Synchronization Problem

[anjali8122]

Hello All,

             We are going to develop a Project on Sound Source Localization using Labview. Still We are on intial stage and going to perform all task on Software base with four mic connected with PC (For initial stage, later on going to develop using NI hardware if possible).

             Initially we acquireing sound from 4 Different Microphones connected with computer through USB. Here all microhpones acquiring sound from single sound source with some delay(mili seconds) beacuse of their different position. But this Sound data acquired by USB are not able to write to sound card simulteneously. This data of sound acquire some hold time while writing to the sound card and we are getting some delay samples while synchronizaing these all sounds. Is there any idea to reduce this hold time of sounds that writes the data to the sound card?

Suppose hold time 10ms, want to reduce this to the micro seconds of nano seconds.

[johnsold]

Does each microphone have a separate USB connection to the computer? If so, you probably cannot do much better than a few milliseconds of synchronization. Why? Because each USB connection makes calls to the OS which then passes the data to the cound card or your program.

One thing you might try is to send out a synchonizing signal after all four microphones are acquiring data. Even a "beep" from the computer speaker might work. Measure and record the distance from the speaker to each microphone. After the "beep" has been captured by all the microphones, you can use the distances to determine the start time for each data set.

Lynn