Communications system with tandem scrambling devices
First Claim
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1. A method of establishing scrambled communications on a communications circuit which utilizes at least two communications links and has an originating scrambling terminal, an answering scrambling terminal, and at least one intermediate scrambler, comprising the steps of:
- detecting, at the intermediate scrambler and the answering scrambling terminal, a first data message sent from the originating scrambling terminal;
determining, at the intermediate scrambler, if the answering scrambling terminal has sent a second data message in response to said first data message; and
placing the intermediate scrambler in a transparent non-scrambling mode if the answering scrambling terminal has sent said second data message.
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Abstract
An intermediate scrambling device for a radiotelephone system is disclosed by which it is possible to establish and maintain scrambled communications between an originating scrambler terminal and the most distant companion scrambler on the circuit. The intermediate scrambler may establish and maintain the scrambled communications if it is the most distant scrambler, or it may become transparent to a more distant scrambler.
59 Citations
17 Claims
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1. A method of establishing scrambled communications on a communications circuit which utilizes at least two communications links and has an originating scrambling terminal, an answering scrambling terminal, and at least one intermediate scrambler, comprising the steps of:
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detecting, at the intermediate scrambler and the answering scrambling terminal, a first data message sent from the originating scrambling terminal; determining, at the intermediate scrambler, if the answering scrambling terminal has sent a second data message in response to said first data message; and placing the intermediate scrambler in a transparent non-scrambling mode if the answering scrambling terminal has sent said second data message. - View Dependent Claims (2, 3)
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4. An intermediate scrambler for a communications circuit employing a seed message to establish scrambled communications and which has at least one terminal scrambler, the intermediate scrambler comprising:
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means for detecting a first seed message sent from a first terminal scrambler; means for determining if a second terminal scrambler has sent a second seed message in response to said first seed message; and means for placing the intermediate scrambler in a transparent non-scrambling mode if said second terminal scrambler has sent said second seed message. - View Dependent Claims (5, 6, 7, 8)
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9. A method of establishing scrambled communications on a communications circuit which utilizes a radiotelephone link and a landline telephone link and further has an originating scrambling terminal at one termination of the communications circuit, an answering scrambling terminal at the other termination of the communications circuit, and at least one intermediate scrambler at the interface of the radiotelephone link and the landline telephone link, comprising the steps of:
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detecting, at the intermediate scrambler and the answering scrambling terminal, a first seed message sent from the originating scrambling terminal to establish scrambled communications; measuring a predetermined period of time following said detection of said first seed message at the intermediate scrambler; determining, at the intermediate scrambler, if the answering scrambling terminal has sent a second seed message in response to said first seed message within said measured predetermined time; and placing the intermediate scrambler in a transparent non-scrambling mode if the answering scrambling terminal has sent said second seed message within said measured predetermined time. - View Dependent Claims (10)
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11. An intermediate scrambler for a communications circuit which utilizes a radiotelephone link and a landline telephone link and further has at least one terminal scrambler at one termination of the communications circuit comprising:
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means for detecting a first data message sent from a first terminal scrambler; means for measuring a predetermined period of time following said detection of said first data message; means for determining if a second terminal scrambler has sent a second data message in response to said first data message within said measured predetermined time; and means for placing the intermediate scrambler in a transparent non-scrambling mode if said second terminal scrambler has sent said second data message within said measured predetermined time. - View Dependent Claims (12, 13, 14)
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15. A method of data transfer or exchange on all or part of a communications circuit which is composed of at least two communications links, a terminal data device, at least one intermediate data device at a junction between two links, and an answering data device, comprising the steps of:
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detecting at an intermediate data device a first data exchange request message transmitted by the terminal data device; detecting at said intermediate data device a second data exchange request message transmitted from an answering data device more distant on the communications circuit from said terminal data device than said intermediate data device; placing said intermediate data device in a transparent mode if said second data exchange request message is detected, thereby permitting said more distant answering data device to directly exchange data with said terminal data device. - View Dependent Claims (16, 17)
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Specification