Agilent Technologies 8719D, User Manual

Page: 282 / 673

Active Channel Keys
The analyzer has four channels for making measurements. Channels 1 and 2 are the primary
channels and channels 3 and 4 are the auxiliary channels. The primary channels can have
different stimulus values (see “Uncoupling Stimulus Values Between Primary Channels,” below)
but the auxiliary channels always have the same stimulus values as their primary channels.
That is, if channel 1 is set for a center frequency of 200 MHz and a span of 50 MHz, channel 3
will have the same stimulus values, This permanent stimulus coupling between primary and
auxiliary channels is:
Channel 1 = channel 3 (by stimulus)
Channel 2 = channel 4 (by stimulus)
This stimulus coupling between a primary channel and its auxiliary is reciprocal; if you change
a stimulus variable in an auxiliary channel, it immediately applies to its primary channel as
well.
Figure 6-3. Active Channel Keys
The and shown in Figure 6-3 allow you to make a channel “active.”
Once active, a channel can be independently of the other channels (except the
stimulus values of an auxiliary channel, see above). The front panel and are
used to a channel while it is active. All of the channel-specific functions that you
select apply to the active channel.
Primary channels 1 and 2 can be made active anytime by pressing
or
respectively. However, before you can activate auxiliary channel 3 or 4 through these keys,
you must do two things:
1. Perform or recall a full two-port calibration.
2. Enable the auxiliary channel through the menu.
Note The and keys retain a history of the last active channel. For
example, if channel 2 has been enabled after channel 3, you can go back to
channel 3 without pressing twice.
Auxiliary Channels and Calibration
A full two-port calibration must be active before an auxiliary channel can be enabled. The
calibration may be recalled from a previously saved instrument state or performed before
enabling an auxiliary channel. If recalled, you may need to modify some of the parameters
from the recalled instrument state in order to apply it to your particular device. The recalled
calibration must cover the range of the device to be tested. If a calibration is performed
while one or both auxiliary channels are enabled, the auxiliary channels will be disabled, then
enabled when the calibration is complete.
Application and Operation