Jump to content
  • 0

Noise when sampling fast from different channels from one MCC device to another


Question

Posted

Hi - I have a USB-3100FS that sends out 3 analog outputs. They go to 2 places, one is a recording device that samples at 30 kHz and another is to a breakout box attached to a MCC PCIe-DAS1602/16 board via its analog inputs (which I use for real time sampling to control an experiment). What I see is the following - when I run code on the computer with the PCIe-DAS1602 board that samples slowly (let's say 10 Hz), everything is fine and I have no issues. However, when I sample rapidly (let's say 10kHz) from two or more of the outputs of the USB-3100FS, I see noise on all of the lines from which I sample (which makes it to the recording device, and I can see it in real time). So essentially, rapid sequential sampling from the USB-3100FS outputs introduces noise. This is entirely predictable from code. If I don't run the code on the PCIe-DAS1602 to do the sampling, everything is fine. As soon as I sample quickly (and it has to be going back and forth between 2 or more channels, and doing it fast) the problem is introduced.

The question is this - is there something I should do to remove this noise? My suspicion is that I need to setup better grounding between my devices, potentially making sure the USB-3100FS and the PCIe-DAS1602 are grounded together. But I'm not sure and would like some guidance.


Thanks!

2 answers to this question

Recommended Posts

  • 0
Posted

Hello @msmith.

The MCC USB-3101FS has a low output impedance of 0.1 Ohms and an output update rate up to 100 kS/s per channel.

The MCC PCIe-DAS1602/16 has an input impedance of 10 MOhms and an aggregate sampling input rate of 100 kS/s, since the analog inputs are multiplexed to the ADC.

What is the output rate and output range of the signals from the MCC USB-3101FS channels?

Configure the analog input channels on the MCC PCIe-DAS1602/16 board for differential mode.

What is the input range of the analog input channels on the MCC PCIe-DAS1602/16 board?  Choose a narrow range.

Regards,

Fausto

  • 0
Posted

The output rate is about 1 kHz, and the range is +/-5V typically (though we've also tried +/- 10V). I configured the PCIe-DAS1602 for differential and that didn't seem to help. I am using comedi in Ubuntu to read from the board, and have been working to specify the input range as well.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...