Claims
- 1. A protocol implemented in a spread spectrum power line communications (PLC) system for a power line exhibiting a carrier synchronous noise spectrum, said communications system comprising a plurality of meters, each of said meters including a respective transmitter for transmitting message bits on a power line, and at least one receiver in a central hub coupled to the power line for receiving messages transmitted by the transmitters, said protocol comprising the steps of:
- synthesizing at a transmitter a waveform s.sub.i (t) having M tones described by ##EQU2## where i is one of a plurality of different signals which may be transmitted simultaneously, f.sub.ik represents a selected frequency, t represents time, and a.sub.ik and b.sub.ik represent fixed amplitude coefficients for the i-th waveform;
- modulating at the transmitter the M tones with data;
- interstitially inserting the M tones in the power line synchronous noise spectrum so as to be effectively disjoint with the noise spectrum; and
- receiving the modulated M tones at the receiver, the transmission of data from the transmitters to the receiver being in a Master/Slave relation of meters to the receiver.
- 2. The PLC protocol of claim 1 wherein at least one of the meters includes an additional receiver and further comprising, at the receiver in the meter, the steps of:
- receiving data from said transmitters in other meters;
- collecting and storing received data;
- reformatting the collected and stored data; and
- relaying the reformatted collected and stored data to said at least one receiver in said central hub.
- 3. The PLC protocol of claim 1 wherein the meters are connected in a power distribution network which is reconfigurable into a plurality of potentially overlapping subnetworks, each subnetwork having at least one subnetwork concentrator, further comprising the steps of:
- reserving a harmonic modulated (HM) signal set for said meters to telemeter their configuration in a subnetwork after a power distribution network reconfiguration; and
- transmitting from a meter using the reserved HM signal set information indicating membership or desire for membership in a subnetwork by said meter after said power distribution network reconfiguration.
- 4. The PLC protocol of claim 1 wherein said central hub includes a transmitter and receiver, and further comprising the steps of:
- polling meters with harmonic modulated signals from the central hub; and
- receiving messages from polled meters by the central hub to determine location of a feeder fault.
- 5. The PLC protocol of claim 1 wherein said central hub includes a transmitter and receiver and each of the meters includes a receiver, said protocol further comprising the steps of:
- receiving at a meter receiver an inbound signal from the central hub;
- detecting marker bits in said signal to derive timing information for inbound message framing at the receiver; and
- controlling start of outbound message timing from said meter in accordance with the derived timing information.
- 6. The PLC protocol of claim 1 wherein said central hub includes a transmitter and receiver and each of the meters includes a receiver, and further comprising the step of allocating a mix of harmonic modulation channels to act as outbound and inbound channels in an outbound/inbound ratio according to message traffic control requirements and power line distribution topology.
- 7. The PLC protocol of claim 6 further comprising the step of allocating a different mix of number of harmonic modulation channels to act as outbound and inbound channels, based on message priority or noise conditions.
CROSS-REFERENCE TO RELATED APPLICATION
This application is related in subject matter to application Ser. No. 08/728,020 filed Oct. 9, 1996, by Hershey et al. for "Power Line Communication System" and assigned to the assignee of this application. The subject matter of that application is incorporated herein by reference.
US Referenced Citations (8)
Foreign Referenced Citations (1)
Number |
Date |
Country |
09509473 |
Apr 1995 |
WOX |