EP0094794A2
Expired / Lapsed
EP
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Communications system
Assignee: Communications Patents Ltd
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Filing: 1983-05-12
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Granted: —
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Expires: 2003-05-12
Abstract
Abstract A communications system comprising at least one exchange, television signal sources located at the exchange, subscriber units each connected to the exchange by a respective direct communications link and provided with a television signal receiver, and selectors located at the exchange for selectively connecting the television signal sources to the communications links. The subscriber units have transmitters for applying data signals to their respective communications links for transmission to the exchange to control the selectors and for transmitting general data to the exchange. The subscriber units may each comprise two subscriber stations each of which has a respective television receiver and data signal transmitter. Each subscriber station is associated with a respective exchange-located selector controlled by that subscriber stations transmitter. Signals transmitted to the subscriber stations are frequency division multiplexed, each subscriber station receiver being tuned to receive a respective one of the FDM signals. Signals transmitted to the exchange are time division multiplexed under the control of a timing signal transmitted from the exchange, the exchange being responsive to said timing signal to identify the source of data signals received from each one subscriber unit.
Inventors
- 👤 Eric John Gargini
- 👤 Henry Louis Baker
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 11:24
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/025; H04N7/03; H04N21/00; H04N21/40; H04N21/47; H04N21/488; H04N21/4888; H04N7/08; H04N7/087; H04N7/088; H04N7/0888; H04N7/10; H04N7/16; H04N7/173; H04N7/17309; H04N7/17345; H04N7/17354; H04N2007/17372
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
180 words
A communications system comprising at least one exchange, a plurality of television signal sources making signals available at the exchange, a plurality of subscriber units each connected to the exchange by a respective direct communications link and each provided with a television signal receiver, and selectors located at the exchange for selectively connecting the television signal sources to the communications links, the subscriber units having transmitters for applying data signals to the respective communications links for transmission to the exchange to control the selectors, wherein each subscriber unit is associated with a respective exchange located selector controlled by that subscriber units transmitter, the selector associated with said at least one subscriber unit applying television signals to the respective communications link at a frequency to which the subscriber units receiver is tuned, and the subscriber unit transmitter being responsive to a timing signal transmitted on the communications link from the exchange to apply data signals to the respedive communications link, the exchange comprising means responsive to said timing signal to identify the source of data signals received from the subscriber units.
Claim 2
Dependent Claim
180 words
A communications system comprising at least one exchange, a plurality of television signal sources making signals available at the exchange, a plurality of subscriber units each connected to the exchange by a respective direct communications link and each provided with a television signal receiver, and selectors located at the exchange for selectively connecting the television signal sources to the communications links, the subscriber units having transmitters for applying data signals to the respective communications links for transmission to the exchange to control the selectors, wherein each subscriber unit is associated with a respective exchange located selector controlled by that subscriber units transmitter, the selector associated with said at least one subscriber unit applying television signals to the respective communications link at a frequency to which the subscriber units receiver is tuned, and the subscriber unit transmitter being responsive to a timing signal transmitted on the communications link from the exchange to apply data signals to the respedive communications link, the exchange comprising means responsive to said timing signal to identify the source of data signals received from the subscriber units.
Claim 3
Dependent Claim
142 words
A communications system according to claim 1, wherein at least one of the subscriber units comprises two subscriber stations each of which has a respective television receiver and data signal transmitter, and each subscriber station is associated with a respective exchange located selector controlled by that subscriber stations transmitter,sthe selectors associated with the subscriber stations of said at least one subscriber unit applying frequency division multiplexed television signals to the respective communications link, each subscriber station receiver being tuned to receive a respective one of the television ' signals applied to the communications link, and the subscriber station transmitters being responsive at different times to the timing signal to apply time division multiplexed data signals to the communications link, whereby the means at the exchange responsive to the timing signal can identify the source of data signals received on the communications link.
Claim 4
Dependent Claim
100 words
A communications system according to claim 2, wherein the exchange comprises a timing signal transmitter providing an AC timing signal periodically clamped to each of a plurality of DC voltages in a predetermined sequence, each subscriber station of said one subscriber unit comprises means for detecting a respective one of the plurality of DC voltages, and means for transmitting data signals to the exchange at a predetermined time related to the timing of the detected DC voltage, and the exchange comprises means for correlating received data signals and the timing signal to identify the source of the received data signals:.
Claim 5
Dependent Claim
29 words
A communications system according to claim 3, wherein each subscriber station comprises means for deriving power for its data signal transmitter from the AC component of the timing signal.
Claim 6
Dependent Claim
33 words
A communications system according to claim 3 or 4, wherein said one subscriber unit comprises three subscriber stations and the timing signal is periodically clamped to each of three DC voltages in turn.
Claim 7
Dependent Claim
46 words
A communications system according to claim 5, wherein the AC component of the timing signal is biased to a first DC voltage, the three DC clamping voltages being this first voltage and the positive and negative peaks of the AC component relative to this first voltage.
Claim 8
Dependent Claim
38 words
A communications system according to any one of claims 3 to 6, wherein the data signal transmitter of each subscriber station when transmitting superimposes on the timing signal data signals in the form of binary coded DC voltages.
Claim 9
Dependent Claim
77 words
A communications system according to any one of claims 3 to 7, wherein the exchange comprises a filter for detecting data signals received from the said one subscriber unit, a switching network for selectively applying detected data signals to respective ones of its outputs, and means for controlling the switching network in response to the timing signal such that data signals from any one subscriber station are applied to a respective one of the switching network outputs.
Claim 10
Dependent Claim
42 words
A communications system according to any one of claims 2 to 8, wherein the exchange comprises a store in respect of each subscriber station into which received data signals are written and means for periodically reading out the content of the stores.
Claim 11
Dependent Claim
55 words
A communications system according to claim 9, wherein each store comprises two sections, the first section storing data signals not related to selector control and the second section storing selector control data signals, and each subscriber station data signal transmitter comprises means for indicating whether or not transmitted data signals constitute selector control data signals.
Claim 12
Dependent Claim
67 words
A communications system according to claim 10, wherein each subscriber station data transmitter comprises a keypad having twelve keys, ten of the keys indicating decimal numbers and the other two keys indicating selector control and not selector control data signals respectively, the exchange store being responsive only to data signals including as a first element the data signal resulting from actuation of one of said two keys.
Claim 13
Dependent Claim
51 words
A-communications system according to claim 11, wherein none of the data signals resulting from actuation of any of said two keys of the subscriber stations of said one subscriber unit are the same and the store is adapted to reject selector control data signals not preceded by the appropriate first element.
Claim 14
Dependent Claim
86 words
A communications system according to claim 10, 11 or 12, wherein the second section of the store comprises two subsections for receiving first and second elements of a selector control data signal, and each subscriber stations selector comprises a first stage arranged to select any one of a plurality of groups of television signals and a second stage arranged to select any one of the selected group of television signals, the first and second selector stages being responsive to respective ones of the two store subsections.
Claim 15
Dependent Claim
96 words
A communications system according to any one of claims 2 to 13, comprising a plurality of exchanges each connected to a head end installation by a trunk communications network, wherein each exchange comprises a store in respect of each subscriber station in which data transmitted to the exchange from that subscriber station is stored, and means are provided for sequentially addressing the stores to read out the stored data onto the communications link in a time division multiplexed data stream, the source of the read out data being identified by its position in the data stream.
Claim 16
Dependent Claim
106 words
A communications system according to claim 14, wherein the exchanges are connected in groups to a plurality of data concentrators that are in turn connected to the head end installation, each data concentrator comprising means for storing data received from the head end to indicate which television channels are to be accessible to individual subscriber stations, means for storing data received from the exchanges indicative of television channels selected by individual subscriber stations, means for comparing the stored data, and means for transmitting signals to the exchanges to control the subscriber stations selectors to prevent access to television channels to which access is to be prevented.
Claim 17
Dependent Claim
43 words
A communications system according to claim 15, wherein the data concentrator comprises means for assembling data received from the exchanges, and means for releasing the assembled data to the head end installations in time slots specific to the source of the received data.
Claim 18
Dependent Claim
71 words
A communications system according to any preceding claim, wherein at least one subscriber unit is provided with a teletext receiver, means are provided for supplying teletext signals on one television channel of the system, and said at least one subscriber unit is allocated exclusive use of one teletext sub-page, the content of the said one sub-page being responsive only to data signals supplied by the said at least one subscriber unit.
Claim 19
Dependent Claim
66 words
A communications system according to claim 17, wherein one television channel is dedicated to full field teletext signals, and a second channel is dedicated to provide interactive services, selection of the second channel by the said at least one subscriber unit automatically switching the associated receiver to its teletext mode, and selection of the said one sub-page of teletext giving access to the said interactive services.
Claim 20
Dependent Claim
26 words
A communications system according to claim 18, wherein use of the interactive services is denied unless the subscriber transmits a predetermined PIN number over the system.
Claim 21
Dependent Claim
111 words
A communications system according to claim 17, wherein a first television channel is dedicated to full field teletext signals, and a second channel is dedicated to provide interactive services, means being provided such that if the said one subscriber unit transmits data over the system in response to information on the second channel a system response is transmitted on the sub-page of teletext dedicated to that subscriber unit, the subscriber units selector at the exchange being automatically controlled to momentously connect the teletext receiver to the said first channel such that the data transmitted on the dedicated sub-page is acquired and inlaid on the picture received from the said second channel.
Claim 22
Dependent Claim
93 words
A communications system comprising a plurality of subscriber units each connected to a communications network capable of delivering any one of a plurality of different signals on respective television channels, wherein at least one subscriber unit is provided with a teletext receiver, means are provided for supplying teletext signals on one television channel of the system, and said at least one subscriber unit is allocated exclusive use of one teletext sub-page, the content of the said one sub-page being responsive only to data signals supplied by the said at least one subscriber unit.
Claim 23
Dependent Claim
93 words
A communications system comprising a plurality of subscriber units each connected to a communications network capable of delivering any one of a plurality of different signals on respective television channels, wherein at least one subscriber unit is provided with a teletext receiver, means are provided for supplying teletext signals on one television channel of the system, and said at least one subscriber unit is allocated exclusive use of one teletext sub-page, the content of the said one sub-page being responsive only to data signals supplied by the said at least one subscriber unit.
Claim 24
Dependent Claim
111 words
A communications system according to claim 21, wherein a first television channel is dedicated to full field teletext signals, and a second channel is dedicated to provide interactive services, means being provided such that if the said one subscriber unit transmits data over the system in response to information on the second channel a system response is transmitted on the sub-page of teletext dedicated to that subscriber unit, the subscriber units selector at the exchange being automatically controlled to momentarily connect the teletext receiver to the said first channel such that the data transmitted on the dedicated sub-page is acquired and inlaid on the picture received from the said second channel.
References Cited (Backward Citations)
No citation records indexed.
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