4 17 17.4 Correlation Funrtioiis For the linear expected value, in accorilarrce with (17.lf, (17.14) arid (17.18) vie ohtaiii T (17.22) i s (iikc all other first order expected valires) indeperitleiil of time From Defiriil ion 24 it is ecluill 10 the As ergodir functions arc sttitiwtiry, the finrar average p time average m AS LEE time average c m in t31iiscase ktc iorincd from a i y sample fimrtittn, the st~mplcf i ~ ~ r iii l ,( ~ f 7.22) ( ~ ~is rio 1c)iige~riidrkivf hy an iurkx (cnirrptiw (17.18)} We will get to knoa the other expected values better in the lollowing sections, iu particaular t irv auto-correlatioiiand crosh-corrclation fiirrctions As me only use second-order rxpectetl vaiizes LPL the f o r m of (17.20), we;lk crgodicitv i d br A sufficiciit pic>-rccluisite First WP cwnsider c o l d a t ion functions of purely red signals The restllts will latcr bc cxtencled to toinplex signals