Calibration system (PXI4464)

[JJJJeb]

Hello guys.

I am using the PXI4464 to perform voltage measurements. On the future, this equipment will be used to take some voltage samples from another device, and it will be enclosed (without access for at least 3 months). Because of that, it is not possible to perform the tests showed in the PXI4464 Calibration Procedure Manual. In this context, I need a system able to verify if the PXI4464 is operating well (without drifts, for example). 

One idea was to use a very precise pulse generator, in order to generate a signal that will be read by the PXI4464. Any divergence from the expected value could mean that the equipment is not operating properly.

Do you know any card from NI or another equipment that could be able to generate a very precisely voltage pulse signal? I was wondering how it is possible to check the quality of the measurements in the case that it is not possible to access the equipment.

Thanks folks.

[SamuRei]

Hey JJJJeb,

There are a couple things I think need to be considered here. 

I am all for skepticism of measurements and redundant checks, but adding in another card to the mix here to supply a voltage that will be checked may cause more problems than it solves. If we are worried about a card failing, adding another card that is *probably* just as likely to drift will introduce the possibility of false positive / negative alarms about measurement accuracy. This may be preferable in your case, I'm not sure.

Another idea here would be to have a second 4464 card in the mix, measuring the same input signal and comparing that to the input to the main card? This could reduce complexity and EMI considerations in your system that will be enclosed. Maybe a similar principle could be applied with a card whose calibration / accuracy is in the 90 day range, rather than the 30 day self cal window of the 4464.

Beyond this, suggestions for "what hardware do I need" are tough without specifics.

> What is a drift in accuracy that actually matters to your application?

> Are you willing and able to calibrate right before the device is sent off?

> Is this 3 month enclosure located in extreme temperature, altitude, or humidity?

> You mentioned a pulse generator, are there specifications beyond voltage level that are important? Frequency domain information?

Best,