US3909510A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direct connection digital transmission apparatus
Assignee: Fujitsu IT Holdings Inc
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Filing: 1973-10-05
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Granted: 1975-09-30
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Expires: 1993-10-05
Abstract
Abstract Apparatus is disclosed for interconnecting digital data stations through a transmission medium such as a directly connected unloaded pair of wires. The apparatus transmits data as polarity, or more correctly, direct current reversals on a pair of wires indicative of ''''ones'''' (1) and ''''zeros'''' (0) or marks and spaces. The apparatus includes means for discriminating against noise spikes which may appear on the line without degrading the quality of valid signals. Control information is uniquely coded as spaces 0 of predetermined lengths which are distinct from any valid data.
Inventors
- 👤 David W Luce
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:47
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L25/00; H04L25/02; H04L25/38; H04L25/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
126 words
Apparatus for interconnecting digital equipment to a direct current passing data transmission loop having at least a pair of line conductors cmprising: a constant line current generator connected to each of said conductors for introducing substantially equal and opposite currents into the respective line conductors forming said loop; means connecting a source of digital data to control the direction of current flow from said constant current generator to line conductors; means for generating a code of alternate marks and spaces; means for generating a plurality of codes of predetermined lengths of spaces indicative of a plurality of control functions; and means for introducing said codes into said connecting means to control the direction of flow of current from said constant current generator to said line conductors.
Claim 2
Dependent Claim
126 words
Apparatus for interconnecting digital equipment to a direct current passing data transmission loop having at least a pair of line conductors cmprising: a constant line current generator connected to each of said conductors for introducing substantially equal and opposite currents into the respective line conductors forming said loop; means connecting a source of digital data to control the direction of current flow from said constant current generator to line conductors; means for generating a code of alternate marks and spaces; means for generating a plurality of codes of predetermined lengths of spaces indicative of a plurality of control functions; and means for introducing said codes into said connecting means to control the direction of flow of current from said constant current generator to said line conductors.
Claim 3
Dependent Claim
52 words
The combination in accordance with claim 1 including means for generating a first code of predetermined length of spaces 0 to denote a disconnect command and means responsive to detection of said code of predetermined length of spaces 0 to disconnect said apparatus from receipt of data from said digital data equipment.
Claim 4
Dependent Claim
30 words
The combination in accordance with claim 2 including means for generating a second code of predetermined length of spaces 0 greater than said first code to denote a test function.
Claim 5
Dependent Claim
56 words
The combination in accordance with claim 1 including means responsive to the detection of a code of alternate spaces (0) and marks (1) for initiating the connection of said digital data equipment for the reception of data wherein any sequence of received data or signals containing such code will initiate the connection of digital data equipment.
Claim 6
Dependent Claim
27 words
The combination in accordance with claim 1 including means responsive to the detection of said codes of predetermined length of spaces 0 for illuminating an indicator lamp.
Claim 7
Dependent Claim
68 words
The combination in accordance with claim 1 including receiver means selectively connected to said pair of line conductors, said receiver including a noise discrimination circuit and means for detecting changes in direction of line current indicative of data; means for detecting an alternating sequence 010 of data or code signals; and means responsive to said last means for generating a signal indicative of connection to a remote station.
Claim 8
Dependent Claim
84 words
The combination in accordance with claim 6 wherein said noise discrimination circuit comprises a monostable multivibrator having a period equal to the minimum allowance pulse width: trigger means for said monostable multivibrator driven by incoming pulses; first input of a NAND gate connected to the output of said monostable multivibrator; and means for applying inverted incoming pulses to a second output of said NAND gate whereby pulses of less than the period of said monostable multivibrator are blocked from passage through said NAND gate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |