Receiver noise

Fundamentals
Title	Receiver noise
Author(s)	J. Sanz Subirana, JM. Juan Zornoza and M. Hernandez-Pajares, University of Catalunia, Spain.
Level	Medium
Year of Publication	2011

The receiver code noise is a white-like error and can be smoothed using a low pass filter.

This error affects both the code and carrier measurements, but in different magnitude: The accuracy of pseudorange measurements is about 1% of the wavelength ("chip"), or better. This means, for instance, a noise with a maximum value of 3 m for the GPS civil C/A code and about 30 cm for the protected P codes (see table 1).However, when smoothing the code with the carrier phase, the C/A receiver noise can be reduced down to about 50 cm.

Table 1: GPS signal structure (source: G. Seeber p. 217)

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The carrier phase noise is at the level of few millimetres (about the 1% of carrier phase wavelength).

Code and carrier phase noise depends on the signal strength, which varies with the elevation angle.