Freq - Agilent Technologies 3458A User Manual

FREQ

Syntax
max._input
%_resolution
Remarks
Frequency. Instructs the multimeter to measure the frequency of the input signal.
You must specify whether the input signal is AC voltage, AC+DC voltage, AC
current, or AC+DC current using the FSOURCE command.
FREQ [max._input][,%_resolution]
Selects a fixed range or the autorange mode. The ranges correspond to the type
of input signal specified in the FSOURCE command. That is, if ACV is the
specified input signal, the max._input parameter specifies an AC voltage
measurement range. To select a fixed range, you specify max._input as the
absolute value (no negative numbers) of the expected peak value of the input
signal. The multimeter then selects the proper range. Refer to the FUNC or
RANGE command for tables showing the ranges available for each type of input
signal.
To select the autorange mode, specify AUTO for max._input or default the
parameter. In the autorange mode, the multimeter samples the input signal before
each frequency reading and selects the proper range.
Power-on max._input = not applicable.
Default max._input = AUTO.
The %_resolution parameter specifies the digits of resolution and the gate time
as shown below (%_resolution also affects the reading rate, refer to the
Specifications in Appendix A for more information).
%_resolution
Parameter
.00001
.0001
.001
.01
.1
Power-on % _resolution = not applicable.
Default %_resolution = .00001
•
The reading rate is the longer of 1 period of the input signal, the gate time, or
the default reading timeout of 1.2 seconds.
•
Frequency (and period) measurements are made using the level detection
circuitry to determine when the input signal crosses a particular voltage on its
positive or negative slope. (This is why you cannot use the LEVEL trigger or
sample event or the LINE trigger event when making frequency or period
measurements.) The power-on or default level triggering values select zero
volts, positive slope. You can control the level triggering voltage and coupling
using the LEVEL command. You can specify either the positive or negative
slope using the SLOPE command.
Selects Digits of
Gate Time Resolution
1s 7
100ms 7
10ms 6
1ms 5
100µs 4
Chapter 6 Command Reference

FREQ

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