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Inside GNSS • January/February 2007

GPS: The Way Ahead

On December 4, 2004, George W. Bush signed a National Security Presidential Directive (NSPD) that established the national policy for U.S. Space-Based Positioning, Navigation, and Timing (PNT). The directive updated the 1996 National Policy on the Global Positioning System (GPS). It also provided guidance for the procurement, management, and protection of GPS and its U.S. government operated augmentations.

Inside GNSS • November/December 2006

Follow the Money

Bank robbery in the United States is nearly as old as the country itself. According to Ron Avery, writing for ushistory.org, the first such robbery occurred in 1798 with the loss of the then-enormous sum of $162,821.

The concentration of generally unidentifiable and readily convertible cash forms an irresistible temptation to both the novice and hardened criminal. As legendary robber Willie Sutton explained when asked why he robbed banks, “That’s where the money is.”

Inside GNSS • November/December 2006

Loran Revives; NDGPS Fades

The Loran terrestrial radionavigation system might well be pulled back from its 12-year-long dance on the brink of extinction, while the Nationwide Differential GPS (NDGPS) radiobeacon-based augmentation system may have finally been pushed over the edge.

Inside GNSS • November/December 2006

Compass: And China’s GNSS Makes Four

China has confirmed what many have been expecting for some time: it will construct the world’s fourth GNSS system — joining the systems operated by the United States, Russia, and Europe.

Inside GNSS • October 2006

GPS: Launches of Satellites and Institutional Initiatives

Successful launch of the second modernized Block IIR satellite, IIR-15(M2), on September 25 and scheduling of another IIR-M launch on November 14 underlines recent progress in the GPS program.

IIR-15(M2), also identified by its space vehicle number (SVN58) and pseudorandom code number (PRN31), will be placed into orbital plane A, slot 2. The U.S. Air Force has designated the satellite to be launched in November as GPS IIR-16/M3, PRN15/SVN55.

Inside GNSS • April 2006

The Big Three: GPSOC, NAVCEN, NOCC

Before the GPS Operations Center (GPSOC) existed, a general officer was once quoted as saying he could get better GPS support by taking off his military hat, putting on his fishing hat, and calling the U.S. Coast Guard’s Navigation Center (NAVCEN). At the time, the Coast Guard was the only governmental organization supporting GPS users.

Inside GNSS • April 2006

GPS Help Line

Inside the Master Control Station at the 2nd Space Operations Squadron (2SOPS), Schriever Air Force Base, Colorado, crews continuously monitor and control the GPS constellation’s navigation signals. By doing so, 2SOPS keeps the GPS signal as accurate as possible, making it a phenomenally successful global utility.

Yet, as GPS users know, other factors — such as differences in receivers, terrain, environment, and platforms — can affect navigational accuracy in the field.

Inside GNSS • September 2006

Player Pianos, Sex Appeal, and Patent #2,292,387

. . . It is simply too good to be true.

But by now we know that Hedy Lamarr and George Antheil were awarded U.S. Patent No. 2, 292,387 on August 11, 1942 for a "Secret Communication System."

And that, indeed, the two artists invented the "frequency hopping" method of radio signal transmission, later to be known as "spread spectrum."
As they explained in their patent application:

GNSS Solutions • September 2006

Atomic Clocks on Satellites and Mitigating Multipath

Q: GPS satellites used to carry two cesium and two rubidium atomic standards on board. Subsequently, GPS switched to all rubidium clocks. Galileo plans to use hydrogen masers instead. What are the relative merits of these clocks for use in navigation satellites?

A: It is well recognized that the space-qualified atomic clocks in the GPS satellites are an enabling technology, if not the enabling technology for the system. However, they are also one of the more difficult technologies to acquire.

Inside GNSS • September 2006

USAF Announces More IIF Delay

The GPS Block IIF program continues to lose ground, with first launch of a satellite now projected as no sooner than May 2008 and as late as January 2009 in a “worst case,” scenario, according to the U.S. Air Force. Program costs are also increasing.

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