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A Workstation for Sensitive Experiments?
etrgQUARK asks: "I am in charge of infrared spectrometers at our research center. One of the setups is used to measure the orientation of monolayers at the air/water interface, i.e. the signal we have to detect is very weak and noisy. We already have a great setup with quality components and electronics, except for one piece of hardware: the computer hooked up to acquire the data. How important is the computer in noise-sensitive data acquisition? What are your experiences? Do you have any suggestions on a workstation suitable for such tasks or is it a waste of money to use anything but the average computer system? Unfortunately, the software used is Windows-only."
PCs and long analog cable runs can definitely be a negative, especially if your signals are low level.
My experiences with this sort of stuff is that you want to move the D/A converters as close to the experiment as possible and to use good instrumentation grade wiring with twisted pairs individually shielded plus a drain wire. If also sounds like your setup may be very sensitive to mechanical vibrations - if your noise source is mechanical nothing electronic will really fix the problem. You can filter stuff in the digital domain but you lose frequency response when you do.
I've had very good luck with Analog Devices D/A stuff in the past; not particularly expensive and pretty good quality modules that you use in a distributed fashion to get into the digital domain as quickly as possible.