The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 22, 1994
Filed:
May. 10, 1991
Howard W Johnson, Sunnyvale, CA (US);
Chin-Chen Lee, San Jose, CA (US);
Amy O Hurlbut, San Francisco, CA (US);
Echelon Corporation, Palo Alto, CA (US);
Abstract
A power line communication (PLC) apparatus wherein transmission mode information is encoded into each data packet while maintaining immunity from single bit errors. In the present invention, a power line communication system includes a transmitter/receiver (i.e. transceiver) which is coupled to a power distribution network. Data is transmitted through the power line by the transceiver in packets. The transceiver includes a preamble generator which creates a preamble for each of the data packets and a preamble decoder that decodes the preamble of a data packet and determines word sync for the packet. The preamble generated by the preamble generator consists of a carrier detect interval, a carrier sync interval, a bit sync interval, and a word sync pattern. The transceiver may select either BPSK or QPSK transmission modes on a data packet by data packet basis by encoding information into the packet preamble. Transmission mode information is encoded into the preamble using one of two seven-bit cross compatible word sync patterns for each data packet. Thus, one word sync pattern is used to define a BPSK transmission while the other word sync pattern is used to define a QPSK transmission. The transmitter may send data packets using either BPSK or QPSK on a packet by packet basis by generating the appropriate word sync pattern for each packet. The receiver uses the word sync pattern to determine the receive mode for each packet.