The Carrier Phase Observable

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

$$\lambda =\frac{c_a}{f}$$

where:

$\lambda$ = the length of each complete wavelength in meters;
$c_a$ = the speed of light corrected for atmospheric effects;
$f$ = the frequency in hertz.

$\begin{array}{l}\lambda =\frac{c_a}{f}\\ \lambda =\frac{300x{10}^{6}mps}{1575.42x{10}^{6}Hz}\\ \lambda =19cm\end{array}$

L1 – 1575.42 MHz carrier transmitted by GPS satellites has a wavelength of approximately 19 cm

$\begin{array}{l}\lambda =\frac{c_a}{f}\\ \lambda =\frac{300x{10}^{6}mps}{1227.60x{10}^{6}Hz}\\ \lambda =24cm\end{array}$

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.