Abstract: Signals in an optical communications network, such as optical channels in an optical WDM network for example, are each identified by at least two low frequency dither tones with which the signal is modulated. The dither tones alternate with a predetermined periodicity to produce a cyclically repeated sequence of dither tones. A network parameter, such as a channel identifier for example, is obtained by the detection of the particular combination of dither tones in the sequence. To detect a number of network parameters a signal is modulated with a number of cyclically repeated sequences of dither tones each uniquely identifying a respective network parameter. In some implementations each dither tone in a cyclically repeated sequence of dither tones is repeated with substantially the same phase and coherent averaging is performed over a number of periods to detect dither tones on low power signals.

Abstract: This invention provides a method for commissioning an optical network using internal Automatic Spontaneous Emission (ASE) light inherently present in the optical network as a light source (the ASE light source) for measuring losses inside and between nodes in the network. A modular segmented approach is adopted and the network is commissioned segment by segment. The method uses techniques for the correction of the Optical Signal to Noise Ratio induced error as well as the Spectral Filtering Error during the loss computation required for adjusting the gains of the amplifiers at each network node to an appropriate value. Since the method does not require an external laser source that needs to be moved manually from node to node, it greatly reduces the commissioning time. Since it uses only the existing components of the network nodes it also leads to a significant saving in cost.

Abstract: A method and apparatus for performing a fast Fourier transform (FFT) computation on large data sizes in real time is provided. The speed at which a FFT is performed is increased by reducing the number of times a Direct Memory Access (DMA) unit must transfer data between an internal memory and an external memory. This is achieved through an algorithm in which data is imported from the external memory into the internal memory and having the CPU perform several calculations on the imported data before it is exported back to the external memory. The imported data in the internal memory has a structure that results in a reduction of the number of times the imported data is swapped between different layers of the internal memory during the FFT computation. Furthermore, the DMA unit import/exports data between the internal memory and the external memory while at the same time having the CPU perform calculations on other data in the internal memory.

Abstract: A multi-stage method and apparatus for determining a faulty component location along an optical path through an optical fiber in an optical network are disclosed. The optical fiber carries a plurality of wavelengths, which may or may not be modulated by low frequency dither tones that are utilized for identification purposes and performance monitoring in the optical network. First, the method comprises measuring a total power of the optical fiber and a total wavelength power as a sum of powers of the individual wavelengths at a plurality of local detection points; comparing the measured powers at the local detection points; and determining whether or not a faulty detection point exists along the optical path. If a fault is identified, the method further provides a multi-stage fault detection procedure, which comprises measuring a total wavelength power loss between a local detection point and an adjacent detection point, between the local detection point and multiple non-adjacent detection points.

Abstract: A method and apparatus for encoding optical power and non-payload data in an optical signal is described. The method involves producing a dither modulating signal having an amplitude of indicative of the optical power in the optical signal and having a phase representing the non-payload data, and modulating the optical signal with the dither modulating signal. The apparatus involves a waveform generator for producing an amplitude adjusted waveform having an amplitude responsive to the optical power of the optical signal and a binary phase shift keying modulator for binary phase shift keying the amplitude adjusted waveform in response to the non-payload data to produce a dither modulating signal having an amplitude indicative of the optical power in the optical signal and having a phase representing the non-payload data.

Abstract: Various methods and apparatuses are provided for performing a radix-M FFT (Fast Fourier Transform) upon N time domain samples to produce N/S frequency domain samples for detecting tones of dithers impressed on channels of a WDM (wavelength Division Multiplexed) optical signal. Successive tones have a tone frequency spacing, &Dgr;fta, and a sampling frequency, fs, is chosen so that fs=N&Dgr;fta/S. S is a spacing given by S=Mw with w being an integer. The radix-M FFT is performed in k=logm(N) stages and within the stages a reduced number of radix-M computations, when compared to the number of radix-M computations of a conventional radix-M FFT, are performed on data points associated with the N time domain samples. This is possible because successive frequency domain samples of the N/S frequency domain samples differ by &Dgr;fta=S&Dgr;f where &Dgr;f is a frequency bandwidth.

Abstract: Various methods and apparatuses are provided for performing a radix-M FFT (Fast Fourier Transform) upon N time domain samples to produce N/S frequency domain samples for detecting tones of dithers impressed on channels of a WDM (wavelength Division Multiplexed) optical signal. Successive tones have a tone frequency spacing, &Dgr;fta, and a sampling frequency, fs, is chosen so that fs=N&Dgr;fta/S. S is a spacing given by S=Mw with w being an integer. The radix-M FFT is performed in k=logm(N) stages and within the stages a reduced number of radix-M computations, when compared to the number of radix-M computations of a conventional radix-M FFT, are performed on data points associated with the N time domain samples. This is possible because successive frequency domain samples of the N/S frequency domain samples differ by &Dgr;fta=S&Dgr;f where &Dgr;f is a frequency bandwidth.

Abstract: A method and apparatus for performing a fast Fourier transform (FFT) computation on large data sizes in real time is provided. The speed at which a FFT is performed is increased by reducing the number of times a Direct Memory Access (DMA) unit must transfer data between an internal memory and an external memory. This is achieved through an algorithm in which data is imported from the external memory into the internal memory and having the CPU perform several calculations on the imported data before it is exported back to the external memory. The imported data in the internal memory has a structure that results in a reduction of the number of times the imported data is swapped between different layers of the internal memory during the FFT computation. Furthermore, the DMA unit import/exports data between the internal memory and the external memory while at the same time having the CPU perform calculations on other data in the internal memory.

Abstract: This invention provides method and apparatus for ancillary data in a wavelength division multiplexed (WDM) system. According to the invention, a low bit rate channel is provided over a amplitude modulated sub-carrier that is in turn used to amplitude intensity modulate an optical data signal that is output from a transmitter in the network. Data carried by the low bit rate channel can by used by another network element (NE) to determine the identity of the channel source, thereby allowing the NE to verify its connectivity to that source via the network. This invention is particularly useful in metropolitan optical networks (MON) where inexpensive methods of determining network connectivity are required.

Abstract: Synthetic 2,3-dimethoxy-5-methyl-1,4-benzoquinone is converted into a series of new 6-alkyl derivatives. These 6-alkyl derivatives have straight carbon chains which are both saturated and unsaturated. The unsaturated derivatives contain one, two, three and four double bonds. These new synthetic quinones are analogs of the naturally occurring forms of coenzyme Q and have the same fundamental electron-transfer capacity of the natural forms of coenzyme Q. Although the degree of the activity of these new synthetic analogs differ, some of these new synthetic analogs are effective substitutes for the natural forms of coenzyme Q.