Patent Application
20110026920
There are a variety of different transmission interfaces for communications, including wireless and wired communications. Wired communications are typically employed over wires dedicated solely for supporting communications, e.g., the public switched telephone network (PSTN). Another type of wired communications, commonly referred to as powerline communications, employs electrical powerlines to carry communications. In particular, communication signals are modulated onto the powerline by a transmitter and then demodulated by a receiver. Because there is a much larger existing infrastructure for electrical powerlines compared to dedicated communication lines, the infrastructure costs of deploying a powerline communication system can be reduced compared to dedicated communication line systems.
Powerlines are noisy environments. For example, powerlines typically act like large antennas, absorbing a variety of radio frequency interference. Moreover, appliances typically introduce interference into powerlines. Conventional techniques for mitigating noise on powerlines involve line filters. These filters, however, are ineffective in removing in and out of band hystersis and noise levels.
In view of the above-identified and other deficiencies of conventional powerline communication techniques, exemplary embodiments of the present invention provide systems and methods of mitigating noise in powerlines. An exemplary system includes a frequency and amplitude selective optical converter coupled to a powerline. The system also includes an optical multiplexer coupled to the optical converter and an optical demultiplexer coupled to the optical multiplexer. The optical converter is tuned to a frequency and amplitude corresponding to voice or data communication signals carried on the powerline.
The optical converter can include a first diode tuned to pass signals with a first frequency and a first amplitude and a second diode tuned to pass signals with a second frequency and a second amplitude, where the first and second frequencies correspond to a frequency bandwidth of a communication signal. The first and second diodes can be PIN diodes or light emitting diodes (LEDs).
The optical converter can also include a third diode tuned to pass signals with a third frequency and the first amplitude and a fourth diode tuned to pass signals with a fourth frequency and the second amplitude, where the third and fourth frequencies correspond to a frequency bandwidth of another communication signal.
The first frequency can be approximately 2.4 GHz, the second frequency can be approximately 2.5 GHz, the third frequency can be approximately 1800 MHz and the fourth frequency can be approximately 1900 MHz.
The first and third diodes are light diodes and the second and fourth diodes are dark diodes.
The system can also include an optical-to-wireless converter coupled to the optical demultiplexer. The optical-to-wireless converter transmits wireless communication signals corresponding to the voice or data communication signals carried on the powerline.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
Powerline-communications coupler 108 provides the combined power and communication signal via cable 114 to transformer 116, which then provides the combined signal via powerline 118 to powerline-communications coupler 120. Powerline-communications coupler 120 can include a filtering and optical conversion system, such as that described in more detail below in connection with
Powerline-communications coupler 132 filters the combined power and communication signals and passes the filtered signals via cable 134 to transformer 136 for delivery to building 140 via powerline 138. Powerline-communications coupler 132 also passes the combined signals via cable 142 to antenna 144 for delivery to buildings 148 and 152 via wireless communication links 146 and 150, respectively. Thus, building 140 can receive both power and access to communication network 102 via powerline 138. Additionally, buildings 148 and 152 can access communications network 102 without being connected by a powerline.
It should be recognized that the system of
The operation of the systems of
Optical converter 210 includes a set of light and dark diodes tuned for each set of frequencies that carry communication signals. For example, assuming that the communication signals are in both the 1800 MHz band and the 2.4 GHz band, then a first filter 212A can have one diode tuned between 1800 MHz and 1850 MHz and a second diode tuned between 1850 MHz and 1900 MHz, and a second filter 212B can have one diode tuned between 2.3 GHz and 2.4 GHz and a second diode tuned between 2.4 GHz and 2.5 GHz. The amplitudes P1 and P2 are selected to be higher than the highest amplitude expected for a communication signal on the powerline. These amplitudes can also include an added hystersis amount above the highest amplitude expected for a communication signal on the powerline to account for any unexpected variations.
The output of filters 212A-212N are passed to optical multiplexer 220, which combines the filtered signals and passes them to optical demultiplexer 230, which again separates the filtered signals into their respective frequency bands. Optical multiplexer 220 and demultiplexer 230 each include a number of lenses that, in addition to the multiplexing and demultiplexing, provide further noise reduction. When the signal is to be passed to an antenna then the signal is passed to optical-to-wireless converter 240. When the signal is to be recombined with a power signal, then the output is passed to recombiner/transformer 250.
The present invention provides an exemplary system for removing noise from communication signals carried on powerlines. In-band noise that occurs at the same frequency as the carrier of the communication signals are filtered by controlling the amplitude passed by the filter and out-of-band noise is filtered by controlling the frequency of the filter. Additionally, the present invention does not require an external power source to operate the system. Instead, the power that is not passed by the filters can be used to power the filters, multiplexer, demultiplexer, optical-to-wireless converter and recombiner/transformer.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
