Cirrus Logic Inc.

Peak Audio, Inc.

Kevin Paul Gross

Charles William Anderson

Derek W Lieb

William W Lowe

Gerrit E Rosenboom

Gerrit Eimbertus Rosenboom

Derek Wearin Lieb

A method is provided for determining the length of node-to-node links in a computer network. The method includes measuring the forwarding time for each node-to-node link in the network, eliminating queuing time from each forwarding time measurement, determining and subtracting store-forward time from each forwarding time measurement, determining and subtracting execution time from each forwarding time measurement to obtain a propagation time for a signal being transmitted on each node-to-node link and, based upon the propagation time for each node-to-node link, calculating a length of each node-to-node link. A network map may also be derived by identifying internal nodes in the network, translating each store-forward time into a hop count, constructing a connectivity map of the network including a connection map of internal nodes and superimposing the calculated link lengths onto the connectivity map to determine cable length between any internal nodes with more than two connections.

Determining characteristics of node-to-node network links from forwarding time measurements

Apparatus and methods are provided for exploiting the existence of a shortest path between a source device and a destination device by identifying the shortest path and using the signal which has taken the shortest path in preference to delayed transmissions or delayed images of the same signal, thereby improving signal distribution. The present invention provides a processor between a phase-sensitive detector and a low pass filter of a phase locked loop for selecting and driving the PLL primarily from the signal which has taken the shortest path.

Exploiting shortest path for improved network clock distribution

Media access control for isochronous data packets in carrier sensing multiple access systems

The present invention has solved the collision problems in a CSMA network protocol and at the same time optimized performance of the network. This is accomplished by giving control of the size of the reserved portion and the size of the reservation portion of the communication frame to stations in the network. Further, the reserved portion is allotted to isochronous data packets each of whose length is variable. Also, only those packets that have a reservation are in the frame, and they are placed in the frame in order in accordance with there position of the permission or reservation list. The network timing is controlled by one of the stations acting as a conductor for the network. This conductor station receives the reservation requests from the other stations and builds a beat packet. The beat packet is transmitted from the conductor station to all stations of the network, and provides the timing or beat of the network that all stations are synchronized with. In addition, the beat packet contains the permission list (reservation list) identifying the stations that will transmit, and the order they will transmit during the frame. The network interrupt handler (46) and the conductor (56) at the conductor station build this beat packet.

Media access control for isochronous data packets in carrier sensing

The present invention has solved the collision problems in a CSMA network protocol and at the same time optimized performance of the network. This is accomplished by giving control of the size of the reserved portion and the size of the reservation portion of the communication frame to stations in the network. Further, the reserved portion is allotted to isochronous data packets each of whose length is variable. Also, only those packets that have a reservation are in the frame, and they are placed in the frame in order in accordance with there position of the permission or reservation list. The network timing is controlled by one of the stations acting as a conductor for the network. This conductor station receives the reservation requests from the other stations and builds a beat packet. The beat packet is transmitted from the conductor station to all stations of the network, and provides the timing or beat of the network that all stations are synchronized with. In addition, the beat packet contains the permission list (reservation list) identifying the stations that will transmit, and when they will transmit during the frame. The network interrupt handler and the conductor at the conductor station build this beat packet.

An order persistent timer is provided in each station on a network to control the timing of transmission of each isochronous data packet from a station, and to also control the timing of transmission of asynchronous data packets that include reservation requests. The OP timer at each station monitors traffic on the network from other stations to detect whether the network is active or idle. In an active state, the OP timer times a set interval of time sufficient to indicate the successful transmission of a packet on the frame. In the idle state (no packet on the network from another station), the OP timer times a number of deferral time intervals that are used with a network interrupt handler at the station to control the transmission of isochronous data packets without collision, and asynchronous data packets thereafter.

Growing community of inventors

Boulder, CO, United States of America

Kevin Paul Gross