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US 5,528,621 AGranted
Packet data communication system
AssigneeSymbol Technologies, Inc.
InventorsFredric Heiman, LaRoy Tymes
Life of this patent
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AssigneeSymbol Technologies, Inc.
InventorsFredric Heiman, LaRoy Tymes
Estimating the term…
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. A frequency-hopping transmission method is used for the RF link. The remote units and base stations are all synchronized to a repeating pseudo-random sequence of frequencies in a band (902-928 MHz) which allows this type of transmission. 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. The reply messages from the base stations to the remotes contain synchronizing information to maintain coherence with the pseudo-random sequence.
A method of transmitting data packets from one of a plurality of remote terminal units to a base station, comprising the steps of:
A system for transmitting data packets from one of a plurality of first stations to a second station, comprising:
A method of transmitting data packets from a first station to a second station, comprising the steps of:
A data transmission system, comprising:
A method of transmitting data packets from a remote station to a base station, comprising the steps of:
Dependencies are inferred from the claim text.