Pulse or digital communications – Transmitters – Keying circuits
Reexamination Certificate
2000-08-28
2002-09-10
Pham, Chi (Department: 2631)
Pulse or digital communications
Transmitters
Keying circuits
C340S315000
Reexamination Certificate
active
06449318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wire communications. More particularly, the present invention relates to telephone twisted pair communications.
2. Background Information
The existing methods for transmitting data communication over the twisted pair use various modulation techniques that manipulate a carrier(s) by phase, amplitude and/or frequency, and uses voltage detection.
FIG. 1
illustrates a diagram of the conventional modulation techniques used in today's transmission technology.
Referring to
FIG. 1
, data
10
includes information that may be transmitted over the twisted pair using one of the illustrated transmission techniques. Data
10
is represented by digital signals that are transmitted in strings of binary 1s and 0s. When amplitude modulation technique
20
is used to transmit data
10
, the data signal is blended into a carrier by varying the amplitude of the carrier. Specifically, the amplitude is modulated when it corresponds to a binary 0 of the data signal. On-off modulation technique
30
uses a transmitter which is turned off every time the transmitted data signal is represented by a binary 0. When frequency modulation using frequency shift keying (FSK) technique
40
is used, the data signal is blended into a carrier by modulating (shifting) the frequency of the carrier. The frequency shift occurs when a binary 0 in the data signal is encountered. Phase modulation using phase shift keying (PSK) technique
50
shifts the phase (e.g., 180°) when the data signal represented by a binary 0 is transmitted.
Some existing communication systems use multiple carrier frequency such as DSS (Digital Spread Spectrum), DMT (Digital Multi-Tone), OFDM (Orthogonal Frequency Division Multiplexing) and others. Using various modulation techniques, the twisted pair communication industry has obtained data rates of up to 52 megabits at 2000 feet. However, these signaling techniques typically require complex algorithms to recover transmitted information. The use of large and complex algorithms causes delays in communication channels and limits the bandwidth by the computational power of the signaling processing chips being used.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a twisted pair communications transmission system that can transmit information at high rates with high QoS (Quality of Service). By using a differential voltage transmitting an offset low frequency sinusoidal signal within the voice spectrum, that uses an on-off keying (OOK) modulator at the rate of the data being transmitted, high bandwidth transmission speeds can be achieved. In one embodiment, the On/Off state of the low frequency sinusoidal signal can be coupled using state of the art techniques used in the digital subscriber line (DSL) field. Using various coupling techniques, the transmitted information may be used in conjunction with existing analog telephone service and plain old telephone service (POTS) being provided on the twisted pair wire by filtering the specific sinusoidal signal frequency out of the circuit.
One of the advantages of the present invention is that the signal transmitted is a transverse electromagnetic (T.E.M.) wave with an ultra-wide bandwidth. When using this transmission technique for video, voice and data communications, the invention may enable the QoS, reliability and bit error rate required for each service provided.
To provide telephone (voice) services to, from and within the home or office, the telephone must work for emergency services when power is out. The present invention may provide the ability to not only transmit and receive high-speed information, but to also provide telephone emergency service in any state that the home or office electrical service is in.
In some embodiments, information may be transmitted over twisted pairs within a building, campus, and/or over the telephone utility outside plant copper wiring. By modulating a low sinusoidal signal frequency (within the voice frequency range), offset signal, using OOK differentially, high speed transmissions (e.g., speeds of 52 megabits per second) may be realized at extended distances (e.g., 18,000 feet) over the existing twisted pair infrastructure.
Another object of the present invention is to provide cable television-type service capabilities over the twisted pair. If a TV is equipped with the present invention, or a set-to-box is connected, digital TV signals may be sent from a source over the twisted pair copper wires to the television receiver over extended distances.
Another object of the present invention is to transmit high volumes of voice transmissions (telephone conversations) over twisted pairs and interconnect this transmission to the existing public telephone network system.
Another object is to use the twisted pair transmission technology to interface into the other transmission equipment environments, such as, for example, providing trunking or concentrating communication traffic from wireless devices, or LAN (local area network) to a centralized location or peer-to-peer connections.
Another object of the invention is the ability for this technology to be channelized to provide isochronous, asynchronous, synchronous, and bi-synchronous transmissions. Video and voice could be isochronous and high-speed data transfers between computers would be asynchronous. In one embodiment, all information is sent serially.
Another object of the invention is the ability for video, voice and data to be intermixed in the twisted pair communication system. This may allow to distribute various applications (e.g., satellite, radio, cellular, microwave, PCS, telephone, audio, Internet & television communication, transmission and reception) over the twisted pair copper wiring.
In one embodiment, the present invention provides differential voltage, offset frequency, OOK as a transmission technology using a base sinusoidal wave (e.g., a base sinusoidal waive between 400 to 26,000 hertz). By adjusting the base sinusoidal wave to the best power spectrum, better signal to noise ratio can be achieved. This sinusoidal wave is OOK to the ON position when a binary 1 (one) is sent from a digital data source and turned to the OFF position when a 0 (zero) is present, however, this configuration may be inverted. Using conventional encoding and decoding schemes known in the industry, all control and timing information may be transmitted within the serial bit stream provided in the transmission technique. In one embodiment, the information/data from a digital source (e.g., PC, computer, audio system, VCR, etc.) may be transmitted into a buffer and then sent to an OOK modulator. The modulator controls the ON and OFF states of the base sinusoidal wave transmission. Each ON state of the base sinusoidal wave transmitted may then be sent as a forward biased low frequency sine wave with enough current to drive the circuit for the duration of the ON symbol. Further, the signal may be sent into a coupler to be connected to the twisted pair wire infrastructure. The transmitted signal may then be received at the far end and decoupled using a filter device. In one embodiment, the signal is received having a resistive load and input into an optocoupler device to convert and isolate the circuit. The receiver is current sensing and converts current to voltage. Once the current has been converted to voltage, the voltage may be sent to a differential Op Amp circuit to amplify the signal. In one embodiment, a low voltage differential signal receiver converts the wave form into a square wave that the receiving communication device can convert into a binary 1 (one) or binary 0 (zero) logic state. The transmission may be detected as a differential current event using the transmission initial conditions. By using a differential signal method and the T.E.M. waveform, the effect of standard noise conditions found in the twisted pair on the transmission is reduced. By providing a differential base voltage, the noise floor on the transmission is raised and the
Blakely , Sokoloff, Taylor & Zafman LLP
Nguyen Dung X.
Pham Chi
TeleNetwork, Inc.
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