Signal equalizer circuit for cable tap

Abstract

A cable television system (100) includes a head end section (105) for generating a cable signal; a communication medium (110, 117), such as fiber optic cable and coaxial cable, coupled to the head end section (105) for routing the cable signal through the cable television system (100), and cable taps (200) coupled to the communication medium (110, 117) for receiving the cable signal and providing subscriber drops to subscribers of the cable television system (100). As the cable signal is routed through the system (100), the signal levels of the signal decrease, and higher frequencies are attenuated more rapidly than are lower frequencies of the signal. Therefore, taps (200) of the cable television system (100) include equalizer circuits (212) for attenuating lower frequencies of the cable signal to provide relatively flat signal levels at the subscriber drops. The equalizer circuits (212) also conveniently attenuate reverse signals, as necessary, so that relatively equivalent reverse signal levels are seen by the headend section (105).

What is claimed is: 
     
       1. A tap for use in a cable television system, the tap comprising an input for receiving a forward cable signal and for transmitting a reverse cable signal;   an equalizer circuit coupled to the input for attenuating lower frequencies of the forward cable signal and the reverse cable signal; and   at least one output for providing the forward cable signal after processing by the equalizer circuit and for receiving the reverse cable signal from equipment to which the tap is coupled.   
     
     
       2. The tap of claim 1, further comprising: a directional coupler coupled to the input of the tap for receiving the forward cable signal, the directional coupler having an output for providing the forward cable signal to the equalizer circuit and a main output for providing the forward cable signal for processing by other cable equipment.   
     
     
       3. The tap of claim 1, wherein the at least one output comprises a plurality of subscriber outputs. 
     
     
       4. The tap of claim 1, wherein the equalizer circuit comprises a high pass filter. 
     
     
       5. A tap for use in a cable television system, the tap comprising: a tap input for receiving a forward cable signal and for transmitting a reverse cable signal;   a directional coupler coupled to the tap input and having a main output for providing the forward cable signal to other cable equipment and an equalizer output;   an equalizer circuit coupled to the equalizer output for attenuating lower frequencies of the forward cable signal and the reverse cable signal; and   subscriber outputs coupled to an output of the equalizer circuit for providing output signals, lower frequencies of which have been attenuated by the equalizer circuit and for receiving and providing reverse cable signals from subscribers to the equalizer output for subsequent processing by the equalizer circuit.   
     
     
       6. The tap of claim 5, wherein the equalizer circuit comprises a high pass filter. 
     
     
       7. A cable television system, comprising: a head end section for generating a forward cable signal;   a communication medium coupled to the head end section for routing the forward cable signal through the cable television system to subscriber equipment and for routing a reverse cable signal from the subscriber equipment to the head end section, wherein higher frequencies of the forward cable signal and the reverse cable signal are attenuated as the cable signal is routed; and   a tap coupled to the communication medium for receiving, at an input, the forward cable signal and for transmitting, at the input, the reverse cable signal, for attenuating lower frequencies of the forward cable signal and the reverse cable signal, for providing, at an output, at least one output signal, the lower frequencies of which have been attenuated by the tap, and for receiving, at the output, the reverse cable signal, which is attenuated by the tap prior to transmission over the communication medium to the head end section.   
     
     
       8. The cable television system of claim 7, wherein the tap comprises: an equalizer circuit for attenuating the lower frequencies of the forward cable signal and the reverse cable signal.   
     
     
       9. The cable television system of claim 8, wherein the tap further comprises: a directional coupler having an input coupled to the communication medium, a main output for forwarding the forward cable signal through the cable television system, and an equalizer output for providing the forward cable signal to the equalizer circuit.   
     
     
       10. The cable television system of claim 9, wherein the equalizer circuit comprises a high pass filter. 
     
     
       11. The cable television system of claim 9, wherein the tap further comprises a plurality of subscriber outputs for providing the forward cable signal after processing by the equalizer circuit. 
     
     
       12. The cable television system of claim 11, further comprising: amplifiers situated along the communication medium for amplifying the forward cable signal.   
     
     
       13. The tap of claim 1, wherein the reverse cable signal is within a frequency range of about 5 to 40 MHz, and wherein all frequencies of the reverse cable signal are attenuated by the equalizer circuit prior to the reverse cable signal being provided at the input for further transmission upstream in the cable television system. 
     
     
       14. The tap of claim 5, wherein the reverse cable signal is within a frequency range of about 5 to 40 MHz, and wherein all frequencies of the reverse cable signal are attenuated by the equalizer circuit prior to transmission of the reverse cable signal by the tap input. 
     
     
       15. The tap of claim 14, wherein the reverse cable signal is received by the tap via the subscriber outputs and is transmitted, after attenuation, upstream within the cable television system via the tap input. 
     
     
       16. The cable television system of claim 7, wherein the reverse cable signal is within a frequency range of about 5 to 40 MHz and is originated by subscriber equipment coupled to the output of the tap. 
     
     
       17. The cable television system of claim 16, wherein all frequencies of the reverse cable signal are attenuated by the tap prior to transmission of the reverse cable signal, via the input of the tap, upstream within the cable television system.