Abstract: In a novel apparatus for and method of discrete spurious frequency leakage cancellation a radio frequency RF switch is used to couple the upstream path signal to the CATV cable only during transmission bursts. In between transmission bursts, the upstream signal is disconnected from the CATV cable. In a circuit for canceling frequency spurs from a victim signal, a radio frequency (RF) switch is operative to connect and disconnect the victim signal to/from the output in accordance with a switch control signal which is generated by a switch control module. The victim signal is coupled to said RF switch output during transmission bursts only.

Abstract: A novel apparatus for and method of discrete spurious frequency leakage cancellation for use in a cable modem. The spurious leakage cancellation mechanism is particularly suitable for use in cable modem systems adapted to implement the DOCSIS 2.0 specification which specifies both downstream and upstream channels. In one embodiment, the spurious emission cancellation mechanism cancels the spurious emissions by first creating a replica of the aggressor clock signal having the same amplitude but 180 degree phase shift as the spurious signal. The phase shifted spurious replica is added to the original spurious signal thus cancelling the spurious signal. In another embodiment, an RF switch is used to couple the upstream path signal to the CATV cable only during transmission bursts. In between transmission bursts, the upstream signal is disconnected from the CATV cable. This embodiment takes advantage of the less stringent spurious requirements in the DOCSIS 2.0 specification for transmission bursts.

Abstract: A novel reduced cost CATV RF tuner circuit that can serve as a replacement circuit for one based on a surface acoustic wave (SAW) filter. The tuner circuit is particularly suitable for use in cable modem systems adapted to implement the DOCSIS 2.0 specification which specifies single channel video reception. The invention replaces the traditional SAW filter functions of image rejection and channel selection with both analog and digital components and circuits. The image rejection function is performed by a combination of analog multiple filters. Digital filtering is then used to perform the channel selection operation. The analog based image reject filter can be constructed using relatively inexpensive passive components, while the digital channel selection filter can be implemented in software, firmware, gate array (FPGA) or ASIC.