Codenoll Technology Corporation

Exxon Research and Engineering Company

Optical Information Systems, Inc.

Frederick W Scholl

Michael H Coden

Harry Francis Lockwood

Peter S Zory, Jr

Nathan H Tobol

Walter B Hatfield, Jr

Stephen J Anderson

Jan Helbers

Through the method and apparatus of the present invention the collision of two packets can be detected with a high degree of accuracy under a variety of conditions. The preamble of each packet transmitted is modified to include collision detection data comprising an initial pulse having an amplitude sufficiently high to be detected even when attenuated and having a pulse width twice the normal data pulse width followed by a transceiver code of a predetermined length unique to each transceiver. Thus, in the event two packets collide, the collision may be detected by recognizing a second large pulse within a time period less than the sum of the packet duration and the gap between packets, by determining if a large initial pulse has a pulse width larger than the generated pulse width, and by determining if the transceiver code echoed back to the transmitting transceiver is equal to transceiver code stored in memory on the transceiver. If a transceiver detects a collision, a large collision detect pulse having an amplitude and pulse width similar to the amplitude and pulse width of the large initial pulse is transmitted within the time period less than the sum of the packet duration and interpacket gap, thus assuring that the collision is detected by all transceivers.

Method and apparatus for detecting the collision of data packets

Through the method and apparatus of the present invention the collision of two packets can be detected under a variety of conditions. The preamble of each packet transmitted is modified to include collision detection data comprising an initial pulse having an amplitude sufficiently high to be detected even when attenuated and having a pulse width twice the normal data pulse width followed by a randomly generated code of a predetermined length in which a predetermined number of pulses of the code are at a high binary data signal level. Thus, in the event two packets collide, the collision may be detected by detecting a second large pulse within a time period less than the sum of the packet duration and the gap, by determining if a large initial pulse has a pulse width larger than the generated pulse width, by determining if a subsequent large pulse occurs within the remainder of the packet and by determining if more than the predetermined number of pulses of the code have a high binary data level.

A high efficiency edge-emitting LED is disclosed in which optical radiation produced in an active layer of the device leaves the device without being substantially absorbed by the material comprising the active layer. The device is constructed so that an optical waveguide is formed such that light produced in the active layer either leaves the device without any reflections or with a maximum of one reflection. The thickness of the active layer and the compositions of the active layer and confining layers are chosen so that electrical carriers are confined in the active layer while light produced in the active layer is not confined therein.

Edge emitting, light-emitting diode

An edge-emitting LED in which light produced in the active layer optically tunnels out of the active layer through a thin confining layer into a single guide layer which is composed of a material which does not absorb light energy. The guide and active layers are constructed so that they are surrounded by layers of lower index of refraction so that an optical wave guide is formed. To minimize light losses by absorption, the non-absorbing guide layer is preferably much thicker than the active and confining layers so that light produced in the active layer travels primarily in the non-absorbing guide layer before it leaves the device at the exit facet of the LED.

Edge-emitting light emitting diode

A method and apparatus are disclosed for recovering data and clock information from high speed self-clocking data streams at rates of up to approximately 50 Mbps. The self-clocking data stream has a predetermined bit period and two voltage levels with negative-going and positive-going voltage level transitions. A pulse is generated for each voltage level transition in the coded stream. This pulse is applied to a non-retriggerable one-shot that produces an output pulse that is approximately the duration of one-half of a bit period. After the output pulse of the one-shot terminates, the one-shot is non-retriggerable for a period of time less than the duration of one-half of a bit period. The output pulse from the one-shot provides clock information derived from the coded bit stream. This clock information is provided to the clock input of a bistable storage device and the coded bit stream is applied to a data input to the storage device. In response to the clock input, the bistable storage device decodes the coded bit stream to provide decoded data information at an output.

Method and apparatus for recovering data and clock information from a

A data communication receiver that provides very low pulse distortion at excellent sensitivity over a wide range of optical signal levels and simplified circuitry for the detection of data collisions. The receiver comprises an amplifier having a series of stages, all but one of which is directly coupled to the preceding stage and one of which is capacitively coupled by a capacitor that also functions as part of an RC differentiator. The output of the amplifier is a series of peak signals that are applied to a Schmitt trigger, the output of which is applied to a collision detection circuit. In a preferred embodiment of the invention, the collision detection circuit comprises a timing circuit for producing an output signal for a period of time equal to the longest interval during which a received data signal can have a first polarity and means for comparing the timing output signal with the received data signal and for producing a collision detection signal when the received data signal fails to change within the duration of the output signal from the timing means. To ensure that the Schmitt trigger produces an initial output representative of the absence of a signal in the communication medium, the amplifier is biased so that the initial output of the Schmitt trigger is low.

Data receiver

Method and apparatus for detecting when a collision occurs between two or more binary data signal packets at a single binary data signal receiver. Whenever a packet is transmitted, a large signal impulse is substituted for the initial bit of the packet. The amplitude of the impulse is such that it is significantly greater than the highest binary signal level transmitted. The receiver recognizes the impulse not as a data bit but as an indication of the beginning of a packet. Every packet has a known duration (or packet period) and is separated from the next packet by at least a known gap period. If two impulses are received within a period less than or equal to the sum of the packet and gap periods, a collision has occurred and a packet collision signal is generated.

The alignment of optical fibers is improved by mounting the optical fiber on a mounting block that has a sloping surface relative to an underlying support that bears both the fiber and a light source or photodetector. As a result, the alignment of the fiber and the light source or photodetector may be maintained in the vertical direction by the correct position of the fiber on the sloping surface of the mounting block. The alignment of the fiber in the horizontal direction is determined by the position of the mounting block on the support. Such an arrangement permits the weight of the fiber to be supported by the block while an appropriate cement is being cured to hold the fiber and block in place. Advantageously the mounting block is transparent to ultraviolet (UV) light and UV curable cements are used to secure the fiber to the mounting block and the block to the support. As a result, when the fiber is aligned both vertically and horizontally, it can be cemented into position quickly by applying cement to secure the fiber to the block and the block to its support and curing all the cement simultaneously by passing UV light through the transparent block.

Method and apparatus for aligning optical fibers

A new package for semiconductor optoelectronic devices is disclosed, which comprises a novel geometrical configuration and provides plug-in capability. The package configuration provides a convenient means for supplying electrical signals to or from the device(s) within the package while maintaining a coaxial geometry, useful in optical and thermal control. Techniques for bonding devices into the package are easily automated using conventional bonding and assembly equipment. The package permits use of the device in a variety of orientations.

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Riverdale, NY, United States of America

Frederick W Scholl