EP0113230A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data transmission system for a local network
Assignee: Toshiba Corp
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Filing: 1983-12-20
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Granted: —
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Expires: 2003-12-20
Abstract
Abstract A local network, in which a plurality of data processors (4a to 4n) are coupled by modems (5a to 5n) to a communication medium (1, 2), is disclosed. Each modem is arranged to shift a carrier frequency to a first and second frequency according to a digital signal from the associated data processor. In order to provide for reliable and quick detection of a collision of signals simultaneously transmitted from a plurality of modems to the communication medium, the difference between the first and second frequencies is set such that one cycle of a beat signal generated on the communication medium due to a collision of signals is not longer than one bit time length of the digital signal.
Inventors
- 👤 Hiroshi Kobayashi
- 👤 Tsuguhiro Hirose
- 👤 Hideaki Haruyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 08:06
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/10; H04L; H04L12/00; H04L12/28; H04L12/2801; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
172 words
A data transmission system comprising: a communication medium (1, 2); a plurality of data processors (4a to 4n); and a plurality of modems (5a to 5n) for coupling said data processors to said communication medium to effect transmission and reception of a digital signal having mark and space bits each of one bit time length among said data processors via said communication medium; each of said modems including: modulating means (11) for shifting a carrier frequency to a first and a second frequency according to a baseband digital signal or a code-modulated digital signal thereof; and collision detecting means (20) for detecting a signal collision on the basis of a beat signal resulting from modulated carrier signals simultaneously transmitted from a plurality of modems to said communication medium to inhibit the associated data processor from issuing the digital signal; the difference between said first and second frequencies being set such that one cycle period of said beat signal is shorter than or equal to one bit time length of the digital signal.
Claim 2
Dependent Claim
172 words
A data transmission system comprising: a communication medium (1, 2); a plurality of data processors (4a to 4n); and a plurality of modems (5a to 5n) for coupling said data processors to said communication medium to effect transmission and reception of a digital signal having mark and space bits each of one bit time length among said data processors via said communication medium; each of said modems including: modulating means (11) for shifting a carrier frequency to a first and a second frequency according to a baseband digital signal or a code-modulated digital signal thereof; and collision detecting means (20) for detecting a signal collision on the basis of a beat signal resulting from modulated carrier signals simultaneously transmitted from a plurality of modems to said communication medium to inhibit the associated data processor from issuing the digital signal; the difference between said first and second frequencies being set such that one cycle period of said beat signal is shorter than or equal to one bit time length of the digital signal.
Claim 3
Dependent Claim
20 words
The data transmission system according to claim 1, characterized in that the code-modulated digital signal is a Manchester code signal.
Claim 4
Dependent Claim
52 words
The data transmission system according to claim 1, characterized in that said communication medium is a double-conductor cable having a transmission line (1) and a reception line (2); and further comprising a headend (3) for coupling a signal transmitted from each modem from said transmission line (1) to said reception line (2).
Claim 5
Dependent Claim
39 words
The data transmission system according to claim 1, characterized in that said communication medium is a single-conductor cable, and further comprising a headend (9) for frequency converting a signal transmitted from each modem into a receiving frequency band signal.
Claim 6
Dependent Claim
172 words
A data transmission system comprising: a communication medium (1, 2, 7); a plurality of data processors (4a to 4n); and a plurality of modems (5a to 5n) for permitting transmission and reception of a digital signal having mark and space bits each of one bit time length among said data processors via said communication medium, each of said modems including modulating means (11) for shifting a carrier frequency (f c ) to a first and a second frequency (f + f d , f c - f d ) according to a digital signal or a code-modulated digital signal thereof; a modulation parameter defined by the product of the difference (2f d ) between said first and second frequencies and one bit time length of the digital signal being set to 1 or above so that one cycle period (f d/ 2) of the beat signal resulting from modulated carrier signals simultaneously transmitted from a plurality of modems to said communication medium is within one bit time length of the digital signal.
Claim 7
Dependent Claim
172 words
A data transmission system comprising: a communication medium (1, 2, 7); a plurality of data processors (4a to 4n); and a plurality of modems (5a to 5n) for permitting transmission and reception of a digital signal having mark and space bits each of one bit time length among said data processors via said communication medium, each of said modems including modulating means (11) for shifting a carrier frequency (f c ) to a first and a second frequency (f + f d , f c - f d ) according to a digital signal or a code-modulated digital signal thereof; a modulation parameter defined by the product of the difference (2f d ) between said first and second frequencies and one bit time length of the digital signal being set to 1 or above so that one cycle period (f d/ 2) of the beat signal resulting from modulated carrier signals simultaneously transmitted from a plurality of modems to said communication medium is within one bit time length of the digital signal.
References Cited (Backward Citations)
No citation records indexed.
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