Radio frequency sensed, switched reverse path tap

Abstract

A bidirectional communications system is provided for sending signals along a cable in a forward path from a central location to a plurality of remote receiver locations and for sending return signals along the same cable in a reverse path from the remote receiver locations to the central location. The communications system includes a plurality of taps placed along the cable for splitting the signals to be sent to the remote receiver locations, and a radio frequency sensed switch placed at each of the plurality of taps for sensing the return signals so as to turn on the reverse path when the return signals are present and to turn off the reverse path when no return signals are present.

What is claimed is: 
     
       1. A bidirectional communications system wherein signals are sent along a cable in a forward path from a central location to a plurality of remote receiver locations and return signals are sent along the same cable in a reverse path from the remote receiver locations to the central location, the communications system comprising: a plurality of taps placed along the cable for splitting the signals to be sent to the remote receiver locations, wherein at least one tap includes a radio frequency (RF) sensed switch for enabling the reverse path when return signals from the remote receiver locations coupled to the at least one tap are present and for disabling the reverse path when no return signals from the remote receiver locations coupled to the at least one tap are present.   
     
     
       2. The communications system of claim 1, wherein the at least one tap comprises: a power supply for providing power to the RF sensed switch.   
     
     
       3. The communications system of claim 1, wherein approximately four to eight remote receiver locations are connected at each of said plurality of taps, including the at least one tap. 
     
     
       4. The communications system of claim 1, wherein the communications system is a cable television system. 
     
     
       5. The communications system of claim 4, wherein the central location is a headend. 
     
     
       6. The communications system of claim 4, further comprising: subscriber equipment located at the remote receiver locations.   
     
     
       7. A method of minimizing reverse noise ingress in a reverse path of a bidirectional communications system wherein signals are sent along a cable in a forward path from a central location to a plurality of remote receiver locations, and return signals are sent along the cable in the reverse path from the remote receiver locations to the central location, the method comprising the steps of: placing a tap along the cable for splitting signals to be sent in the forward path to subscriber equipment located at remote receiver locations coupled to the tap, wherein the tap includes an RF sensed switch for selectively enabling the return signals through the tap;   operating the RF sensed switch to enable the reverse path through the tap when a return signal from the subscriber equipment is present; and   operating the RF sensed switch to disable the reverse path through the tap when no return signal from the subscriber equipment is present.   
     
     
       8. The method of claim 7, further comprising the step of placing approximately four to eight remote receiver locations at the tap. 
     
     
       9. The method of claim 7, further comprising the step of determining that signal energy in the reverse path of the tap exceeds a predetermined threshold, in response to which the enabling step occurs. 
     
     
       10. The method of claim 7, wherein the disabling step is a default condition that occurs automatically. 
     
     
       11. A tap for use in a cable television system, the tap comprising: a forward path for routing RF signals to output terminals to which subscriber equipment is coupled;   a reverse path for routing signals from the subscriber equipment to the cable television system; and   an RF sensed switch for selectively enabling the reverse path in response to detecting the presence of a signal from the subscriber equipment.   
     
     
       12. The tap of claim 11, further comprising: a direct current power supply coupled to the RF sensed switch for providing power thereto.   
     
     
       13. The tap of claim 11, wherein the forward path comprises: a directional coupler for splitting off the RF signals from the cable television system;   a filter coupled to the directional coupler for filtering the RF signals; and   a multiple output splitter for dividing the RF signals for transmission to the output terminals.   
     
     
       14. The tap of claim 11, wherein the reverse path comprises: a filter for filtering return signals from the subscriber equipment; and   a detector for controlling the RF sensed switch.   
     
     
       15. The tap of claim 11, further comprising: a detector for detecting the presence of a return signal from the subscriber equipment in response to which a control signal is provided by the detector to the RF sensed switch to enable the reverse path.   
     
     
       16. The tap of claim 15, further comprising: a threshold adjuster coupled to the detector for setting a threshold, wherein the detector provides the control signal in response to determining that return signal energy exceeds the threshold