Electronics > Metrology

3458A autozero on/off for uV measurements

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splin:
Has anyone seen or have a copy of this paper? I requested a copy but got no response.

https://www.researchgate.net/publication/224481276_Noise_investigation_of_a_high_precision_digital_multimeter_model_HP3457A_or_HP3458A_for_microvolt_level_dc_voltage_measurements


--- Quote ---Two setting states, auto-zero on (AZ-ON) and off (AZ-OFF) are tested and one important conclusion derived is that the state of AZ-OFF has a more extensive potential of performing to the full specifications for measurements of ?V level dc voltage than that of AZ-ON
--- End quote ---

With AZ off the measurement rate will be approximately twice that with AZ on thus reducing noise in the measurment by sqrt(2) - but AZ should remove a lot of the 1/f noise which I assumed would more than offset the lower sampling rate especially when measuring over very long periods (minutes).

Can anyone suggest why disabling AZ might improve uV measurments?

zlymex:
If someone let Usain Bolt to run 10,000 meters, no one will say it's good idea.

Same applies for 3458A that the 10V DC range with NPLC=100 is at its best.

What is the point of testing an 3458A on 0.1V range with NPLC=1?

acbern:
I think that the text implies AZ on results in worse results than AZ ON when doing low voltage measurements (such as e.g. using the meter as a null-meter for voltage comparisions in a bridge). That would be unexpected. NPLCs is a different storry. Seems the text is available for 30usd download or 4usd rent (haven't tried yet).

Dr. Frank:
If somebody has a university library account, it's accessible for free..

zlymex:
I got the file. If anyone interested, drop me a message with e-mail.

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