The present invention provides a method for synchronizing timekeeping devices in a system of clocks using a master/slave system and expandable data packet transmission protocol, and an apparatus for implementing such synchronizing system. The method includes embedding a circuit and data packet for transmission into each timekeeping device in the system. Time is synchronized by transmitting time information contained in the data packet protocol from the master timekeeping device to other slave timekeeping devices. Further, slave devices may transmit time information also contained within the data packet protocol to other slave timekeeping devices that are not within range of the master device. A hop count register in the data packet is also relied upon for synchronizing the time as close to the master device. Slave devices requesting time information accept the time from the transmitting device with the lowest hop count. Transmitting devices with higher hop counts are ignored, and the system is synchronized according to a time of the master timekeeping device.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/369,653, filed Apr. 2, 2002, titled METHOD AND APPARATUS FOR SYNCHRONIZING TIMEKEEPING DEVICES, which is incorporated herewith by reference in its entirety.
7483392 - Multinode arrangement - Owned by BBN Technologies Corp. (Cambridge, MA) Verizon Corporate Services Group, Inc. (New York, NY)
The present invention provides a multinode arrangement that utilizes a plurality of nodes that communicate with each other by RF transmissions and hardwire communications. The use of both hardwire and RF transmission provides the advantages obtained with both forms of transmission.
Methods and apparatus are provided for a fail-operational global time reference for a synchronous redundant data bus including multiple pluralities of timing servers cross-coupled between a plurality of buses in said redundant synchronous data bus system, the apparatus comprising each said timing server of the multiple pluralities of timing servers configured to transmit, receive, and monitor synchronization signals, to store a unique constant, and to independently and automatically select as timing master one or more timing servers from among the multiple pluralities of timing servers based on said synchronization signals received from one or more of said timing servers of said multiple pluralities of timing servers and further based upon a relationship among said unique constants stored in each timing server. Methods comprising selection protocols are also provided.
If a control section fails to detect a connectable device by Inquiry/Page_Scan before an OFF timer times out, the control section halts the Inquiry/Page_Scan. The control section keeps this state until time-out of an ON timer. Upon time-out of the ON timer, the control section starts Inquiry/Page. The control section issues a request for a role switch to the connectable device detected by Inquiry/Page. Upon acceptance of the request, the control section effects a master/slave role switch.
