Signal transmission in teaching system
First Claim
1. A teaching system comprising a master station including at least one source of main signals in a first frequency band, a source of audio signals, a source of control signals, and signal transmission apparatus comprising means for modulating a subcarrier with said audio signals so as to provide a first auxiliary signal in a frequency band removed from said first frequency band, means for modulating a subcarrier with said control signals so as to provide a second auxiliary signal in a frequency band removed from said first frequency band and said frequency band of the first auxiliary signal, means for multiplexing said main signals and said first and second auxiliary signals so as to provide a composite signal therefrom, means for modulating a carrier of predetermined frequency with said composite signal, and transmitting means for transmitting said carrier modulated with the composite signal;
- and at least one student station spaced from said master station and at each of which there are situated reception means tunable to said predetermined frequency of said carrier, demodulating means for obtaining said composite signal from the received modulated carrier, and filter means for separating said main, audio, and control signals from the demodulated composite signal;
wherein said control signals from said source include a plurality of command signals each associated with a respective student station to selectively control the operation of the associated respective student station, and each said student station includes control circuitry responsive to its respective command signal so that each said student station is selectively controlled in response to said respective command signal notwithstanding that said control signals are also received by other such student stations.
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Abstract
In a teaching system having a central or master station and one or more student stations remote from the master station, there are provided, at the master station, at least one source of main signals in a first frequency band, which source may be constituted by a tape or other record player for reproducing teaching or instructional materials, a microphone or other source of audio signals from a proctor or supervisor of the teaching system, and a source of control signals which may include address signals for identifying one of the student stations and command signals for controlling various operations of the addressed student station. The audio and control signals are employed to modulate respective carriers so as to provide first and second auxiliary signals, respectively, in frequency bands which are removed from each other and from the first frequency band of the main signals, whereupon the main signals and the first and second auxiliary signals are multiplexed to provide a composite signal which, in turn, modulates a carrier of predetermined frequency suitable for being transmitted to each of the student stations.
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Citations
12 Claims
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1. A teaching system comprising a master station including at least one source of main signals in a first frequency band, a source of audio signals, a source of control signals, and signal transmission apparatus comprising means for modulating a subcarrier with said audio signals so as to provide a first auxiliary signal in a frequency band removed from said first frequency band, means for modulating a subcarrier with said control signals so as to provide a second auxiliary signal in a frequency band removed from said first frequency band and said frequency band of the first auxiliary signal, means for multiplexing said main signals and said first and second auxiliary signals so as to provide a composite signal therefrom, means for modulating a carrier of predetermined frequency with said composite signal, and transmitting means for transmitting said carrier modulated with the composite signal;
- and at least one student station spaced from said master station and at each of which there are situated reception means tunable to said predetermined frequency of said carrier, demodulating means for obtaining said composite signal from the received modulated carrier, and filter means for separating said main, audio, and control signals from the demodulated composite signal;
wherein said control signals from said source include a plurality of command signals each associated with a respective student station to selectively control the operation of the associated respective student station, and each said student station includes control circuitry responsive to its respective command signal so that each said student station is selectively controlled in response to said respective command signal notwithstanding that said control signals are also received by other such student stations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- and at least one student station spaced from said master station and at each of which there are situated reception means tunable to said predetermined frequency of said carrier, demodulating means for obtaining said composite signal from the received modulated carrier, and filter means for separating said main, audio, and control signals from the demodulated composite signal;
Specification