Agilent Technologies 8935 Series Manual do Utilizador descarregar pdf (Página 115)

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’

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Agilent Technologies 8935 Series Manual do Utilizador Página 115