Settling Time Measurements of LO

Dear all,
We are going to measure the "Frequency Settling Time" of the local oscillator.
The following are test procedure we followed to configure LO:
Initially LO is configured to some X MHz frequency
Then we are configuring the LO frequency with X + 200KHz or X - 200KHz
Here we are going to measure the time taken from the LO will get unlocked to the existing output frequency (X MHz) and will be locked to the frequency of 200 KHz +or - the existing frequency.
The requirement for the settling time is <500usec
Please adivice which instrument we can use to measure the settling time?

I dont see the attachment. Trying again.
Sastry Vadlamani
RF and Communications Software R&D
National Instruments
Attachments:
PLL Tuning Time.llb ‏234 KB

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I dont see the attachment. Trying again.
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Attachments:
PLL Tuning Time.llb ‏234 KB

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Settling Time Measuremen​ts of LO

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Settling Time Measurements of LO