Internet-assisted, on-site special test performed by NIST. (News Briefs).

Staff at NIST have completed the first Internet-assisted, on-site special test of an electronic instrument. The test was performed for the Sandia National Laboratories (SNL) and the instrument under test was a multifunction calibrator used to test the five electrical functions available on most digital multimeters (DMMs). The reference at NIST was a similar calibrator, which has been calibrated using basic NIST electrical standard artifacts. This type of artifact calibration is also used at many industrial standards laboratories; however, even with automation, it takes a skilled metrologist about 1 week to perform the tests. The objective of the new service is to relieve NIST customers of this burden by performing an on-site test of their calibrators using a precision DMM, calibrated by a NIST reference calibrator, as a traveling standard. The DMM and the calibrators are fully programmable, and the control software used to calibrate them implements a specific test procedure for each instrument. For the on-sit e test to be effective, it is critical that the same test procedures are employed at both laboratories. While the concept of this type of remote calibration was proved last year, this is the first instance of an official report being issued.

As a first step, an Internet-based video conference was established between NIST and SNL. SNL metrologists described their test procedures and equipment, including the calibrator under test and the proposed traveling standard. NIST staff described the recommended test procedures and the NIST-developed control software, which had been sent electronically to SNL. The traveling DMM was then tested using both SNL and NIST control software to ensure compatible procedures. After several discrepancies were resolved, the traveling DMM was sent to NIST where it was tested and returned to SNL for follow-up tests.

The uncertainties of the on-site measurement were typically five times better than the calibrator specifications, proving the effectiveness of supporting these instruments in the field. Collaboration with SNL is underway to further improve uncertainties and to simplify the measurement process.

CONTACTS: Barry Bell, [phone]; [e-mail].