Interactive television and data transmission system
First Claim
1. A method of communicating information within an area served by a commercial broadcast station, said commercial broadcast station having a broadcast station transmitter and a broadcast station modulator for transmitting over the air on a broadcast station carrier and within a broadcast station frequency band comprising the steps of:
- (a) using a modulator other than said broadcast station modulator, modulating the information to be communicated by a carrier other than the broadcast station carrier;
(b) transmitting, from a transmitter other than the broadcast station transmitter, at least one sideband of the modulation of step (a);
(c) receiving at a remote location a signal containing the carrier of the broadcast station and the at least one sideband transmitted from the transmitter other than the broadcast station transmitter;
(d) demodulation t the remote location the signal received in step (c) using the carrier of the broadcast station as a reference to recover a signal corresponding to the signal transmitted in step (b), and;
(e) demodulating at the remote location the signal recovered in step (d) to recover the information to be communicated.
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Accused Products
Abstract
A spread spectrum system provides bidirectional digital communication on a vacant television (TV) channel for simultaneous use by more than 75,000 subscribers using time and frequency division multiplex signals locked to horizontal and vertical sync pulses of an adjacent channel Host TV station. The system, whose operation is analogous to a radar system, comprises (1) the Host TV station to send down-link sync and data pulses to subscribers during the horizontal blanking interval (HBI), (2) subscriber "transponders" which detect those signals and transmits up-link "echo" data pulses only during the HBI to eliminate interference to TV viewers, and (3) a central receiver which also uses the host TV sync pulses to trigger range gates to detect the up-link data pulses. In a preferred embodiment the central receiver employs directional antennas to determine direction to transponders and to define angular sectors partitioning the service area into pie-link "cells" which permit frequency re-use in non-contiguous sectors (like cellular radio). The system thus operates like a radar to measure elasped time between receipt of TV sync pulses and receipt of transponder response pulses and measures bearing to transponders to thereby determine the location of fixed or mobile subscribers as well as provide data links to them. Transponders may share user'"'"'s existing TV antenna or may operate on cable TV and could be packaged as "RF modems" for personal computers, as transceivers for mobile or portable use, or they may be integrated with a TV receiver to provide "interactive television".
424 Citations
57 Claims
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1. A method of communicating information within an area served by a commercial broadcast station, said commercial broadcast station having a broadcast station transmitter and a broadcast station modulator for transmitting over the air on a broadcast station carrier and within a broadcast station frequency band comprising the steps of:
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(a) using a modulator other than said broadcast station modulator, modulating the information to be communicated by a carrier other than the broadcast station carrier; (b) transmitting, from a transmitter other than the broadcast station transmitter, at least one sideband of the modulation of step (a); (c) receiving at a remote location a signal containing the carrier of the broadcast station and the at least one sideband transmitted from the transmitter other than the broadcast station transmitter; (d) demodulation t the remote location the signal received in step (c) using the carrier of the broadcast station as a reference to recover a signal corresponding to the signal transmitted in step (b), and; (e) demodulating at the remote location the signal recovered in step (d) to recover the information to be communicated. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of communicating information within an area served by a broadcast station transmitting on a broadcast station carrier and within a broadcast station frequency band comprising the steps of:
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(a) modulating the information to be communicated by a carrier other than the broadcast station carrier; (b) transmitting at least one side band of the modulation of step (a); (c) receiving at a remote location a signal containing the carrier of the broadcast station, and the at least one sideband transmitted in step (b); (d) demodulating the signal received in step (c) using the carrier of the broadcast station as a reference to recover a signal corresponding to the signal transmitted in step (b), and (e) demodulating the signal recovered in step (d) to recover the information to be communicated. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24)
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22. The method of claim 79 wherein said broadcast station has an antenna that is at the same location as an antenna for transmitting said at least one sideband.
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25. A method of receiving and recovering information transmitted within an area served by a broadcast station transmitting on a broadcast station carrier and within a broadcast station frequency band, the information as transmitted being modulated by a carrier other than the broadcast station carrier to form a modulated information signal, comprising the steps of;
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(a) receiving at a remote location a signal containing the carrier of the broadcast station and the modulated information signal; (b) demodulating the signal received in step (a) using the carrier of the broadcast station as a reference to recover the modulated information signal, and; (c) demodulating the modulated information signal recovered in step (b) to recover the information. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. Apparatus for communicating information within an area served by a commercial broadcast station transmitting over the air on a broadcast station carrier and within a broadcast station frequency band comprising:
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modulation means for modulating the information to be communicated by a carrier other than the broadcast station carrier and for providing an output responsive thereto; transmitter means coupled to said modulation means for transmitting, from a transmitter other than the broadcast station transmitter, the output of said modulation means; a receiver at a remote location with respect to said transmitter means for receiving as a receiver signal a signal containing the carrier transmitted by the broadcast station and the signal transmitted by said transmitter means, said receiver means having; a first demodulator for demodulating said receiver signal using the carrier of the broadcast station as a reference to recover a signal corresponding to the signal transmitted by said transmitter means, and; a second demodulator coupled to said first demodulator for demodulating the signal recovered by the first demodulator to recover the information to be communicated. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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41. Apparatus for communicating information within an area served by a broadcast station transmitting on a broadcast station carrier and within a broadcast station frequency band comprising:
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modulation means for modulating the information to be communicated by a carrier other than the broadcast station carrier and for providing an output responsive thereto; transmitter means coupled to said modulation means for transmitting the output of said modulation means; a receiver at a remote location with respect to said transmitter means for receiving as a receiver signal a signal containing the carrier transmitted by the broadcast station and the signal transmitted by said transmitter means, said receiver means having; a first demodulator for demodulating said receiver signal using the carrier of the broadcast station as a reference to recover a signal corresponding to the signal transmitted by said transmitter means, and; a second demodulator coupled to said first demodulator for demodulating the signal recovered by the first demodulator to recover the information to be communicated. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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Specification