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US4337465A Expired / Lapsed US ⏱️ 0.0 years remaining

Line driver circuit for a local area contention network

Assignee: Unisys Corp
•
Filing: 1980-09-25
•
Granted: 1982-06-29
•
Expires: 2000-09-25
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Abstract

Abstract This disclosure relates to a line driver circuit for a station in a data transmission network, which driver circuit is adapted to drive the channel medium with a constant current so that conflicts or collisions with data transmissions from other stations will be cancelled out thereby preventing any particular station from dominating reception of a neighboring station. Each station is adapted to operate in a cyclic mode for contending for access to the network channel where a three-state cycle is employed, which states are the idle state, the packet-being-transmitted state and the acknowledgment period state. Each station will not begin transmission until it determines that the tunnel is in an idle state. Once the station has determined that the channel is idle, it will then delay for a period of time that is randomly chosen and, if the channel is still idle, will then begin transmission. Following transmission, the channel will again be quiescent for a short period of time before the acknowledgment signal is transmitted from the receiver. Each packet of data to be transmitted is of a fixed length so as to provide for synchronization between the various stations contending for access to the channel.

Inventors

  • 👤 John E. Spracklen
  • 👤 Mark L. C. Gerhold

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-23 20:11
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L12/00; H04L12/28; H04L12/40; H04L12/407; H04L12/413

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 171 words
A station in a local area data communication network coupled to a local area communication channel, said station comprising: sensing means to detect when said channel is inactive; clock means to determine a random period of time after said sensing means detects no activity on said channel; and transmitting means to transmit an information packet on said channel after said random period of time and when there is no activity on said channel, said transmitting means including line driver means comprising: a pulse transformer having a primary winding with a center tap and a secondary winding, said secondary winding being coupled to said communication channel; a constant current source coupled to said center tap of said primary winding; and circuit means coupled to the respective ends of said primary winding to receive current from one end thereof or the other end thereof in accordance with a data signal to be transmitted on said channel so as to cancel out signals being transmitted by other stations contending for access to said channel.
Claim 2
Dependent Claim 171 words
A station in a local area data communication network coupled to a local area communication channel, said station comprising: sensing means to detect when said channel is inactive; clock means to determine a random period of time after said sensing means detects no activity on said channel; and transmitting means to transmit an information packet on said channel after said random period of time and when there is no activity on said channel, said transmitting means including line driver means comprising: a pulse transformer having a primary winding with a center tap and a secondary winding, said secondary winding being coupled to said communication channel; a constant current source coupled to said center tap of said primary winding; and circuit means coupled to the respective ends of said primary winding to receive current from one end thereof or the other end thereof in accordance with a data signal to be transmitted on said channel so as to cancel out signals being transmitted by other stations contending for access to said channel.
Claim 3
Dependent Claim 29 words
A station according to claim 1 wherein: said circuit means includes a pair of open collector drivers to respectively couple a corresponding end of said primary winding to ground.
Claim 4
Dependent Claim 24 words
A station according to claim 1 further including: enable means to place said circuit means and said constant current means in a conducting condition.
Claim 5
Dependent Claim 29 words
A station according to claim 2 further including: receiving means to receive an acknowledgment signal on said channel within a fixed time interval after said packet has been transmitted.
Claim 6
Dependent Claim 18 words
A station according to claim 2 wherein: said clock means includes counter means driven by a random clock.
Claim 7
Dependent Claim 19 words
A station according to claim 2 wherein: said transmitting means transmits said packet during a fixed period of time.
Claim 8
Dependent Claim 34 words
A station according to claim 2 further including: channel state means to maintain said station in a sequence of states which include, in order, the channel idle state, packet-being-transmitted state, and acknowledgment period state.

References Cited (Backward Citations)

US3297954A Cited
US3358216A Cited
US3486040A Cited
US3959665A Cited
US3969639A Cited
US3993935A Cited
US4063220A Cited
US4149030A Cited
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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1985-06-28 1985-12-28 1986-06-29 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1989-06-28 1989-12-28 1990-06-29 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1993-06-28 1993-12-28 1994-06-29 $7700.00 Window Closed / Lapsed

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