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GNSS Positioning
Satellite navigation solution for the receiver's position (geopositioning) involves an algorithm. In essence, a GNSS receiver measures the transmitting time of GNSS signals emitted from four or more GNSS satellites (giving the pseudorange) and these measurements are used to obtain its position (i.e., spatial coordinates) and reception time. The following are expressed in inertial-frame coordinates. The solution illustrated Image:Light cones.svg, Essentially, the solution shown in orange, \scriptstyle (\hat_,\, \hat_), is the intersection of light cones. Image:Evolution light cones 0.gif, The posterior distribution of the solution is derived from the product of the distribution of propagating spherical surfaces. (Seanimation) Calculation steps # A global-navigation-satellite-system (GNSS) receiver measures the apparent transmitting time, \displaystyle \tilde_i, or "phase", of GNSS signals emitted from four or more GNSS satellites (\displaystyle i \;=\; 1,\, 2,\, 3,\, 4,\, .. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Pseudorange
The pseudorange (from pseudo- and range) is the ''pseudo'' distance between a satellite and a navigation satellite receiver (see GNSS positioning calculation), for instance Global Positioning System (GPS) receivers. To determine its position, a satellite navigation receiver will determine the ranges to (at least) four satellites as well as their positions at time of transmitting. Knowing the satellites' orbital parameters, these positions can be calculated for any point in time. The pseudoranges of each satellite are obtained by multiplying the speed of light by the time the signal has taken from the satellite to the receiver. As there are accuracy errors in the time measured, the term ''pseudo''-ranges is used rather than ranges for such distances. Pseudorange and time error estimation Typically a quartz oscillator is used in the receiver to do the timing. The accuracy of quartz clocks in general is worse (i.e. more) than one part in a million; thus, if the clock hasn't been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |