Loosely coupled distributed computer system with node synchronization for precision in real time applications

Claim 1

In a loosely coupled distributed computer system for real time applications, comprising a plurality of loosely coupled node computers each including a local real time clock, I/O subsystems, and a communication unit, said node computers being interconnected by a transmission medium for serial communication therebetween, the improvement comprising each node computer including a synchronization unit for synchronization of the local real time clocks in each of the computer nodes with the real time clocks of other nodes, each synchronization unit being connected with a digital output line of a local real time clock associated therewith for supply of unsynchronized time signals from said digital output line to a digital input of said synchronization unit, said synchronization unit having a digital output supplying global synchronized time signals to digital inputs of other I/O subsystems and being operatively connected with said communication unit for obtaining therefrom a first information as to a point in time of sending a message to said communication unit, said message being measured in a metric of the local real time clock of a sender, and a second information as to a point in time of arrival of the message in a metric of the local real time clock of a receiver, said synchronization unit generating said global synchronized time signals on the digital output line thereof as a function of said first and second information of other computer nodes and the local unsynchronized time signals supplied to the digital input thereof by an associated local real time clock of the synchronization unit, said synchronized time signals on said digital output line of said synchronization unit applying a known synchronization algorithm.