took advantage of his experience in assembly language programming and his mechanical background on a new United States space program called GPS.

Easy decision, he said.

Turns out, the manager from the interview was in charge of the Block II/IIA payload, and he became Czopek’s first boss on GPS.

But First, This Flashback
A lot happened in between Czopek ‘s Motor City adventures and the advent of the operational GPS constellation.

As a kid, Czopek remembers watching Walter Cronkite’s enthusiastic television coverage of the GEMINI launches, NASA’s human spaceflight program of 1965 and 1966. A meticulous German mechanical engineer named Günter Wendt, famous for his engineering rigor, oversaw the closure of each space capsule and was the last guy to see each astronaut. Czopek thought that looked pretty interesting.

This was one of the influences that inspired him to pursue mechanical engineering in college, and in 1980 he received a bachelor of science degree from Michigan Technological University (MTU). Located in Houghton on Michigan’s Upper Peninsula, MTU was known for cold winters and tight connections to Detroit, the center of the then-dominant U.S. auto industry.

But Czopek knew he wanted to do something other than cars. With the excitement of those early launches in mind, he set his sights on space. After interviewing with an MTU alumna at TRW Inc., developers of the first ICBM and parent company of many aerospace and automotive parts corporations, Czopek was easily lured west to sunny southern California in 1980 for a job with Boeing, then called Hughes Aircraft.

He didn’t come alone. At MTU, Czopek had met a girl. And one day, while he sat on top of a washing machine waiting for the spin cycle to finish, she offered him a Big Mac. One thing led to another, and Czopek married Jeanine Bowman in 1982.

In California, Czopek started as a mechanical designer on space hardware but became interested in the possibility of computers controlling systems (such as heating and lights) in homes, a field that spilled over into the early days of embedded software programming.

In one of his first jobs, Czopek needed to create an acceptance test for a tank’s ammunition magazine. He decided to use Assembly Language to use the math routines needed to calculate running torque but was limited to only a one-bit processor, which required him to learn Boolean math and Karnaugh maps.

Along the way, he also learned how to design and interface with the 10-horsepower motors, shaft encoders, and control systems — also with a one-bit processor. These skills required the ability to synchronize timing between several concurrent processes, which brought his resume to the attention of Rockwell’s Space Systems Division at that fateful job fair.

Block II: Making It Happen
When Czopek made the move to Rockwell in 1984, he became a member of the company’s GPS Block II payload system engineering team. At the time, the Block II qualification satellite was in the middle of testing, and the first hardware for the Block II production program was being built.

The schedule supporting the first launch in 1986 aboard the space shuttle was aggressive and included a vigorous production rate of seven satellites per year. Czopek remembers juggling three satellite configurations between two different cost structures.

“While the Block II satellites in production required fewer functions than the GPS 12 (qualification) vehicle, we added more functions to Block IIA satellites later in the production line,” he said.

Challenges and opportunities appeared everywhere. Czopek’s team worked all aspects of the design, from the test floor to the unit vendors and segment interfaces, to figure out if the satellites performed as required by the interface, and if they did not, what had to change to make sure the system could meet user expectations.

Up until that time, Czopek was a lead guy on the engineering team, but he neither managed the program nor helped shape GNSS. He recalls the point at which that all changed. It started with being selected as NAV payload lead for the IIR proposal.

While working on this proposal, bigger questions of GPS sustainment planning began to arise. He participated in three more proposals that revolved around balancing the minimum requirement for a full constellation with the need for continuous, high-quality coverage that met evolving GNSS needs (M-code and civil signals).

“Those proposals boiled down to when to launch the next GPS satellite with what capabilities and at what cost,” Czopek says of the sustainment role.

“Those meetings opened windows for me into the minds of the GPS leadership as they struggled with planning. The opportunities and risks of these discussions seemed enormous.”

Czopek was so busy on the next-generation satellite proposals that one day he came in to the office and someone had to tell him that Boeing had launched GPS 14, the first GPS Block II satellite. “About the time we handed in the [new] proposal, the Block II navigation payload was activated,” he recalls.

After the win of the IIF proposal, the GPS wing awarded a separate II/IIA support contract. Boeing’s management took a gamble and promoted Frank to program manager of that contract, which came in on time and under budget. It remains a highlight of his years with the program.

GPS IIF: Pulse Line
By the time the GPS IIF program began, Czopek was fully immersed in GPS. He enjoyed participating in these discussions and the challenge of tying the old lessons to the new challenges to come up with a solution.

He began monitoring some of the other GNSS systems under development and heard the same questions and debates: How do you sustain and improve accuracy, meet emerging needs, and make it all affordable without interfering with current navigation services?

And he looked at the issues of the future: Is the current cost curve for launches sustainable, as constellation size and satellite mass increase? Where is the industry going? What innovation needs does it have?

In a partial answer to his questions, Czopek is now working with a GPS IIF program team on system engineering and interface control document processes. Their job is to make sure that the unit hardware is ready for assembly on the satellite. The IIF generation of space vehicle is the first being produced using Boeing’s pulse line to assemble satellites.

The GPS pulse line is similar to a traditional airplane assembly line, where the satellite moves from one work area to the next in a steady rhythm to increase speed, efficiency and quality. Today, it takes 10 months for a IIF satellite to go through each of the 14 workstations on the pulse line.

“Our goal is to get that down to eight months, as we gather lessons learned, come up with new ideas and just get more practice at it,” Czopek said.

Sounds like the Frank Czopek of 1972 — as with the family’s backyard Corvair project, he’s still involved with the heavy lifting and getting things off the ground.

The 1972 Corvair Assembly Team

Here’s how the Czopek brothers did it.

On weekends, Frank and his brothers Greg and Pete paid $25 apiece for “transportation specials.” They usually ended up with rear engine–mounted, air-cooled Chevrolet Corvairs, because these were the cheapest. The goal: to get one fully functioning car out of the deal.

The Corvairs always seemed to need brakes and a clutch which required them to remove the engine. To do this, Frank’s youngest brother Pete would scoot under the car. All three brothers then removed the engine bolts causing the 400-pound engine to drop on Pete’s chest.

Quickly, Greg would raise the rear of the Corvair up while Frank would grab hold of Pete’s legs to pull him and the engine out from underneath the car. Frank and Greg than had to lift the engine off Pete’s chest so that he could breathe.
To install the engine, all they had to do was reverse the steps.  This process was improved when cardboard was placed under Pete to make his pulling out easier and further refined when they got a dolley.

(Kids, don’t try this at home.)

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Return to main article

Engineering Specialties

Mechanical space hardware, real-time embedded programming, Boolean Logic, Assembly Language.

His Compass Points

Return to main article

Engineering Specialties

Mechanical space hardware, real-time embedded programming, Boolean Logic, Assembly Language.

His Compass Points

• My wife Jeanine for putting up with me and GNSS for the last 26 years.

• “Pad Führer” Günter Wendt, who was always the last guy to see a Gemini program astronaut as they sealed the capsule. I never met him, but I distinctly remember Walter Cronkite talking during the launch broadcasts about Wendt being a “mechanical engineer!” And that helped me select my career field. 

• My high school junior year math teacher, Calvin Cathers, who told me, “You should go into engineering.”

• My sons Scott and John, now completing degrees in physics, math, and economics. We have always set aside at least one day per week for “family day” and have visited all 50 states, walked on the Great Wall in China, panned for gold in Alaska, dug for diamonds in Arkansas, taken air boat rides in alligator-infested waters, and visited the Tower of London.

What influences, if any, does engineering have on your daily non-work life?

Engineering influences all of my daily non-work life. For example, we’ve had an annual Thanksgiving Day Rocket Launch for the last 29 years. Friends and family spend the day in the mountains and construct the rockets on the day of the launch. Retrieving lost rockets in the mountain brush is challenging. During dry seasons, we abort the launches and resort to potato guns!

GNSS Event that most signifies to you that GNSS had “arrived.”

In 1990-91, colleagues told me that parents were coming up to the gates of the Seal Beach Boeing facility to ask if they could buy a GPS receiver that would help keep their sons safe in the first Gulf War.

What popular notions about GNSS most annoy you?

GPS “brownouts” — the fear that satellites will fail sooner than predicted. The GPS Standard Positioning Service performance standard requires operational 24 satellites; currently there are 35 on orbit. A dozen of those are Block IIAs, which are operating way past their design lives. But two GPS satellites have never failed at the same time, and the new Boeing Block IIF satellites will lessen the risk of brownouts even more.  The IIF satellites are more complex and accurate, and have higher power and a longer design life (12 years) than previous GPS satellites.

Favorite Equation

Karnaugh Map for C/A code taps — involving a method to simplify Boolean algebra expressions that takes up to 15 pages of analysis to describe.

As a consumer, what GNSS product, application, or engineering innovation would you most like to see?

“I just returned from the ION GNSS 2010 meeting in Portland, Oregon, where speakers described technologies now available that would allow a car to drive itself.  These include GPS receivers that can track in urban canyons, accurate inertial/MEMS sensors, and collision avoidance sensors. I’d like to see that!”

Project Genealogy: Key past projects and events

Czopek was in the room when a receiver successfully tracked a Block II navigation payload producing Y-code for the first time. He also led a team that found the reason why a GPS satellite would randomly go off line for 6 seconds.  This event was first noticed when a commercial jet was performing a landing under GPS control and was forced to abort. His team’s investigation resulted in changes in the control segment software that prevented this from recurring. 

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Amid continuing debate over how to handle budgetary shortfalls in building a European GNSS, the European Space Agency (ESA) signed a €194 million ($270.5 million) contract on October 25 with SpaceOpal to provide space- and ground-based services to operate the Galileo constellation once it has been fully deployed.

Amid continuing debate over how to handle budgetary shortfalls in building a European GNSS, the European Space Agency (ESA) signed a €194 million ($270.5 million) contract on October 25 with SpaceOpal to provide space- and ground-based services to operate the Galileo constellation once it has been fully deployed.

On the occasion of the contract signing, European Commission Vice-President Antonio Tajani, Commissioner for Industry and Entrepreneurship said, “Galileo is becoming a reality. . . . We are fully committed to the roll-out of the system. Given the increased reliance of companies and citizens on satellite navigation, Galileo will play an important role in our daily lives.”

Three days later on October 28, the European Commission (EC) issued a communication on industrial policy that emphasized its commitment “to complete the Galileo constellation and put in place a new governance scheme.”

In between, European Union (EU), EC, ESA, and industry leaders debated the best ways to cut costs and raise additional funds for the Galileo program during discussions at a high-level conference in Brussels under the theme, “A New Space Policy for Europe.”

The contract awarded to SpaceOpal GmbH — the fourth of six planned “work packages” to support creation of an initial operational capability for Galileo — covers the industrial services needed to support ESA in operation of the satellites as well as the ground infrastructure. The two remaining procurement contracts, for the completion of the ground mission infrastructure and the ground control infrastructure, willbe awarded in early 2011, according to the EC.

SpaceOpal GmbH is a joint venture between Gesellschaft für Raumfahrtanwendungen (GfR,Space Applications Company) GmbH established by the German Aerospace Centre (DLR GfR), and Telespazio S.p.A. of Italy. Other members of the SpaceOpal team come from various ESA member states across Europe.

Galileo is now expected to achieve initial operational capability in 2014/15 and, under current plans, will provide three services at first: the Open Service (free), the Public Regulated Service (PRS) and a search-and rescue Service. Launches of the first of four in-orbit validation (IOV) satellites has been repeatedly delayed for technical and financial reasons and is now scheduled to occur in the second half of 2011.

Cost overruns in the IOV phases and higher than expected launcher costs led the EC late last year to acknowledge that the €3.4 billion allocated to the project would not be enough to complete the FOC system with a 27-satellite constellation.

Only enough funds for 14 satellites (plus the IOV spacecraft) were available. Consequently, full operational capability (FOC) has been pushed back to the 2016–18 timeframe and will require additional funds.

Backers of the program in the European Parliament said that new funds for Galileo need to be available in 2012 and 2013 and suggested that guarantees should be included in the 2011 EC budget, which is currently being negotiated.

EGNOS Service Back on Track

Meanwhile, problems with a monitoring station GPS receiver that delayed the start of the European Geostationary Navigation Overlay Service (EGNOS) safety of life operations appears to be nearing resolution.

Implementation of the EGNOS safety of life (SoL) service has been delayed due to a glitch with a GPS receiver in an EGNOS monitoring station.

The problem appeared on August 2, when the European Satellite Services Provider (ESSP) responsible for managing EGNOS operations initiated the procedure to transition towards the SoL service. A few minutes later, EGNOS transmitted “NOT MONITORED” messages for all GPS satellites and for the ionosphere correction data, rendering the service unusable.

It turned out that one type of GPS receiver used in the monitoring stations had performed an unnecessary check of the EGNOS GEO-ranging function. According to ESSP, the receiver performed a check on the value of bit 0 of the “Health and Status” parameter contained in Message Type 17 (MT17). 

Because the GEO-ranging function is not activated for EGNOS, this bit 0 of MT17 is set to 1 (Off) in EGNOS transmissions. The receiver wrongly interpreted this status as a fault condition and reported this condition to the EGNOS processing facility. On August 6, ESSP reverted to the OS signal, that is, it transmitted the EGNOS signal with Message Type 0 (“Don’t Use for Safety Applications”).

ESSP says that all events observed at the system level have been traced back to a single cause at the level of the receiver in the monitoring station. A
correction has been developed and is now being tested. 

ESSP expects that these remedial activities will be concluded in time for the SoL transition procedure to be completed by the end of the year. If all
goes well and the SoL service is then declared available, the first EGNOS approaches with vertical guidance (APV) could used by suitably equipped
aircraft beginning in January 2011 — although the EC may postpone an official announcement of the service until March.

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With activation of three modernized GLONASS (GLONASS-M) satellites launched on September 2 and plans to put four more space vehicles (SVs) into orbit before the end of this year, the Russian GNSS system will have more than enough spacecraft for an FOC declaration in the not-too-distant future.

With activation of three modernized GLONASS (GLONASS-M) satellites launched on September 2 and plans to put four more space vehicles (SVs) into orbit before the end of this year, the Russian GNSS system will have more than enough spacecraft for an FOC declaration in the not-too-distant future.

A triple launch of GLONASS-Ms is planned in early December, with the first demonstration flight of the next-generation GLONASS-K expected before the end of the year. The latter spacecraft will transmit the first CDMA signals in addition to the system’s traditional FDMA and is expected to be launched about December 24 or 25 on a Soyuz rocket from the Plesetsk, Russia, launch site rather than on Proton launchers from Baikonur, Kazakhstan. 

The constellation currently has 23 operational satellites, two non-functional spares, and another that recently had a navigation payload failure and will be removed from service. About 11 more GLONASS-M satellites will be launched by the end of 2012, according to Sergey Revnivykh of the Russian Federal Space Agency (Roscosmos).

Russian military controllers brought the latest trio of GLONASS-M satellites on-line fairly quickly — between October 4 and 11.

Currently, the system provides 98 percent global coverage with dilution of precision (DOP) of less than 6, assuming a five-degree masking angle. Moreover, system accuracy continues to improve with the modernized space vehicles (SVs) — now producing a 1.8 meter user range error, Revnivykh said. He predicted that GLONASS performance would be comparable with GPS by the end of 2011.

Apparently, several versions of the new GLONASS-K satellites are planned. GLONASS-K1 satellites will have a 10-year design life and clock stability of 5×10-14. Only one more GLONASS-K1 satellite will be built and launched after that.
A new design, GLONASS-K2, will start launching in 2013. The K2 satellites will have a 10-year design life and a clock stability of 1×10-14.

The first CDMA signal will transmit on L3 — a QPSK(10) modulation centered at 1202.025 MHz. — and use truncated Kasami ranging codes. CDMA signals will also be transmitted on L1 and L2. According to a paper presented at the ION GNSS 2010 conference in Portland, Oregon, last month, “intensive studies for developing new CDMA signals” at these frequencies are under way with particular attention being paid to ensure low power spectral density (-238 dBWt/m2·Hz) in radio astronomy band 1610.6–1613.8 MHz.

The GLONASS-K satellites will transmit the legacy FDMA satellites in addition to the CDMA signals.

A modernized GLONASS-K satellite, GLONASS-KM, is now under study, Revnivykh said. In addition to transmitting legacy FDMA signals on L1 and L2 and CDMA signals on L1, L2, and L3, CDMA signals may also be transmitted on the GPS L5 frequency at 1176.45 MHz. If approved and built, the GLONASS-KMs would not launch until after 2015.

The accompanying chart shows Roscosmos’s current plans for introducing new generations of GLONASS satellites and CDMA signals.

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Experts at the German Aerospace Center (DLR) are analyzing signals from Japan’s first quasi-zenith satellite, Michibiki, which began transmissions (including the first transmission from space of the new civil signal, L1C) on October 26, according to the Japan Aerospace Exploration Agency (JAXA).

Experts at the German Aerospace Center (DLR) are analyzing signals from Japan’s first quasi-zenith satellite, Michibiki, which began transmissions (including the first transmission from space of the new civil signal, L1C) on October 26, according to the Japan Aerospace Exploration Agency (JAXA).

The accompanying figures show the spectral flux density and a scatter plot of the QZS-1 L1 signals that were recorded with DLR´s 30-meter high-gain antenna at Weilheim last week. The L1 signal contains two GPS-compatible L1C and L1 C/A components, and the L1-SAIF which is a signal compatible with GPS satellite-based augmentation systems.

JAXA’s initial functional verification of Michibiki is expected to last about three months.

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