ABSTRACT
The Vestigial Sideband (VSB) transmission system approved achieves the level of performance that it does through a very clever and elegant combination of techniques applied both at the transmitter and the receiver. Despite the decision by the technical subgroup to approve the VSB approach for testing, an effort seems likely to be undertaken by a group of broadcast interests to develop a coded orthogonal frequency division multiplexing (COFDM) implementation tailored for use in countries with 6 MHz channels. By virtue of the relationship between the VSB symbol rate and the NTSC line rate, it is possible to design a fairly simple comb filter in the receiver that will place nulls at the frequencies of the NTSC visual carrier, color subcarrier, and aural carrier. The interference rejection filter effectively creates inter-symbol interference because of the signal delay associated with it. A channel equalizer is required in the receiver to compensate for echoes and for tilts in the channel response.
