Abstract: In one example, an apparatus includes e first beam splitter having a first output and a second output. A first optical waveguide is coupled to the first output, and a second optical waveguide is coupled to the second output. A first tunable phase delay is further coupled to the second optical waveguide and has a third output. A first set of phase modulators is coupled to the first optical waveguide, and a second set of phase modulators is coupled to the third output of the first tunable phase delay. At least one of the first set of phase modulators and the second set of phase modulators includes a phase modulator that is driven to three or more distinct phase states. A second beam splitter has a first input coupled to the first optical waveguide and a second input coupled to the second optical waveguide.

Abstract: A high-speed interface apparatus and method of correcting skew in the apparatus are provided. A high-speed transmitter includes a transmission D-PHY module that generates and transmits a clock signal through a clock channel, generates a deskew synchronous code and test data in response to a deskew request signal, transmits the deskew synchronous code followed by the test data through a data channel, and transmits a normal synchronous code followed by normal data through the data channel in normal mode.

Abstract: A high-speed interface apparatus and method of correcting skew in the apparatus are provided. A high-speed transmitter includes a transmission D-PHY module that generates and transmits a clock signal through a clock channel, generates a deskew synchronous code and test data in response to a deskew request signal, transmits the deskew synchronous code followed by the test data through a data channel, and transmits a normal synchronous code followed by normal data through the data channel in normal mode.

Abstract: We disclose an optical transport system configured to transport the same data using two different channels of an optical transport link in a manner that enables an optical receiver to use direct detection of the optical power received through each of the two channels to measure the in-phase and quadrature components of the modulating electromagnetic field. In an example embodiment, an optical carrier of the modulated optical signal transported using the first of the two channels and an optical carrier of the modulated optical signal transported using the second of the two channels have a fixed relative phase offset of approximately 90 degrees. The resulting ability of the optical receiver to measure each of the in-phase and quadrature components of the modulating electromagnetic field advantageously enables the optical receiver to perform electronic signal equalization, including but not limited to electronic dispersion compensation.

Abstract: A method for transmitting a binary digital transmit signal over an optical transmission link includes creating a differential optical duobinary signal, supplying the differential optical duobinary signal to a first end of the optical transmission link, transmitting the differential optical duobinary signal to a second end of the optical transmission link, and receiving the differential optical duobinary signal as a receive signal at the second end of the optical transmission link. The differential optical duobinary signal may be created by pre-coding the binary digital transmit signal having a given bit interval (T) in two pre-coding steps each with a signal delay of a single bit interval or in a single pre-coding step with a signal delay of twice the bit interval. In each case the pre-coding applies a non-XOR or equivalent operation.

Abstract: A decision feedback equalizer is provided for correcting ISI on a first postcursor without using received decision data of a preceding bit. The decision feedback equalizer includes an amplifying circuit that is to be supplied with received data, a duobinary signal decision device for determining an output signal from the amplifying circuit, the duobinary signal decision device including a flip-flop, a shift register for successively shifting a decision result held by the flip-flop, and a plurality of current control blocks that are to be supplied with respective output signals from the shift register, and feeding back output signals to an output terminal of the amplifier to control the potential thereof.

Abstract: A common mode of a waveform of a duobinary transmission signal (IN) is set to 0 and the size of a data eye is set to Veye; and reference potentials Vref_H and Vref_L are set to the following values: Veye/?{square root over (3)}?Vref—H?Veye/?{square root over (2)}??(1) ?Veye/?{square root over (2)}?Vref—L??Veye/?{square root over (3)}??(2) More particularly, effect becomes remarkable by setting the reference potentials Vref_H and Vref_L to central values in ranges shown in Equations (1) and (2), respectively. In the central values, fluctuation (jitter) of transition data becomes the smallest, and a jitter characteristic of a reproducing clock becomes the best. Consequently, a clock reproducing apparatus in which a received clock from duobinary transmission data is reproduced with high accuracy is provide.

Abstract: An integrated circuit containing a communication channel is described. This communication channel includes a transmit circuit configured to transmit signals using a voltage-mode driver, a receive circuit, and a capacitive link that couples the transmit circuit to the receive circuit. The communication channel includes a filter with a capacitive-summing junction to equalize signals communicated between the transmit circuit and the receive circuit.

Abstract: Provided is a test apparatus that tests a device under test, comprising a pattern generating section that generates a test pattern determined according to a test signal to be supplied to the device under test; a timing signal generating section that generates a timing signal indicating a timing for supplying the test signal to the device under test; a digital filter that filters the test pattern to output a jitter control signal representing jitter corresponding to the test pattern; a jitter injecting section that injects the timing signal with jitter by delaying the timing signal according to the jitter control signal; and a waveform shaping section that generates the test signal formed according to the test pattern, with the timing signal into which the jitter is injected as a reference.

Abstract: When a receiver (200) receives a signal transmitted from a transmitter, an A/D converter (204) converts the signal into a digital signal having two or more levels by A/D conversion. A zero-level detector (207) converts the signal into a two-level digital signal of positive and negative levels. The converted signals are subjected to spectrum despreading by correlators (206, 208), respectively. Whichever signal has a higher intensity is selected by absolute value detectors (209, 210), a comparator (211), and a switch (212). A decoder (213) decodes the selected signal. In a receiving state where the zero-level detector (207) is selected, the transmitter transmits the transmission signal after the signal is converted into a two-level signal. In a receiving state where the A/D converter (204) is selected, the transmitter transmits the transmission signal after the signal is converted into a signal having two or more levels.

Abstract: A rotary joint for transmission of data from a data source to a data sink, between a rotating part and a stationary part, includes a transmission line arrangement fed from a transmission means, and also a receiving means which taps signals from the transmission line arrangement with the aid of a receiving coupler arrangement. A control unit controls the data source. For transmission of data having a small band-width an encoder is provided which converts the data from the data source to a duobinary code.

Abstract: Precoded data transmitted from transmitting apparatus (101) is received by receiving apparatus (102) as duobinary data being ternary data via transmission path (103), and the duobinary data is converted into differential data being binary data by absolute value converter (121) comprising an AND gate and an OR gate.

Abstract: The method for reducing the rate of registration in CDMA-based mobile networks is a method for preventing a traveling mobile device from registering within a new, or secondary, registration area, prior to physically relocating from a first, or current, registration area to the new registration area. The mobile device has a storage memory associated therewith, for storing a database containing geographic coordinates defining boundaries of a plurality of registration areas. The mobile device scans for a new registration pilot signal associated with a new registration area, and upon detection, the geographic location of the mobile device is determined. This geographic location is compared with the coordinates of the boundaries stored within the database, and if the mobile device is determined to be within the boundary defining the new registration area, the mobile device is then registered with a base station of the new registration area.

Abstract: An encoder encodes sound data and the like to generate a binary signal. A mapper converts the binary signal into a four-level symbol and outputs the four-level symbol. A base band filter includes a root raised cosine filter and a sinc filter. The base band filter blocks a predetermined frequency component of a symbol to shape the symbol into a waveform signal and outputs the waveform signal shaped. An FM modulator transmits a signal subjected to FM modulation according to a magnitude of an amplitude of a waveform signal to a receiving unit. When a symbol of ±3 is outputted from the mapper, a frequency shift of a signal transmitted from the FM modulator has a predetermined value in a range of 0.822 [kHz] to 0.952 [kHz]. This makes it possible to provide a modulating apparatus, a mobile communication system, a modulating method, and a communication method that use a modulating method that can conform to the FCC rule to be enforced in 2005 without using a linear power amplifier.

Abstract: A method of reducing distortion in the output of an amplifier is provided. The method comprises subtractively combining an error signals with the appropriate phase shift with input signals to be amplified. The error signal being generated by subtractively combining a fed-forward portion of the input signal with a portion of the fed-back amplified output signal, and signal processing applied to it between its generation and application to correcting the input signal in the baseband domain. The error therefore being down-converted, filtered, and up-converted in the feedback path. The filtered baseband error signal components providing inputs to a controller which adjusts active elements of the amplification and feedback path in order to minimize the distortion within the output of the amplifier.

Abstract: In the present multilevel signal receiver, an output signal of a comparator which judges a high-level of a multilevel signal and a signal obtained by inverting an output signal of a comparator which judges a low-level of the multilevel signal are input to an edge-triggered RS-FF, and an output signal of the edge-triggered RS-FF is fed back to the comparator on the high-level side via a LPF, so that a high-level threshold voltage is regulated. At the same time, a signal obtained by inverting the output signal of the comparator on the high-level side and the output signal of the comparator on the low-level side are input to an edge-triggered RS-FF, and an output signal of the edge-triggered RS-FF is fed back to the comparator on the low-level side via a LPF, so that a low-level threshold voltage is regulated.

Abstract: A data receiving device comprises amplifying circuit 41 that amplifies received duobinary data with a given gain into an output signal, offset canceler 56, 57 that cancel an offset of the output signal from amplifying circuit 41, data determiner 43, 44 that sample the output signal from amplifying circuit 41 based on a first reference voltage and a second reference voltage which is of a lower level than the first reference voltage to determine which one of three levels of the duobinary data the received duobinary data have.

Abstract: According to an aspect of an embodiment, a communication system includes a transmission apparatus with a coding section that generates multi-level-coded signals and transmits the multi-level-coded signals; and a deskew signal generation section that generates and transmits a deskew signal related to the multi-level-coded signals. The communication system also includes a receiving apparatus with a decoding section that decodes the multi-level-coded signals to generate decoded signals, and a deskew processing section that performs deskew processing for compensating skew among the decoded signals of the multiple channels. The deskew signal generation section generates the deskew signal that has been framed by extracting a part of the data from each of the channels of the input signals, adding framing data for enabling a receiving apparatus to recognize which channel the extracted data has been extracted from, and performing rate conversion.

Abstract: A variety of adaptable electronic duobinary generating filters to be used in communication systems are provided, each filter generating an adaptable electronic duobinay signal which is optimized for system impairments. According to one exemplary implementation, an adaptable electronic duobinary generating filter comprises an adaptable delay-and-add circuit, having an adaptable electronic delay element having a delay ?T: 1/T being the bit rate of the binary data input into the adaptable delay-and-add circuit, and a being an adaptation parameter which can be optimized depending on the system impairments. In one optional implementation, the adaptable electronic delay element can be programmably adaptable to optimize against deterministic system impairments. In another optional implementation, the adaptable electronic delay element can be dynamically adaptable to optimize against dynamically varying system impairments.

Abstract: A (binary) signal is transmitted through an electrical backplane, and the received signal is interpreted as a duobinary signal. In order to ensure that the received signal can be properly interpreted as a duobinary signal, the data signal is preferably filtered prior to being interpreted. The filter is preferably designed such that the combination of filter and the backplane approximates a binary-to-duobinary converter. In one embodiment, an (FIR-based) equalizing filter is applied to the data signal prior to transmission to emphasize the high-frequency components and flatten the group delay of the backplane. The resulting, received duobinary signal is converted into a binary signal by (1) splitting the duobinary signal, (2) applying each copy to a suitably thresholded comparator, and (3) applying the comparator outputs to a suitable (e.g., XOR) logic gate. The transmission system enables high-speed data (e.g., greater than 10 Gb/s) to be transmitted over relatively inexpensive electrical backplanes.

Abstract: The apparatus for transmitting and receiving data according to the invention contains a transmitter (1) for serial data transmission and a receiver (3) for receiving a transmitted data signal (g(t)). The receiver (3) in turn comprises a first sample latch (11) for sampling the received data signal (g(t)) with a first clock (f2) and for generating a first sample value (an). The receiver (3) also comprises a second sample latch (13) for sampling a first shifted received data signal (g(t)+V1) with a second clock (f1) and for generating a second sample value (yn). The receiver (3) further comprises a third sample latch (14) for sampling a second shifted received data signal (g(t)?V1) with the second clock (f1) and for generating a third sample value (zn). Finally the receiver (3) comprises a logic unit (15) for recovering data (dn) out of said first, second and third sample values (an, yn, zn).

Abstract: An apparatus and method for tunably delaying a signal and using that delayed signal in a duobinary transmitter is described. The transmitted duobinary signal is representative of the binary signal, and is formed by, among other things, introducing into a copy of the binary signal a delay that may be adjusted to be greater than or less than the bit period of the signal. Once the binary signal has been converted into a duobinary signal, it may then be converted into an optical duobinary signal. Alternatively, the conversion from binary to duobinary in accordance with the invention may be performed in the optical domain.

Abstract: A method and apparatus are provided for implementing soft-input soft-output iterative detectors/decoders. Soft-input information is added directly to incoming channel samples. Input signals comprising the received incoming channel samples with the added soft-input information are detected using a detector trellis. Branch metric terms are transformed to shift all time varying terms with the added soft-input information and some constant terms after an add compare select (ACS) unit. The shifted time varying terms with the added soft-input information and the shifted constant terms are added directly to state metric terms. The soft-input information is added directly to incoming channel samples and the computation of branch metrics is not affected. This allows optimization of a dual-max detector and soft-input soft-output Viterbi detector architectures to minimize hardware complexity and power consumption.

Abstract: A code conversion circuit provided with a bit distributing unit for dividing a high speed input signal into N ways of low speed signals, N number of code converters for performing code conversion on the N ways of low speed signals, and a bit combining unit for receiving as input code-converted low speed signals output from the N number of code converters and logically adding and combining these to produce a code-converted high speed output signal, whereby it becomes possible to ease the harsh restriction on the delay time with respect to one time slot imposed on a delay element in a pre-coder used for optical duobinary transmission.

Abstract: A method and apparatus for the multi-level coding for communication for computer bus data transfers are described. An input signal and delayed versions of the input are combined to create an encoded output signal. An input signal and delayed versions of the output are combined to create a decoded output signal.

Abstract: A synchronous encoder with an output that is limited by the propagation delay of only a single component. The encoder signal, which is initially NRZ, is first aligned with the clock data, then converted to RZ, using a synchronized signal part. Then, it is converted from RZ to NRZ-M, and the output is retimed. The signal can be used to drive an optical modulator for the purpose of generating an optical RZ output.

Abstract: A pulse signal transmitting circuit generates a pulse signal having an enhanced high-frequency component with a reduced power loss. A pulse signal is transmitted to a load circuit through a transmission cable connected to a secondary winding of a transformer. First and second transistors are connected to a primary winding of the transformer. A voltage output from an external power source is input to the primary winding of the transformer when at least one of the first and second transistors is conductive so that a pulse voltage signal is input to the transformer. A booster power supply circuit is located between the external power source and a middle point of the primary winding of the transformer. The booster power supply circuit superimposes a boost voltage onto the voltage input to the primary winding of the transformer so that a high-frequency component of the pulse voltage signal input to the primary winding of the transformer is enhanced.

Abstract: Disclosed is a method for generating a duobinary signal which has the step of: modulating individually an intensity and a phase of a carrier wave. Also disclosed is a duobinary-manner optical transmitter which has: a laser device which outpus signal light; an optical intensity modulator which intensity-modulates the signal light according to a first data signal generated by dividing a data signal into two signals; a precoder which inputs a second data signal generated by dividing the data signal into two signals; and an optical phase modulator which phase-modulates the intensity-modulated signal light according to a signal which is obtained delaying 0.5 bit an output signal of the precoder.

Abstract: Methods and apparatus are provided for implementing high-speed and area efficient architectures for Viterbi detection of generalized partial response signals using both partial matched filter and matched filter metrics. In the method of the invention, branch metric terms are transformed to shift all time varying terms and some constant terms after an add compare select (ACS) unit. The total number of non-zero constants on trellis branches is minimized. The shifted time varying terms and the shifted constant terms are added directly to state metric terms. The time varying terms are expressed as outputs Zn of a partial matched filter or as outputs Wn of a matched filter. For a given generalized partial response target, the time-invariance property of the Viterbi detector enables identifying the minimum number of non-zero constants on trellis branches without resorting to heuristics.

Abstract: The present invention relates to an optical duobinary transmitter system and method using optical intensity modulation. The system comprises an input terminal (51) arranged to receive a first binary signal, a driving circuit (53) connected to the input terminal and arranged to convert the first binary signal into a second and a third binary signal, a double electrode optical modulator (55) connected to the driving circuit in such a way that its upper and lower electrode may be driven by said second and third binary signal, respectively, said modulator being further arranged to modulate the amplitude and phase of an optical carrier according to the binary driving signals so as to provide an optical duobinary signal corresponding to said first binary signal and with a predetermined negative modulation chirp parameter, and an output terminal (57) connected to the optical modulator and arranged to feed an optical transmission line with the modulated optical duobinary signal.

Abstract: A data symbol sequence detector for choosing data symbol sequences likely to be represented by corresponding sequences of samples received by the detector with these sample sequences formed by sampling data signals obtained from magnetically stored data through a data retrieval channel which asymmetrically affects the magnitudes of the data signals. An expected sample value estimator provides estimated expected magnitude values for a selected set of samples in the sequence, and a magnitude difference determiner is used for obtaining representations of differences between values of the samples in the sequence and the corresponding estimated expected values. These differences representations can be limited in algebraic form.

Abstract: Disclosed is a method for generating a duobinary signal which has the step of: modulating individually an intensity and a phase of a carrier wave. Also disclosed is a duobinary-manner optical transmitter which has: a laser device which outputs signal light; an optical intensity modulator which intensity-modulates the signal light according to a first data signal generated by dividing a data signal into two signals; a precoder which inputs a second data signal generated by dividing the data signal into two signals; and an optical phase modulator which phase-modulates the intensity-modulated signal light according to a signal which is obtained delaying 0.5 bit an output signal of the precoder.

Abstract: Apparatus for implementing the application of duo-binary signal encoding in high-power, high-speed transmission systems which may be employed to mitigate the problem of stimulated Brillouin scattering. A dual-drive Mach-Zehnder interferometer modulator is used, with data being applied to both modulation inputs. The voltage difference between the two modulation inputs is between -V.sub..pi. and + V.sub..pi.. In one embodiment, the data signal is applied to one input, and the same signal, delayed by one bit, is applied to the second input, and the modulator is biased so as to have minimum throughput when both inputs are identical. In the second embodiment, the data signal is applied to one input and the complementary data-bar signal, delayed one bit, is applied to the second input, with the modulator biased to minimum throughput when both inputs are identical. This novel implementation has been verified experimentally showing a power penalty of less than 1 dB relative to a conventional binary signal.

Abstract: In a transmitter side in an optical transmission system, an input binary signal is converted into a duobinary signal, and the duobinary signal is applied to an optical modulation device which provides an optical intensity modulation signal, wherein the optical intensity for a center value of the duobinary signal is a minimum, the optical intensity for the other two values of the duobinary signal is a maximum, and an optical phase for those two values is opposite to each other. In a receiver side, simple direct detection is carried out for receiving optical signal through an optical transmission line to provide a demodulated binary signal. Thus, an original binary signal is recovered without a duobinary decoder and receiver sensitivity degradation.