To shed some light on the connection between these properties: they arise from the fact that the coding sequence _is_ pseudo random noise. Specifically, white noise.
White noise has this nice property that its autocorrelation is ideally a discrete delta function, aka a 1 at t = 0 and 0 everywhere else. In the time domain, this means that only an exactly aligned code sequence matches itself – ideal for communication symbols.
Spectrally, white noise is flat and fills the entire available frequency spectrum. This produces the “spreading” of digital spread spectrum sequences (DSSS).
Any kind of white noise could be used for this, but as far as I remember, the Gold codes used in GPS are: easy to generate and maximally different from each other.
White noise has this nice property that its autocorrelation is ideally a discrete delta function, aka a 1 at t = 0 and 0 everywhere else. In the time domain, this means that only an exactly aligned code sequence matches itself – ideal for communication symbols.
Spectrally, white noise is flat and fills the entire available frequency spectrum. This produces the “spreading” of digital spread spectrum sequences (DSSS).
Any kind of white noise could be used for this, but as far as I remember, the Gold codes used in GPS are: easy to generate and maximally different from each other.