Instrumentation Synchonization Techniques for Large Microphone Arrays

Abstract

In many acoustic measurement applications, there is a need to correlate data acquired from different systems or synchronize systems together with precise timing. Signal Based and Time Based are the two basic methods of synchronizing instrumentation. In Signal Based synchronization, clocks and triggers are physically connected between systems. Typically this provides the highest precision synchronization. In many acoustic applications size and distance constrains physically connecting the systems needed for making measurements though the inter-channel phase information of simultaneously sampled signals is crucial. In Time Based synchronization, system components have a common reference of what time it is. Events, triggers and clocks can be generated based on this time. This is an overview of how you can use a variety of time references including GPS, IEEE-1588, and IRIG-B to correlate and synchronize measurements anywhere in the world with absolute timing with and without a direct connection between the measurement systems. The level of precision of the variety of methods that can be used for timestamping, generating a trigger at a user specified time as well as synchronizing multiple instrumentation types is covered. Specific applications where this has been applied to large microphone arrays will be described.