A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

An optical communication device and related method are provided for reducing power variations among wavelength division multiplexing (WDM) signals. The device includes a dynamic gain equalizer (DGE) coupled to an optical communication path carrying WDM optical signals. The DGE is controlled in response to signals generated by an optical channel monitor (OCM). The OCM monitors signals coming into the DGE and monitors the signals leaving the DGE to thus monitor the WDM spectrum for optical signal power variations and adjust the DGE to reduce the signal power variations.

Circuit and method for modulating filter coefficients of a frequency channelizer having a filter bank include: receiving a wide spectrum input signal; modulating the filter coefficients of the filter bank to sweep a center frequency of each channel of the frequency channelizer, using a modulation scheme; and inputting frequency offset compensation caused by the modulation, and output signals of the frequency channelizer to an application processing circuit to convert the output signals to their original center frequencies.

A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

An auto-equalization network device for optical transmitting and receiving is provided. The device includes a network device having an optical transmitter and an optical receiver. The network device is configured to determine a frequency domain forward transmission loss characterization for a signal transmitted by the optical transmitter, looped back and received by the optical receiver. The device is configured to generate a model in the frequency domain having control points based on the characterization, generate and load finite impulse response (FIR) filter taps into a finite impulse response filter based on the model in the frequency domain. The device is configured to iterate transmission of a signal with frequency-dependent preemphasis by the finite impulse response filter, characterization for the frequency-dependent preemphasized signal as looped back and received by the optical receiver, comparison to previous characterization, adjustment of the control points, and reloading the finite impulse response filter taps, until the comparison meets an optimum, so that the network device is auto-equalized for optical transmitting.

A circuit and method for mitigating multi-path interference in direct detection optical systems is provided. Samples of an optical signal having a pulse amplitude modulated (PAM) E-field are processed by generating a PAM level for each sample. For each sample, the sample is subtracted from the respective PAM level to generate a corresponding error sample. The error samples are lowpass filtered to produce estimates of multi-path interference (MPI). For each sample, one of the estimates of MPI is combined with the sample to produce an interference-mitigated sample.

An embodiment includes a host-equalized optical transceiver. The host-equalized optical transceiver includes a driver analog interface, a linear laser diode driver (LLDD), and an optical transmitter. The driver analog interface is configured to interface with a host integrated circuit (IC) of a host system. The LLDD is directly electrically coupled to a host IC of the host system via the driver analog interface. The LLDD is configured to receive an equalized electrical data signal directly from the host IC via the driver analog interface and to generate a driving signal based on the equalized electrical data signal. The equalized electrical data signal is a linear signal. The optical transmitter is electrically coupled to the LLDD. The optical transmitter is configured to receive the driving signal from the LLDD and to generate an optical signal that is representative of the driving signal.

It are provided an optical communication system and an optical communication method. The system comprising at least two optical channels for communicating optical data signals; at least one optical filter arrangement for compensating distortions of the optical data signals communicated via the optical channels and/or crosstalk between the optical channels. The optical filter arrangement comprises at least one optical filter assigned to one of the optical channels and at least one optical filter assigned to the other one of the optical channels, wherein each one of the optical filters is configurable in such a way that different wavelength components of an incoming optical signal will be modified individually.

Embodiments include techniques for transmitting and receiving radio frequency (RF) signals, where the techniques for generating, via a digital analog converter (DAC), a frequency signal, and filtering the frequency signal to produce a first filtered signal and a second filtered signal. The techniques also include transmitting the second filtered signal to a device under test, and filtering the second filtered signal into a sub-signal having one or more components. The techniques include mixing the first filtered signal with the sub-signal to produce a first mixed signal, subsequently mixing the first mixed signal with an output signal received from the device under test to produce a second mixed signal, and converting the second mixed signal for analysis.

Circuit and method for modulating filter coefficients of a frequency channelizer having a filter bank include: receiving a wide spectrum input signal; modulating the filter coefficients of the filter bank to sweep a center frequency of each channel of the frequency channelizer, using a modulation scheme; and inputting frequency offset compensation caused by the modulation, and output signals of the frequency channelizer to an application processing circuit to convert the output signals to their original center frequencies.