Packet data communication network
DCFirst Claim
1. 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.
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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.
433 Citations
20 Claims
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1. A hand-held bar code reader comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating a hand-held bar code reader comprising the steps of:
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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. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification