Im using the 6071E to record voltages on 6 channels which are then fed into a FFT operation for frequency analysis. (Like Frequency Response Function).
I always need to sample CH1 - which is my source signal - and I then iterate through a list of CH2->6; CH7-11; etc. Therefore my sample list looks like
CH1, CH2, CH3, CH4, CH5, Ch6
CH1, CH7, CH8, CH9, CH10, CH11,
.....
CH1, CH49, CH50, CH51, CH52, CH53
Under some sets of circumstances; CH1 will be measuring in the +-10V range; and the remaining channels in +-1V or +-1mV range. These circumstances depend upon our system under test.
I understand that with the 6071E these channels are sampled asynchronously; and when the inputs have a high impedance there can be a problem with the ADC not being cleared (i.e. some the second sampled channel sees the wrong voltage). Currently some of the channels (e.g. 2,3) will be corrupted.
What is the best way to ensure that the channels sample the correct voltages and see no influence from the different ranges / charge? Would it make sense to record CH1 on a seperate DAQ card; and in which case how can I ensure synchronisation?
Thanks,