Apparatus and method for transmitting digital data over various communication media

A monitoring system for twenty four hour monitoring of a parking lot, in which monitoring signals are transmitted though a lighting power system of the parking lot, the monitoring system comprising:

• a master modem configured to receive a plurality of modulated signals from the lighting power system of the parking lot, and provide a plurality of demodulated signals to a recording device, and
• a plurality of slave modems, each of which is configured to receive a video signal from a camera, modulate the video signal and provide the modulated signal to the lighting power system, wherein each of the slave modems and each of the cameras receive operating power from the lighting power system, wherein the lighting power is available for only a portion of each twenty four hour period, and wherein each slave modem and each camera includes means for operating when the lighting power is not available.

A security monitoring system which utilizes a line power within a structure for transmission of signals between the components thereof, comprising:

• a master modem configured to receive a plurality of modulated signals from the power line, to provide a demodulated signal for transmission over the Internet and to receive commands from the Internet, and
• a plurality of slave modems, each of which is configured to receive a video signal from a camera, modulate the video signal and provide the modulated signal to the power line, wherein the video signal from any one of the cameras may be selected for transmission over the Internet by the reception of an appropriate one of the commands.

A system for transmitting a video signal over an electrical power line connected to a plurality of premises comprising:

• a first modem, the output of which is connected to the power line, said modem receiving the video signal from a source and providing a modulated signal to the power line;
• a second modem, the input of which is connected to the power line, said modem demodulating the modulated signal, and
• a display device connected to the output of said second modem, wherein the video signal is transmitted from the source to said first modem via the Internet.

A system for transmitting a video signal over an electrical power line connected to a plurality of premises comprising:

• a first modem, the output of which is connected to the power line, said modem receiving the video signal from a source and providing a modulated signal to the power line;
• a second modem, the input of which is connected to the power line and the output of which is connected to the Internet at a first access point, said second modem demodulating the modulated signal, and
• a display device connected to the Internet at a second access point for displaying the video signal.

A system for transmitting a cable television signal over an electrical power line connected to a plurality of premises comprising:

• a first modem for receiving the cable television signal, the output of said first modem being connected to the power line;
• a second modem, the input of said second modem being connected to the power line for receiving the cable television signal, and
• a display device connected to the output of said second modem, wherein orthogonal frequency division modulation or frequency modulation-orthogonal frequency division modulation is used for transmitting the cable television signal over the power line.

A system for transmitting and receiving a communication signal using a conductor of a power line comprising:

• a first transmitter/receiver connected to the power line, said first transmitter/receiver configured to output a first OFDM or FM-OFDM signal to the power line and receive a second OFDM or FM-OFDM signal from the power line, the power line having a conductor adapted to radiate the first OFDM or FM-OFDM signal received from the first transmitter and to wirelessly receive the second OFDM or FM-OFDM signal;
• and
• a second transmitter/receiver configured to wirelessly transmit the second OFDM or FM-OFDM signal to the power line and to wirelessly receive the first OFDM or FM-OFDM from the power line.

A system for communicating over a power line comprising:

• a master modem connected to the power line and adapted to transmit a plurality of OFDM or FM-OFDM signals over the power line, each of which is transmitted within one of N distinct transmit frequency bands and to receive a plurality of OFDM or FM-OFDM signals from the power line, each of which is received on one of N distinct receive frequency bands, pairs of the transmit and receive frequency bands corresponding to operating frequencies of a sub-network;
• a plurality of slave modems connected to the power line, each which being configured to operate in one of the N sub-networks and adapted to receive the OFDM or FM-OFDM signal from the master modem in a corresponding transmit frequency band and to transmit an OFDM or FM-OFDM signal to the master modem in a corresponding receive frequency band, wherein the slave modems in each sub-network transmit a time division multiplexed signal.