Think you for your reply and pointing out about missing attachment.

I'm sorry, I forgot to attach a PDF file.
I sent the pdf file and psdata files by email.

In case someone else want see it, I've attached the PDF file as JPG image here.

Thanks

I have got some strange spikes in my measurement that appear only when I measure 2 channels but not only one channel. I have attached pdf showing weveform with 1 and 2 channels measurement. I connected A channel to michrophone and B channel to measuring object. My question is what is the reason I ge...