How it Works The acronym GPS stands for Global Position System. That GPS or navigation system in your car isn’t really a GPS though it’s a GPS receiver meaning it gets info from the real GPS. You might be surprised to learn that the GPS is comprised of 27 satellites in outer space arranged in such a way that at any given time anywhere on earth at least four are “visible” in the sky.

The job of your GPS receiver is to locate those satellites figure out how far away they are and then use that info to determine your exact location. The GPS satellites continuously send out high-frequency low-powered radio waves that your receiver picks up. Your receiver then measures the amount of time it took to get the signal from each satellite and determines your precise location. For this both the GPS and the receiver need their clocks synchronized to the nanosecond (one billionth of a second). Therefore each satellite is equipped with a powerful atomic clock and each receiver with a quartz clock. Both are super accurate.

Wow! A lot of info being transmitted from space to your device. Most GPS receivers can also trace your path across a map as you move. If the receiver is on it stays in constant communication with GPS satellites to see how your location is changing. With this information and its built-in clock the receiver can give you some valuable information such as:

• How far you’ve traveled
• How long you’ve been traveling
• Your current speed
• Your average speed
• A trail showing you exactly where you’ve traveled on the map
• Your ETA (estimate time of arrival) 

The Invention of the GPS

Which inventor went all out (in space) to provide humanity with such a precise and detailed map of the earth? It must have cost billions of dollars. After all trips to space are very expensive and they require a lot of specialized research training and equipment.

Actually the GPS wasn’t invented for map tracking at all; its invention was a chronology of various world events which happened to result in one of the most important technologies of the 20th and 21st centuries.

Here are some key events:

October 4 1957. The US and Russia were deep into the Cold War each side trying to outdo the other in science and research of nuclear weapons and space exploration. The entire world was amazed by the launch of Russia’s Sputnik satellite the first artificial satellite sent out to space to orbit the earth. This upped the tension and the fervor of the US to get their own satellites out there.

Scientists at MIT (Massachusetts Institute of Technology) had their eyes on the skies. They noticed that the frequency of the radio signals transmitted by Sputnik increased as it approached and decreased as it moved away. This gave them the grand idea to track the satellite from the ground based on the radio signals it was emitting.

Next to follow was the US Navy looking to track submarines. They wanted to be perfectly sure they knew the exact locations of all Russian submarines and were prepared for any type of attack and attacker. They developed the TRANSIT system which started out with six satellites and then added another four. This project costed roughly $8 billion. One step up for the US war effort — Russians watch your subs carefully! 

(Excerpted from Mishpacha Jr. Issue 667)