Patent US4375103A successfully refreshed from Google Patents.
US4375103A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus of signalling request to send clear to send delay
Assignee: International Business Machines Corp
•
Filing: 1980-09-17
•
Granted: 1983-02-22
•
Expires: 2000-09-17
Abstract
Abstract Disclosed are a method and apparatus for exchanging information between a data terminal equipment (DTE) and data circuit terminating equipment (DCE) or controller connected to the data terminal equipment over a communications line. The specific information to be exchanged is the information indicating the delay period between a request to send received at the DCE and a clear to send condition occurring sometime later in response to the request to send. This function is normally handled by separate signalling lines, but for the so-called mini interface, no clear to send communication line exists. A method and apparatus employed in the present invention utilizes the transmitter signal element timing or clock line to convey the information from the DCE to the DTE. In response to receipt at the DCE of a request to send signal from the DTE, the DCE temporarily stops the transmitter signal timing clock, thus preventing the DTE from transmitting data. When the DCE modem has established carrier frequency and has completed its synchronization routine, a clear to send condition exists and the delay inherent between a request to send and clear to send signal is over. To signal this condition without the use of a clear to send signalling line, the DCE re-enables the transmitter signal element timing clock. The clock remains enabled at all times except during the request to send/clear to send delay period.
Inventors
- 👤 August P. Arneth
- 👤 Curtis L. Foshee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:34
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/14; H04L5/1461; H04L9/00; H04L9/40; H04L69/00; H04L69/30; H04L69/32; H04L69/322; H04L69/323
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
207 words
In a data communications system interface defining the connection between two communicating terminals or systems comprising a local unit and a remote unit, and in which the communications interface includes a time clock signal output line and a request to send line but does not include a separate external control line for granting to a remote requesting station a clear to send authorization control signal, but does include a fixed delay period timing element for generating an internal clear to send authorization control signal responsive to the elapse of a fixed delay period the improvement comprising: a transmission clock means resident in the local communications equipment and supplying clock signals to said clock signal output line; means in said local unit for detecting a request to send input signal from the remote unit; logic means in said local unit responsive to the request to send signal for interrupting said clock signals from emanating on said clock signal output line and for initiating said fixed delay period timing element and including means for indicating the completion of said fixed delay period; and responsive to an indication that said delay period has elapsed for passing said clocking signal to said line, thereby permitting said remote equipment to begin transmission.
Claim 2
Dependent Claim
207 words
In a data communications system interface defining the connection between two communicating terminals or systems comprising a local unit and a remote unit, and in which the communications interface includes a time clock signal output line and a request to send line but does not include a separate external control line for granting to a remote requesting station a clear to send authorization control signal, but does include a fixed delay period timing element for generating an internal clear to send authorization control signal responsive to the elapse of a fixed delay period the improvement comprising: a transmission clock means resident in the local communications equipment and supplying clock signals to said clock signal output line; means in said local unit for detecting a request to send input signal from the remote unit; logic means in said local unit responsive to the request to send signal for interrupting said clock signals from emanating on said clock signal output line and for initiating said fixed delay period timing element and including means for indicating the completion of said fixed delay period; and responsive to an indication that said delay period has elapsed for passing said clocking signal to said line, thereby permitting said remote equipment to begin transmission.
Claim 3
Dependent Claim
168 words
In a data communications system interface defining the connection between two communications terminals or systems comprising a local unit and a remote unit, and in which the communications interface includes a timing clock signal output line and a request to send line but does not include a separate control line for granting to a remote requesting station a clear to send authorization control signal, an improved method of indicating the delay period between a request to send signal receipt and an establishment of carrier synchronization and frequency so that transmission may begin, comprising steps at said local unit of: detecting a request to send input from said remote unit at said local unit; initiating a delay period in response to detecting said request to send signal; and interrupting said timing clock signal output line in response to said receipt of request to send signal; and re-establishing said transmission clock signal output in response to the completion of said delay period, thereby permitting said remote equipment to begin transmission.
Claim 4
Dependent Claim
168 words
In a data communications system interface defining the connection between two communications terminals or systems comprising a local unit and a remote unit, and in which the communications interface includes a timing clock signal output line and a request to send line but does not include a separate control line for granting to a remote requesting station a clear to send authorization control signal, an improved method of indicating the delay period between a request to send signal receipt and an establishment of carrier synchronization and frequency so that transmission may begin, comprising steps at said local unit of: detecting a request to send input from said remote unit at said local unit; initiating a delay period in response to detecting said request to send signal; and interrupting said timing clock signal output line in response to said receipt of request to send signal; and re-establishing said transmission clock signal output in response to the completion of said delay period, thereby permitting said remote equipment to begin transmission.
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) | 1986-02-21 | 1986-08-23 | 1987-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-21 | 1990-08-23 | 1991-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-21 | 1994-08-23 | 1995-02-22 | $7700.00 | Window Closed / Lapsed |