GPS Source, Inc.

Atomic clocks are incredibly accurate and are constantly in use for GPS measurements. But atomic clocks can drift due to magnetism, electrical fields, and microscopic jostling. I just read an article that discussed researchers building a nuclear clock that would lose only one-tenth of a second over 14 billion years. It would measure time based on a Thorium neutron, which is not susceptible to vibrations or electromagnetic forces. An ultraviolet laser would excite a single thorium atom’s nucleus and then keep time by using the oscillations of its neutrons. Right now, scientists are trying to figure out the exact frequency of the ultraviolet laser emissions needed to make the thorium nucleus react in the correct manner.

The proposed design would be 100 times more accurate than current atomic clocks. High precision GPS satellites and scientific experiments would benefit from this kind of application. The full article on using lasers will appear in Physical Review Letters.

PUEBLO, Colorado (February 2012) – The United States Air Force Air Mobility Command Systems Group (AMC SG) at Wright-Patterson Air Force Base has awarded Safety of Flight Approval for GPS Source’s GLI kits aboard US Air Force C-130 (E/H/J models) and C-17 aircraft.

Safety of Flight Approval confirms the safe operation of GLI kits aboard military aircraft. It also provides an official USAF account of the testing which was accomplished in order to grant full flight approvals.

Robert Horton, CEO of GPS Source, said “Supporting our military with first class products like our GLI kits is an honor. It is important that the United States Air Force considers them to be safe and effective in supporting HAHO or HALO, SOF parachutists, precision airdrop capability and time-critical applications during humanitarian relief operations. The military can depend on our kits in the most extreme situations.”

The GPS Source GLI-kits enables an end user to perform JPADS and Military Free Fall (MFF) Missions with guaranteed mission equipment compatibility, greater ease and reliability. The mil-spec designed systems ensure 100% GPS L1/L2 signal coverage throughout the cargo compartment and flight deck of any medium to large military transport aircraft.

About GPS Source, Inc.
Founded in 2000, GPS Source, Inc. designs, development and manufactures solutions that bring GPS inside for the military, defense, aerospace, and other markets. This includes a complete line of mil-spec GPS antennas, splitters, repeaters, cables, etc. The “GPS Live Inside” products ensure GPS signal availability inside. GPS Source, Inc. is a veteran owned, AS9100 certified company. For more information, visit www.GPSSource.com.

Just read an article in GPSWorld that states the Czech government has signed a deal for Prague to host the headquarters for Galileo. Galileo has been on and off the shelf for years in Europe as an ambitious satellite navigation system. It is being built to compete with the U.S. Global Positioning System and Russia’s GLONASS.

Europe is marketing Galileo as more precise and more reliable than GPS, while controlled by civil authorities.

As far as reliable…if it is as reliable as my European car, don’t give up GPS just yet!! Galileo will handle the same type of applications in the commercial sector as GPS, ranging from precision agriculture to accurate positioning for search-and-rescue missions. The EU hopes it will be a very profitable endeavor.

The system, with a network of 30 satellites is expected to become operational in 2014. But we will see, as earlier prognosticators said Galileo was suppose to become operational by 2012. The operational dates have been repeatedly moved back. Right now, initial service is expected around 2014 and completion by 2019.

There are several GPS devices on the market that are designed to pass low voltage (2.5V) to an active antenna. There are also several active antennas on the market that state their ability to work at 2.5V. Unfortunately, if the antenna has not been specifically designed to work at 2.5V, it may only give nominal performance. If you are sourcing an antenna for a device that passes 2.5V, make sure the antenna has been designed for that voltage. Be aware that there are several antennas on the market that will state their ability to work at 2.5V, but they may not give optimum performance at 2.5V. In fact, their gain may be so weak, it may appear as if they are not working at all!

GPS Source has designed and manufactured all of their antennas for optimal performance at the voltage range stated. For example, antennas made by GPS Source that state they will work at 2.5V – 16V are designed to perform at 2.5V or 16V with optimal gain. GPS Source antennas designed to perform at 5V – 16V will have optimal gain at 5V or 16V. GPS Source antennas work as expected at the stated voltage range with rigorous testing and data to ensure customer satisfaction.

It is always a good engineering practice to use a 50 ohm load to terminate any unused splitter port. It will always ensure that the splitter performs to its optimum capabilities and ensures the greatest output power consistency through each splitter port. However, it is very common that applications change and the original intended use for splitters can vary many different times in the lifetime of a splitter. It is also quite common that the loads that may have existed with the splitter originally are long gone or were taken to be used in some other application. The difficulty of keeping loads with their splitters is one reason why loads are being requested with chains that are permanently attached to each splitter port.

The amount of isolation between adjacent splitter ports is probably the most important factor in determining the importance of terminating an unused splitter port. If the splitter is passive or has the maximum amplification available, the importance of using the 50 ohm load is more important. The vacant adjacent splitter port will cause some amount of signal leakage or loss of power. If the splitter has higher isolation between the adjacent ports, then the potential for any significant leakage through a vacant port is much less.

A good GPS splitter will offer high isolation, low insertion loss and good VSWR. You do not encounter a power splitter with high isolation and poor VSWR, nor high isolation with a poor insertion loss spec. Why? Because poor insertion loss specs generally result from improper matching or slight variations in stray capacitances at each end of the transformer; these effects; however, adversely affect insertion loss as well as isolation.

Everything in our digital world these days involves timing. The use of cell phones and the use of GPS navigation devices are perfect examples. Both require absolutely precise timing. Precise timing is available because of work by the likes of Norman Ramsey. He invented a new technique of measuring the frequency of radiation from atoms using two electromagnetic fields. It is known among physicists as “The Ramsey Method”. His work eventually led to the development by others of the cesium atomic clock. This clock is the worlds’ most accurate timekeeper. How accurate is it? The time during which the cesium atom makes 9,192,631,770 oscillations is defined as 1 second.

Why is this important? Well, if you are in the world of GPS, this matters a great deal! First, satellites send a signal to a GPS receiver. The signal contains the time it was sent and the satellite’s location. The electromagnetic signal travels at the speed of light. By measuring the time it takes for the signal to reach our GPS receiving device, we can calculate the distance we are orbiting from the satellite. So this relies on a very accurate clock to measure time. Each satellite contains two Rubidium and two Cesium atomic clocks. These are monitored against atomic clocks on the ground, and the whole system is continuously calibrated against the world wide time standard, Universal Coordinated Time (UTC). GPS is constructed as a time signal, so it is fairly straightforward to use GPS as a precise reference for time.

Norman Ramsey, who in 1989 shared the Nobel Prize in physics for his work with atomic energy levels that led to the creation of the atomic clock and MRI machines, died last Friday at the age of 96. He was considered the father of the atomic clock.

There are many benefits to a dual frequency antenna (L1/L2). Receiving signals from satellites on two frequencies has inherent redundancy. The L2 by design (military encryption), increases resistance to jamming. The L2 system’s signal is stronger and allows for increased reception in troublesome areas.

Besides redundancy and increased resistance to jamming, a critical benefit of having two frequencies transmitted from one satellite is the ability to measure directly, and therefore remove, the ionospheric delay error for that satellite. Advances in the technology used on both the GPS satellites and the GPS receivers has made ionospheric delay the largest remaining source of error in the signal.

GPS Source offers L1/L2 GPS Antennas with several different options. Call GPS Source to determine which GPS L1/L2 antenna is best for you.

I have finally managed to have enough time to follow up on current Lightsquared news. In mid-September, Air Force General William Shelton, Commander of Air Force Space Command, told Congressional leaders that the White House tried to make him change his congressional testimony to favor Lightsquared. They wanted him to alter his testimony to indicate that the military would continue to test the proposed bandwidth for ways LightSquared could still use the spectrum without interfering with GPS. The general refused to make the changes suggested by the White House!

In fact, the general told members of Congress “the GPS satellite constellation operates in a ‘quiet neighborhood’ in terms of bandwidth, and it’s this lack of interference that helps shield the GPS system from harmful interference in its critical operations. The LightSquared project would be the equivalent of a rock band moving into the neighborhood and blasting its music. All the testing the military did on LightSquared’s systems indicated major disruptions in the GPS system.”

Three cheers for a sign of integrity in Washington, DC…

GPS Source is hiring a Senior RF Engineer. We are looking for someone with a lot of experience in the GNSS/RF field. A Masters in Electrical Engineering is preferred. See the full job posting at www.gpssource.com/senior-rf-engineer

I  just read an article written in 1967, by a Major William Bender, Jr., AFRes (don’t know if he is still a Major…might have a different rank by now.)  He noted the following:

“When man was first impelled to drop things from military aircraft, he was chiefly concerned with messages. In the typical World War I story, the scout plane zoomed over the beleaguered troops and threw down a note-customarily tied to a wrench—which said reinforcements and ammunition were on the way.

Today (1967) the situation has changed drastically. The plane now drops the reinforcements and ammunition, along with howitzers, jeeps, fuel, medical supplies, rations—and maybe even the wrench, if it’s needed. Messages can be left to the communications experts.”

Today (2012), planes are still dropping reinforcements, ammunition, vehicles, fuel and other types of cargo.  But today, the parachuted drops are primarily guided to the ground with the help of GPS.  It has clearly affected the way a mission is executed.