Keysight NFA Series Performance Verification And Calibration Manual page 36

Test Descriptions
10 MHz Out Frequency Reference Accuracy
Step 13. Compare the Positive Frequency Change and Negative Frequency
Change values recorded in the Worksheet and record the largest value in
the Worksheet as the Maximum Frequency Change.
Step 14. Divide the Maximum Frequency Change by 2 (Maximum Frequency
Change/2) and record the result as the settability in the Worksheet.
Step 15. Ensure that the calculated measurement figure given in the Worksheet
is within the published specification of ±5 Hz (±0.1 Hz for Option 1D5).
Step 16. Once verified that the value is within specifications, Counter Reading 1
with 0.1 Hz resolution is then taken as the actual frequency reference of
the Noise Frequency Analyzer and this reading is recorded on the Test
Record.
Step 17. Once verified that the value is within specifications, the measured
frequency is then recorded on the Test Record.
16 Chapter 2