Abstract: 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.

Abstract: 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.

Abstract: 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.