Complex sentence: Channel 6 doubled as Flint's CBS affiliate for many years as its signal (the second strongest in Michigan at the time it began broadcasting) decently covers the city and surrounding Genesee County.
Split into simpler sentences: Channel 6 doubled as Flint's CBS affiliate for many years. Its signal (the second strongest in Michigan at the time it began broadcasting) decently covers Flint itself and surrounding Genesee County.