Cable television two-way communication system

Claim 2

A two-way communications system including a central station and a plurality of remote stations coupled to a coaxial cable with said remote stations arranged to be polled by the central station, first means at said central station for transmitting polling signals in a first frequency encoded logic bit form over the cable to said remote stations, each polling signal including an address code-word peculiar to one remote station, each of said remote stations comprising a shift register, means for demodulating the frequency encoded signal and applying the demodulated signal serially to said register, a return message register for storing information in logic bit form indicative of a condition at the remote station, means coupled to said shift register for identifying the address of a demodulated signal therein, means responsive to said identifying means for transferring data in said return message register to said shift register, second transmitting means for serially frequency encoding the data in said shift register at a second frequency, and means for shifting data in said shift register to said second transmitter, the output of said second transmitter being coupled to the cable.

Claim 3

A two-way communications system for use on a television cable comprising a central station and a plurality of user terminals connected to said cable, means at said central station for transmitting polling signals in a first frequency encoded logic bit form over said cable, each of said polling signals containing an address code of one user terminal, each of said user terminals including means for demodulating each polling signal to logic bit form, a shift register for receiving the demodulated polling signal, means for identifying a demodulated polling signal addressed to that user terminal, a video signal frequency converter, a user register adapted to store data in logic bit form indicative of at least one condition of the frequency converter, means responsive to said identifying means for transferring data in said user registEr to said shift register in parallel, a modulator for serially frequency encoding the data in said shift register, means for shifting the contents of the shift register to said modulator, said modulator being operable at a second frequency lower than said first frequency, and means for applying the output of said modulator to the cable.

Claim 4

A two-way communications system for use on a television cable comprising a central station and a plurality of user terminals connected to said cable, means at said central station for transmitting polling signals in a first frequency encoded logic bit form over said cable, each of said polling signals containing an address code of one user terminal, each of said user terminals including means for demodulating each polling signal to logic bit form, a shift register for receiving the demodulated polling signal, means for identifying a demodulated polling signal addressed to that user terminal, a video signal frequency converter, a user register adapted to store data in logic bit form indicative of at least one condition of the frequency converter, means responsive to said identifying means for transferring data in said user registEr to said shift register in parallel, a modulator for serially frequency encoding the data in said shift register, means for shifting the contents of the shift register to said modulator, said modulator being operable at a second frequency lower than said first frequency, and means for applying the output of said modulator to the cable.

Claim 5

For use in combination with a coaxial cable transmission medium for providing video signals together with messages including single user addresses to individual ones of a plurality of user terminals where the messages are transmitted on said cable in frequency encoded serial data bits together with frequency encoded clock pulses; a user terminal comprising means for demodulating the frequency encoded bits and clock pulses to serial logic level pulses and local clock pulses synchronous with the transmitted clock pulses, a shift register, means for applying the demodulated logic level pulses serially to said shift register in time with the clock pulse, means responsive to data in said shift register for identifying a message to the user terminal, a user register for storing data in logic bit form, means responsive to said identifying means for transferring the data in said user register to said shift register, and a modulator coupled to said shift register and said clock pulses adapted to frequency encode data from said shift register, and transmit return messages to the cable.

Claim 6

For use in combination with a coaxial cable transmission medium for providing video signals together with messages including single user addresses to individual ones of a plurality of user terminals where the messages are transmitted on said cable in frequency encoded serial data bits together with frequency encoded clock pulses; a user terminal comprising means for demodulating the frequency encoded bits and clock pulses to serial logic level pulses and local clock pulses synchronous with the transmitted clock pulses, a shift register, means for applying the demodulated logic level pulses serially to said shift register in time with the clock pulse, means responsive to data in said shift register for identifying a message to the user terminal, a user register for storing data in logic bit form, means responsive to said identifying means for transferring the data in said user register to said shift register, and a modulator coupled to said shift register and said clock pulses adapted to frequency encode data from said shift register, and transmit return messages to the cable.

Claim 7

The arrangement of claim 2 wherein the messages transmitted to said user terminals are polling signals to determined if any data is stored in said user registers.

Claim 8

The arrangement of claim 4 wherein said polling signals transmitted to said user terminal are transmitted at a frequency above the VHF video frequency range.

Claim 9

The arrangement of claim 3 wherein the data in said shift register including the station address are transmitted to said cable at a second frequency below the VHF video frequency range.

Claim 10

The combination of claim 2 wherein said polling signals are sequentially transmitted to each of said user terminals.

Claim 11

The combination of claim 7 wherein each of said user terminals has a different address.

Claim 12

The combination of claim 2 wherein said user terminals are arranged in groups connected to separate branch cables, each of the user terminals on a branch cable having a return frequency different from those of other branch cables.

Claim 13

In a system including a transmitter arranged to transmit video signals over a coaxial cable and transmit messages including single user addresses to individual ones of a plurality of user terminals where the messages are transmitted in frequency encoded serial data bits together with frequency encoded clock pulses; a user terminal comprising a video signal frequency converter having a video channel selector, means for demodulating the frequency encoded bits to serial logic level bits and local clock pulses, a shift register, means for applying the demodulated bits serially to said shift register under control of the local clock pulses, means responsive to data in said shift register for identifying a message to the user terminal, a user register adapted to store data in logic level bit form representative of a condition at the user terminal and including the video channel selected by said converter selector, means responsive to said identifying means for transferring the data in said user register to said shift register, a modulator adapted to frequency encode logic level bits, and means for applying the logic level bits in said shift register to said modulator under control of the local clock pulses to provide a return message, the output of said modulator being coupled to said cable.

Claim 14

In a system including a transmitter arranged to transmit video signals over a coaxial cable and transmit messages including single user addresses to individual ones of a plurality of user terminals where the messages are transmitted in frequency encoded serial data bits together with frequency encoded clock pulses; a user terminal comprising a video signal frequency converter having a video channel selector, means for demodulating the frequency encoded bits to serial logic level bits and local clock pulses, a shift register, means for applying the demodulated bits serially to said shift register under control of the local clock pulses, means responsive to data in said shift register for identifying a message to the user terminal, a user register adapted to store data in logic level bit form representative of a condition at the user terminal and including the video channel selected by said converter selector, means responsive to said identifying means for transferring the data in said user register to said shift register, a modulator adapted to frequency encode logic level bits, and means for applying the logic level bits in said shift register to said modulator under control of the local clock pulses to provide a return message, the output of said modulator being coupled to said cable.

Claim 15

The system of claim 2 further including means at said user terminals for disabling said frequency converter.

Claim 16

In a system for use in the transmission of video signals including a main cable connected to a central station, said central station including means to transmit a plurality of video Signals over said cable and messages to individual user stations coupled to the cable in frequency encoded logic level bit form together with frequency encoded clock pulses, each transmitted message including an address peculiar to one user station, a plurality of remote user stations coupled to said cable; each of said user stations including a video frequency converter and channel selector adapted to tune to selected video channels; each user station comprising means for demodulating a transmitted message to serial logic level bits and the frequency encoded clock pulses to local clock pulses, a storage register responsive to the local clock pulses for serially receiving the logic level pulses, means responsive to the message in said storage register for identifying a message to the addressed remote station, a return register adapted to store information derived at the remote station in logic level bit form, means responsive to said identifying means for transferring the information in said return register to said storage register, a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting to the cable in frequency encoded serial form the data content of said storage register and the clock pulses, and means for encoding the position of said converter channel selector and applying the encoded position to said return register.

Claim 17

In a system for use in the transmission of video signals including a main cable connected to a central station, said central station including means to transmit a plurality of video Signals over said cable and messages to individual user stations coupled to the cable in frequency encoded logic level bit form together with frequency encoded clock pulses, each transmitted message including an address peculiar to one user station, a plurality of remote user stations coupled to said cable; each of said user stations including a video frequency converter and channel selector adapted to tune to selected video channels; each user station comprising means for demodulating a transmitted message to serial logic level bits and the frequency encoded clock pulses to local clock pulses, a storage register responsive to the local clock pulses for serially receiving the logic level pulses, means responsive to the message in said storage register for identifying a message to the addressed remote station, a return register adapted to store information derived at the remote station in logic level bit form, means responsive to said identifying means for transferring the information in said return register to said storage register, a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting to the cable in frequency encoded serial form the data content of said storage register and the clock pulses, and means for encoding the position of said converter channel selector and applying the encoded position to said return register.

Claim 18

A remote station for use with a two-way communications system which includes a transmitter at a central station which transmits over a coaxial cable to a plurality of remote stations connected in parallel to said cable and where each remote station has an identifying address peculiar to that station, said transmitter transmitting frequency encoded serial data bits and clock pulses on a carrier, said data bits identifying the address of one remote station; each remote station comprising means for demodulating the frequency encoded data bits to serial logic level pulses and the frequency encoded clock pulses to local clock pulses, a storage register responsive to the local clock pulses for serially receiving the logic level pulses, means responsive to the address in said storage register for identifying a message to the addressed remote station, a return register for storing information at the remote station in logic level bit form, means responsive to said identifying means for transferring the information in said return register to said storage register, and a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting in frequency encoded serial form the content of said storage register to the cable.

Claim 19

A remote station for use with a two-way communications system which includes a transmitter at a central station which transmits over a coaxial cable to a plurality of remote stations connected in parallel to said cable and where each remote station has an identifying address peculiar to that station, said transmitter transmitting frequency encoded serial data bits and clock pulses on a carrier, said data bits identifying the address of one remote station; each remote station comprising means for demodulating the frequency encoded data bits to serial logic level pulses and the frequency encoded clock pulses to local clock pulses, a storage register responsive to the local clock pulses for serially receiving the logic level pulses, means responsive to the address in said storage register for identifying a message to the addressed remote station, a return register for storing information at the remote station in logic level bit form, means responsive to said identifying means for transferring the information in said return register to said storage register, and a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting in frequency encoded serial form the content of said storage register to the cable.

Claim 20

The system of claim 13 wherein said storage register is a serial shift register, and said means for transferring data in said return register to said shift register transfers such data in parallel.

Claim 21

For use in combination with a central station which transmits over a coaxial cable to a plurality of remote stations connected in parallel to said cable and where each remote station has an identifying address peculiar to that station and the central station has transmitting means for transmitting on said cable a polling message in frequency encoded serial data bits and clock pulses on a carrier, each message, including an address peculiar to one remote station; a remote station, said remote station including means for demodulating the frequency encoded data bits to serial logic level bits and the frequency encoded clock pulses to local clock pulses, a storage register having a plurality of stages and responsive to the local clock pulses for serially receiving the logic level bits in said stages, means responsive to the logic level bits in said storage register for identifying a message to the addressed remote station, a return register having a plurality of stages for storing information indicative of a condition at the remote station in logic level bit form, means responsive to said identifying means for transferring the informatIon in said return register to said storage register, and a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting in frequency encoded serial data bits the content of said storage register to said cable.

Claim 22

For use in combination with a central station which transmits over a coaxial cable to a plurality of remote stations connected in parallel to said cable and where each remote station has an identifying address peculiar to that station and the central station has transmitting means for transmitting on said cable a polling message in frequency encoded serial data bits and clock pulses on a carrier, each message, including an address peculiar to one remote station; a remote station, said remote station including means for demodulating the frequency encoded data bits to serial logic level bits and the frequency encoded clock pulses to local clock pulses, a storage register having a plurality of stages and responsive to the local clock pulses for serially receiving the logic level bits in said stages, means responsive to the logic level bits in said storage register for identifying a message to the addressed remote station, a return register having a plurality of stages for storing information indicative of a condition at the remote station in logic level bit form, means responsive to said identifying means for transferring the informatIon in said return register to said storage register, and a local transmitter coupled to said storage register and to the local clock pulses of said demodulator for transmitting in frequency encoded serial data bits the content of said storage register to said cable.

Claim 23

The remote station of claim 15 wherein data in said return register is transfered to said storage register in parallel.

Claim 24

The system of claim 15 further including a signal responsive device at said remote station and means at said remote station responsive to an identified polling message for controlling operation of said signal responsive device.

Claim 25

The system of claim 15 further including a video signal frequency converter at said remote station, said return register arranged to store data indicative of a condition of said converter.