Acoustic Camera

[Gogodog]

Hello everybody,

I´m new in Labview but I have to do a project called acoustic Camera. I have an array with about 16 microphones and try to localize a single sound source, which produce a 500Hz sinus signal. I began to measure at first the phase shift between 2 microphones and then calculate the time delay between them. Then I want calculate where the noise is coming from. But the problem is to calculate the phase shift with LabVIEW. I searched already in this forum but I didn't found something that fits to this issue. The phase shift jumps up and down even when the source is always on the same place. For my measurement I use a NI USB 6211 device. The Phase detection VI´s don´t work useful so I tried something else shown in the picture. I think when I get a solution about how I can measure the phase shift between two mic´s the rest will be pretty similar.

In the end a webcam produce a picture and an intensity graph, cover up the pic, will show where the soundsource will be.

I´m pretty sure someone has an idea or even any suggestions to help me. I´ld be very thankful for any help.

[reschri]

Have you tried a Cross Correlation with your signal chunks? This does not wield a phase, but a time shift but is very robust an works even for noisy signal and phase shift greater +-pi. You can calculate the phase shift from the time shift with the momanteanous frequency, which for example, you can get from a hilbert transform. A these tools are on the LabView Palettes.