Patent US5290511A successfully refreshed from Google Patents.
US3875332A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital transmitter for data bus communications system
Assignee: National Aeronautics and Space Administration
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Filing: 1973-12-27
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Granted: 1975-04-01
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Expires: 1993-12-27
Abstract
Abstract Disclosed is an improved digital transmitter for transmitting serial pulse-code modulation (pcm) data at high bit rates over a transmission line. When not transmitting, the transmitter features a high output impedance which prevents the transmitter from loading the transmission line. The pcm input is supplied to a logic control circuit which produces two discrete logic level signals which are supplied to an amplifier. The amplifier, which is transformer coupled to the output isolation circuitry, converts the discrete logic level signals to two high current level, ground isolated signals in the secondary windings of the coupling transformer. The latter signals are employed as inputs to the isolation circuitry which includes two series transistor pairs operating into a hybrid transformer functioning to isolate the transmitter circuitry from the transmission line. An effective increased amplitude, balanced, differential output signal is produced by the transmitter from the serial pcm input data to provide an improved transmitted signal to the transmission line.
Inventors
- 👤 James C Administrator Fletcher
- 👤 George Eugene Proch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:55
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L25/4904
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
218 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means including electronic switching means responsive to a first control signal for providing either a low impedance or a high impedance pathway to said transmission line for a first output signal, said first control means including a first transistor pair being emitter-connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means including electronic switching means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transmission pair being emitter-connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair and the collector of one of the transistors in said second transistor pair being connected to the collector of one of the transistors in said first transistor pair; and c. means for holding said pathway in one of said control means at a high impedance when the pathway in the other of said control means is at a low impedance.
Claim 2
Dependent Claim
218 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means including electronic switching means responsive to a first control signal for providing either a low impedance or a high impedance pathway to said transmission line for a first output signal, said first control means including a first transistor pair being emitter-connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means including electronic switching means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transmission pair being emitter-connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair and the collector of one of the transistors in said second transistor pair being connected to the collector of one of the transistors in said first transistor pair; and c. means for holding said pathway in one of said control means at a high impedance when the pathway in the other of said control means is at a low impedance.
Claim 3
Dependent Claim
208 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means responsive to a first control signal for providing either a low impedance or a high impedance pathway to said transmission line for a first output signal, said first control means including a first transistor pair being emitter-connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transistor pair being emitter-connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair and the collector of one of the transistors in said second transistor pair being connected to the collector of one of the transistors in said first transistor pair; and c. current limiting means in each of said pathways for limiting current flow through either of said pathways when the other of said pathways is providing a low impedance.
Claim 4
Dependent Claim
208 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means responsive to a first control signal for providing either a low impedance or a high impedance pathway to said transmission line for a first output signal, said first control means including a first transistor pair being emitter-connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transistor pair being emitter-connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair and the collector of one of the transistors in said second transistor pair being connected to the collector of one of the transistors in said first transistor pair; and c. current limiting means in each of said pathways for limiting current flow through either of said pathways when the other of said pathways is providing a low impedance.
Claim 5
Dependent Claim
31 words
A transmitter as defined in claim 2 wherein said current limiting means includes maximum current limiting means comprising resistance means in the base circuits of said first and second transistor pairs.
Claim 6
Dependent Claim
243 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means responsive to a first control signal for providing either a low impedance or a high impedanCe pathway to said transmission line for a first output signal, said first control means including a first transistor pair connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transistor pair connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair; c. current limiting means in each of said pathways for limiting current flow through its associated pathway when the other of said pathways is providing a low impedance; d. signal forming means for providing an inverse relationship between said first and second control signals; and e. means for simultaneously supplying said first and second signals to the bases of said first and second transistor pairs, said signal forming means including transformer means with plural secondary winding means, and one of said secondary winding means being included in the base-to-emitter circuit of each said transistor pairs.
Claim 7
Dependent Claim
243 words
An improved digital transmitter having an isolating coupling circuit means for coupling the transmitter to a transmission line, said isolating coupling circuit means comprising: a. first control means responsive to a first control signal for providing either a low impedance or a high impedanCe pathway to said transmission line for a first output signal, said first control means including a first transistor pair connected together to provide said first output signal when said first control signal is supplied to the bases of said first transistor pair; b. second control means responsive to a second control signal for providing either a low impedance or a high impedance pathway to said transmission line for a second output signal, said second control means including a second transistor pair connected together to provide said second output signal when said second control signal is supplied to the bases of said second transistor pair; c. current limiting means in each of said pathways for limiting current flow through its associated pathway when the other of said pathways is providing a low impedance; d. signal forming means for providing an inverse relationship between said first and second control signals; and e. means for simultaneously supplying said first and second signals to the bases of said first and second transistor pairs, said signal forming means including transformer means with plural secondary winding means, and one of said secondary winding means being included in the base-to-emitter circuit of each said transistor pairs.
Claim 8
Dependent Claim
27 words
A transmitter as defined in claim 4 wherein the primary of said transformer means is connected with amplifying circuit means providing two high current, ground isolated signals.
Claim 9
Dependent Claim
30 words
A transmitter as defined in claim 5 wherein said amplifying circuit means is connected with logic control means for forming two similar output signals from a single data input signal.
Claim 10
Dependent Claim
31 words
A transmitter as defined in claim 6 wherein said logic control means includes electronic switching means responsive to an input control signal for controlling the operation of said logic control means.
Claim 11
Dependent Claim
41 words
A transmitter as defined in claim 7 wherein said logic control means includes means for forming said two similar output signals only when said single input data signal and said input control signal are simultaneously supplied to said logic control circuit.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |