Atek HP 8753D, User Manual, Page: 82 / 677

3. T o activate a marker to measure the group delay at a particular frequency , press:
4 MARKER 5 and turn the front panel knob or enter a value from the front panel keypad.
Figure 2-32. Group Delay Example Measurement
Group delay measurements may require a specic aperture (1f) or frequency spacing between
measurement points . The phase shift between two adjacent frequency points must be less than
180 , otherwise incorrect group delay information may result.
4. T o vary the eective group delay aperture from minimum aperture (no smoothing) to
approximately 1% of the frequency span, press: 4 A VG 5
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
SMOOTHING ON .
When you increase the aperture , the analyzer removes ne grain variations from the
response . It is critical that you specify the group delay aperture when you compare group
delay measurements .
Figure 2-33. Group Delay Example Measurement with Smoothing
2-34 Making Measurements