Surveying with GPS 2

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The carrier wave of the coded signal is used rather than the coded signal itself.

The carrier wave can be used as an accurate ruler to measure the range to the satellite because 1 wavelength approximately equals 20 cm. This gives a more accurate range than a code derived pseudorange.

The range to the satellite is computed by calculating the whole number of wavelengths between the receiver and the satellite. Computation requires a time span of GPS data.

The final result of the data processing is computation of the baseline between the two receivers.

The computation of the baseline combines the data from both receivers. Due to this combination of data many of the errors in the data cancel out, giving an accurate baseline result.

Two carrier waves (L1 and L2) of different wavelength are recorded. This requires a dual frequency receiver.

Using two wavelengths enables the atmospheric errors to be accurately modelled.