Tektronix PSM3000 Series, Руководство пользователя

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Power Meter Application
Minimum Loss Pad The instrument has a 50 Ω input impedance. However, for applications requiring
a 75 Ω input impedance, you may attach a 75 Ω minimum loss pad (MLP) to the
input. You can correct for the pad by selecting 75 ohm MLP from the Offsets &
Response menu. The instrument will adjust its measurements accordingly and
the display will indicate “75ohm-MLP”, if selected.
Menu (Triggering) This button calls the Triggering setup menu. From here you can set triggering to
internal or external continuous, and internal or external single. You can also set
the TTL trigger in/out, inverted trigger, and trigger timeout.
NOTE.
When the trigger timeout is set to long and triggers occur slowly, the
Power Meter interface will respond slowly to mouse clicks.
Trigger In.
The external trigger input is assumed to be a TTL level and positive
edge trigger. Trigger in can be enabled, disabled, or inverted. After the trigger
is detected, the measurement will commence and will continue for the speci
fi ed
number of averages. In External Single mode, the system will wait for you to
click the Single button and then it will monitor the trigger in port. If a trigger is
not detected in the allotted time, the system will time out and return an
ext trig?
indicator.
When the trigger in is inverted, the system will look for a negative edge (instead
of a positive edge) and begin the measurement when a negative edge is detected.
You can set a trigger timeout period for an external trigger input, up to 30 seconds.
Trigger Out.
The trigger output is compatible with TTL levels. It can be enabled,
disabled, and inverted. A trigger out pulse occurs at the beginning of each
measurement. Even if the external trigger is disabled and trigger out is enabled, a
trigger will be produced each time a measurement is made.
By default, the trigger output is normally low. The start of the trigger is indicated
by a rising edge on the output. The output stays at a TTL high level for a few
microseconds and then returns to a low level. If the trigger out is inverted, it will
transition from a high to a low TTL level to indicate when a trigger has occurred.
NOTE.
When multiple Power Meter instances are running, the absence of a
trigger in one instance of the Power Meter application will cause other instances
to update at a slower rate or even time out. This would occur, for example, if an
instrument lost its external trigger source.
Single
Enable this button from the Triggering drop down menu by selecting internal or
external single triggering. Click the button to initiate a single measurement.
24 RF and Microwave Power Sensors/Meters