Brain Murmurs
Guerrilla computing in the mountains of Seattle
| The Global Positioning System (GPS), is the only fully-functional satellite navigation system. More than two dozen GPS satellites orbit the Earth, transmitting radio signals which allow GPS receivers to determine their location, speed and direction. A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS radio signal gives the distance to each satellite, since the signal travels at a known speed. The signals also carry information about the satellites' location. By determining the position of, and distance to, at least three satellites, the receiver can compute its location using trilateration. Receivers do not have perfectly accurate clocks, and must track one extra satellite to correct their clock error. |
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We are GPS experts. Many developers are familiar with how to read data from standard handheld GPS devices, but we actually understand how to take raw pseudoranges, look up high-precision satellite emphera, and compute a GPS position from hand. The most difficult work we have done in GPS required us to synthesize position information from data sets corrupted by multipath effects and limited satellite coverage. This work become the foundation of the Nielsen Outdoor program. We are well-versed in NMEA message protocols and have written parsers for NMEA GGA, GGL, GSA, RMC, VTG, and ZDA messages. We also have experience handling and parsing data traffic from both Fastrax and uBlox embeddedGPS modules. Related Technologies Related Clients | |