US3612781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Simultaneous bidirectional transmission system
Assignee: International Business Machines Corp
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Filing: 1969-07-24
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Granted: 1971-10-12
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Expires: 1989-07-24
Abstract
Abstract This specification describes a circuit which permits the simultaneous transmission of data in two directions on a common transmission line without the use of frequency or time discrimination. The circuit includes at each location a differential amplifier with two inputs, one input receives data to be transmitted onto the line from the particular location and the other input receives both the data being transmitted onto the line from the location and the data being received on the line at the location. The two inputs are isolated from each other so that the output of the differential amplifier which goes to the location receiver is a function only of the data received on the line at the location.
Inventors
- 👤 Donald J Da Costa
- 👤 Robert Y Noguchi
- 👤 Leonard F Winter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:14
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/14; H04L5/1423; H04L12/00; H04L12/28; H04L12/40
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
287 words
A bidirectional transmission circuit comprising: a. differential circuit means having an input terminal, a reference terminal and an output terminal, said differential circuit means including a differential amplifier having two transistors with their emitters coupled together to a constant current source, the base of the first of the two transistors coupled to the reference terminal, the base of the second of the transistors coupled to the input terminal and the collector of the first of the two transistors to the output terminal to provide an output signal at the output terminal indicative of the magnitude of the potential at the input terminal relative to the magnitude of the potential at the reference terminal; b. transmission line means coupled to the input terminal to transmit data to the input terminal of the differential circuit means for comparison of said data to the potential at the reference terminal; c. receiver means coupled to the output terminal for the reception of output signals from the differential circuit means; d. sending means coupled to the transmission line means for the sending of information signals on the transmission line means and coupled to the reference terminal for changing the potential at the reference terminal as a function of the information signals so that the output of the differential circuit means does not change substantially with the information signals; and e. isolating means coupled between the transmission line means and the reference terminal to isolate the reference terminal from the data on the transmission line whereby the output of the differential circuit transmitted to the receiver means reflects only the data received on the transmission line means and not the information signals being placed on the transmission line means by the sending means.
Claim 2
Dependent Claim
287 words
A bidirectional transmission circuit comprising: a. differential circuit means having an input terminal, a reference terminal and an output terminal, said differential circuit means including a differential amplifier having two transistors with their emitters coupled together to a constant current source, the base of the first of the two transistors coupled to the reference terminal, the base of the second of the transistors coupled to the input terminal and the collector of the first of the two transistors to the output terminal to provide an output signal at the output terminal indicative of the magnitude of the potential at the input terminal relative to the magnitude of the potential at the reference terminal; b. transmission line means coupled to the input terminal to transmit data to the input terminal of the differential circuit means for comparison of said data to the potential at the reference terminal; c. receiver means coupled to the output terminal for the reception of output signals from the differential circuit means; d. sending means coupled to the transmission line means for the sending of information signals on the transmission line means and coupled to the reference terminal for changing the potential at the reference terminal as a function of the information signals so that the output of the differential circuit means does not change substantially with the information signals; and e. isolating means coupled between the transmission line means and the reference terminal to isolate the reference terminal from the data on the transmission line whereby the output of the differential circuit transmitted to the receiver means reflects only the data received on the transmission line means and not the information signals being placed on the transmission line means by the sending means.
Claim 3
Dependent Claim
92 words
The bidirectional transmission circuit of claim 1 wherein: said isolating means comprises two separate differential means each having a separate transistor with its collector coupled to the base of a different one of said two transistors, an input transistor coupled to a common current source with the separate transistor for the receipt of the information signals to be sent out on the transmission line whereby said separate transistors effect the bases of the two transistors in an identical manner so that said information signals do not effect the output of the 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) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |