Model
8901B
Operation
Leaving
Trigger
Hold.
The instrument leaves Trigger Hold mode when
it
receives a trigger until
the measurement
is
complete. The Modulation Analyzer also leaves Trigger Hold when
it
receives:
a. the F’ree Run code
(TO),
or
b.
when
it
is
returned
to
local operation,
c. a Device Clear Message (DCL
or
SDC),
or
d.
Instrument Preset
(IP).
TRIGGERS (T2, T3, GET,
and
the
CLEAR
Key)
All triggers are available in both Free Run and Trigger Hold modes, but
after
a
trigger is received
(except the CLEAR key), the instrument enters Trigger Hold mode.
Trigger Immediate
(12).
When the Modulation Analyzer receives the Trigger Immediate code,
it
makes one measurement and displays the result without a settling time delay.
Measurement results obtained via Trigger Immediate are normally valid only when the instrument
is
in a steady, settled state. The first result received from the instrument (using T2) may not be accurate.
Trigger With Settling (T3)
NOTE
The use of Digger With Settling does not remove the need to
observe the normal warm-up precautions when using either the RF
Power, AM,
or
FM Calibrator. Refer to the procedures “RF Power
Calibration”, “AM Calibration”,
or
“FM Calibration” in the
Detailed
Operating Instructions.
0
If the settling time provided with
T3
is
not adequate
to
produce
accurate measurements, use TO (Free-run) and write a sub-program
which compares measurement values until they are within a specified
tolerance. (Delays, not included in the T3 settling time, in the source
and/or the thermocouple in the Power Sensor can prevent accurate
measurements.)
Trigger With Settling is identical to Trigger Immediate except the Modulation Analyzer inserts a
settling-time delay before taking the requested measurement.
Group Execute Trigger
(GET)
Message
When in remote and addressed to listen, the Modulation
Analyzer responds to a Trigger message (GET) by executing a settled-measurement cycle. The
Modulation Analyzer responds exactly as
if
it
had received the program code T3 (Trigger With Settling).
Triggering Measurements With the CLEAR Key (CL)
When the Modulation Analyzer
is
in Trigger
Hold mode
(Tl)
and not in Local Lockout, the front-panel CLEAR key may be used to issue a
Trigger With Settling. Each time the CLEAR key is pressed, the Modulation Analyzer performs a
settled-measurement cycle. The CLEAR key will not cause the instrument to enter Trigger Hold mode.
In Free Run mode the CLEAR key will clear the display, but not affect the timing
of
measurements
and will not cause the instrument to enter Trigger Hold.
3-23
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