USB-6009 has artifact at about 9900 Hz

[p15218]

We purchased two of USB-6009 8 input multifunction DAQ devices. They both seem to output an artifact at around 9900 Hz with either a 24kHz or 48kHz sample rate, input lines shorted to each other (diff mode) or to ground (rse mode). Differential input mode is worse with the offending signal about 20 dB greater than the noise floor.

A simple spectrum analyzer with the DAQ Assistant and Spectral Measurement express VIs shows the problem. I tried one and two channel versions (at 24k sample rate) and both channels have the same ~9900 Hz artifact.

thanks

[CWolf]

For clarification, you are doing analog input with the USB 6009, and, in addition to your input signal, you are seeing a 1 kHz signal in the analog input.  Is that correct?

I have a few questions for you:

1. Does the same problem occur on all channels?
2. If you generate a DC output voltage on one of the device's analog output channels and read this back into the analog input channels, do you see the same abnormalities?
3. What voltage input range are you using? If you change the range do you see a significant change in this artifact?
4. Do you only see this at 24 and 48 kHz sampling rates, or at other frequencies as well?  Also, does it happen regardless of the frequency of the signal you are reading in?
5. If possible, could you try connecting the USB-6009 to another computer and seeing if the same problem occurs?
6. Finally, if you could provide screenshots of what you're observing, then that will help me understand the behavior.

-Christina

[p15218]

For clarification, you are doing analog input with the USB 6009, and, in addition to your input signal, you are seeing a 1 kHz signal in the analog input.  Is that correct?

Christina 

-----All correct except the artifact is around 10 kHz 

I have a few questions for you:

1. Does the same problem occur on all channels? ------Yes
2. If you generate a DC output voltage on one of the device's analog output channels and read this back into the analog input channels, do you see the same abnormalities? ---I'll have to rewire the connection and try this later
3. What voltage input range are you using? If you change the range do you see a significant change in this artifact? ----0.1 is target, but problem is really worse at default 10 Volt range. It gets smaller with more sensitive ranges
4. Do you only see this at 24 and 48 kHz sampling rates, or at other frequencies as well?  Also, does it happen regardless of the frequency of the signal you are reading in? ---If I change sample rate to 20kHz, the artifact moves to about 6 kHz. The input signal has no effect on the artifact.
5. If possible, could you try connecting the USB-6009 to another computer and seeing if the same problem occurs? ---I did, same result
6. Finally, if you could provide screenshots of what you're observing, then that will help me understand the behavior. -- See attached file

---Bob

[p15218]

After re-reading the specifications there is a little thing of "System noise of 5 mV"

Looks like I may need to notch out the artifact with a LabView filter and be done with it.