Agilent Technologies 53220A, Руководство пользователя

Страница: 126 / 294

126 53220A/53230A User’s Guide
4 53220A/53230A Input Signal Conditioning
Input Coupling
The input to the 53220A/53230A counter is either DC (direct) coupled or AC
(capacitive) coupled, and is set using the the command:
INPut[{1|2}]:COUPling {AC|DC}
INPut[{1|2}]:COUPling?
(query form)
AC
coupling removes the signal’s DC content and centers the signal at 0V. The
measurable frequency range (channels 1 and 2) with AC coupling is:
• AC = 10 Hz - 350 MHz
• DC = 1 mHz - 350 MHz
DC
coupling extends the frequency range across the full bandwidth of the
instrument (1 mHz - 350 MHz).
CONFigure
and
MEASure
do not change the
coupling setting. Following a reset (
*RST
) or front panel preset (
Preset
), the
coupling is set to
Α
C
.
When selecting AC or DC coupling, the amplitude of the input signal must also
be considered. DC coupling is applicable for most measurements, especially
those requiring a specific trigger level. Rather than reducing the signal ampli-
tude by changing the counter range, AC coupling can be used to bring the sig-
nal in contact with the hysteresis window defined by the trigger level. This is
represented in Figure 4-2 (also see ‘Threshold Level and Sensitivity’).
DC AC
10 Hz
1 mHz