Advanced Micro Devices Corporation

Allied Telesis, Inc.

Allied Telesyn International Corporation

Allied Telesyn, Inc.

Microalign Technologies, Inc.

Shinkyo Kaku

Krishna Rallapalli

Chung-Li Yu

Vitali Tikhonov

Leonid Velikov

Igor Gurevich

Vinod Menon

Victor Faibishenko

Nikolai Fedyakin

David R Staab

George W Li

Shabbir M Latif

Anan Nagarajan

Severino Tolentino

Koichi Kagawa

Nikolai Fediakine

Steven Gary

Greg W Barr

A method for automated calibration of an avalanche photodiode receiver includes measuring two values of avalanche photodiode biases at two successive times, measuring and comparing a bit error rate corresponding to each value. When the bit error rate of the second value is equal to or greater than the bit error rate of the first value, then a third value and a fourth value of avalanche photodiode bias closer together are measured. When the bit error rate of the fourth value is smaller than the bit error rate of the third value, two subsequent values as third value and fourth value are measured, and an optimum avalanche photodiode bias when the bit error rate of the fourth value is equal to the bit error rate of the third value is measured.

Apparatus and method for automated adjustment and setting of APD optical receiver operation point

A system and method for an Avalanche photo-diode ('APD') optical receiver and laser system to adjust its performance during system operation without disturbing network traffic. Very small changes may be adaptively applied to some key portions of the system by controlling a set of main system parameters including Q-factor; Bit Error Rate (BER); histograms of '1' and &#x201c;0&#x201d; levels; input optical power; and laser output power. This adaptive routine may be performed during operation of the system to keep the main system parameters close to their optimum value. During adjustment, the system may be divided into separate portions. The adjustment of each portion may be independent of the other portions of the system. For the optical network system, optimization and priority of different portions may be assigned based on network channel architecture.

Apparatus and method for adaptive adjustment and performance monitoring of avalanche photo-diode optical receiver and laser transmitter for fiber link long haul applications

Disclosed are an in-line monitoring apparatus, an optical receiver and a method for monitoring an input power of an optical signal in which one or more power monitoring stages, for example can measure the input power over an extended input power range. In one embodiment, an apparatus includes an avalanche photodiode ('APD') configured to receive the optical signal and an input configured to bias the APD. It also includes one or more power monitoring stages coupled to the input in parallel with the APD for generating one or more measurement signals in-situ. In one embodiment, a range selector selects which one of the one or more power monitoring stages is to provide a measurement signal indicative of the input optical power. The power monitoring stages can provide for a wide range of linear current measurements as well as a range of measurable currents to monitor low-powered optical signals.

In-situ power monitor providing an extended range for monitoring input optical power incident on avalanche photodiodes

Disclosed are an in-line monitoring apparatus with a temperature compensator, an optical receiver and a method for stabilizing gain of an avalanche photodiode ('APD') over an extended range of input power values and across temperature variations. The apparatus can include one or more power monitoring stages coupled in parallel to the APD for generating one or more measurement signals in-situ. The apparatus also includes a temperature compensator configured to adjust an operational parameter for the APD as a function of temperature and the measurement signal. The temperature compensator adjusts the bias to maintain a substantially uniform gain across temperature variations to facilitate an increased sensitivity with which to monitor the input power at lower levels than if the temperature compensator did not adjust the bias in response to the temperature. One of the power monitoring stages can be configured to monitor the low-powered optical signals.

In-situ power monitor having an extended range to stabilize gain of avalanche photodiodes across temperature variations

The optical signal multiplexer/demultiplexer of the invention is characterized by incorporating a bidirectional optical transceiver which is capable of using individual channels working in a transmitting and receiving modes simultaneously. The device consists of a number of optical prisms combined into a single module and provided with appropriate dichroic mirrors and interferrometric filters located on the outer surfaces of the prisms. According to one embodiment of the invention, the module consists of two sequentially arranged parallelogram prisms, a single-channel signal input/output unit with an optical collimator/focusator on one side of the prism module and a two-channel signal output/input unit with a respective optical collimator/focusator on the other side of the prism module. The first prism, which is located on the single-channel side has a first antireflective coating transparent to all input/output signals (&#x3bb;, &#x3bb;, &#x3bb;) and a second coating located on the two-channel side of the first prism that reflects one optical signal (&#x3bb;) and passes the remaining two optical signals (&#x3bb;and &#x3bb;). Thus, the input/output signals of several different wavelengths can be multiplexed/demultiplexed while passing in a multi-bounce zigzag expanded beam light paths in various combinations of signal-propagation directions. A pair of prism modules described above may be built-into a section of the main signal transmission/reception line and the output side of each prism module may be connected to a respective bidirectional optical signal transceiver.

Bidirectional optical signal multiplexer/demultiplexer

The optical module of the invention for high-speed bidirectional transceiver consists of a signal receiving unit, a signal transmitting unit, a common receiving-transmitting optical fiber, and a fiber coupling unit. The laser diode and the photodiode are arranged parallel to each other in closely located recesses of the module housing. Such an arrangement makes it possible to shorten distances for guiding lead wires from the terminals of the PC board to the respective terminals of the transmitting and receiving diodes. The laser diode emits a first transmitting laser beam that passes through a microobjective that collimates the beam and directs into onto a full-reflection mirror located inside the module housing. The full-reflection mirror reflects the first transmitting beam at an angle of 90&#xb0; and transmits it to the end face of an optical fiber through an optical fiber collimator that centers the beam with the fiber core. The module is provided with a second mirror, which is fully transparent to the aforementioned first transmitting beam, but is fully reflective to a second transmitting beam that may propagate in a direction opposite to the first transmitting beam on a different wavelength. Alignment of the optical components is facilitated due to the fact that it is carried out with diffractionally limited and collimated beams.

Optical module for high-speed bidirectional transceiver

A method of generating a lookup table includes receiving an input address; generating a compressed address from the input address, the compressed address having fewer bits than the input address; selecting a first set of bits from the compressed address; determining whether a memory location pointed to by the first set of bits in an address lookup table includes an unoccupied memory slot; determining whether the input address matches any address stored in the memory location pointed to by the first set of bits in the address lookup table; and selecting a second set of bits from the compressed address in response to there not being an unoccupied memory slot in the memory location pointed to by the first set of bits and the input address not matching any address stored in the memory location pointed to by the first set of bits. A lookup table generator includes an address compressor, a barrel shifter, and an address lookup table that includes a memory location that is pointed to by the first set of bits. A control state machine is coupled to the barrel shifter and the address lookup table and is configured to shift the barrel shifter so that a second set of bits is selected from the compressed address in response to there not being an unoccupied memory slot in the memory location pointed to by the first set of bits and the input address not matching any address stored in the memory location pointed to by the first set of bits.

Method and apparatus for adaptive address lookup table generator for networking application

An apparatus for coupling signals between a CSMA/CD data transmission medium and a plurality of data terminals. Collisions between data signals transmitted from more than one of the data terminals are detected to generate an internal collision signal. An external collision signal is generated in response to detected collision signals on the transmission medium. The internal and external collision signals are merged and broadcast through an isolating transformer to each of the data terminals.

Multiple port medium attachment unit for a network

An apparatus for rotating bit-mapped data includes a specially designed data array (9) that includes a normal port (10) for accessing horizontal words of data and a rotated port (15) for accessing vertical words of data. In addition, address generating logic (6) is provided that automatically generates proper address seqences for accessing the normal words or the vertical words as appropriate during a rotation operation. The apparatus is cascadable (FIG. 29) to provide effectively any size data array.

Bit map rotation processor

A device controls in real time the assembly of data for a bit map scanning device, such as a laser printer, under supervisory control of a host processor. The image data words are stored in a source memory and assembled in a video buffer, and automatically scanned out to the scanning device. The host processor generates a simplified set of control words that defines graphics, text and layout of the page to be assembled. A raster interface synchronizes the output of the assembled data with the scanning device. Three basic modes are supported: (1) dispatch mode, (2) font read/write mode, and (3) graphics load mode. The dispatch mode is the normal operational mode which provides for dispatching data from a source memory location to the video memory and for supplying data from the video memory out to the raster printer. The font read/write mode gives the host the ability to read/write font or graphics data from/to the source memory or the video memory. The graphics load mode provides for transfer of a bit mapped window data to the video memory from the processor. The video memory can be divided into two bands.

Apparatus for assembling data for supply to a scanning output device

A decoder receives a series of input words defining variable length facsimile codes and generates pixel data to form a facsimile of an image. A code windowing apparatus selects a variable length code from the received series of words. A decoding ROM generates intermediate codes and code window control signals in response to the selected variable length codes. A reference windowing apparatus connected to receive pixel data generated during the decode of a previous scan line of the facsimile, selects a reference window of pixel data from a previous scan line. A color change detector indentifies a position of a color change picture element in the reference window. Output pixel data is generated in response to the intermediate codes and the position of the color change picture element in the reference window.

Apparatus for decoding facsimile coded data to image data with coding

Binary image data is converted to CCITT standardized coded data by utilizing two barrel shift registers for selecting a window of image data from a reference line and from a coding line, two color changing detectors for converting the image data in a window to color changing codes, and one specially designed state machine for generating facsimile coded data from those color changing codes. The state machine operates on color change location data for the selected window to generate intermediate codes. The intermediate codes are then translated to an output format such as the CCITT standard.

Two-dimensional facsimile encoding apparatus with coding and reference

A method and device for speeding the transmission and reception of documents by digital facsimile systems employing two-dimensional coding. Information regarding a reference line of a document need not be reaccessed from memory during the processing of the scan line next-following a uni-color reference line. A user-accessible paper-width register utilized in conjunction with a comparator according to the speed-up method permits ready detection of uni-color lines and permits encoding and decoding according to either of two international standards. Utilization of the paper-width register affords ready availability of the accumulated run-length of picture elements within uni-color lines without the need to accumulate the run length or reaccess the uni-color reference line.

Speed-up method and apparatus for two-dimensional facsimile coding and

A high speed picture element generator for use in a digital facsimile receiver for reforming picture elements from decoded facsimile transmission signals. The picture element generator receives the decoded facsimile signals in the form of run length data of sequential color units in a line of picture. An input register of the picture element generator receives the run length data of a color unit, and an output register holds the picture element data. A decoder, coupled to the input register, generates the picture element data for the output register from the run length data. The decoder is also coupled to the output register so that the generated picture data fills portions of the output register unoccupied by the picture element data of previous color units.

Picture element generator for facsimile receiver

A method and device for decoding two-dimensionally encoded digital facsimile signals. The method includes (a) accumulating the run lengths of color change picture elements in the reference line, (b) decoding a codeword to generate a displacement value, (c) combining the accumulated run length of a reference line color change picture element and a displacement value to obtain accumulated run lengths of coded line color change picture elements, and (d) determining the difference between accumulated run lengths of a coded line color change picture element. The difference is the decoded data. The device has a control logic, a reference line processor for generating the accumulated run lengths of color change picture elements in the reference line, a coded line processor for generating displacement values from the encoded codewords, and a combining part for combining the reference line accumulated run lengths and the displacement values to obtain the accumulated run lengths of color change picture elements in the coded line and for determining the differences between coded line accumulated run lengths, which are the decoded run lengths of the color units in the coded line.

Growing community of inventors

San Jose, CA, United States of America

Shinkyo Kaku