A system for time synchronization in a computer cluster is provided. For the system of the present invention a master node sends a SYNC message including a first time stamp to a slave node. The slave node adds a second time stamp and returns the SYNC message to the master node. The master node then adds a third time stamp to the SYNC message. Using the three time stamps, the master node determines if the time clock within the slave node leads or follows the time clock in the master node. The calculation does not depend on the assumption that transmission delays to the slave node are the same as the transmission delays from the node. If the time clocks do not match, the master node sends an INFO message to the slave node informing the slave node of the correct time for clocks within the computer cluster.

System and method for synchronizing time across a computer cluster

A system for acquiring, and displaying, data such as physiological data, from a plurality of data connection devices, each of which monitor one or more different parameters and output data at different sampling frequencies based on their own system clocks. The system receives the data signals at different sampling frequencies and associates each sample of each signal with a time stamp derived from a single master clock. Low rate and high rate data are treated differently. Low rate data is associated with the current value of the master clock, where as high rate data is time stamped by giving the first sample a time stamp equal to the current value of the current master clock, subsequent samples being given an estimated time stamp based on the expected interval between samples derived from the sampling frequency of the data collection device, and the timescale given to the first example. The estimated time stamp may be periodically corrected, and the estimation calculation can be improved by correcting the value used for the interval between samples. The different signals can be displayed together on a display aligned with respect to a time axis. The system can display, the data in two different timescales, one showing a few seconds of data and one showing a few hours of data. The data traces are scrolled across the time axis, new data being added to one end of the trace.

System and method for acquiring data

A control station (12) initiates a system timing signal transmission which is re-transmitted from a satellite (14). In response to receiving the system timing signal, the control station (12) then generates a time correction factor which is distributed to a plurality of transmission stations (16, 18). The transmission stations (16, 18) in response to receiving the system timing signal transmission and the time correction factor distributed from the control station (12) generate a time adjustment factor which is used to correct the local transmission clocks (36, 36'), thereby providing time synchronization of data transmissions generated from the transmission stations (16, 18).

Simulcast synchronization and equalization system and method therefor

A synchronized timing system is disclosed for one or more of a plurality of network interconnected computers. The system utilizes a global satellite system and includes a receiver device for detecting out-of-phase signals from a plurality of satellite sources of the satellite system. A mechanism is provided for processing and phase correlating these signals to generate a single absolute time reference signal therefrom. An interface device is disposed in each computer for receiving the reference signal and adapting this signal as the internal master clock reference for the operating system of the computer. Finally, a mechanism interconnects each computer in the network of computers to synchronize the internal master clocks of the computers to the absolute time reference signal to create a plurality of network interconnected time synchronized computers. These computers may be additionally time synchronized and interconnected to other networks of computers through a global communication system such as the global Internet.

System for synchronizing multiple computers with a common timing reference

A coherent reverse channel, a per-chip spreading function, orthogonal spreading functions and a time alignment of all traffic channels are implemented such that the main signal of each channel arrives at a base-station within a fraction of a chip of one another in accordance with the invention. With this, the orthogonality among all channels is maintained, and, when demodulated, all channels except the channel of interest provides a cross-correlation of substantially zero with respect to the remaining signals.

Method and apparatus for time aligning signals for reception in a code-division multiple access communication system

A master (virtual) clock is situated at a central data gathering station, and slave (physical) clocks are situated at one or more (functionally or spatially) remote stations. Time signals are exchanged between the master clock at the central station and each slave clock at each corresponding remote station. From these signals (i) the ratio between the frequencies of the central station master clock and the corresponding remote station slave clock is determined, (ii) the difference in reference (starting) time value between the central station master clock and the corresponding remote station slave clock is determined, and (iii) the transmission time between the central station master clock and the corresponding remote station slave clock is determined. Averages of the clock ratio, reference time, and transmission time are determined across successive time signals to provide improved accuracy. The clock ratio and reference time values are used to derive data referenced to the master clock at the central station from data collected via the slave clock at the remote stations so that the time and data values associated with the data correspond to time and data values generated by the master clock at the central station. If desired, a (virtual) master clock can be determined having time values which are the average of the master clock and all slave clock time values.

Method for referencing multiple data processors to a common time reference

A master clock is situated at a central data gathering station, and slave clocks are situated at one or more (functionally or spatially) remote stations. Time signals are exchanged between the master clock at the central station and each slave clock at the corresponding remote station. From these signals (i) the transmission time between the central station and the corresponding remote station is determined, and (ii) the ratio between the frequencies of the central station master clock and the corresponding remote station slave clock is determined. The transmission time and clock ratio so determined are averaged between successive determinations to provide improved accuracy. The transmission time value is used to set the slave clock to a reference value accurately corresponding to the time kept by the master clock; and thereafter the clock ratio value is used to insure that the slave clock is incremented at a rate corresponding to the frequency of the oscillator in the master clock. If desired, the master clock can be synchronized to a reference time which is the average of the reference times of the various clocks, and/or to a frequency which is the average of the frequencies of the oscillators in the various clocks.

Steven K. Burns

Papers

Method for referencing multiple data processors to a common time reference

Method for adjusting clocks of multiple data processors to a common time base