Power-line carrier communications system with interference avoidance capability
First Claim
Patent Images
1. A system for communicating data over a medium, comprising:
- a plurality of data stations each having means coupled to said medium for receiving a carrier therefrom to recover that one of a data word and acknowledgement message modulated upon said carrier; and
means for transmitting via said medium a carrier modulated with a selected one of a data word and an acknowledgment message responsive to receipt of a data word in said receiving means;
each of said transmitting and receiving means simultaneously programmable to the same one of a plurality K of communications carrier frequencies;
means cooperating with each transmitting and receiving means for causing a data packet to be transmitted a predetermined number S of times;
said causing means being disabled if an acknowledgment message is received after any one of the data packet transmissions;
means in each station and responsive to said causing means for changing the communications carrier frequency to the next one of said plurality K of communications carrier frequencies if all predetermined number S of transmissions on a previous one of said plurality K of frequencies are not acknowledged; and
means for resetting said causing means to cause the transmitting means to transmit said data packet for an additional predetermined number of times on the next selected carrier frequency.
1 Assignment
0 Petitions
Accused Products
Abstract
The operating frequency of a multi-station power-line-carrier-communications system is automatically changed to avoid narrowband interference. Any one of the plurality of stations in the system can initiate a command to shift operating frequency, when the communications signal reception degrades below a predetermined criterion. An interfering signal itself can initiate a shift in operating frequency when the characteristics of the interfering signal are sufficient to deteriorate communications on an existing operating frequency.
-
Citations
16 Claims
-
1. A system for communicating data over a medium, comprising:
-
a plurality of data stations each having means coupled to said medium for receiving a carrier therefrom to recover that one of a data word and acknowledgement message modulated upon said carrier; and
means for transmitting via said medium a carrier modulated with a selected one of a data word and an acknowledgment message responsive to receipt of a data word in said receiving means;
each of said transmitting and receiving means simultaneously programmable to the same one of a plurality K of communications carrier frequencies;means cooperating with each transmitting and receiving means for causing a data packet to be transmitted a predetermined number S of times;
said causing means being disabled if an acknowledgment message is received after any one of the data packet transmissions;means in each station and responsive to said causing means for changing the communications carrier frequency to the next one of said plurality K of communications carrier frequencies if all predetermined number S of transmissions on a previous one of said plurality K of frequencies are not acknowledged; and means for resetting said causing means to cause the transmitting means to transmit said data packet for an additional predetermined number of times on the next selected carrier frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method for communicating data between a plurality of stations interconnected by a medium, comprising the steps of:
-
(a) transmitting a data message from a transmitting one of the stations over the medium on a first one of a plurality K of predetermined frequencies; (b) recovering the data message from a signal received from the medium at a receiving one of the plurality of stations; (c) transmitting an acknowledgement message from the receiving one of said stations onto the medium; (d) recovering the acknowledgement message upon receipt from the medium at the transmitting one of the plurality of stations; (e) repeating step (a) up to S times if the acknowledgement message is not received at the transmitting station within a predetermined time interval after each transmission; (f) changing frequency to a next subsequent one of the plurality K of frequencies if step (e) is completed without receipt of the acknowledgement message; and (g) repeating steps (a) and (e) sequentially, for all K of the frequencies, if the acknowledgement message recovery step (d) does not occur within the predetermined time interval after each transmission. - View Dependent Claims (12, 13, 14, 15, 16)
-
Specification