Patent ID: 7068730

Claim:
A wideband multi-channel direct-to-RF QAM modulator for modulating a plurality of digital data streams onto a single multi-RF output, comprising: a high-frequency master clock source operating at a master clock frequency; encoding means for encoding each of the digital data streams into a set of QAM encoded-streams; processing means for simultaneously converting the plurality of QAM-encoded streams into a single digital multi-channel IF stream encoding the multiple QAM encoded streams onto a set of uniformly spaced carrier frequencies in an intermediate frequency band, said processing means including an inverse FFT (IFFT) and a post-IFFT combined filtering means, said combined filtering means performing a combined equivalent of baseband and anti-imaging filtering; digital-to-analog conversion means for converting the single digital multi-channel IF stream into an analog multi-channel IF stream; synchronously-clocked quadrature modulation means to frequency-shift the analog multi-channel IF stream upward by one-half of the master clock frequency onto said single multi-RF output; and digital quadrature correction means between the combined filtering means and the digital-to-analog conversion means for compensating quadrature error in the synchronously clocked quadrature modulation means.