B
Electronic Calibration of the 3458A (Product Note 3458A-3)
118
Keysight 3458A Calibration Manual
Introduction
A voltmeter has four basic functional
blocks.
The input signal must first pass through some
type of signal conditioner. For a DC input
voltage, the signal conditioner may consist of an
attenuator for the higher voltage ranges and a
DC amplifier for the lower ranges. If the input
signal is an AC voltage, an RMS converter
changes the AC signal to an equivalent DC value.
By supplying a DC current, an ohms converter
changes resistance to a DC voltage. In nearly all
cases, the input signal conditioner converts the
unknown quantity to a DC voltage that is within
the range of the A-to-D converter.
The job of the A-to-D converter is to take a
pre-scaled DC voltage and convert it to digits.
A-to-D converters are single range DC voltage
devices. Some take a 1 V full-scale input while
others take a 10 V full-scale input. For this
reason, the signal conditioner must attenuate
higher voltages and amplify lower voltages to
give the voltmeter a selection of ranges.
Let's take an example. Suppose we apply 250 V
AC to a voltmeter with an A-to-D converter that
requires a 1 V DC input. The AC signal is
attenuated on the 1000 V AC range and
converted to a DC voltage equal to 0.25 V. The
final reading appears as “250.0 V AC.” (In
general, AC in the 3458A multimeter uses 2 V
full-scale.)
These first two building blocks govern the
voltmeter's basic characteristics such as its
number of digits, its ranges, and its sensitivity.
The A-to-D converter governs a voltmeter's
speed, resolution, and, in some cases, its ability
to reject noise.
The logic block manages the flow of information
and the correct sequence of various internal
functions. The logic also acts as a communicator
with the outside world. Specifically, the logic
manages the outward flow of digital information
and accepts programming instructions from
other devices. The display communicates visually
the result of a measurement. In selecting a
voltmeter to fill a specific application, these
building blocks combine to give the instrument
its specific performance characteristics.
Содержание 3458A
Страница 1: ...Keysight 3458A Multimeter Calibration Manual ...
Страница 10: ...10 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...
Страница 14: ...14 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...
Страница 16: ...16 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...
Страница 18: ...18 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...
Страница 39: ...Adjustment Procedures 3 Keysight 3458A Calibration Manual 39 Figure 3 1 4 terminal short ...
Страница 52: ...3 Adjustment Procedures 52 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...
Страница 59: ...Performance Verification Tests 4 Keysight 3458A Calibration Manual 59 Figure 4 1 General test procedure ...
Страница 109: ...Command Summary 5 Keysight 3458A Calibration Manual 109 Related commands ACAL CAL SECURE ...
Страница 116: ...A Specifications 116 Keysight 3458A Calibration Manual THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...