Scientific-atlanta, Inc.

Paul E Quesenberry

Saleh R Al-Araji

Forrest M Farhan

Herman A Kruse

Edward W Brumley, Jr

Dale Patterson

The present invention is directed towards an optical transmitter including a noise generator. The noise generator provides noise signals that are filtered to below a frequency spectrum. The filtered noise signals are combined with RF signals to provide continuous modulation of a laser. The combined signals are converted to optical signals by the laser and transmitted over an optical link.

Spurious free dynamic range in optical communications systems

An amplifier ( ) includes at least one gain stage ( ) for amplifying a signal received by the amplifier ( ). The amplifier ( ) also includes an AGC circuit ( ) that adjusts the amplification of the gain stage ( ). The AGC circuit ( ) determines whether the input signal to the amplifier ( ) is a digital signal or an analog signal and transforms either signal into the frequency domain, thereby automatically adjusts the processing method depending upon the type of pilot carrier signal. The AGC circuit ( ) also possesses the ability to process a change in the frequency of a pilot carrier signal remotely.

Frequency agile adaptive automatic gain control circuit

An ingress monitoring device ( ) for monitoring and detecting reverse signals that may include ingress signals. The ingress monitoring device ( ) includes a processor ( ) for resolving the reverse signals into predetermined sub-bands at a first resolution. A power computation circuit ( ) computes a power level for each of the sub-bands. A threshold comparison circuit ( ) then compares the power level that is indicative to the power level of the ingress signals for each of the sub-bands with a predetermined threshold value. When ingress signals are detected by the ingress monitoring device ( ), an alarm signal is sent that indicates the specific communications equipment in which the ingress signals have been detected.

Ingress monitoring device in a broadband communications system

Systems and methods for a distortion monitoring system that detects an abnormal amount of signal distortion occurring in a transmission system. The distortion monitoring system includes a system amplifier section for amplifying and coupling an input signal to provide first and second outputs and a distortion monitoring section for processing the second output. The amount of distortion present is represented by an output from the distortion monitoring section of the system. In one embodiment, the distortion monitoring section can include an envelope detector for receiving the second output signal, a lowpass filter coupled to the envelope detector for cutting off frequencies below the Nyquist rate, and a voltage amplifier coupled to the lowpass filter for amplifying the signal. An analog to digital converter coupled to the voltage amplifier digitizes the signal, a memory buffer coupled to the analog to digital converter captures the digital data from the analog to digital converter, and a digital signal processor extracts the converted signal. In yet another embodiment, the digital signal processor includes an on-chip memory. A status monitor coupled to the output of the distortion monitoring section provides for monitoring the output signal.

Distortion monitoring system for CATV transmission networks

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

Systems and methods for digitizing broadband signals using multiple analog-to-digital converters (ADCs) and a calibration system for adjusting the phase and bias of the sampled signal such that the output digitized, sample closely approximates the input broadband analog signal. A calibration signal is combined with the broadband signal and the combined signal is converted to digital. The combined signal splits into portions equal to the number of ADCs in the system. An off-line digital signal processor (DSP) analyzes samples representing a portion of the combined signal and computes any necessary adjustments to phase and amplitude of the digitized samples. If adjustments are required, a real-time DSP adjusts the phase and amplitude of the digitized sample, by use of a multiplier and/or adder included in the real-time DSP. The separate portions of the digitized sample are recombined by a multiplexer to create a single digitized output representing the broadband analog signal.

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Marietta, GA, United States of America

Paul E Quesenberry