Search results
Results From The WOW.Com Content Network
GPS broadcast signal. For the ranging codes and navigation message to travel from the satellite to the receiver, they must be modulated onto a carrier wave. In the case of the original GPS design, two frequencies are utilized; one at 1575.42 MHz (10.23 MHz × 154) called L1; and a second at 1227.60 MHz (10.23 MHz × 120), called L2.
However, one can often account for most of the discrepancy by the introduction of gravitational time dilation, the slowing down of time near gravitating bodies. In case of the GPS, the receivers are closer to Earth than the satellites, causing the clocks at the altitude of the satellite to be faster by a factor of 5×10 −10, or about +45.8 ...
tech: the GPS signal strength measured at the surface of the Earth. [clarification needed] [5] 10 −16: 2 × 10 −16: −127 dBm biomed: approximate theoretical minimum luminosity detectable by the human eye under perfect conditions 10 −15: femto-(fW) 2.5 × 10 −15: −116 dBm tech: minimum discernible signal at the antenna terminal of a ...
A major subclass is made of geopositioning systems, used for determining an object's position with respect to Earth, i.e., its geographical position; one of the most well-known and commonly used geopositioning systems is the Global Positioning System (GPS) and similar global navigation satellite systems (GNSS).
This is one reason the GPS spacecraft transmit on at least two frequencies, L1 and L2. Ionospheric delay is a well-defined function of frequency and the total electron content (TEC) along the path, so measuring the arrival-time difference between the frequencies determines TEC and thus the precise ionospheric delay at each frequency.
Due to the relative geometry of any given satellite to a receiver, the precision in the pseudorange of the satellite translates to a corresponding component in each of the four dimensions of position measured by the receiver (i.e., , , , and ). The precision of multiple satellites in view of a receiver combine according to the relative position ...
The United States' Global Positioning System (GPS) consists of up to 32 medium Earth orbit satellites in six different orbital planes. The exact number of satellites varies as older satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS is the world's most utilized satellite navigation system.
GPS is simply not accurate enough to replace ILS systems. Typical accuracy is about 15 metres (49 ft), whereas even a "CAT I" approach, the least demanding, requires a vertical accuracy of 4 metres (13 ft). This inaccuracy in GPS is mostly due to large "billows" in the ionosphere, which slow the radio signal from the satellites by a random ...