Subscription television system and switching station therefor

Claim 2

In a subscription television system wherein television signals are distributed via a cable, a switching station comprising: coupling means for connection to said cable for receiving a composite signal including television signals and interrogation signals; signal splitting means connected to said coupling means for separating the received signals; switching means connected to said signal splitting means for receiving said television signals and for coupling said television signals therethrough in response to a switching signal; output means connected to said switching means for providing signals to a subscriber drop cable; sensing means connected to said output means and to said switching means for providing a switching signal to said switching means when the presence of a subscriber demand signal from the subscriber drop cable is detected thereby; and interrogating means connected to said coupling means, said signal splitting means, and said sensing means for providing a signal to said coupling means indicative of the signal from said sensing means in response to said interrogation signals.

Claim 3

A switching station as defined in claim 1 wherein said sensing means includes means for detecting switching of a switch coupled to said output means.

Claim 4

A switching station as defined in claim 1 wherein said television signals include subscription and non-subscription television signals, said signal splitting means separates said subscription television signals from said non-subscription television signals and couples said subscription television signals to said switching means, and said output means includes signal combining means connected to said switching means and said signal splitting means for recombining said subscription and non-subscription television signals.

Claim 5

A switching station as defined in claim 1 wherein said interrogating means includes receiving means connected to said signal splitting means for detecting said interrogation signals, signal generating means connected to said sensing means and to said receiving means for providing a signal indicative of the signal from said sensing means in response to a signal from said receiving means, and modulating means connected to said signal generating means and to said coupling means for modulating the signal from said signal generating means and for providing the modulated signal to said coupling means.

Claim 6

A switching station as defined in claim 1 wherein said television signals include first and second subscription television signals, said switching means includes first and second switching circuits connected to said signal splitting means for receiving said first and second subscription television signals, respectively, said sensing means includes first and second detecting circuits for detecting the presence of first and second subscriber demand signals, respectively, for providing switching signals to said first and second switching circuits, respectively, and a signal provided by said interrogating means is indicative of the signals provided by said first and second detecting circuits.

Claim 7

A switching station as defined in claim 1 wherein said switching means includes a PIN diode switching circuit.

Claim 8

A switching station as defined in claim 6 wherein said switching circuit includes first and second PIN diodes connected between an input and an output of said switching circuit, third and fourth PIN diodes connected tO said input of said switching circuit for providing a simulated load, and means coupling said switching signal to each of said PIN diodes for forward biasing said first and second PIN diodes and reverse biasing said third and fourth PIN diodes when a subscriber demand signal is detected and for reversing the bias on each of said PIN diodes when no subscriber demand signal is detected.

Claim 9

In a subscription television system wherein subscription and non-subscription television signals are distributed from a central station via a cable distribution network to a plurality of subscribers, a switching station comprising: first coupling means for connection to said cable for receiving a composite signal including said television signals and interrogation signals from said cable and for providing return signals to said cable; signal splitting means connected to said first coupling means for separating the received signals; a plurality of switching means each connected to said signal splitting means for receiving said subscription television signals therefrom; a plurality of signal combining means each connected to said signal splitting means for receiving said non-subscription television signals and to respective ones of said switching means; a plurality of second coupling means connected to respective ones of said signal combining means for providing television signals to respective subscriber drops; a plurality of sensing means connected to respective ones of said second coupling means and to respective ones of said switching means each for providing a switching signal to the corresponding one of said switching means when the presence of a subscriber demand signal is detected thereby; and interrogating means connected to said signal splitting means for receiving said interrogation signals therefrom, to each of said sensing means, and to said first coupling means for providing a return signal indicative of the signals from said sensing means in response to said interrogation signals.

Claim 10

In a subscription television system wherein subscription and non-subscription television signals are distributed from a central station via a cable distribution network to a plurality of subscribers, a switching station comprising: first coupling means for connection to said cable for receiving a composite signal including said television signals and interrogation signals from said cable and for providing return signals to said cable; signal splitting means connected to said first coupling means for separating the received signals; a plurality of switching means each connected to said signal splitting means for receiving said subscription television signals therefrom; a plurality of signal combining means each connected to said signal splitting means for receiving said non-subscription television signals and to respective ones of said switching means; a plurality of second coupling means connected to respective ones of said signal combining means for providing television signals to respective subscriber drops; a plurality of sensing means connected to respective ones of said second coupling means and to respective ones of said switching means each for providing a switching signal to the corresponding one of said switching means when the presence of a subscriber demand signal is detected thereby; and interrogating means connected to said signal splitting means for receiving said interrogation signals therefrom, to each of said sensing means, and to said first coupling means for providing a return signal indicative of the signals from said sensing means in response to said interrogation signals.

Claim 11

A switching station as defined in claim 8 wherein each of said sensing means includes means for detecting switching of a switch coupled to the respective one of said second coupling means.

Claim 12

A switching station as defined in claim 8 wherein each of said switching means includes first and second switching circuits connected to said signal splitting means for receiving respective ones of first and second subscription television signals, each of said sensing means includes first and second detecting circuits connected to respective ones of said first and second switching circuits for providing a switching signal to the corresponding one of said switching circuits upon detecting the presence of first and second subscriber demand signals, respectively, and said interrogating means provides a return signal indicative of the signals provided by said first and second detecting circuits of each of said sensing means.

Claim 13

A switching station as defined in claim 10 wherein each of said switching circuits includes a first PIN diode connected between an input and an output thereof, a second PIN diode connected between the input and a reference point for providing a simulated load, and means coupling said switching signal to said first and second PIN diodes for forward biasing said first PIN diode and reverse biasing said second PIN diode when a subscriber demand signal is detected and for reversing the bias on said first and second PIN diodes when no subscriber demand signal is detected.

Claim 14

A switching station as defined in claim 8 wherein each of said sensing means includes a first detecting circuit connected to the respective one of said switching means for providing a signal thereto when the presence of a subscriber demand signal is detected, and a second detecting circuit for providing a signal when the presence of a subscriber alarm signal is detected, and said interrogating means provides a return signal indicative of the signals froM said first and second detecting means.

Claim 15

A switching station as defined in claim 12 wherein each of said sensing means includes first and second signal generators for generating first and second signals and said first and second detector circuits detect modification of the first and second signals by switching of switches coupled to the corresponding subscriber drop.

Claim 16

A switching station as defined in claim 8 wherein said interrogating means includes receiving means connected to said signal splitting means for detecting said interrogation signals, signal generating means connected to each of said sensing means and to said receiving means for providing a a signal indicative of the signals from each of said sensing means, and modulating means connected to said signal generating means and to said first coupling means for modulating the signal from said signal generating means and for providing the modulated signal to said first coupling means.

Claim 17

A switching station as defined in claim 14 wherein said signal generating means includes a shift register having a plurality of stages wherein the state of each stage is controlled by the corresponding signal from one of the sensing means and the signal provided by said signal generating means is provided by shifting said shift register.

Claim 18

A cable television system for distributing subscription and non-subscription television signals comprising: first signal generating means for providing a plurality of nonsubscription televison signals and at least one subscription television signal; second signal generating means for sequentially providing a plurality of coded interrogation signals; a cable distribution network connected to said first and second signal generating means for distributing said television signals and said interrogation signals to a plurality of locations; a plurality of switching stations each at a respective one of said locations and each including coupling means connected to receive said telivision signals and said interrogation signals from said cable distribution network, signal splitting means connected to said input means for separating said subscription television signal, said non-subscription television signals, and said interrogation signals, a plurality of subscriber controlled switching means each connected to said signal splitting means for receiving said subscription telivision signals therefrom, a plurality of output means each including signal combining means and each connected to said signal splitting means and to a respective one of said switching means for combining said non-subscription television signals with subscription television signals from the corresponding one of said switching means and for coupling the combined signal to a subscriber drop, a plurality of sensing means each connected to a respective one of said output means for detecting the presence of a subscriber demand signal received via the corresponding subscriber drop and connected to the corresponding one of said switching means for providing a switching signal thereto, and interrogating means connected to each of said sensing means for receiving signals therefrom and connected to said signal splitting means for receiving the interrogation signals therefrom and for providing a return signal to said coupling means indicative of the signals provided by each of said sensing means in response to an interrogation signal with a particular code; and return signal receiving means connected to receive the return signals via said distribution network from each of said plurality of switching stations.

Claim 19

A cable television system for distributing subscription and non-subscription television signals comprising: first signal generating means for providing a plurality of nonsubscription televison signals and at least one subscription television signal; second signal generating means for sequentially providing a plurality of coded interrogation signals; a cable distribution network connected to said first and second signal generating means for distributing said television signals and said interrogation signals to a plurality of locations; a plurality of switching stations each at a respective one of said locations and each including coupling means connected to receive said telivision signals and said interrogation signals from said cable distribution network, signal splitting means connected to said input means for separating said subscription television signal, said non-subscription television signals, and said interrogation signals, a plurality of subscriber controlled switching means each connected to said signal splitting means for receiving said subscription telivision signals therefrom, a plurality of output means each including signal combining means and each connected to said signal splitting means and to a respective one of said switching means for combining said non-subscription television signals with subscription television signals from the corresponding one of said switching means and for coupling the combined signal to a subscriber drop, a plurality of sensing means each connected to a respective one of said output means for detecting the presence of a subscriber demand signal received via the corresponding subscriber drop and connected to the corresponding one of said switching means for providing a switching signal thereto, and interrogating means connected to each of said sensing means for receiving signals therefrom and connected to said signal splitting means for receiving the interrogation signals therefrom and for providing a return signal to said coupling means indicative of the signals provided by each of said sensing means in response to an interrogation signal with a particular code; and return signal receiving means connected to receive the return signals via said distribution network from each of said plurality of switching stations.

Claim 20

A system as defined in claim 16 further including a switch in each subscriber location coupled to the respective one of said sensing means, and wherein each of said sensing means detects switching of the corresponding switch.

Claim 21

A system as defined in claim 16 wherein said first signal generating means provides a plurality of subscription television signals, said signal splitting means separAtes said plurality of subscription television signals into separate signals, each of said switching means includes a plurality of switching circuits each connected to said signal splitting means for receiving a respective one of said plurality of subscription television signals, each of said sensing means includes a plurality of detecting circuits connected to said interrogating means and to respective ones of said switching circuits for detecting the presence of respective ones of a plurality of subscriber demand signals, and said interrogating means provides a return signal indicative of the signal from each of said plurality of detecting circuits.

Claim 22

A system as defined in claim 18 further including a plurality of subscriber demand signal generators each including a switch for providing said demand signals to said detecting circuits upon switching of the corresponding one of said switches.

Claim 23

A system as defined in claim 19 wherein said subscriber demand signal generators are located in said switching station and the corresponding switches are located in the corresponding subscriber''s premises.

Claim 24

A system as defined in claim 19 wherein said subscriber demand signal generators are located in the corresponding subscriber''s premises.

Claim 25

A system as defined in claim 16 wherein said interrogating means includes receiving means connected to said signal splitting means for detecting said interrogation signals, signal generating means connected to each of said sensing means and to said receiving means for providing a signal indicative of the signals from each of said sensing means, and modulating means connected to said signal generating means and to said coupling means for modulating the signal from said signal generating means and for providing the modulated signal to said coupling means.

Claim 26

A system as defined in claim 22 wherein said signal generating means includes a shift register having a plurality of stages wherein the state of each stage is controlled by the corresponding signal from one of the sensing means and the signal provided by said signal generating means is provided by shifting said register.