Generation of Two Radio Frequency Channels From a Digital Synthesizer
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
A method is described whereby digital techniques are used to create two separate radio frequency (RF) channels from a single frequency, for use with RF modems. Since RF modems must adhere to stringent frequency specifications when connected to cable television media, the modems are rigorously filtered to prevent the generated harmful effects of harmonic frequency components. To overcome the harmonic problems, this concept describes the use of digital square waves to produce "ODD" harmonic components (3, 5, 7... times the carrier frequency) to create two separate channels using only one filter for both channels. The concept, as shown in the drawing, uses a digital frequency synthesizer 10, a divide-by-two flip-flop 11, and filter 12.