Packet data communication network
AssigneeSymbol Technologies, Inc.
InventorLaRoy Tymes
Life of this patent
Estimating the term…
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.
Claims20
A hand-held bar code reader comprising:
- a) a light source for directing light toward a bar code symbol to be read and a light detector responsive to reflected light from a bar code symbol to generate an electrical signal containing bar code data;
- b) an RF transmitter/receiver transmitting a data packet containing an encoded representation of said electrical signal, and activated to receive an acknowledge packet only in response to said data packet.
A method of operating a hand-held bar code reader comprising the steps of:
- a) directing light beam toward a bar code symbol to be read and detecting light reflected from the bar code symbol to generate an electrical signal containing bar code data;
- b) transmitting from the reader a data packet containing an encoded representation of said electrical signal, at a time selected at said scanner;
- c) and receiving by the reader an acknowledge packet only in response to said data packet.
Dependencies are inferred from the claim text.