US5479441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Packet data communication system
Assignee: Symbol Technologies LLC
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Filing: 1994-01-18
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Granted: 1995-12-26
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Expires: 2014-01-18
Abstract
Abstract A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.
Inventors
- 👤 LaRoy Tymes
- 👤 John W. Kramer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:28
CPC Classifications
G; G06; G06K; G06K17/00; G06K17/0022; G06K7/00; G06K7/0008; G06K7/10; G06K7/10009; G06K7/10316; G06K7/10356; H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04L; H04L1/00; H04L1/12; H04L1/16; H04L1/1607; H04L1/1671; H04L1/1678; H04L1/18; H04L1/1867; H04L5/00; H04L5/14; H04L5/1469; H04L5/1484; H04W; H04W88/00; H04W88/02; H04W88/06; H04B1/7073; H04B1/7075; H04L2001/0092; H04L2001/0093
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
89 words
A method of transmitting data packets from one of a plurality of remote terminal units to a base station, comprising the steps of: a) transmitting a data packet from said one unit to said base station during a first time period selected by the unit; b) receiving at said one unit from said base station a reply signal during a second time period occurring only during a selected time window after said first time period, said second time period being the same for at least some of said units.
Claim 2
Independent Claim
89 words
A method of transmitting data packets from one of a plurality of remote terminal units to a base station, comprising the steps of: a) transmitting a data packet from said one unit to said base station during a first time period selected by the unit; b) receiving at said one unit from said base station a reply signal during a second time period occurring only during a selected time window after said first time period, said second time period being the same for at least some of said units.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein said steps of transmitting and receiving are by spread spectrum RF signals.
Claim 4
Dependent Claim
27 words
A method according to claim 1 wherein said remote terminal unit is one of a plurality of remote stations associated with the transmitter of said reply signal.
Claim 5
Dependent Claim
32 words
A method according to claim 3 wherein said remote stations are hand-held data-gathering units which include manual control elements, and wherein at least some of said remote stations include bar-code reading devices.
Claim 6
Dependent Claim
46 words
A method according to claim 1 wherein said reply signal is transmitted by a second station which is one of a plurality of said second stations physically spaced from one another, and there are a plurality of said remote terminal units for each said second station.
Claim 7
Dependent Claim
31 words
A method according to claim 1 including the step of listening at said unit prior to said step of transmitting said data packet to see if other like units are transmitting.
Claim 8
Independent Claim
103 words
A system for transmitting data packets from one of a plurality of first stations to a second station, comprising: a) a transmitter in said one first station for transmitting a data packet from said one first station to the second station during a first time period selected by said one first station; b) a receiver in said one first station for receiving a reply signal from the second station during a second time period occurring only in a time window referenced to said first time period by a selected delay, said selected delay being the same for all said plurality of first stations.
Claim 9
Independent Claim
103 words
A system for transmitting data packets from one of a plurality of first stations to a second station, comprising: a) a transmitter in said one first station for transmitting a data packet from said one first station to the second station during a first time period selected by said one first station; b) a receiver in said one first station for receiving a reply signal from the second station during a second time period occurring only in a time window referenced to said first time period by a selected delay, said selected delay being the same for all said plurality of first stations.
Claim 10
Dependent Claim
16 words
A system according to claim 7 wherein said transmitter and receiver employ spread spectrum RF signals.
Claim 11
Dependent Claim
26 words
A system according to claim 7 wherein said first station is one of a plurality of remote stations associated with a transmitter of said reply signal.
Claim 12
Dependent Claim
32 words
A system according to claim 9 wherein said remote stations are hand-held data-gathering units which include manual control elements, and wherein at least some of said remote stations include bar-code reading devices.
Claim 13
Dependent Claim
45 words
A system according to claim 7 wherein said reply signal is transmitted by a second station which is one of a plurality of said second stations physically spaced from one another, and there are a plurality of said first stations for each said second station.
Claim 14
Dependent Claim
29 words
A method according to claim 7 including means for listening at said first station prior to said transmitting said data packet to see if other like units are transmitting.
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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) | 1998-12-25 | 1999-06-26 | 1999-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-25 | 2003-06-26 | 2003-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-25 | 2007-06-26 | 2007-12-26 | $7700.00 | Window Closed / Lapsed |