88 Keysight Infiniium MXR-Series Real-Time Oscilloscopes User's Guide
6 Testing Performance
Procedure 1 Make sure the 10 MHz OCXO has been powered on for at least 2 hours,
preferably longer if possible.
2 Configure the E8257D sine wave source to output a 0 dBm (633 mVpp) sine
wave into 50 ohms with a frequency of 10.00002000 MHz. Note: Make sure the
E8257D is locked to the GPS or equivalent reference. The EXT REF indicator on the
E8257D will be on when locked.
3 Click Control > Factory Default on the oscilloscope.
4 Set the vertical scale of channel 1 to 100 mV/div.
5 Set the oscilloscope sampling rate to 100 kSa/s (Setup > Acquisition...). (The
resulting measurement will be aliased.)
6 Set the horizontal scale of the oscilloscope to 20 ms/div.
7 Set the measurement thresholds for all waveforms to a fixed voltage level of 0 V
and ±20 mV hysteresis:
a Click Measure > Thresholds....
b Select Custom: level +/- hysteresis from the Thresholds drop-down list box.
c Enter 20 mV in the Hysteresis field and 0 V in the Threshold Level field.
8 Enable a frequency measurement on channel 1.
9 On the oscilloscope, press [Stop].
10 Press [Clear Display].
11 Press [Run], wait until 10 acquisitions have accumulated, and then press [Stop].
12 Convert the average frequency value to time scale error by subtracting 20 Hz
and dividing by 0.01 Hz/ppb. Record the result in the Measured Time Scale
Error (ppb) column of Table 12 of the Performance Test Record.
13 Record the time since the previous calibration (in years) in the table. Click
Utilities > Calibration... to find the most recent Time Scale calibration.
14 Calculate the specification for Time Scale Accuracy based on the oscilloscope's
last time scale calibration using the following formula:
TSA = ±(8 ppb + 75 ppb(years since last time scale calibration))
15 Compare the measured time scale error to the TSA specification.
16 Record the results in Table 12.
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