This same 1 percent rule of thumb can illustrate the increased precision of the carrier phase observable over the pseudorange. First, the length of a single wavelength of each carrier is calculated using this formula
= the length of each complete wavelength in meters;
= the speed of light corrected for atmospheric effects;
= the frequency in hertz.
L1 – 1575.42 MHz carrier transmitted by GPS satellites has a wavelength of approximately 19 cm
L2 – 1227.60 MHz carrier transmitted by GPS satellites has a wavelength of approximately 24 cm
The resolution available from a signal is approximately 1% of its wavelength. 1% of these wavelengths is approximately 2mm.
Carrier phase observations are certainly the preferred method for the higher precision work most have come to expect from GPS.