Scientific-atlanta, Inc.

Forrest M Farhan

Alberto P Gaibazzi

Joseph Graham Mobley

Leo Montreuil

Paul E Quesenberry

Michael J Labiche

Graham Mobley

Donald Sipes

A cable television system () having forward and reverse paths includes, in the reverse path, a digital optical transmitter () for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system () also includes an optical receiver () for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter () and receiver () are coupled by fiber optic communication media ().

Digital optical transmitter

A broadband communication system includes headend equipment for transmitting downstream signals and for processing upstream signals and communication devices coupled to one another in a bi-directional ring, where one of the communication devices functions as a hub that is coupled to the headend equipment for providing the upstream signals to, and receiving the downstream signals from, the headend equipment. A clockwise communication path couples the communication devices to one another for the reception and transmission of clockwise-traveling signals that include the downstream signals and at least a portion of the upstream signals, and a counterclockwise communication path couples the communication devices to one another for the reception and transmission of counterclockwise-traveling signals that include the downstream signals and at least a portion of the upstream signals. The system also includes subscriber equipment coupled to the communication devices for receiving the downstream signals and for generating the upstream signals. When a malfunction is detected in one of the communication paths, the functioning path is then employed to transmit the downstream signals to the communication devices that are no longer able to receive the downstream signals via the malfunctioning path.

Bidirectional communication system with ring configuration

A cable television system ( ) having forward and reverse paths includes, in the reverse path, a digital optical transmitter ( ) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system ( ) also includes an optical receiver ( ) for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter ( ) and receiver ( ) are coupled by fiber optic communication media ( ).

A transmitter ( ) for use in a communication system ( ) includes clock input for receiving a clock signal and input ports ( ) coupled to external signal sources for receiving input signals that are synchronously modulated at modulation frequencies rationally and fractionally related to the clock frequency and to each other. Additionally, the clock frequency should be greater than any of the modulation frequencies. An analog-to-digital converter ( ) receives the analog input signals and converts them to a digital format, and a multiplexer ( ) then processes the digital input signals and signals from the converter ( ) to generate a single serial output signal. An output port of the transmitter ( ) then transmits the single serial output signal as a digital signal having a bit rate equivalent to the number of input signals multiplied by the sampling frequency, plus additional overhead for optional framing and error correction.

Multiplexing digital communication system

A cable television system ( ) includes a transmitter ( ) for generating a digital optical signal ( ) and a receiver ( ) for receiving said digital optical signal and converting it to an analog signal. The transmitter ( ) includes a processor ( ) for processing inputs and generating a gain/loss parameter which is applied via a gain/loss amplifier ( ) to an incoming analog signal ( ). The modified digital signal received by the digital optical receiver ( ) decodes the applied gain/loss parameter at a converter ( ) and applies the information to the output analog signal via a gain/loss amplifier ( ).

Digital optical transmitter with improved noise power ratio

A cable television system ( ) having forward and reverse paths includes, in the reverse path, a digital optical transmitter ( ) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system ( ) also includes an optical receiver ( )for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter ( ) and receiver ( ) are coupled by fiber optic communication media ( ).

A broadband network, such as a cable television system, includes a synchronous code generator that converts an analog signal into a digital signal and inserts a synchronous code in the digital signal. The synchronous code generator is in communication with an optical link, which transmits the digital signal. An optical performance monitor receives the digital signal from the optical link and determines performance of the optical link based on errors in the synchronous code. The optical link performance monitor includes an error detector, which detects errors in the synchronous code, and, in response thereto, signals a counter of the error. The counter accumulates the errors detected by the error detector for a period of time. A processor, which is in communication with the counter, determines the optical performance of the optical link based upon the number of errors accumulated by the counter. A user interface displays the results of the processor.

Methods and systems for detecting optical link performance of an optical link in a hybrid fiber coaxial path

A node ( ) for receiving analog signals transmitted within a broadband communication system ( ) includes a summer ( ) for summing the analog signals to generate a summed analog signal and an analog-to-digital (A/D) converter ( ) coupled to the summer ( ) for converting the summed analog signal into a digital electrical signal. The node ( ) also includes a digital signal processor (DSP) ( ) coupled to the A/D converter ( ) for filtering the digital electrical signal in accordance with a filter algorithm to generate a filtered digital signal. The DSP ( ) including a control port for receiving a control signal ( ) indicative of the filter algorithm that is to be used. The filtered signal is then transmitted upstream within the system ( ) by a transmitter ( ) coupled to the DSP ( ).

Digital signal processing optical transmitter

A cable television system ( ) includes forward and reverse paths. In the reverse path, an optical transmitter ( ), which could be located in an optical node ( ), receives an analog information signal from subscriber equipment ( ) and transmits in accordance therewith a digital optical signal. The optical transmitter ( ) digitizes its incoming signal, compresses the signal, and generates therefrom the digital optical signal. The cable television system ( ) also includes an optical receiver ( ) for receiving the digital optical signal, decompressing information included in digital optical signal, and recovering therefrom an analog signal representative of the analog information signal. The optical receiver ( ) could be included in a hub or headend equipment ( ) of the cable television system ( ).

Digital optical transmitter with compression

A cable television system ( ) includes a transmitter ( ) for generating a digital optical signal and a receiver ( ) for receiving such digital optical signal and converting it to an analog signal. The receiver ( ) includes a digital filter ( ) disposed between a deserializer ( ) and a digital-to-analog converter ( ), which digital filter conditions the digital electrical signal received from the deserializer ( ). 1o The digital filter ( ) is employed as a digital noise mitigation block so as to improve the quality of the signals in the reverse path, returning to the cable television system ( ) headend ( ).

Digital optical receiver for cable television systems

A broadband communication system ( ), such as a cable television system, includes a forward path for transmitting information from headend equipment to subscribers and a reverse path for transmitting information from the subscribers to the headend equipment. The reverse path includes a transmitting station ( ) that receives a first analog signal, converts the first analog signal to a first digital signal having a first number of bits, encodes the first digital signal to generate a second digital signal having a second number of bits less than the first number of bits, then optically transmits the second digital signal. A receiving station ( ), also located in the reverse path, receives the second digital signal, decodes the second digital signal to generate a third digital signal having a third number of bits greater than the second number of bits, then converts the third digital signal to a second analog signal that approximates the first analog signal.

Broadband communication system for efficiently transmitting broadband signals

A cable television system ( ) includes a clock source ( ) for generating a clock signal, an optical receiver ( ) coupled to the clock source ( ) for recovering the information in accordance with the clock signal, and an optical transmitter ( ) that has input ports ( ) for receiving first and second information signals and a clock port ( ) for receiving the clock signal. An interleaver ( ) within the transmitter ( ) is coupled to the input ports ( ) and to the clock port ( ). The interleaver ( ) interleaves bits of the information signals in accordance with the clock signal to generate a serial bit stream that is used to modulate a laser diode ( ), thereby generating a digital optical signal that is transmitted to the optical receiver ( ) over an optical communication medium ( ).

A cable television system ( ) for transmitting information in forward and reverse directions includes forward and reverse paths over which information is transmitted and a reverse path transmitter ( ) and a reverse path receiver ( ), both located in the reverse path. The reverse path transmitter ( ) receives an analog electrical signal and an external digital signal from an external source, such as a PCS terminal or router. The transmitter ( ) then generates a single digital bit stream from the external digital signal and the digital electrical signal and transmits the single digital bit stream modulated at a first wavelength over a fiber optic communication medium ( ) that couples the transmitter ( ) and the reverse path receiver ( ). The reverse path receiver ( ) receives and demodulates the single digital bit stream to regenerate the digital electrical signal and the external digital signal, converts the digital electrical signal to the analog electrical signal for processing within the cable television system ( ), and forwards the external digital signal for processing by a second external source outside the cable television system ( ).

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Duluth, GA, United States of America

Forrest M Farhan