Agilent Technologies HP 8642A/B Especificações descarregar pdf (Página 266)

VCO CONSTANT: This is the VCO Tuning Constant the system used for

the measurement. The accuracy of the Tuning Constant determines the

accuracy of the PLL noise measurement for offset frequencies greater

than or equal to the phase lock loop bandwidth. The accuracy of the

Tuning Constant is verified if the PLL Suppression is Verified. The Tuning

Constant times the Voltage Tuning Range determines the Peak Tune Range

(PTR) value for the measurement. The PTR sets the drift tracking and

close-in noise suppression capabilities of the system.

Ignore Out Of Lock Mode

The Ignore Out Of Lock Test Mode enables all of the troubleshoot mode

functions, plus it causes the HP 3048A to not check for an out of lock

condition before or during a measurement. This allows you to measure

sources with high close-in noise that normally would cause an out of

lock condition and stop the measurement. When Ignore Out Of Lock is

selected, the user is responsible for monitoring phase lock. This can be

accomplished using an oscilloscope by connecting it to the HP 11848A

AUX. MONITOR port; verify the absence of a beatnote and monitor the

dc output level.

Considerations for the Test Mode Function

This Test Mode function, like all Special Functions, is considered an

Advanced Feature. Use of these features can change the outcome of the

measurement. It is sometimes left to the user to ensure measurement

validity when changes have been made within the Special Functions.

Remember:

• When Ignore Out Of Lock is selected, the system will not verify

the phase lock of the measurement. The user must ensure that the

measurement maintains phase lock during the measurement.

• Any changes entered into the 11848A Control screen can effect the

measurement results or even the ability of the system to complete the

measurement.

5-8 Test Mode

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Agilent Technologies HP 8642A/B Especificações Página 266