When To Specify Resolution - Agilent Technologies 3458A User Manual

When to Specify
Resolution
For analog AC measurements, if you default, the %_ resolution parameter,
the integration time will be that specified by the last NPLC command
executed.
For sampled ACV or ACDCV, random sampling (SETACV RNDM) has
a fixed resolution of 4.5 digits that cannot be changed. For synchronous
sampling (SETACV SYNC) a %_resolution parameter of 0.001 = 7.5 digits;
0.01 = 6.5 digits:
0. 1= 5.5 digits: and 1 = 4.5 digits.
For frequency and period measurements, %_ resolution specifies the gate
time and the digits of resolution as shown in Table 19. For example, the
following program specifies frequency measurements from a voltage input
using the 10V range. The %_resolution parameter in line 20 (.0000l) specifies
a gate time of 1 second and 7 digits of resolution.
10 OUTPUT 722; "FSOURCE ACV"
20 OUTPUT 722;"FREQ 10,.0000l"
30 END
If you default the %_resolution parameter for FREQ or PER measurements,
the multimeter sets %_resolution to .0000l which selects a gate time of 1
second and 7 digits of resolution.
Table 19: Frequency/Period Gate Time and Resolution
%_resolution
Parameter
.00001
.0001
.001
.01
.1
For analog ACV or ACDCV (SETACV ANA), ACI, and ACDCI
measurements, you should specify resolution when you need more
resolution than that provided by the NPLC command. For example, in the
following program, line 10 specifies 0.0001 PLC of integration time, which
selects 5½, digits of resolution resulting in an actual resolution of 100 µV on
the 10V range. However, for this application, 10 µV of resolution is required
with a max._input of 10V. The preceding equation produces a %_resolution
parameter of 0.0001 (1E-4) which is specified in line 30 (for this resolution,
a reading takes about 40 seconds).
10 OUTPUT 722;"NPLC .0001"
20 OUTPUT 722;"SETACV ANA"
30 OUTPUT 722;"ACV 10,1E-4"
40 END
For synchronous sampled ACV or ACDCV (SETACV SYNC), FREQ,
and PER measurements specifying resolution is the only way to change the
actual resolution. For these measurements, the integration time is fixed and
no interaction occurs between the NPLC command and the %_resolution
parameter. The multimeter achieves the specified resolution for sampled AC
voltage by varying the number of samples taken. (If you default the
%_resolution parameter, the multimeter sets the %_resolution to 0.01
Selects Gate
Time
1s 7
100ms 7
10ms 6
1ms 5
100µs 4
Chapter 3 Configuring for Measurements
Digits of
Resolution
69