Amplitude varying on the change of the input frequency


I using NOR-5752 scanner to measure the analog inputs of high frequency. NOR-5752 is connected to the module FLEX RIO 7966R and entry to the NOR-5752 is provided using the SMB-2145 terminal outlet box.

Now, I'm the animals the 0.5Vpp @ different frequencies of tektronix generator of functions directly and by measuring using the digitizer. On the change of the frequency, measured amplitude is changed.


For the NI 5752 frequency response strange behavior is expected.  CDA in NI 5752 is the TI AFE5801 (, and if you look at Figure 19 (p.13), you will see that frequency response of the ADC is only flat after about 1 Mhz.  I checked this with our R & D Department and they said they are not aware of any combination of parameters that gives a uniform frequency response at these low frequencies.

If a flat frequency response is necessary for these lower frequency ranges, then the 5751 NOR is much better suited because it has a different ADC.  (  The frequency response of this device is very flat in the low frequencies (see Figure 11 p.15).

So both devices, NI 5752 and the 5751 OR are designed to measure different frequency ranges.  I hope this helps.

Tags: NI Products

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