Lines 441 and 443 are coupled to a summer 445 which sums the two waveforms and outputs them on the shared transmission media via line 412. [0308] In some embodiments, the line 412 may be coupled to suitable interface circuitry to drive the signal on line 412 into a wireless or cellular system, a terrestrial microwave link, a coaxial cable of a cable TV, telephone or other system, a fiber