Recently we purchase a PXI data acquisition system consisting of 4-slots 3U chasis (NI PXI-1031), quad core controller (NI PXI-8110), 8-channel, 24-bit simultaneous sampling ADC board (NI PXI 4472) and 8-channel analog output board (NI PXI-6713).
While recording the data using the PXI 4472, the noise level is very high. I tried the example program provided along with the LabVIEW (Hardware Input and Output>DAQmx>Analog Measurements>Sound Pressure>Cont Acq snd Pressure Samples-Int Clk.vi). Two screen shoots are also attached along with this. Fig1.JPG is in the absence of any signal, i.e., noise only. It can be seen that the noise level is very high. Fig2.JPG is for the case where the word ‘Hello’ is recorded. The recording was in a quite lab environment.
So I just want to know what is the reason for this noise and how to solve this problem. The microphone used was GRAS 4PL IEPE microphone. I tried with IEPE microphone from other manufacturer also. The same noise is present in all the channels.
The program which I used to record the data is also attached along with this. Another problem is while using all the 8 channels at higher sampling frequency, say 44.1kHz, it is giving time out error. How this problem can be solved?
