An experimental RF noise cancellation analysis for cable access systems

This article presents the design of an experimental RF noise cancellation system to demonstrate the reduction of interference signals from LTE or other RF devices that overlap with the DOCSIS® or Cable TV spectrum. The main components of the demonstration system include a four-path RF reconstruction circuit board, SNR monitoring and control module, an adjustable Gradient Control Algorithm in software, and two DOCSIS 3.1 FPGA boards. The configuration for this demonstration system includes an antenna attached to the RF reconstruction circuit. The antenna is used to receive a reference of the interfering signal. The amplitude and phase of the reference signal is dynamically adjusted to cancel the undesirable component of the RF signal. The main experimental analysis is focused on a 20MHz wide LTE signal in 700MHz bands. The designed system is able to achieve an optimal noise cancellation result by adjusting the amplitude and phase of the reference signal to minimize the interference signal transmitted in the coax cable.