Reduced bandwidth transmitter method and apparatus

摘要

A reduced bandwidth 8VSB, ATSC transmitter transmits to conventional DTV receivers having bandpass filters with root raised cosine (RRC) band edge responses. The transmitter includes a vestigial sideband modulator for transferring energy in a portion of a spectrum on a first side of a predetermined frequency to a second side of the predetermined frequency. At the low band edge of the spectrum, the predetermined frequency is the pilot carrier frequency. At the high end of the spectrum, the predetermined frequency is the Nyquist sampling frequency. The energy transfer is such that no energy is transmitted between at least one band edge of the spectrum and an intermediate frequency between the band edge and the predetermined frequency. The energy is transferred on a frequency to frequency basis as a function of the energy in the RRC transition and the amplitude of a weighting function extending between the intermediate frequency and the predetermined frequency.