Digital television receivers that digitize final I-F signals resulting from triple-conversion

摘要

Receiving apparatus for digital television signals digitizes a final intermediate frequency signal supplied from a triple-conversion radio receiver and synchrodynes the digitized final intermediate frequency signal to baseband. The triple-conversion radio receiver selects one of a plurality of digital television signals for upconversion to that portion of the electromagnetic frequency spectrum above the channels that are used for television broadcasting, amplifies a first intermediate-frequency signal in a first intermediate frequency band generated by that upconversion, amplifies a second intermediate-frequency signal in a second intermediate frequency band generated by downconverting the amplified first intermediate-frequency signal, and supplies a third intermediate-frequency signal in a third intermediate frequency band generated by downconverting the amplified second intermediate-frequency signal. This third intermediate-frequency signal is the final intermediate-frequency signal supplied to the analog-to-digital converter for being linearly converted to a digitized third intermediate-frequency signal. Digital synchrodyning circuitry synchrodynes the digitized third intermediate-frequency signal to baseband and thereby generates at least a real component of digital baseband signal. Circuitry responsive to at least the real component of the digital baseband signal recovers a stream of digital data descriptive of the video and audio portions of television programming.