Upstream noise suppression circuits and related radio frequency subscriber drop equipment and methods
Upstream noise suppression circuits include a splitter and a combiner that are connected by first and second communications paths. An information signal removal circuit is provided on the second communications path and is configured to remove an upstream information signal therefrom. A phase shifter is also provided on the second communications path between the upstream information signal removal circuit and the combiner.
1. A method of reducing upstream noise funneling in a communications network, comprising:
splitting an upstream signal into a first component that is transmitted over a first communications path and a second component that is transmitted over a second communications path, the second component including an information signal and a noise signal;
removing the information signal from the second component while retaining at least a portion of the noise signal of the second component to provide a modified second component;
phase shifting the modified second component; and
combining the first component and the phase-shifted modified second component;
wherein removing the information signal from the second component while retaining at least a portion of the noise signal of the second component to provide a modified second component comprises:
detecting the presence of the information signal;
terminating the second communications path in response to detecting the presence of the information signal; and
reestablishing the second communications path in response to detecting the absence of the information signal.
2. The method of claim 1 , wherein a burst detector is used to detect the presence of the information signal, and wherein a switching circuit is used to selectively terminate the second communications path.
3. The method of claim 1 , wherein terminating the second communications path comprises terminating a signal carrying component of the second communications path.
4. The method of claim 3 , wherein a burst detector is used to detect the presence of the information signal, and wherein a switching circuit is used to selectively filter the second communications path.
5. The method of claim 1 , wherein the method is performed on an upstream communications path of an RF signal amplifier.
6. The method of claim 1 , wherein the method is performed in an RF tap unit.
7. The method of claim 1 , wherein the modified second component that is combined with the first component is phase shifted by approximately 180 degrees with respect to the first component.
8. The method of claim 1 , wherein a phase shifter circuit is used to phase shift the second component.
9. The method of claim 8 , wherein the phase shift is phase shifted approximately 180 degrees.
10. The method of claim 8 , wherein the phase shifter circuit includes a burst detector that is configured to detect the presence of the upstream signal that is contained within the second component on the second communications path.
11. The method of claim 1 , wherein the method is performed on an upstream communications path of an RF signal amplifier.
12. The method of claim 1 , wherein a switching circuit is used to selectively terminate the second communications path.