US 4,429,299 A · Two-way AC power line communications system

Abstract

An AC power line communications system includes means for transmitting data to and receiving data from a plurality of transceivers over a conventional AC power distribution network. A central procession unit is provided to poll a plurality of room control units which are placed in each room or designated area of a hotel, hospital or building complex. The central processing unit conducts this polling sequence by periodically transmitting, over the neutral and ground lines of the power distribution network, and interrogation signal having an address portion and a data portion. Each room control unit is arranged to receive the interrogation signal and to compare the address portion of this signal with an address previously programmed into the unit. If the address portion of the interrogation signal corresponds with the programmed address of the room control unit, the unit transmits a return signal to the central processing unit. The room control units uses the data portion of the interrogation signal to report a number of different features of functions within the room (or area) in which the room control unit is located. A sequence of successive, identical addresses is used to allow the room control unit to accept data from the central processor. The central processing unit processes the data contained in the return signal insuring that the data received by the room control unit coincides wih the data transmitted to it by the central processing unit and permitting a record of the data accumulated by the room control unit to be made. This AC power line communications system is well suited to be used in combination with a room status indicating system to monitor the status of each room in buildings such as a hotel, motel, or hospital complex, to monitor the condition of a smoke detector located in each room of the complex, to remotely control the operation of the heating and cooling equipment in each room of the complex, to convey message-waiting information to each room in the complex and to perform an automatic wake-up operation.

Claims35

Dependent claims

A two way data transmission communication system for effecting two way transmission of data on an AC power line which has interferring noise thereon and which is located within a building or building complex comprising:

a plurality of transceivers each of which is located in a different room or area of said building or building complex and connected to said AC power line for transmitting data between the transceivers each of said transceivers having a transmit mode and a receive mode during the operation thereof, each of said transceivers further having:
(1) a receiver means for detecting address signals transmitted over the neutral and ground of the AC power line associated with said building or building complex;
(2) means for accumulating data from various external sources;
(3) transmitter means for transmitting a return signal over the neutral and ground of said AC power line, said return signal being representative of the data accumulated by said transceiver;
(4) means for initiating transmission of said return signal upon receipt of a preselected address signal, said system further including a central processing unit having
means for selectively polling each of said transceivers by transmitting over the neutral and ground of said AC power line an address signal which is representative of the transceiver being polled,
receiver means for detecting return signals transmitted over the neutral and ground of said AC power line;
and
means for processing said return signals.

6 more elements

An AC power line communications system for transmitting digital information to and from separate locations or areas on an AC power line which may have interferring noise thereon and which is located within a building or building complex, said digital information capable of being reliably used upon receipt at many locations, said system comprising:

a central processing unit having
receiving means for accumulating information and memory means for storing information pertaining to a particular location or area;
said central processing unit also including a
transmitting means for transmitting an interrogation signal to said particular location or area over the neutral and ground of an AC power distribution network associated with said location or area, said interrogation signal having an address portion which is representative of said particular location or area and an information portion which is representative of the information pertaining to said particular location or area;
a plurality of transceivers each of which is located in a different location or area, each of said transceivers having
means for receiving interrogation signals transmitted by said central processing unit;
means for transmitting digital information to said central processing unit;
and
means for accepting the information portion of a received interrogation signal if the address portion of said received interrogation signal is representative of the particular location or area in which said transceiver is located.

6 more elements

In an AC power line communications system which is exposed to noise, said system comprising a plurality of transceivers each of which is located in a different room or area in a building or building complex, each of said transceivers being operable to accumulate data from various external sources and being assigned a unique address code, and a central processing unit having a memory means for storing the data accumulated by each of said transceivers, a method for updating the stored data pertaining to a particular transceiver, said method comprising the steps of

transmitting from said central processing unit an address signal which is representative of the address code assigned to said particular transceiver on the AC power line associated with said building or building complex;
transmitting from said particular transceiver a first return signal on the neutral and ground of the AC power line associated with said building or building complex upon receipt of said address signal by said particular transceiver, said return signal being representative of the data accumulated by said particular transceiver,
comparing in said central processing unit the data provided to said central processing unit by said first return signal with the stored data pertaining to said particular transceiver, and
transmitting from said central processing unit a succession of address signals which is representative of the address code assigned to said particular transceiver over the AC power line associated with said building or building complex if said comparing step yields a preselected difference.

1 more element

Dependencies are inferred from the claim text.

Two-way AC power line communications system

Life of this patent

Two-way AC power line communications system

Life of this patent

Abstract

Claims35