User`s manual

Chapter 6 115
Advanced Operations
Increasing Measurement Throughput
2. Autoranging
The autoranging functions continuously calculate and adjust gain to
provide the optimum instrument setup for each measurement. This
results in greater measurement accuracy but increases measurement
cycle time. The autoranging functions can be turned off to decrease the
measurement cycle time.
Time-to-first-reading after making new settings is usually much slower
than the repetitive reading rate once the first reading has been
returned. The main contributor to first-reading measurement time is
hardware autoranging. Hardware autoranging time can be eliminated
by first establishing the expected AF and RF signal levels into the Test
Set. With these signal levels present, the Test Set will autorange,
allowing the operator to determine the attenuation and gain settings of
the RF input attenuator as displayed in the RF ANALYZER screen, and
to determine the various IF and audio gains as displayed in the AF
ANALYZER screen. The attenuation and gain settings determined in
manual mode should be recorded for use in writing the program.
In the control program, select Gain Control, Hold (default is Auto), and
make the settings recorded in manual mode. When the control program
runs, the signal levels into the Test Set need to remain relatively
constant since autoranging has been disabled.
If the automatic functions are turned off, the control program must set
the gain stages before triggering a measurement. The automatic
functions can be turned off as follows:
Disable RF autoranging by setting the Input Atten field to Hold using
the following command:
Example 6-1 Example
:RFAN:ATT:MODE ’HOLD’
Disable AF autoranging by setting the Gain Cntl field to Hold using
the following command:
Example 6-2 Example
:AFAN:RANG ’HOLD’