Integra Research and Development, LLC

Photonics Products, Inc.

Other

Photon Products, Inc.

Paul N Huntley

Chen-Kuo Sun

Ronald F Mathis

Dingbo Chen

Stephen R Mathis

James A Crawford

Barry L Dorr

William L Floyd

Charlie Chen

Ali Ghiasi

Eric Liu

The present invention pertains to systems and methods for equalizing a digitally modulated input signal for transmission as an optical signal over an optical fiber. In detail, this equalization is accomplished prior to the signal's conversion to an optical signal, and prior to the signal being filtered by a vestigial sideband (VSB) filter. In particular, equalization is accomplished by giving weights to the taps of a tapped delay equalizer, wherein weights for respective taps are derived from the output signal after its conversion to a digital signal at the downstream end of the optical fiber.

Adaptive equalization for vestigial sideband (VSB) transmissions

An analog signal processing device for equalizing a low pass filter to create a Nyquist filter in accordance with the present invention includes a low pass filter for passing a predetermined bandwidth, and a tapped delay filter connected with the low pass filter to create the Nyquist filter. In more detail, the tapped delay filter is used to sample an input analog signal having a predetermined symbol rate. The samples from the input signal are then respectively weighted to establish a system transfer function for the Nyquist filter. The purpose here is to minimize both inter-symbol interference and transmission bandwidth. A decision circuit can be provided to convert the input signal into a desired data format for creation of an output signal to be transmitted by the data transmission system. Also, the Nyquist filter can be selectively evaluated as an 'eye diagram' and the system transfer function appropriately adjusted accordingly.

Analog nyquist shaping of a low pass filtered transmission system

In accordance with the present invention, a driver chip is provided for transmitting optical signals over an optical fiber. The driver chip includes, in combination, a tapped delay equalizer, an amplifier and control circuitry. Operationally, the tapped delay equalizer modifies an input digital signal to create a compensated signal by compensating for anticipated impairments and distortions introduced during signal transmission. The amplifier then receives the compensated signal to provide gain and bias in order to establish a proper operating point for an E/O device. The control circuitry is interconnected with the tapped delay equalizer and with the amplifier to establish and control tap weights for the tapped delay equalizer to compensate for electrical and optical bandwidth limitations, along with optical dispersion effects.

Driver chip for minimizing transmission impairments and for boosting signal transmission rates

Methodologies for designing and assembling an analog Nyquist filter require a filter unit which includes a low pass filter in cascade with at least one tapped delay filter. A Signal Generator is used to generate a test pattern for input into the filter unit in order to create a reaction signal from the filter unit. This reaction signal is then compared with a desired Nyquist response. Based on this comparison, amplifier gains for taps in the tapped delay filter are weighted to establish a transfer function in the filter unit. In operation the transfer function shapes analog input signals with the desired Nyquist response for use as an output from the Nyquist filter.

Method for designing an analog Nyquist filter

A waveform acquisition system that captures and digitizes a wideband electrical signal through a bank of front end filters, frequency down converters, and conventional digitizers (A/D converters). A software algorithm reconstructs the composite input signal and applies the necessary corrections to remove the effects of hardware impairments. This approach is possible because it uses a class of filters that exhibit the quality of perfect waveform reconstruction, allowing signals whose spectral components overlap multiple filter bands, to be faithfully reconstructed. A calibration generator switched into the input port serves as a reference for quantifying and removing hardware errors. The channelized analog-to-digital converter (ADC) effectively multiplies the bandwidth and sampling rate of the conventional digitizer performance in a single channel by the number of channels in the system.

Channelized analog-to-digital converter

A waveform acquisition system that captures and digitizes a wideband electrical signal through a bank of front end filters, frequency down converters, and conventional digitizers (A/D converters). A software algorithm reconstructs the composite input signal and applies the necessary corrections to remove the effects of hardware impairments. This approach is possible because it uses a class of filters that exhibit the quality of perfect waveform reconstruction, allowing signals whose spectral components overlap multiple filter bands, to be faithfully reconstructed. A calibration generator switched into the input port serves as a reference for quantifying and removing hardware errors. The channelized analog-to-digital converter (ADC) effectively multiplies the bandwidth and sampling rate of the conventional digitizer performance in a single channel by the number of channels in the system. The use of digital local oscillators enable a compact, low power, monolithic architecture.

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Poway, CA, United States of America

Paul N Huntley