Wang Laboratories, Inc.

Codenoll Technology Corporation

Walter B Hatfield, Jr

Alfred M Nelson

Frederick W Scholl

Houshang Rasekhi

Frederick A Rupinski

Nathan H Tobol

James P Johnston

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

There is provided improvements in magnetic recording head arrangements, such as may employ multiplexing, which provide substantially higher speeds of recording and require fewer components. The recording head is comprised of a compact, four-layer laminate structure mountable on a supporting substrate, in which the entire array of recording elements forms a flexible, uniquely arranged first layer, the return paths of the recording elements comprise a flexible second layer which has the dual utility of substantially reducing the recording element circuit inductance, the third layer is a rigid printed circuit board structure providing a mount for the blocking diodes and the conductive paths of the associated multiplexing scheme, and the fourth layer is a ground plane located between the first and third layers and insulated therefrom for further reducing the inductance associated to the circuitry of the first layer and for substantially minimizing the circuit inductance of the third layer.

Magnetic recording heads

Growing community of inventors

Fair Haven, NJ, United States of America

Walter B Hatfield, Jr