How Does GPS Work? - Breaking It Down
The first thing a GPS receiver does is search for a satellite’s signal. because the signal is relatively weak, the receiver must have a direct line of sight to the satellite (another reason to have lots of satellites in the air). When it finds one, it can distinguish which satellite it is 1 through 24 because each has a unique identifier in as Pseudo Random Code (PRC).
PRC is a mishmash of uniquely coded frequencies that tells the GPS receiver it has a satellite and not some interference or other device operating on the same frequency range. Read the rest of this entry »
How Does GPS Work? - Part 2
Continued From How Does GPS Work?
The first equation, R-T=D, is straight forward. Your speedometer provides verification of this as you leave home for work. If you want an idea of how long it would take you to go from point A to point B, you would simply input numbers into that equation. For example, let’s say point A is 40 miles from point B and that you’ll be traveling at 65 miles per hour. Using some algebra (you knew it would come in handy someday), the equation now reads: time=distance/rate. plug in the numbers and you get 400/65, or 6.15 hours.
The geometry equation is just as simple. If you know two of the sides of the triangle, you can find the third. GPS uses this technique, called triangulation, to find your location. You and a single satellite equal but two points; a third is needed. To obtain a truly accurate reading, a fourth point is used (which is why there are so many GPS satellites).
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How Does GPS Work?
Each satellite weighs in at approximately 2,000 punds and, including solar panels, measures 17 feet wide. Transmitter power is only 50 watts compared to 100,000 watts for a radio station and it transmits on three frequencies Civilian GPS uses the “L1″ frequency of 1575.42 MHz. Read the rest of this entry »